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Evaluation of Four Low-Chill Peach (Prunus persica L. Batsch) Cultivars in Three Climatic Zones in Florida

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 Title Page
 Dedication
 Acknowledgement
 Table of Contents
 List of Tables
 List of Figures
 Abstract
 Literature review
 Materials and methods
 Evaluation of vegetative and flower...
 Fruit quality and yield of four...
 Conclusions
 References
 Biographical sketch
 

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EVALUATION OF FOUR LOW-CHILL PEACH ( Prunus persica L. Batsch) CULTIVARS IN THREE CLIMATIC ZONES IN FLORIDA By TODD WALTER WERT A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2006

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Copyright 2006 by Todd Walter Wert

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This thesis is dedicated to my parents Ke rmit and Irene Wert and to my brother Terry Wert for the love and support they have given me.

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iv ACKNOWLEDGMENTS I would first like to thank my parents Ke rmit and Irene Wert and my brother Terry Wert for all the love, support, and encouragement they have given me. I would also like to thank all of my friends dow n here and at home for their support through thick and thin, good and bad. For the immense amount of help they have provided me throughout this process, I am indebted to my committ ee members, Dr. Jeffery Williamson, Dr. Jose Chaparro, and Dr. Robert Rouse. For their help and support, a most sincere thank you goes to Paul and Donna Miller ; without their help I do not think this would have been possible. I would also like to thank my harvesting crew fo r helping me pick and process endless quantities of peaches. I thank all the people in Fi field Hall who took peaches off of my hands when I needed to get rid of them.

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v TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iv LIST OF TABLES.............................................................................................................ix LIST OF FIGURES...........................................................................................................xi ABSTRACT.....................................................................................................................xiii CHAPTER 1 LITERATURE REVIEW.............................................................................................1 General Information......................................................................................................1 History and Importation................................................................................................3 Low-Chill Peach Market...............................................................................................4 Temperature Effects on Other Fruits............................................................................6 Red Skin Color and Anthocyanin Concentration..................................................7 Titratable Acidity and Soluble Solids..................................................................10 Fruit Development Period (FDP)........................................................................11 Fruit Size, Yield, and Shape................................................................................13 Floral Development.............................................................................................15 Other Aspects of Development...........................................................................16 Climate and Temperature and Their Effect on Peaches.............................................17 Endodormancy, Chilling, and Bloom..................................................................18 Fruit Development Period (FDP) and Fruit Size.................................................20 Fruit Shape...........................................................................................................21 Yield....................................................................................................................22 Post Harvest Quality Characteristics...................................................................22 Blind Nodes.........................................................................................................23 Other Aspects......................................................................................................23 Factors Other Than Temperature That Affect Fruit Quality......................................24 Thinning..............................................................................................................24 Canopy Position...................................................................................................24 High Nitrogen......................................................................................................25 Light....................................................................................................................26 2 MATERIALS AND METHODS...............................................................................27 Locations.....................................................................................................................27

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vi Cultural Practices........................................................................................................27 Frost Protection and Pruning...............................................................................27 Irrigation..............................................................................................................28 Weed Control.......................................................................................................28 Fertilization..........................................................................................................28 Temperature.........................................................................................................29 Disease Control...................................................................................................29 Measurements.............................................................................................................30 Shoot Measurements...........................................................................................30 Trunk Measurements...........................................................................................31 Bloom and Flower Counts...................................................................................31 Fruit Set Measurements and Thinning................................................................31 Harvest........................................................................................................................32 Total Yield...........................................................................................................32 Fruit Size, Weight, and Blush..............................................................................33 Chromicity...........................................................................................................33 Blossom End........................................................................................................34 Firmness, Soluble Solids Concentr ation, Titratable Acidity, and pH.................34 Statistical Analysis......................................................................................................35 3 EVALUATION OF VEGETATIVE AND FLOWER BUD DEVELOPMENT, AND FRUITING OF FOUR DIFFER ENT CULTIVARS OF LOW-CHILL PEACH.......................................................................................................................36 Introduction.................................................................................................................36 Materials and Methods...............................................................................................37 Locations.............................................................................................................37 Cultural Practices.................................................................................................38 Temperature.........................................................................................................39 Bud Data Collection............................................................................................39 Bloom..................................................................................................................39 Node Characterization and Bud Density.............................................................40 Statistical Analysis..............................................................................................40 Results........................................................................................................................ .40 Chilling and Bloom.............................................................................................40 Bud Percentage....................................................................................................42 Nodes with only vegetative buds.................................................................42 Nodes with vegetative and flower buds.......................................................42 Nodes with only flower buds.......................................................................43 Blind nodes...................................................................................................43 Buds per Node.....................................................................................................44 Vegetative buds............................................................................................44 Flower buds..................................................................................................44 Flowers.........................................................................................................45 Bud Density.........................................................................................................45 Vegetative buds............................................................................................45 Flower buds..................................................................................................46

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vii Flowers.........................................................................................................46 Fruit..............................................................................................................47 Blind nodes...................................................................................................47 Nodes............................................................................................................48 Discussion...................................................................................................................48 Chilling and Bloom.............................................................................................48 Percentage of Vegetative, Floral, and Blind Nodes............................................50 Number of Buds per Node and Bud Density.......................................................53 General Conclusions............................................................................................54 4 FRUIT QUALITY AND YIELD OF FOUR LOW-CHILL PEACH CULTIVARS GROWN IN THREE LOCATIONS...................................................66 Introduction.................................................................................................................66 Materials and Methods...............................................................................................67 Locations.............................................................................................................67 Cultural Practices.................................................................................................68 Fruit Development Period...................................................................................70 Harvest.................................................................................................................70 Total yield and weight..................................................................................70 Trunk measurements....................................................................................71 Fruit size, weight, and blush.........................................................................71 Chromicity values........................................................................................72 Blossom end.................................................................................................72 Firmness, soluble solids concentr ation, titratable acidity, and pH...............72 Statistical Analysis..............................................................................................73 Results........................................................................................................................ .73 Fruit Development Period...................................................................................73 Fruit Number, Weight, and Set............................................................................74 Fruit Blossom End...............................................................................................75 Post Harvest Quality............................................................................................76 Color....................................................................................................................78 Percent blush................................................................................................78 Colorimeter...................................................................................................79 Individual Fruit Weight.......................................................................................81 Fruit Size.............................................................................................................82 Discussion...................................................................................................................83 Fruit Development Period...................................................................................84 Fruit Size, Shape, and Yield................................................................................87 Color....................................................................................................................90 Fruit Quality........................................................................................................92 General Conclusions............................................................................................93 5 CONCLUSIONS......................................................................................................108

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viii LIST OF REFERENCES.................................................................................................112 BIOGRAPHICAL SKETCH...........................................................................................123

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ix LIST OF TABLES Table page 1 Mean date of full bloom for both 2004 and 2005 across three locations for four low-chill peach cultivars................................................................................56 2 Mean vegetative and flower buds per node for the 2004 season, for four lowchill peach cultivars within three different locations.............................................62 3 Mean vegetative and flower buds per node for the 2005 season, for four lowchill peach cultivars within three different locations.............................................62 4 Vegetative bud, flower bud, and blind node density for four low-chill peach cultivars for the 2004 season within three different locations...............................63 5 Vegetative bud and blind node density for four low-chill peach cultivars for the 2005 season within three different locations....................................................63 6 Flower bud and flower density for four low-chill peach cultivars for the 2005 season within three different locations..................................................................64 7 Main effects of fruit and node density for four low-chill pe ach cultivars, and three different locations, for the 2004 and 2005 seasons.......................................65 8 Bloom dates, harvest dates, and fru it development period (FDP) for four lowchill peach cultivars for the central and southwest locations for 2004..................95 9 Bloom dates, harvest dates, and fru it development period (FPD) for four lowchill peach cultivars for the north-central location for 2004..................................95 10 Bloom dates, harvest dates, and fru it development period (FPD) for four lowchill peach cultivars for the central and southwest locations for 2005..................96 11 Bloom dates, harvest dates, and fru it development period (FPD) for four lowchill peach cultivars for the north-central location for 2005..................................96 12 Main effects of percentage fruit set during 2005 and adjusted marketable number of fruit for both 2004 and 2005 for four low-chill peach cultivars and three locations........................................................................................................97

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x 13 Adjusted yield for 2004 and 2005 for four low-chill peach cultivars within three locations........................................................................................................98 14 Post harvest quality measurements fo r four low-chill peach cultivars during 2004, within the central and southwest locations, for measurements of TA, SSC, and Pressure................................................................................................100 15 Post harvest quality measurements fo r four low-chill peach cultivars during 2004, within the north-central location, fo r measurements of TA, SSC, and Pressure................................................................................................................100 16 Main effects for TA for four low-ch ill peach cultivars and three locations during 2005..........................................................................................................101 17 Post harvest quality measurements fo r four low-chill peach cultivars during 2005, within the central and southwest lo cations, for measurements of SSC, Ratio, and Pressure...............................................................................................101 18 Post harvest quality measurements fo r four low-chill peach cultivars during 2005, within the north-central location, fo r measurements of SSC, Ratio, and Pressure................................................................................................................102 19 Main effects for the ratio of SSC:TA for four low-chill peach cultivars and three locations during 2004..................................................................................102 20 Fruit blush, weight, and dimension m easurements for four low-chill peach cultivars during 2004 within the central and southwest locations.......................103 21 Fruit blush, weight, and dimension m easurements for four low-chill peach cultivars during 2004 within th e north-central location.......................................103 22 Fruit blush, weight, cheek diameter, a nd suture diameter measurements for four low-chill peach cultivars during 2005 within the centr al and southwest locations...............................................................................................................104 23 Fruit blush, weight, cheek diameter, a nd suture diameter measurements for four low-chill peach cultivars during 2005 within the north-central location.....104 24 Main effects for fruit length for four low-chill peach cultivars and for three locations during 2005...........................................................................................105 25 Colorimeter measurement values for the 2005 harvest season for both the most blushed and least blushed location on each fruit, for L*,C*h* values at three different locations for f our low-chill peach cultivars.................................106

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xi LIST OF FIGURES Figure page 1 Total chill unit accumulation for hours below 7.2 C among locations for the 2004 and 2005 seasons for four low-chill peach cultivars from early November to January 31 for each year..................................................................55 2 Main effects for the percentage of nodes with only vegetative buds during 2004 for four low-chill peach cultivars..................................................................57 3 Main effects for the percentage of nodes with only vegetative buds during 2004 for three locations.........................................................................................57 4 Main effects for the percentage of nodes with only vegetative buds during 2005 for four low-chill peach cultivars..................................................................58 5 Main effects for the percentage of nodes with only vegetative buds during 2005 for three locations.........................................................................................58 6 Percentage of nodes with both vegeta tive and flower buds for four low-chill peach cultivars during the 2004 season within three locations..............................59 7 Percentage of nodes with both vegeta tive and flower buds for four low-chill peach cultivars during the 2005 season within three locations..............................59 8 Main effects for the percentage of nodes with only flower buds during 2005 for four low-chill peach cultivars...........................................................................60 9 Main effects for the percentage of nodes with only floral buds during 2005 between two locations............................................................................................60 10 Percentage of blind nodes for four lo w-chill peach cultiv ars during the 2004 season within three locations.................................................................................61 11 Percentage of blind nodes for four lo w-chill peach cultiv ars during the 2005 season within three locations.................................................................................61 12 Percentage of peach fruit with sunke n, flattened, and extended blossom ends within the North-central (NC), Central (C), and Southwest (SW) locations.........99

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xii 13 Hue and croma chart for the highest and lowest blushed locations on four low-chill peach cultivars at three locations in Florida.........................................107

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xiii Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science EVALUATION OF FOUR LOWCHILL PEACH ( Prunus persica L.Batsch ) CULITIVARS IN THREE CLIMATIC ZONES IN FLORIDA By Todd Walter Wert December 2006 Chair: Robert E. Rouse Cochair: Jeffrey G. Williamson Major Department: Horticultural Sciences Four low-chill peach cultivars (Flordaprince, Flordaglo, UFGold, and TropicBeauty) were grown in three different lo cations in Florida. These locations were in north-central, central, and southwest Florida. The eff ects of different climatic conditions were observed on vegetative and re productive growth, and on fruit quality and yield. Climate was observed to have an eff ect on the different cultivars within each location. TropicBeauty was observed to have greater fruit weight and size ; however, it also had longer fruit development period (FDP), lower blush, and higher amounts of blind nodes than other cultivars. UFGold had lowe r mean fruit weight a nd smaller fruit size, but had a higher SSC:TA ratio, higher yields, and set higher amounts of floral buds than other cultivars. Blush values were higher for Flordaprince than for the other cultivars. In several cultivars fruit weights were higher, and blush values were lower than previously reported.

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xiv Differences among the locations were observed for amounts of fruit blush, SSC:TA ratios, blind nodes, and blossom end ratings. Generally higher blush values and SSC:TA ratios were observed in southwest Flor ida along with fruit with more pronounced blossom ends. Higher amounts of blind nodes we re also observed in southwest Florida, and chilling accumulation was lowest at th is location. The le ngth of the FDP was influenced by mean temperature during fruit development at all three locations. A longer FDP was observed in north-central Florida wh ere temperatures were lowest, and a shorter FDP was observed in southwest Florid a where temperatures were highest. There was an accidental application of exce ss fertilizer at the north-central Florida location. Rates were at least 2.5 times greater at this loca tion. This higher rate of nitrogen may have affected fruit quality and development. Mean blush values were lower, fruit weights were higher, SSC valu es were lower, and the SSC:TA ratio was lower compared to the other two locations. Fruit yield adjusted fo r trunk cross-sectional area (TCA) was also higher in north-central Florida compar ed to the other locations. It could be recommended that cultivars which exhibit large numbers of blind nodes and greater percentage of fru it with extended tips be grown in locations further north. Cultivars that do not have these problems should be planted further south to acquire the higher blush values and SSC:TA ratios that are preferred in the market provided their chilling requirement is met. Through the higher nitrogen rates applied at the northcentral location it could be concluded that current reco mmendations for amounts of nitrogen fertilizer are too low for production in Florida and rates probably need to be increased. Further research needs to be done in nitrogen rates in peach to determine the optimum amount needed to increase fruit size an d yield without sacrificing fruit quality.

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1 CHAPTER 1 LITERATURE REVIEW General Information The peach is classified as a member of the genus Prunus and a member of the species persica Other common members of the Prunus genus include Japanese plum ( Prunus salicina ), European plum ( Prunus domestica ), nectarine ( Prunus persica ), apricot ( Prunus armeniaca ), almond ( Prunus dulcis ), sour cherry ( Prunus cerasus ), and sweet cherry ( Prunus avium ). The peach was first classified by Carolus Linneaeus in 1753; the present name of Prunus persica was given to the peach by August Johann Georg Batsch in 1801 (Faust and Timon, 1995) and has been used since. The peach fruit has a double sigmoid growth curve, with three distinct stages of growth (Connors, 1919). The first stage occurs after bloom and lasts un til initiation of pit hardening. Rapid fruit growth occurs during th is stage and it is generally associated with cell division (Addoms et al., 1930; Ragland, 193 4). The beginning of pit hardening starts the second stage of growth, or lag phase, in wh ich the diameter of the fruit increases very little but dry weight of the fruit increases due to endocar p lingification (Tukey, 1933). This stage has also been associated with a rapid increase in th e development of the embryo (Tukey, 1933). Once pit hardening is co mplete the third stage of growth occurs in which a rapid increase in fruit diameter con tinues until harvest. This stage is generally associated with cell expansion (Ragland 1934). There are many types and combinations of types of peaches grown today. There are fruits that can have yellow, white, or re d flesh, with yellow being the most common.

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2 Fruits can have either melting or nonmelti ng flesh, the difference being the amount of endo-polygalacturonase enzyme between the ty pes. Nonmelting flesh peaches contain very low levels of endo-polyglacturonase, and the flesh remains firm (Pressey and Avants, 1978). Melting flesh peaches have normal levels of endo-polygalacturonase, allowing the flesh to soften and melt from the pit. The nonmelting trait is particularly useful for processing. Melting flesh type s tend to fall apart du ring processing, while nonmelting flesh peaches maintain their integrity and stay firm. The majority of cultivars on the market are generally round, though ther e are peaches which are flat, these are called Peento peaches and are usually named in the market as saucer peaches. The adherence of the pit or stone to the flesh is cl assified as clingstone or freestone. The pit of a freestone peach is easily removed from the flesh, with little or no flesh adhering to the pit, once the peach becomes soft ripe; for the clingstone peach it is not possible to cleanly separate the pit from the adjoining flesh. There are types which fall between the two; these are called either semifree or se micling, again depending on adhesion of the flesh to the pit at the soft ripe stage. Peach es can also be classified as to the amount of acidity at harvest. Low acid types are ge nerally called honey peaches; these peaches generally have a high amount of sugar and, as the name implies, low amounts of acid. High acid types are, as the name implies, hi gher in acid. The higher acid cultivars are generally found in the U.S. market and low acid types are preferred by the Asian market (Byrne et al., 2000). The nectarine is a peach without fuzz. A single gene is the difference between the two, but this gene affects severa l different characteristics (Byr ne et al., 2000). Nectarines are generally smaller, rounder, redder, higher brix, have a higher acid content, and are

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3 denser (Byrne et al., 2000). Nectarines and peach can be prone to a condition called skin speckles or sugar speckles. Skin speckles ha ve been shown to vary with the amount of sugar within the flesh of the nectarine or peach (Topp and Sherman, 2000; Wu et al., 2003). Generally, nectarines are two brix units higher than peaches. The higher brix in nectarines makes them more prone to skin sp eckles. Skin speckles appear as rough spots lacking pigment on the cheeks and tip of the fruit (Topp and Sherman, 2000). Skin speckling has been associated with increased transpiration rates in the parts which contained the speckles (Wu et al., 2003). History and Importation The generic name of Prunus is Latin for Plum (Faust and Timmon, 1995). The Romans acquired the peach from Persia, so it was thought the origin of the peach was from there (Faust and Timmon, 1995); hence it was given the specific name persica It is now thought that the cultivated peach is na tive to China (Yu-lin, 1985). The peach probably made its way to Persia, from China, in the first or second century B.C., by way of caravans (Faust and Timmon, 1995). It wa s not long after the importation of the peach to Persia that Romans acquired it; from ther e it spread throughout Europe. During the Spanish conquest of the Americas, the Span iards brought the peach to Mexico, and also introduced it into what is now the state of Florida. From Mexico the peach spread into what are now the states of New Mexico, Ca lifornia, and Arizona (Faust and Timmon, 1995). Importation into Florida was about 1565 in the area around Saint Augustine. From the importation into Florida it spread Nort h and West to what ar e now the states of Louisiana, Arkansas, Georgia, the Carolin as, New Jersey and New York during the 1600s, 1700s, and 1800s (Faust and Timmon, 1995).

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4 During the mid 1800s there were a few dir ect imports from China to the U.S. These peaches were commonly given the name of Chinese Cling (Faust and Timmon, 1995). It is believed that one of these Chin ese Cling peaches may have been pollinated by an Early Crawford peach tree to give rise to the modern American peach genotypes Elberta and Georgia Be lle (Faust and Timmon, 1995). Three importations of peaches with low-chil l genes from South Asia came into the United States during the mid 20th century, and have been used extensively in the University of Florida peach breeding progr am. One group was imported into Charleston, South Carolina; the second group was importe d into Hawaii (Hawaiian group); and the third group was imported as seed from Okinawa (Sherman and Lyrene, 2003). Low-Chill Peach Market The low-chill peach in the state of Fl orida fills a market window that would otherwise be devoid of peaches. The time pe riod between April and May has relatively few peaches in the market. During this time period importations from the southern hemisphere have declined, and domestic peaches have not matured. The early blooming peaches with short fruit development peri ods (FDP) developed by the University of Florida peach breeding program could fill th is market window. There is a negative correlation between the temperature and th e length of the FDP (Topp and Sherman, 1989a). Therefore, cultivars planted in the southern portions of the state should ripen earlier than the same cultivars in the northern portions of the state. Rouse and Sherman (2002a) demonstrated that cultivars which nor mally ripen in the Gainesville area of Florida around early to mid May ripened in mi d to late April in South Florida. This early-ripening germplasm could fill the April to May market window keeping a constant

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5 flow of peaches in the market between the e nd of importations and the start of domestic production in other sections of the country. Peaches have a large amount of variation for chilling requirement. A chilling unit as defined by Weinberger (1950a) is one hour at 45F (7.2C) or below. Peach cultivars are known that have chilling requirements vary ing from ~50 cu (Red Ceylon) to more than 1100 cu (Mayflower) (Okie, 1998). With in Florida, cultivars are classified as being low-chill (<300 cu), medium-chill (300 to 525 cu), or high-chill (>525 cu) (Williamson et al., 2005). Chilling requireme nt is essential to the survival and reproduction of peach trees. Dormancy preven ts the tree from growing during transient warm periods that are favorable for growth dur ing the winter when subsequent frosts and freezes could kill developing flower buds and cambium (Weinberger, 1950b). Once chilling is satisfied trees must acquire the ap propriate amount of heat units to initiate growth. As defined by Muoz et al. (1986, p. 520) a heat unit is the time needed for the completion of a developmental process wei ghted by the prevailing temperature above a base temperature. In this case we are talking about initiatio n of growth after endodormancy. Peaches with the lowest chilling generally flower first. Peach cultivars with a high chilling requiremen t from northern areas are not adapted to subtropical areas like Florida because they are not exposed to enough chilling to break endodormancy (Sherman and Lyrene, 2003). In the state of Florida, the chilling can va ry from 700 chill units in the western part of the panhandle to as few as 50 chill units or less in areas of the southern tip of the state. This means that cultivars with different chi lling requirements need to be developed to fill each of these climatic zones. The low-chill peach breeding program at the University of

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6 Florida was started by R.H. Sharpe in 1953. His goal for the program was to develop commercially acceptable peach and nectarine cu ltivars ripening in sequence from late April until early June for the 100 to 600 ch ill unit zones (Sherman and Rodriguez Alcazar, 1987, p. 1235). By commercially acceptable he meant that the peach cultivars had to be low-chill, have a FDP of 70 100 days, be firm, yellow-fleshed, and be of at least moderate size (Sharpe, 1961). Another criteriaon used in the Florida peach breeding program is a high amount of red over color or blush. This along with a bright yellow ground color is desired by U.S. consumers (Anderson and Sherman, 1994). The genes for low-chilling were obtained from the South Asian and Hawaiian peach germplasm mentioned previously. The peaches imported during the mid 1500s by the Spanish were not used in the University of Florida peach breeding program because they ripened too late in the season and were of moderate chilling. Temperature Effects on Other Fruits Temperature can have major effects on ma ny different aspects of the development of fruit crops. Of the various environmental factors, temperature can have the greatest effect on fruit growth (Correll i-Grappadelli and Lakso, 2004). It can affect the color as well as its perceived sweetness. Effects on fr uit shape and size have also been noted. Work done in Ireland on apple has shown th at the two environmental factors which seamed to be the most important in the gr owth of the fruit were sunlight and night temperature (Blanpied and Kennedy, 1967). Bu t temperature affects more than just quality parameters. There have been severa l reports on effects on floral buds and fruit development. Reductions in yields have also been reported. The problem with determining the effects of temperature on deve lopment of fruit and ot her aspects of tree

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7 development is that, it can be confused w ith rootstock and soil effects (Monselise and Goren, 1987). Red Skin Color and Anthocyanin Concentration Anthocyanins are a class of pigments re sponsible for the red coloration of some flowers and fruits. The six major groups of anthocyanidins are: pelargonidin, cyanidin, peonidin, delphinidin, petunidi n, and malvidin, with cyanid ins being the most common type of anthocyanin. Cyanidin glycosides ar e typically responsible for the scarlet reds, pelargonidin glycosides for orange-red colors, and delphini din glycosdes for bluish-red colors (Lancaster, 1992). Some of the most documented effects of temperature on growth and development have been in relation to the development of re d skin color and synthe sis of anthocyanins. Temperature can have a major effect on the synthesis of anthocyanin and subsequently fruit color. During the last month of fru it maturation, the red pigm entation in the skin, which is important for consumer acceptance in several different types of fruit, increases with cooler night temperatures rather than warmer night te mperatures (Sherman et al., 2003). There has been considerable work done in apples in relation to changes in skin coloration, concentration of anthocyanins in the apple peel, and the relationship between the two with temperature. Fruit maturity in apple orchards can be influenced by several factors including temperature and envi ronmental conditions during development (Warrington et al., 1999). Night temperatures coincide better with coloration than day temperatures (Uota, 1952). It was concl uded that the pigments responsible for the formation of anthocyanin are affected by temper atures during the late part of the growing season. Color development can be prompted by even a small number of cool night

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8 temperatures and warm sunny days (Curry, 1997). A similar result was found in which skin coloration was decreased by warm night temperatures (Blankenship, 1987). In contrast Arakawa (1991) observed that as temperatures increased during fruit development, the amount of anthocyanin increased as well. Similar re sults were obtained by Reay and Lancaster (2001) in Gala a nd Royal Gala apples where they observed that anthocyanin accumulation increased less at 10C than at 20C but only for early harvests. Alternating temperat ures have also shown to have an effect on skin coloration and anthocyanin accumulation. It was observe d in detached Granny Smith apples that alternating temperatures, at which there wa s a period of low temperature followed by a period of high temperature, favored the accumulation of anthocyanin (Reay, 1999). A similar effect was observed in Crisps Pink apple (Marais et al., 2001). But this is contrasted by Tromp (1999) who reports, temperature difference during the harvest period had little if any effect on the developm ent of Elstar and Coxs Orange Pippin skin color. Similar results were fo und by Fragher (1983) in ripe apples. Climate effects on skin color and anthoc yanin accumulation in apple have been reported by several other authors. It has been observed that when the prevailing weather conditions are cooler and moister, anthocya nin content in the skin can be higher at harvest (Igelesias et al., 2002). A similar re sult was found in which apples grown in a semi-arid, cool, and high irradiant climate favored the accumulation of anthocyanins more than if they were grown in a moist, warm, and low irradiant climate (Li et al., 2004). Different cultivars and strains of cultiv ars can have different reactions to temperature. Iglesias et al (1999) reported significant diffe rences among seven strains of

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9 Delicious apple for fruit coloration. When the seven strains were tested for three seasons, the apples achieved the highest coloration during the season where weather conditions were cooler and moister. Red pigmentation in the skin of different pear cultivars has be en observed to be affected by the passage of cold fronts during the end of fruit development (Steyn et al., 2004a). As with apples, cultivar difference s were observed. The cultivar Rosemarie developed better color while Bon Rouge had no response to temperature change (Steyn et al., 2004a). It was concluded that cold fronts passing through th e area during fruit development helped the development of red co loration in the pears. Other observations indicate an interaction of both the synthesi s and degradation of an thocyanin occurs at different temperatures, and this interaction determines the color of red pear fruit (Steyn et al., 2004b). One factor which c ould reduce the rate of anth ocyanin synthesis and hence final coloration of the organ could be substrat e limitation. If substrate limitation reduces the rate of anthocyanin synthesis than co loration of the organ would occur at lower temperatures (Steyn et al., 2004b). High temperatures can have a major e ffect on anthocyanin accumulation and subsequent coloration in grape skins. An thocyanin accumulation in Merlot grape was observed to be deterred by abnormally high te mperatures (Spayd et al., 2002). This confirms an earlier report by Kliewer (1970) using Cardinal grap es which showed a marked difference between those that ripene d at low verses high temperature. He reported that color formation in grapes was more uniform at lower temperatures. Varying effects have also been observe d in other fruits. Flesh and surface coloration of strawberries can be darker and redder when grown at warmer temperatures

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10 (Wang and Camp, 2000). Blackberry juice colo r increased when fruits were grown at lower temperatures (Naumann and Wittenbur g, 1980). A similar result was found in pomegranate (Shulman et al., 1984). For cra nberries, colorimeter r eadings of red color intensity were higher in cooler areas (Hall and Starke, 1972). Many reports have been published regardi ng the influence of both temperature and climate on fruit coloration a nd anthocyanin development. Conflicting reports abound in the literature, among fruits and cultivars. In apples alone, increased coloration has been observed at higher temperatures, lower temperat ures, and alternating temperatures. There appears to be no one single answer for the e ffect of temperature and climate on coloration in fruit. Titratable Acidity and Soluble Solids Soluble solids concentration (SSC) can be used as an estimate of sugar content. In addition to sugars, the com ponents that make up the SSC can include organic acids, amino acids, phenolic compounds, and soluble pectins (Mitcham et al., 1996). SSC is measured using a refractometer and is expr essed in terms of Brix or percent SSC. Titratable Acidity (TA) is a measure of th e amount of acid found within a commodity. An estimation of TA is ge nerally determined by taking a known volume of juice and titrating it to a pH of 8.2 (Mit cham et al., 1996). Depending on the fruit, TA is expressed as either the percent of malic, citric, or tartaric acid (Mit cham et al., 1996). The ratio between both the SSC and TA can give a good estimation of the perceived sweetness of an organ. For a given SSC value, fruit with lower TA are perceived as being sweeter and those with a higher TA are perceived as being tarter. Both TA and SSC can be affected by high and low temperatures. A reduction in TA at locations with higher temperatures ha s been observed for several different types of

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11 fruit. A decrease in TA has been observe d in strawberry (Wang and Camp, 2000), grape (Kliewer, 1968; Spayd et al., 2002), blackberry (Naumann and Wittenburg, 1980), and pomegranate (Shulman et al., 1984) at warmer temperatures. In citrus, juice sacks had lower levels of TA at harvest and higher TA levels during early fruit development for fruit grown at warmer temperat ures (Richardson et al., 1997). The SSC of the whole fruit of Satsuma ma ndarin was reported to be greater when grown at warmer temperatures (Richardson et al., 1997). A later arti cle reported that the increase in SSC was evident at early stages of citrus fruit development (Marsh et al., 1999). Both pomegranate (Shulman et al., 1984) and persimmon (M owat et al., 1997) had higher SSC in warmer regions compared to cooler regions. Similar results were observed in apple (W arington et al., 1999). Conversely Islam and Khan (2000), Ka no (2004), Nauman and Wittenburg (1980), Tromp (1999), and Tukey (1952) all reported higher fruit SSC as temperatures decreased for various fruits (tomatoes, watermelon, blackb erry, apple, and cherr y, respectively). An early report in tomato may explain why higher temperatures reduce SSC in some fruits. It was concluded that when night temperatures were low, tran slocation of sugar out of the leaves and into the fruit was hi gher, and that these sugars we re not being used for growth, thus fruit were sweeter (Went and Cosper, 1945). Fruit Development Period (FDP) The FDP is the period from the peak time of bloom to the peak harvest time. There are several factors which can affect the FD P. Included in this is the prevailing temperature in the area and the genetic tenden cies of the cultivar. Each cultivar has a characteristic FDP. Howeve r, this can be affected by the temperatures during fruit development. Tufts in (1929) observed three di fferent apricot orchards in California with

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12 cool, intermediate, and warm temperatures. He noticed that apricots of the same variety ripened earlier at the warmest site. The di fference was six to eight days between warm and intermediate sites, and two to three w eeks between the warm and cool sites (Tufts, 1929). Like peach, apricot and cherry, have double sigmoidal growth curves with three distinct stages of deve lopment. Any one of these stages can be affected by temperatures. Tukey (1952, p. 162) stated that warm temp eratures immediately following full bloom (during stage I) decrease the number of days until fruit maturity. However, warm temperatures late in the season (stage III) noticeably lengthen the number of days to maturity. A similar finding for apricot wa s also observed (Baker and Brooks, 1944). Another study in apricot in which a shelter was built around a limb, and heated at night to 20F above the outside ambient temperat ure; it was observed that the warmer temperatures within the shelter shortened th e first phase of fruit development by 22 days (Lilleland, 1936). Lilleland concluded that this decrease in the lengt h of the first growth phase of the apricot was in response to its environment, presumably the warmer night temperatures in the shelter. The length of the entire FDP decreased for fruits within the shelter compared to fruits outside of the shelte r. In another shelter containing a spur with only fruit the FDP was reduced by twenty eight days compared to fruit outside of the shelter. Lilleland (1936) concl uded that fruit growth can be affected independently from the rest of the tree by exposure of only fruits to fluctuations in temperature. Later Baker and Brooks (1944) reported that this reduction in the FDP is due to additional heat units early in the season. Stone fruit are not the only fruits which can be affected by warmer temperatures. Usually warmer temperatures reduce the numbe r of days to fruit maturity from full

PAGE 27

13 bloom, but it has been shown that this is no t always the case. Harvest began one month earlier for figs grown in warmer areas than fi gs grown in cooler areas (Botti et al., 2003). In grapes it was observed that higher temper atures during the day increased the number of degree days for ripening of Pinot noir fruits from veraison to fruit maturity, compared to lower day time temperatures (Kliewer and Torres, 1972). Cooler temperatures can also have an effect on ripeni ng of fruits. Prematur e ripening of Bartlet pears has been reported when temperatures we re cool one month pr ior to normal ripening (Wang et al., 1971). The FDP, of any fruit can be affected by several different thi ngs including bloom time, temperature during fruit development, and genetic influence. Stone fruit can be affected at all three stages of development. Increased temperature during the first stage of growth can shorten the FDP considerably, while during the third stage it can lengthen it. Higher temperatures during later developmental stages have also increased the FDP of other fruits such as grapes. Fruit Size, Yield, and Shape Several effects of temperature on fruit si ze (both weight and diameter) have been reported. Effects on fruit size can in turn have an effect on harvestable yield. Environment can influence severa l factors related to raspberry fruit size, including; ovule number and durpelet set and weight (Dale, 1986) Significant increase s in fig weight and diameter have been observed at warmer locatio ns (Botti et al., 2003). Sour cherry fruits that received a very high temperature trea tment, (25F above the average outdoor night temperature), had the smallest fruits comp ared to a medium (10F) and high (20F) temperatures treatments (Tukey, 1952). Reut her et al. (1969) found that citrus fruit grown in warmer areas generally were larg er than those in cooler areas. Warm

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14 springtime temperatures have also been reported to affect citrus fruit enlargement (Cooper et al., 1963). In a produc tion study for cranberry in five regions in the U.S. the number of days needed to accumulate 0.5 g of fresh mass was determined (DeMoranville et al., 1996). It was shown that in New Jers ey high temperatures limited growth of the fruit and that the opposite was true in Oregon and in Washi ngton where low temperatures limited fruit growth. Documented effects in yield of several commodities have been observed. In cranberry fruit yield was affected the most by temperature (Degaetano and Shulman, 1987). They found that temperatures above 32.2C during the time period when flowers were opening and during berry formation were detrimental to yields. Raspberry yield has been observed to be affected by the interacti on of cultivar and above ground temperatures (Prive et al., 1993). Citrus yields can be adversely affect ed by the maximum temperature during the time of June drop (Jones and Cree, 1965). Several reports have been published for different commodities concerning climatic and temperature effects on the shape of fru it. Higher temperatures generally produce rounder fruit and lower temperatures produce fr uit that are more el ongated (Sherman et al., 2003). Several studies on peppers have s hown that low night temperature can affect the shape of the developing fruits. More flattened pepper fruits have been observed at a lower night temperature of 12C verses fruit gr own at a temperature of 18C (Aloni et al., 1999). They also found that at the lower temp erature the fruits we re parthenocarpic. Both deformed fruits and parthenocarpic fruits were also observed at lower temperatures in an earlier study by Rylski and Spiglman (1982) who also worked with peppers. Seedless pepper fruits were again observed at lower temperatures and larger fruits at

PAGE 29

15 higher temperatures by Polwick and Sawheney (1985). Conversely, apple fruit shape was not directly affected by environment but was affected by the number of seeds per fruit (Tromp, 1990). Citrus fruit shape has been observed to be influenced by temperature. The condition of sheepnosing or ste m end tapering in gr apefruit is re ported to be an effect of low temperatures. In a controlled environment study by Wutscher (1976) where grapefruit plants were exposed to a fixe d day temperature and three different night temperatures, the lower the night temperatur es resulted in greater fruit elongation. Temperature effects have also been seen in Valencia oranges and ma ndarins. Fruit grown in warmer areas were rounder compared to t hose grown in cooler areas which were flatter (Nauer et al., 1974). Similar effects were al so reported for navel oranges (Nauer et al., 1972), and grapefruit and lemons (Nauer et al., 1975). Fruit size, yield, and shape can all be aff ected by temperature. In several reports fruit size was increased under warmer temper ature conditions. In contrast there are several reports where fruit size was reduced at warmer temperatures. Reduction in fruit size due to unfavorable temper atures during growth can lead to reduced yields. Lower temperatures have been shown to produce fl attened pepper fruits and sheepnosing in citrus fruits. Warmer temper atures have produced larger pe pper fruits and citrus fruits which were rounder. Floral Development Development of flowers and floral bu ds can be affected by the prevailing temperature in an area. In work with pers immon George et al. ( 1994) found that larger flowers were produced at lower temperatures Abnormalities in floral development at lower temperatures have also been repor ted in pepper. They include abnormal

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16 development of the petals, stamens, and gynoecia (Polwick and Sawhney, 1985). On the other hand, it has been found in some flow ers that increased temperatures promote flowering. Higher day temperatures promoted flowering of Elegance chrysanthemum, but higher night temperatures delayed fl owering (Cockshull et al.,1981). Winter temperatures in different areas can also play a role in the development of flower buds in blackberry. Continuous floral bud development occurred during the winter at sites that were above 2C (Oregon), but not at sites with winter temperatures below 2C (West Virginia and Arkansas) (Takeda et al., 2002). Bud failure in almonds is a genetic disorder which is passed on through vegetatively propagated material, and is in fluenced by high temperatures (Kester and Asay, 1978). It is similar to blind wood in peaches. Bud failure is due to higher temperatures during the previous summer (Kes ter and Asay, 1978). They state: that bud failure potential increased as one shifts from a low temperature location to a high temperature location, howeve r shifting from a high temperature location to a low temperature location did not decrease th e bud failure potential, but masked the symptoms. Other Aspects of Development There are many other aspects of plant development which can be affected by temperature and climate. It has been re ported in cranberry that bud formation and production of non-fruiting stems are favored by warmer temperatures (Degaetano and Shulman, 1987). Coagulation of soluble tannin s in persimmon fruit has been reported to occur throughout the fruit development period in warm climates verses twenty three weeks after full bloom in cool climates (Mow at et al., 1997). Temp eratures during fruit

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17 development have also been reported to eff ect the development of fruit translucency in pineapple (Chen and Paull, 2001). Increased temperatures have also been shown to affect the development of shoots and leaves. Apricot limbs which were placed in a heated shelter had more growth than those which were not in the shelter (Lillela nd, 1936). High night temperatures have been shown to affect the colorati on of sour cherry leaves, w ith leaves grown at warmer temperatures having less green color than at cooler temperatures (Tukey, 1952). Numerous reports have been documente d for temperature effects on citrus. Variations in peel thickness have been associ ated with variations in temperature and have been reported by several au thors (Cohen et al., 1972; Hilgeman, 1966; Iwasaki et al., 1986; and Young et al., 1969). Temper ature also affects peel colo r of citrus. Orange peel color in citrus is mainly due to the accumulati on of carotenoids in the peel. The effect of temperature on carotenoid accumulation in citrus peel was demonstrated in a controlled environment experiment by Young and Er ickson (1961). They found that 12C soil temperature, 7C night temperature and 20 C day temperature produced highly colored fruits. They also observed an increase in a ny one of these temperature parameters caused a reduction in the orange color of the peel. Similar results were obtained in Redblush grapefruit by Young et al. (1969). This was su bstantiated in the field by Reuther et al. (1969) when it was reported that when night temperatures were higher during the months of December to February, color development in the peel occurred at a slower rate. Climate and Temperature and Their Effect on Peaches Fruit color, size, shape, firmness, and tast e are some of the char acteristics which are most important in determining fruit value (Por ter et al., 1996). Effects of temperature on the development of different parts of the peach tree have been documented. Time of

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18 bloom, length of the FDP, fruit size, fruit shape, proportion of blind nodes, as well as other aspects of fruit and tree developm ent can be influenced by the prevailing temperatures in the localiti es where peaches are grown. Endodormancy, Chilling, and Bloom As stated earlier different cultivars of p eaches have different chilling requirements to release them from endodor mancy. This limits where certa in cultivars of peaches can be grown. Higher chill cultivars in the 700+ ra nge are more suited to traditional peach growing areas like central Georgia and South Ca rolina. When grown in areas like Florida where the winters are mild, these cultivars will not receive adequate chilling and will not flower. Low-chill cultivars which receive < 300 chill units (Williamson et al., 2005) are more suited to subtropical areas like Florida. A chill unit has been defined as one hour at 45F (7.2C) or below (Weinberger, 1950a). Ot her models have been developed in an attempt to obtain better estimates of chilli ng for different regions. Another model uses the amount of hours between 32F (0C) and 45F (7.2C), and the Utah model developed by Richardson et al. (1974) categorizes th e hours even more thoroughly. Richardson et al. (1974) proposed that one chill unit is accumulated when temperatures are 37F (2.5C) to 48F (9.1C), one half of a chill unit is accumulated when temperatures are 35F (1.5C) to 36F (2.4 C) or 49F (9.2C) to 54F (12.4C); below 34F (1.4C) no chill units are accumulated. They also proposed the idea of negative chill units or chilling negation, where between 61F (16C) and 65F (18C) a half of a unit is lost and at temperatures above 65F (18C) a whole chill unit is lost (Richardson et al., 1974). It has been re ported that a condition of sec ondary dormancy can be induced when temperatures are 20C or greater (Erez and Lavee, 1971). On the other hand Maxwell and Lyons (1969) did not find chi lling negation at temperatures above 70F

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19 (21.1C). They also observed that temperat ures of 50F (10C) can satisfy the cold requirement for peaches with South Asian parent age. Rest breaking ability has also been reported in temperatures above 45F by seve ral other authors (Erez and Lavee, 1971; Gurdian and Biggs, 1964). Another model re ported by Sherman et al. (1978) seems to give a good estimate of chilling in the south east U.S. Their mode l uses the number of hours below 7.2C during the coldest month in the winter season at a location, and this number is multiplied by 2.5. Other m odels have reported success using December/Janurary (Weinberger, 1956) and Janu rary (Sharpe, 1969) mean temperatures. If for some reason adequate amounts of ch illing are not accumulated in an area in the spring a condition called prolonged dormancy can occur. As defined by Weinberger (1950b, p. 129) prolonged dormancy of peaches is a condition in which leaf and flower buds are delayed beyond the usual time of opening in the spring, even though favorable growing temperatures occur. E ffects of prolonged dormancy are a delay in bloom, a period of bloom which is spread out several weeks, buds on the tips of shoots blooming long before those at the base of the shoot, vegetative buds breaking in the center of the tree first and then laterals, and in severe cases flower buds abscise before opening (Couvillon, 1995; Sherman et al., 2003; Weinberger, 1950b). Other problems with prolonged dormancy of peaches can include reduced fruit set and fruit that have a pronounced tip (Byrne and Bacon, 1992, Camp bell et al., 1995, Koffmann and Patten, 1992; Rouse and Sherman, 2002a; Rouse and Sh erman, 1989a). It has been suggested that the effect of temperature on the pr onounced tip is more attributed to higher temperatures during early development of the fruit rather than prolonged dormancy

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20 (Sherman and Rodriguez-Alcazar, 1994). Othe r problems with lack of chilling are that the fruit may have a greener ground color or reduced firmness (Byrne and Bacon, 1992). Bloom period can be affected by temp erature. Rouse and Sherman (1989a) reported that bloom in the area around the Lo wer Rio Grande Valley of Texas was earlier by 7 to 10 days as compared to Gainesville Florida. This area is warmer than Gainesville. Similar results were report ed by Topp and Sherman (1989a). Floral development can be affected adversely by high temperatures. Kozai et al. (2004) reported that flower development was s uppressed at temperatures above 25C. Fruit Development Period (FDP) and Fruit Size The FDP or period of time between peak bloom to peak harvest differs among cultivars. The FDP can be highly temperat ure dependent (Anderson and Sherman, 1994). Generally speaking peaches with a longer FDP us ually have larger fruit and peaches with a short FDP have smaller fruit. It is difficult to breed a large peach with a short FDP (Porter et al., 1996). The effect of temperat ure on the FDP of peach is cultivar specific and differs among the cultiv ars (Boonprakob et al., 1992). Night temperature can have a substantial effect on maturity of Early Redhaven peach (Batjer and Martin, 1965). During ea rly development, warmer temperatures accelerated fruit maturity and cooler temperatur es delayed it. It has also been reported that low temperatures followi ng bloom can prolong the FDP, th is was also observed to be cultivar specif ic (Blake, 1930). Topp and Sherman (1989a) observed that a decrease of 1C in the mean temperature during the growing season increased the FDP by 5 days. They also reported that temperatures two months following full bloom were the most important. Similar results were obtained by Boonpr akob et al. (1992) for 30 to 45 days after full bloom, and

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21 by Rouse and Sherman (1989a). The quickest time from bloom to harvest for peaches has been observed at a night temperature a bove 10C and day temperatures below 38C (Sherman et al., 2003). Since fruit size and the FDP are correlated there should be a reduction in fruit size in warmer locations verses cooler loca tions, which was also reported by Topp and Sherman (1989b) where they observed that a 1C increase in mean monthly FDP temperature caused a decrease in the diameter of the fruit by 0.7 mm. The date of the first commercial harvest at a location can be more variable than the date of full bloom, this is due to temperature fluctuations during fruit development (Topp and Sherman, 1989a). Fruit set is another component which can be affected by the prevailing temperatures in an area. Exposure of trees to several di fferent temperature regimes, for three weeks resulted in a complete reduction in fruit set at 21 29C (day/night) and a reduction in the FDP at 15 23C verses 12 20C (Erez et al., 2000). The accumulated temperatures during the FDP can be defined in terms of heat units. The growth during fruit development is dependent on the accumulati on of these heat units; the more units accumulated, the faster the growth (Sherman et al., 2003). As was reported earlier for sour cherri es (Tukey, 1952) and apricot (Baker and Brooks, 1944) that high temperatur e increased the FDP, an in crease of the FDP was also reported by Batjer and Martin (1965) for p eaches. Trees subjected to a 70F (21.1C) night temperature late in the season had a four day increase in FDP. Fruit Shape The stylar tip on the fruit can also be a ffected by temperature. It has genetic tendencies in some cultivars and can be more pronounced in some areas. Generally,

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22 more pronounced tips have been observed in wa rmer locations, and rounder tips in cooler locations (Topp and Sherman, 1989b; Salvador et al., 1998). Yield There are two main components which can determine fruit yield, the total number of fruit which are set and the final size of these fruit (Campbell et al., 1995). Fruit set can be affected by temperature duri ng early states of fruit develo pment right after bloom or at the time of bloom. Night temperature seems to be particularly important. Different cultivars can react differently to higher temper atures. Some low-chil l peach cultivars like Flordaprince and TropicBeau ty have a high tolerance to high night temperatures and have the ability to set a full crop almost every year, while other cultivars which are not heat tolerant can have little or no crop set (Rouse and Sherman, 2002b). The effect of temperature on fruit set can be very importa nt in areas where low-chill peaches are grown. It has been stated that stone fruits cant be grown in tropical areas because year round warm conditions can cause a reduction in fruit set (Diaz, 1992). This was shown by Kozai et al. (2004) where they reported that temperatures above 25C had a significant effect on set of Hakuho peach. Post Harvest Quality Characteristics The various post harvest quality character istics such as red blush, ground color, firmness, SSC, and TA, can all be affected by temperatures within a region or locality. One of the characteristics most affected is the degree of red blush. The red pigments comprising surface blush of peaches are composed of anthocyanins. More intense blush has been observed in the Lower Rio Grande Valley of Texas compared to Gainesville Florida for several cultivars of low-chill peaches (Rouse and Sherman, 1989a). This difference was attributed to the warmer prevailing temperatures in that area. On the other

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23 hand it has been reported that there is no correlation betwee n temperature and red blush (Topp and Sherman, 1989b). But Topp and Sherman (1989b) did find that firmness increased as temperatures incr eased. Greater surface blush co verage in warmer areas and lower TA in cooler areas has also b een observed by Salv ador et al. (1998). Blind Nodes A blind node as defined by Boonprakob a nd Byrne (1990) is the condition in which a node has no obvious vegetative or reprod uctive buds. It is generally associated with higher temperatures during bud formati on during the late summer months and is more prevalent in warmer peach producing areas verses cooler peach producing areas. Some cultivars of peach have a genetic tend ency for blind nodes and this condition is expressed in areas which have high temper atures during shoot growth (Sherman and Rodriguez-Alcazar, 1994). High daily temperatur es seem to favor the formation of blind nodes (Boonprakob and Byrne, 1990). In particul ar mean temperatures above 22C have been reported to favor high amounts of blind nodes (Boonprakob and Byrne, 2003) Other Aspects There are other aspects of development which can be altered by the prevailing temperature in a given area where peaches are grown. Peach pubescence can be longer for the same varieties when grown in areas wi th warmer temperatures during fruit growth compared to areas with cooler temperatures (Sherman et al., 2003). Another aspect of growth that can be affected by temperature is vegetative growth of the tree. Vegetative growth can be ten times higher for the lo w-chill versus the high-chill genotypes (Campbell et al., 1995). Since vegetative growth occurs durin g the same time that the fruit are maturing, excessive growth can shade out fruit and reduce coloration of the skin of the fruit in the interior portions of the canopy. Furthermore, more labor is required to

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24 prune vigorous trees, either during the summer or winter. Buds also have a tendency to be laid down closer to the terminals of the s hoots. If these buds are set higher up in the canopy prior to pruning because of excessi ve growth they may be pruned off. In some areas where the temperatures are high during the fall the trees do not defoliate as they normally would in cooler locat ions. When this occurs, zinc sulphate is sprayed on the trees to induce leaf fall (Diaz et al., 1986). Factors Other Than Temperature That Affect Fruit Quality There are factors other than temperature that can affect the quality of fruit. Levels of fertilizer, light intercepti on, thinning, and location of the fruit within the canopy can all affect the final size, color and flavor of the fruit. Thinning Fruit thinning generally takes place just prior to or at the beginning of the second stage of fruit growth referred to as pit hardening. It wa s reported by Tukey and Einset (1938) that fruit thinning early during stage one of growth resu lted in the largest size, best red color, and least reduction in yield compared to other treatments where, either no thinning was done, or thinning was done at othe r stages of growth. Wider spacing of the fruit on shoots resulted in larger fruit with greater SSC (Corelli-G rappadelli and Coston, 1991). Most likely this was due to reduced competition for assimilates among fruits. Forty leaves per fruit gave the best fruit si ze and quality in a leaf area study conducted by Weinberger (1931) in which the amount of leaf area in relation to the size of the fruits was observed. Canopy Position Location of the fruit within the canopy has an effect on various quality parameters. Significant differences in fruit weight, blush color, SSC, and firmness were all compared

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25 between the upper and lower portio ns of the canopy (Farina et al., 2005). Fruit from the upper portions were significantly larger, redd er, and had a higher SSC than those at the bottom of the canopy. Redder fruit were also reported in the upper canopy as compared to the lower canopy (Bible and Singha, 1993). Dry weight and SSC of fruits have also been shown to be higher in the upper por tions of the canopy (Dann and Jerie, 1988). High Nitrogen Several authors have shown that high leve ls of nitrogen can have an effect on both yield and color of fruit. Th e effect of nitrogen on yield has been reported by Shoemaker and Gammon (1963). They reported that the hi ghest yield was recorded with the highest nitrogen concentrati on and the lowest yield was record ed with the lowest nitrogen concentration. They also reported that the tr ees which received the highest nitrogen level had the highest amounts of red color, they c oncluded that this wa s from the increased crop load opening up the tree to more light. Similar results were observed by Saenz et al. (1997), who also reported larger fruit. Hi gh nitrogen treatments have been shown to decrease Brix, increase TA, decrease ant hocyanin, and increase green ground color (Jia et al., 1999). They also reported in sensor y tests that fruit from the high nitrogen treatment were rated as being, sour, bitter and astringent. Greener fruit with higher nitrogen rates were observed by Meheriuk et al. (1995). They also reported that the increased nitrogen rates did not increase fruit weight or re d blush. Increased rates of nitrogen fertilization can increase the FDP of the peach. Trees with higher nitrogen rates had a 7 to 12 day delay in harvest (Saenz et al., 1997). This confir ms an earlier report that on average a 6.5 day increase in FDP wa s observed with a heavy application of nitrogen (Blake, 1930).

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26 Light The amount of light which the fruit recei ves can have a pronounced effect on the amount of red blush. Reflective mulch was us ed to increase light le vels and shade cloth to reduce light levels in p each trees (Lewallen and Marini, 2003). The reflective mulch increased the amount of red blush on the fruits ; they also reported more fruit with an orange ground color with the reflective much and more fruits with a yellow to yellowish green ground color in the shaded trees. In an experiment where peach fruits were covered with aluminum foil, the developmen t of anthocyanin was markedly increased when the foil was removed and the fruit were ex posed to short periods of direct sunlight (Erez and Flore, 1986). They also reported a re duction in the color of the fruit when trees were shaded with shade cloth.

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27 CHAPTER 2 MATERIALS AND METHODS Locations Three sites representing differe nt climates from north-central to south Florida were chosen to grow several cultivars of low-chill peach trees. The north-central site was located in Archer, Florida (Lake fine sand, 29.52N 82.53W), the second or central location was in Winter Garden, Florida (Calander fine sand, 28.57N 81.58W Elev. 32.0 m), and the third or southwest location was in Immokalee, Florida (Immokalee fine sand, 26.43N 81.41W). Four cultivars, (Flordagl o, Flordaprince, TropicBeauty, and UFGold) were planted at each site. All trees were graf ted onto a greenleaf nematode resistant rootstock (Fl 9-04). Trees were planted in Februa ry, 2002, at all locations using a north/south row orientation at a distance of 4.57 m between trees (346 trees/hectare) in a randomized complete block design, with five replications and singl e tree plots, within each location. Cultural Practices Frost Protection and Pruning Overhead irrigation was used for frost pr otection at the northcentral site during bloom in 2004 and 2005. Neither the central or southwest locations received any frost protection. All trees were wint er pruned in early to mid-January each year. Trees were pruned to an open vase form and headed back to a height of ~2.5 meters. The trees were also summer pruned in early J une of both years as needed.

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28 Irrigation Trees at the north-central location received overhead irrigation and they were not water stressed at any time during either se ason. Within the central location, trees were irrigated by microsprinkler emitters for twen ty five minutes each morning before dawn. During 2004, over a two-week period between mid to late March, a substantial leak occurred in the main irrigation line and the tr ees did not receive any irrigation during that period. Microsprinkler emitters were also used at the southwest location. There were two microsprinkler emitters per tree at the central location, and one per tree at the southwest location. Weed Control Weeds controlled at all locations by ma intaining a herbicide band under the canopy of the trees and among trees in the row. Th e application band was three to four meters wide. Weed control was accomplished at the north-central and central locations with glyphosate and a water conditioning agent (b lend of polyacrylic, hydroxyl carboxylic, and phosphoric acids). Applications were ma de with a five gallon backpack sprayer when needed. At the so uthwest location, both glyphosat e and paraquat were used. Fertilization Fertilizer at the north-central location was applied by hand in three applications during the year, early February, early June, and late September. During both seasons, crossover fertilizer applications from an adjacent commercial bl ueberry field occurred eight times from a mechanical fertilizer spr eader on the east side of the trees. These times were: early February, early March, late March, late May, early July, late July, late August, and early September. When the fert ilizer was hand broadcast it was primarily placed under the west half of the tree to compensate for the unequal distribution of

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29 fertilizer from the mechanical applications. Fert ilizer application times at the central location were the same as at the north-cen tral location. Within the central location, reclaimed water was used for irrigation. To tal amount of nitrogen applied via reclaimed irrigation water was obtained by calculating an average N concentration of reclaimed water (.0072428 g N/L) between July, 2005, and January, 2006. Additionally, emitter output, line pressure an d irrigation schedule were used to determine total N applied from reclaimed water which was calculated at 33.86 kg/ha/season. Nitroge n fertilizer rates varied among locations. For 2004, they were 276 kg/ha at the north -central location, 103 kg/ha at the central locati on and 112 kg/ha at the southw est location. For 2005, N rates were 313 kg/ha at the north-ce ntral location, 114 kg/ha at th e central location and again 112 kg/ha at the southwest location. Temperature The temperature was recorded at the north -central and central locations with a HOBO H8 Pro Series temperatur e sensor (Onset Computer Corporation, Bourne, MA) starting the first week in November and ending in the last week of May. At the southwest location, temperatures were obtained from a FAWN (Florida Automated Weather Network) station. Chilling was determined at each location from early November to January 31. Disease Control Paraffinic hydrocarbon oil was use to control white peach scale ( Pseudaulacaspis pentagona (Targioni Tozzetti)), as needed during the dormant season. Fruit were handthinned just prior to pit hardening to a dist ance of 15 cm between fruit. After thinning, phosmet and captan were applied to control plum curculio ( Conotrachelus nenuphar (Herbst)) and peach scab ( Cladosporium carpophilum (Thum.)), respectively.

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30 Postharvest sprays at the north-central lo cation, were a combination of copper sulfate (20% metallic Cu equivalent), a non-ionic surfactant (alkylphenol etozylate, sodium salts of soya fatty acids, and isopropyl alcohol), and phosphoric acid, which were applied every three weeks until mid-Octobe r to control bacterial spot ( Xanthomonas arboricola pv. pruni (= X. campestris pv. pruni )). At the central locati on, trees were sprayed until late August and early July in 2004 and 2005, respectively. Chlo rothalonil, or a combination of pyraclostroblin and boscalid, wa s applied as needed to control peach rust ( Tranzschelia discolor (F. Chl.) Trans. and Litr.) at the north-central and central locations. For all pesticide applications tree s were sprayed early in the morning. Spray was applied by using a hydraulic sprayer (John Bean sprayers, Modular Hydraulic Sprayer, Model DM10E200FERH, Hogansvill e, Ga), with a handgun, at 500 psi on all parts of the tree until run off occurred. At the southwest loca tion, azoxystrobin and myclobutanil were used mont hly to manage peach rust. Measurements Shoot Measurements Three, one-year-old, shoots of average length were selected at random from each tree at a height between 1.5 to 2 m during midJanuary of both years. This was after the completion of winter pruning, but prior to bud break. A 150 mm dial caliper (Spi 31414) was used to measure the shoot diameter at the shoot base, and a 150 cm measuring tape was used to measure the length of each s hoot from the base to the tip. Each node on each shoot was observed and determined to be vegetative only, vegetative with one floral bud, vegetative with two floral buds, or blind (neither vegetati ve nor floral buds present). The total number of each bud type was determin ed for all selected shoots on each tree. During the spring of 2005, it was noted that several nodes had groupings with either

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31 single, double, or triple flor al buds without vegetative buds. The procedure was changed slightly to account for these node classifications. Trunk Measurements Every six months after leaf fall, and af ter fruit harvest, trunk circumference was measured. Readings were taken using a 150 cm dressmakers tape at a pre-determined spot 15 cm above the soil surface. This in formation was used to calculate trunk crosssectional area (TCA). Bloom and Flower Counts A visual estimation of the overall prog ress of bloom on each tree was done in 2004 and 2005. Bloom was rated twice each week (when applicable) using a 10% to 100% scale, and the date of petal fall was reco rded. In 2004, biweekly flower counts were made on tagged shoots (when applicable). Fl owers were considered open when both the anthers and stigmata were visible. The number of open flowers and fruitlets were counted on each shoot and recorded together In 2004, the number of aborted flowers was not recorded, which gave only the number of flowers which set fruit. The procedure was changed slightly during 2005 to take into account the nu mber of aborted flowers so the total number of open flower s on the selected shoots could be determined. Each node on each shoot was observed weekly to determine whether the flowers set or aborted. Both open flowers and fruitlets were recorded together. The date of 50 to 60% bloom or full bloom and first commercial fruit harvest wa s used to calculate the fruit development period (FDP). Fruit Set Measurements and Thinning During fruit development in late March of both 2004 and 2005 the numbers of fruit on the tagged shoots were counted to determ ine percent fruit set. Thinning was done

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32 manually and fruit were thinned to a distan ce of 10 to 15 cm. The number of fruit on each shoot was counted prior to thinning to de termine fruit set, and the number of fruit removed in thinning was also recorded. During 2005, the number of fruit on tagged shoots were counted again prior to harvest to determine if pre-harves t fruit drop occurred. Harvest Total Yield During the 2004 harvest, each of the trees were harvested individually, and the number and weight of both marketable and nonmarketable fruit were recorded. Nonmarketable fruit were delineated as those which were <4.5 cm, showed signs of wind scaring, catfacing, bacterial spot, insect predati on, split pits, deep sutured fruit, or rotten fruit. Fruit were harvested at a firm ripe stage of development; harvest occurred twice each week at all locations. Fruit from th e north-central location were counted and weighed directly in the field. Fruit from th e central location were bought directly to the laboratory and counted and weighed. Marketable fruit were weighed, and the weight and the number of fruit were recorded for each tr ee at each harvest date. The same procedure was applied to the nonmarketable fruit. After marketable fruit were weighed a nd counted at the no rth-central location, eleven representative fruit from each tree for each harvest date were selected at random and placed in peach trays that were obtained from a local grocery store. The trays were then placed in plastic Rubbermaid containers for transport to the laboratory. Fruit from the central Florida location were harvested and transported to the laboratory, then weighed, and samples of eleven representativ e fruit were selected as described above. During 2005, the procedure was changed slightly so that fruit from the central Florida location were weighed directly on site Fruit selection and transport were the

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33 same. At the north-central location the east side s of the trees appeared to have fewer fruit than the west sides of the trees. This looke d to be true for all four cultivars. To determine if there was a difference in locat ion of fruit in the tree canopy, each tree was divided into east and west sectors, and counted and weighed as such. Fruit Size, Weight, and Blush Fruit sub-samples were placed directly into a walk in cooler (3 5C) to remove field heat. Prior to fruit quality measuremen ts fruit were removed from the cooler and allowed to warm to room temperature. Ten fruit from each sub-sample were measured in three different orientations: blossom end to stem end, cheek to cheek, suture to opposite suture side. Each 10-fruit sample was wei ghed and each fruit was rated for a visual estimation of the amount of red blush under fluorescent light. Chromicity In 2005, at early (first commercial) harv est and mid harvest (greatest number of fruit removed per tree), a Konica Minolta CR 400/410 Chroma meter (Konica Minolta, Osaka, Japan) was used to test the chromi city values on the most blushed and least blushed area of five fruit from each 10fruit sub-sample. The chroma meter was calibrated using a standard calibration plate prior to each use. The colorimeter measured three variables; L*, a*, and b*, where L* is th e lightness of the object, -a* is the degree of greenness, +a* is the degree of redness, b* is the degree of bl ueness and +b* is the degree of yellowness on a CIELAB color chart (F rancis, 1970). The values of hue angle (h*) and chroma (C*) were computed from both a* and b*, where h* is a measure of the color of the sample and C* is a measure of th e intensity of that co lor. The same five fruits that were used for chromicity meas urements during 2005 were used for soluble solids concentration (SSC), titratable acidity (TA), pH, and pressure measurements.

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34 During 2004 the five fruits were selected at random from the ten fruit sample for fruit size, weight, and blush at early and mid-harvest. Blossom End During the 2005 season, fruit blossom end tip s were rated as recessed, flattened, or extended. Thirty fruit were selected at ra ndom from the marketable fruit for each tree during peak harvest and rated in the field for blossom end tip. Fruit which would be damaged in shipping were considered extended tip fruit. Firmness, Soluble Solids Concentrat ion, Titratable Acidity, and pH Flesh firmness was measured using a pe netrometer (McCormick Fruit Tech, Yakima, Wa) with a 6 mm probe attached to a drill press stand. Two measurements per fruit were taken (from the cen ter of each cheek) from 5-fruit samples. The epidermis was removed from the test area prio r to measuring flesh firmness. Fruit were peeled and flesh samples were collected from the cheek area of each fruit (avoiding the points were pressure measurements were taken, and the su ture and opposite the suture). A composite flesh sample was obtained for each 5-fruit subsample. Flesh samples were quick frozen in a -80C freezer and stored at -30C. Fl esh samples were removed from the freezer, allowed to thaw at room temperature, and homogenized in a blender. The slurry was centrifuged for twenty minutes at 14,000 rpm at 5C. The samples were then filtered through two layers of cheese cloth into a 50 ml beaker. Six g of supernatant diluted with 50 ml of deionized water was used to measure TA. Samples were titrated to an end point of 8.2 using an automatic titrimeter (Fishe r Titrimeter II, No. 9-313-10, Pittsburg, Pa), and expressed as ml NaOH. The normality of NaOH used was 0.1N. The remainder of the undiluted supernatant was used to test bo th the pH of the sample and the SSC. A Digital Refractometer (Reichert-Jung, Mark Abbe II Refractometer, Model 10480,

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35 Depew, NY) was used to measure the SSC of the undiluted sample and expressed in Brix. The pH of the sample was measur ed using a pH meter (Corning Scientific Instruments, pH mete r 140, Medfield, Ma). Statistical Analysis Statistical analysis was achieved using SA S 9.1 (SAS Institute Inc., Cary, NC). Means were determined using PROC GLM and means separations among and within locations were by Tukeys HSD at the P 0.05 level.

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36 CHAPTER 3 EVALUATION OF VEGETATIVE AND FL OWER BUD DEVELOPMENT, AND FRUITING OF FOUR DIFFERENT CU LTIVARS OF LOW-CHILL PEACH Introduction Climate is one of several factors that can greatly influence growth and development of reproductive organs, which in turn can aff ect crop yield. George et al. (1994) reported that larger flowers were produced at lower temperatures in persimmon. Floral abnormalities from low temperatures have been reported in pepper (Polwick and Sawhney, 1985). Cockshull et al. (1981) reporte d that higher day temperatures promoted flowering for Elegance chrysanthemum, but they also reported that higher night temperatures delayed it. Bud failure in al mond is a condition where buds fail to emerge in the spring. This condition has been attri buted to environmental factors such as warm temperatures (Kester and Asay, 1978). Peaches initiate their floral and vegetative buds in the summer and fall prior to flowering. Generally a node with a single vegetative bud is fla nked on both sides by a floral bud. However, different combinations of flower a nd vegetative buds can occur; nodes with a vegetative bud only, nodes with only one floral bud, or nodes that are blind. A blind node is a condition where there is no obvious vegetative or reproductive bud. Blind nodes are generally associated with higher temperatures during bud formation during the late summer months (Boonprakob and Byrne, 1990). This condition is more prevalent in subtropical or tr opical regions, verses temper ate regions. Boonprakob et al. (1996) concluded that blind node formation wa s due to failure of buds to differentiate.

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37 Flower bud densities have been documen ted in peach and other stonefruit. Genotype has a greater effect on the floral bud density than th e environment in areas that receive the same amount of chilling (Okie and Werner, 1996). Werner et al (1988) also observed the genotypic differences in floral bud density in pe ach, in that peach genotypes released from eastern breeding programs gene rally had more flower buds than those from western breeding programs. Al burquerque et al (2004) observe d genotypic differences in apricot where early flowering varieties had the highest flower bud density and highest percentage of fruit set. The objective of this experiment was to evaluate the performance of four low chill peach cultivars at three different locations in Florida with respect to several vegetative and reproductive characteristics. These incl uded: 1) the relative amount of different bud types; 2) bud, flower, and fruit dens ities; and 3) dates of full bloom. Materials and Methods Locations Three sites were chosen that represente d different locations and climates from north-central to south Florida. The northcentral site was located in Archer, Florida (Lake fine sand, 29.52N 82.53W), the second or central location was in Winter Garden, Florida (Calander fine sand, 28.57N 81.58W El ev. 32.0 m), and the third or southwest location was in Immokalee, Florida (Imm okalee fine sand, 26.43N 81.41W). Four cultivars, (Flordaglo, Flord aprince, TropicBeauty, and U FGold) were planted at all three sites. All trees were gr afted onto a greenleaf nematode resistant rootstock (Fl 9-04). Trees were planted in February, 2002, at all locations using a north/s outh row orientation at a distance of 4.57 m between trees (346 tree s/hectare) in a random ized complete block design, with five replicati ons and single tree plots.

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38 Cultural Practices General horticultural practices were used to control weeds, insects, and diseases. Trees were winter pruned in early January and summer pruned after ha rvest in early June as needed. Fertilizer at the north-cen tral location was applied by hand in three applications during the year: ear ly February, early June, and late September. Crossover applications of fertilizer from an adjacen t commercial blueberry field occurred eight times from a mechanical fertilizer spreader on the east side of the trees. These times were: early February, early March, late Marc h, late May, early July, late July, late August, and early September. When the fert ilizer was hand broadcast at the north-central location, it was placed primarily under the west half of the tree to compensate for the unequal distribution of fertilizer fr om the mechanical applications. Fertilizer application times at the central location were the same as at the northcentral location. Within the central locati on reclaimed water was used for irrigation. Total amount of nitrogen applied via r eclaimed irrigation water was obtained by calculating an average nitroge n (N) concentration of recl aimed water (0.0072 g N/L) between July 2005 and January 2006. Additionally, emitter output, line pressure, and irrigation schedule were used to determine to tal nitrogen applied per acre from reclaimed water that was calculated at 33.86 kg/ha/season. Nitrogen fert ilizer rates varied among locations. For 2004, they were 276 kg/ha at th e north-central locati on, 103 kg/ha at the central location and 112 kg/ha at the southwest locati on. For 2005, N rates were 313 kg/ha at the north-central lo cation, 114 kg/ha at the central location and again 112 kg/ha at the southwest location.

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39 Temperature Temperatures were recorded at the no rth-central and central location with a HOBO H8 Pro Series temperatur e sensor (Onset Computer Corporation, Bourne, MA) starting the first week in November and ending in the last week of May. At the southwest location, temperatures were obtained from a FAWN (Florida Automated Weather Network) station. Chilling was determined at each location from early November to January 31. Bud Data Collection Three one-year-old shoots of average le ngth were selected at random from each tree at a height between 1.5 to 2 m. during midJanuary of both years. This was after the completion of winter pruning, but prior to bud break. A 150mm dial caliper (Spi 31-414) was used to measure the diameter of the s hoot at the base, and a 150 cm measuring tape was used to measure the length of each shoot from the base to the tip. Each node on each shoot was observed and determined to be vege tative only, vegetative with one floral bud, vegetative with two floral buds, or blind (neith er vegetative nor floral buds present). The total number of each bud type was determined for all selected shoots on each tree. During the spring of 2005, it was noted th at several nodes had groupings with either single, double, or triple floral buds without vegeta tive buds. The procedure was changed slightly to account for these node classifications. Bloom A visual estimation of the overall bloom on each tree was done in 2004 and 2005. Bloom was rated twice each week (when appl icable) using a 10% to 100% scale, and the date of petal fall was recorded. In 2004, biweekly flower counts were made on tagged shoots (when applicable). Flowers were considered ope n when both the anthers and

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40 stigmata were visible. The number of ope n flowers and fruitlets were counted on each shoot and recorded together. The number of aborted flowers was not recorded, which gave only the number of flowers that set frui t. The procedure was changed slightly during 2005 to take into account the number of a borted flowers so the total number of open flowers on the selected shoots could be de termined. Each node on each shoot was observed weekly to determine whether the flow ers set or aborted. Both open flowers and fruitlets were recorded together. Information regarding numbers of open flowers was unavailable from the southwest location for bot h years. After bloom, but before thinning, fruits were counted on each of the sel ected shoots to de termine fruit set. Node Characterization and Bud Density From the information collected the followi ng variables were calculated: percentage of nodes with vegetative buds, percentage of nodes with vegetative and floral buds, percentage of nodes with floral buds only ( 2005), percentage of blind nodes, vegetative buds/node (VB/N), floral buds /node (FB/N), flowers/node (FL/N), vegetative buds/cm (VB/cm), floral buds/cm (FB/cm), flower s/cm (FL/cm), fruit/cm (FT/cm), blind nodes/cm (BN/cm), and nodes/cm (N/cm). Statistical Analysis Statistical analysis was achieved using SA S 9.1 (SAS Institute Inc., Cary, NC). Means were determined using PROC GLM and means separation among and within the locations were by Tukeys HSD at the P 0.05 level. Results Chilling and Bloom Chilling was significantly different among locations. However, the numbers of chilling hours recorded during both years, were very similar for each location. The

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41 greatest number of chill hours was observed in north-central Florida followed by central and then southwest Florida (Figure 1). In 2004, UFGold bloomed later than the ot her cultivars at the north-central and central Florida locations. However, UFGol d bloomed earlier (J anuary 31) at the southwest location than in central (February 9) or north-central (February 13) Florida (Table 1). Conversely, TropicBeauty bloomed earlier at the centr al location (January 28) than at the southwest location (February 1). No significant differences for bloom date were observed among cult ivars at the southwest site. During 2005, significant differences in bloom period were observed among cultivars and sites. Flordaprince bloomed ear lier (January 30) in southwest Florida then in north-central (February 2) or central (February 14) Florid a. UFGold had an earlier bloom (February 1) at the southwest location compared to the north-central (February 12) and central (February 28) loca tions. Bloom in central Flor ida for both Flordaglo and TropicBeauty was later than for the other two locations. Bloom of all cultivars at the central location during 2005 was delayed nearly one month compared to the previous year. Full bloom dates for TropicBeauty, Flordaprince, Flordaglo, and UFGold were the 23rd, 24th, 28th, and 28th of February, respectively. Flordaprince and TropicBeau ty bloomed earlier than either Flordaglo or UFGold. At the north-central locati on, UFGold bloomed later than the other cultivars. No significant differences were obs erved for bloom date among cultivars at the southwest site.

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42 Bud Percentage Nodes with only vegetative buds No significant interactions between locati on and cultivar were found in either year for the percent of nodes with only vegetative buds. Therefore only the main effects are presented. During 2004, the percentage of nodes with only vegetative buds was significantly higher in UFGold than in the other cultivars (Figure 2). There were a higher percentage of nodes with vegetative buds at the southwest location compared to the north-central and central locations (Figure 3). During 2005, a higher percentage of nodes with only vegetative buds were observe d in Flordaprince than TropicBeauty (Figure 4). There were no differences observed among loca tions during 2005 (Figure 5). Nodes with vegetative and flower buds During 2004, the percentage of nodes with both vegetative and flower buds was greater for Flordaprince and Flordaglo than for either UFGold or TropicBeauty in north-central Florida; and gr eater than UFGold in sout hwest Florida (Figure 6). Significant differences were not observed among cultivars at th e central site. A higher percentage of nodes with vegetative and flow er buds were observed at the north-central location than the central location for Flordap rince. A higher percentage of nodes with both vegetative and flower buds were obs erved at the north-central location for Flordaglo compared to the other locations. The percenta ge of nodes with vegetative and flower buds was lowest for U FGold at the southwest location. During 2005, there were no significant diffe rences observed among cultivars at the north-central location (Figure 7) Within the central location, Flordaprince had a larger percentage of nodes with vege tative and flower buds than UFGold, and at the southwest location TropicBeauty had a smaller percentage than the other cultivars. In general,

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43 lower percentages of nodes with vegetative a nd flower buds were observed at the central location compared to other locations. Nodes with only flower buds Nodes that had only flower buds were only measured during 2005 and only in north-central and central Florida. There we re no significant interactions between location and cultivar. Therefore, only the main eff ects are presented. A higher percentage of nodes with only flower buds were observed for UFGold than for the other cultivars (Figure 8). No differences we re observed between locations (Figure 9). TropicBeauty had a lower percentage of nodes with only fl ower buds than UFGold or Flordaglo. Blind nodes During 2004 the percentage of blind nodes was greater for TropicBeauty than for the other cultivars at all loca tions (Figure 10). Similarly, the percentage of blind nodes was greater for TropicBeauty than for UFG old in central Florida and greater than Flordaprince in southwest Florida. A hi gher percentage of blind nodes were observed in the central than the southwest location fo r Flordaprince. A higher percentage of blind nodes were observed in UFGold at th e southwest location co mpared to the northcentral location. During 2005, at the north-central locati on, more blind nodes were observed for TropicBeauty and Flordaglo than for UFGol d (Figure 11). Tr opicBeauty also had a larger percentage of blind nodes than U FGold in central Florida and a larger percentage than all other cultivars at the s outhwest location. A lower percentage of blind nodes were observed in the north-central location than the other locations.

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44 Buds per Node Vegetative buds During 2004, the number of vegetative buds per node was significantly less for TropicBeauty than for the other cultivars at the north-central location (Table 2). Similarly they were less for TropicBeauty th an for UFGold in central Florida, or for Flordaprince at the southw est location. The number of vegetative buds per node was higher in southwest Florida than central Florida for Flordaprince. Higher values were observed at the north-central location than at the southwest locati on for UFGold during 2004. During 2005 no significant differences were observed among the cultivars in north-central Florida (Table 3). However, UFGold had fewer ve getative buds per node than the other cultivars at the central loca tion and TropicBeauty had fewer than the other cultivars at the southw est location. The number of vegetative buds per node was generally lowest for Flordaprince, Flordag lo, and TropicBeauty in central Florida. Flower buds During 2004, more flower buds per node were observed for Flordaglo than for either UFGold or TropicB eauty in north-central Florid a, or for UFGold at the southwest location (Table 2). Flordaglo had a higher amount of flower buds per node than Flordaprince in central Florida. Location differences were observed for several cultivars during 2004. The number of flower buds per node for Flordaprince was higher in north-central Florid a than in central Florida. Flower buds per node for Flordaglo were also higher at the north-ce ntral location than at the other locations. UFGold had higher flower bud counts per node at the north-central location than at the southwest location.

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45 During 2005 significant differences among cultivars were not observed at the north-central location (Table 3). In cent ral Florida more flower buds per node were observed for UFGold than for Flordaglo or TropicBeauty. TropicBeauty had the least flower buds per node at the southwest site. Among loca tions the number of flower buds per nodes was higher for all cultiv ars at the north-central location. Flowers The number of flowers per node was not observed during 2004 and only at the north-central and central locations during 2005. Significant differences were not detected in north-central Florida (Table 3). In central Florida, more flowers per node were observed for UFGold than for Flordaglo or TropicBeauty. Between the two locations, the number of flowers per node was hi gher in north-central Florida than in to central Florida. Bud Density Vegetative buds Vegetative bud density (buds/cm shoo t length) during 2004 was greater for UFGold than for Flordapri nce or TropicBeauty at th e north-central location, and greater than TropicBeauty in central Flor ida (Table 4). At the southwest location Flordaprince had a greater vegetative bud de nsity than TropicBeauty. A lower density of vegetative buds was observed at the southwes t location than to the other locations in both Flordaglo and UFGold. Lower dens ities were observed fo r TropicBeauty in southwest Florida compared to central Florida during 2004. Significant differences were not observed during 2005 amon g cultivars at the northcentral site (Table 5). However, lower valu es were observed for UFGold than for the other cultivars at the central location, or for TropicBeauty at the southwest location.

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46 Higher densities of vegetative buds were obser ved at the southwest location for UFGold followed by the north-central and central loca tions. Lower densities were observed for TropicBeauty in southwest Florida compared to north-central or central Florida. Flower buds During 2004, greater flower bud density (flower buds/cm shoot length) was observed for Flordaglo than for UFGold in north-central Florida (Table 4). Within the central location, Flordaglo had greater flower bud density th an Flordaprince. Flower bud density was less for UFGold than for Flordaprince or Flordaglo at the southwest location. The north-central lo cation had a higher flower bud density for Flordaprince than the central or southwes t locations. Lower values for flower bud density were observed in Flordaglo and U FGold at the southwest location compared to the other locations. During 2005, significant differen ces were not observed in the north-central site (Table 6). At the central lo cation UFGold had higher flow er bud densities than either Flordaglo or TropicBeauty. In southwest Florida Tr opicBeauty had lower values than Flordaglo or UFGold. High values for flower bud density were observed for Flordaprince at the north-central loca tion, and low values were observed at the southwest location for UFGold. Higher fl ower bud densities were observed in northcentral Florida for Flordaglo than in southwest Florida. Flower bud density was highest for TropicBeauty at the north-central lo cation followed by the central and southwest locations. Flowers Flower density (flowers/cm shoot lengt h) was not observed during 2004. During 2005 flower density was observed at the nor th-central and centr al locations. No

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47 differences were observed among cultivars at th e north-central location (Table 6). There were higher flower densities observed in UFGold in centr al Florida compared to the other cultivars. Higher flower densities were observed in north-central Florida for Flordaprince, Flordaglo, and Tro picBeauty than in central Florida. Fruit No significant interactions were found be tween location and cult ivar during either 2004 or 2005 for fruit density (fruit/cm shoot le ngth). Therefore, only the main effects are presented. During 2004, higher fruit density was observed for UFGold than for the other cultivars (Table 7). During 2005, hi gher fruit densities were observed for Flordaglo and UFGold than for Flordap rince or TropicBeauty. There were no significant differences observed between th e two locations during either year. Blind nodes During 2004, significant differences in th e frequency of blind nodes (blind nodes/cm shoot length) were observed among cultivars at all locations. Blind node frequency at the north-central location was greatest for TropicBeau ty (Table 4). In central Florida, frequencies were greater for TropicBeauty than for UFGold. At the southwest location, blind node frequencies were higher for TropicBeauty than for Flordaprince or Flordaglo. Blind node frequencies for Flordaprince, Flordaglo, and TropicBeauty were highe st at the central location. During 2005, the frequency of blind nodes wa s lower for UFGold than for either Flordaglo or TropicBeauty in north-central Florida (Tab le 5). Higher values were observed for TropicBeauty than for UFG old at the central location, and at the southwest site values for TropicBeauty were higher than for all other cultivars. Lower

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48 amounts of blind nodes were observed in north -central Florida th an in central or southwest Florida. Nodes No significant interactions for node dens ity were observed between locations and cultivars during either year. Therefore, only main effects are reported. Significant differences were not detected among the cu ltivars during 2004 (Table 7). During 2005 a higher density of nodes was observed in Tropi cBeauty than in Flordaprince. During both years node density was higher in centr al Florida than at the other locations. Discussion Chilling and Bloom The location where trees are grown can a ffect many aspects of development. Temperatures in an area can affect when bloom occurs and the development of buds during the summer and fall. There have al so been several reports on the effect of temperature on fruit set of peach (Edwards 1987; Erez et al., 2000; Rouse and Sherman, 2002b) and apple and pear (Tromp and Borsboom, 1994). Chilling hours accumulated during the late fa ll and winter are important in breaking endodormancy of peaches (Weinberger, 1950a). The amount of chilling required varies by cultivar (Weinberger, 1950a) as well as by bud type (Scalabrelli and Couvillon, 1986). The cultivars observed in this experiment were low-chill, and require only 150 200 hours of chilling (Rouse and Sherman, 1989b; Sherman and Lyrene, 1997; Sherman and Lyrene, 1989; Sherman et al., 1982). A delay in bloom at the central location was observed during 2005. This delay in bloom was probably the result of early defolia tion from bacterial spot combined with severe winds from several hurricanes in the summer, 2004. During summer, 2004, the

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49 incidence of bacterial spot wa s very high at the central Fl orida location. Infection and defoliation had already begun in May, 2004. Th e trees were not sprayed at this time because fruit were still being harvested. Th e disease was already well established within the orchard and on several nearby plum trees wh en a spray program was initiated in early June. Wind and rain aid in the spread of this disease. During 2004, several major hurricanes (Category 2 or highe r prior to landfall) passed through the area. Hurricanes Charley, Frances, and Jeanne all affected cr ops within the area. Leaf shredding and tearing was common at all three orchard site; however, the central location was directly hit by all three hurricanes. These storms likel y increased the spread of bacterial spot within each tree and among trees. The high sustained winds and strong gusts shredded leaves and caused partial defo liation. The damaged leaves were likely points of infection for bacterial spot and some trees were comple tely defoliated from both bacterial spot and tropical storm force winds by the end of September. The early defoliation in 2004 resulted in a late summer/early fall growth flush that may have delayed the onset of dormancy and chill accumulation. Early defoliation from the combined affect of three major hurricanes, high incidence of bacter ial spot, and late summer growth probably resulted in the marked delay in bloom expe rienced at the central location during 2005. Such a delay in bloom can be very detrimental to fruit set. Low yields may result when flowering and fruit set occur under warmer temperature conditions (Rouse and Sherman, 2002). The progressive delay in bloom observed fo r UFGold as the locations progressed further north may have resulted from this cultivar accumulating the necessary heat units for bloom at a faster rate at the southwes t location. There was a twelve day difference

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50 between the north-central and southwest locations for date of full bloom in UFGold. Generally full bloom was within about thr ee days of each other for Flordaprince, Flordaglo, and TropicBeauty between north-central Florida and southwest Florida. Chilling in UFGold may have been satisfied at all three locations at approximately the same time. However, in the southwest location, more heat units may have been accumulated in a shorter period of time than at the central or north-central locations resulting in earlier bloom in southwest Florida. Weinberg er (1948) reported a two day delay in full bloom for Elberta Peach betw een the Fort Valley area of Georgia (central GA.), and areas in northern Georgia. This ear lier bloom may facilitate an earlier harvest in more southern locations. However it has b een reported that the temperatures following bloom can be important in reducing FD P (Boonprakob et al., 1992; Topp and Sherman, 1989a; Weinberger, 1948). Percentage of Vegetative, Floral, and Blind Nodes The percentage of vegetative, floral, a nd blind nodes can indicate how well adapted cultivars are to different climatic zones, and indicate which cultivars have a high cropping potential. This can give an indi cation of what conditions are favorable or unfavorable for development of certain types of nodes, mainly blind nodes. A blind node is a condition where there is no vegetative or floral bud located at a node (Boonprakob et al., 1996). This can be caused by high temperatures during bud development (Boonprakob and Byrne, 1990). During 2005, there were some nodes without ve getative buds that had at least one flower bud. There appeared to be a greater percentage of these node types set for UFGold than for the other cultivars. The percentage of flower bud only nodes in UFGold ranged form 31% at the north-central location to 39% at the central location.

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51 Percentages ranged from 8% to 18% among the other three cultivars. This data supports the cultivar release information which states that UFGold tends to set high amounts of flower buds (Sherman and Lyrene, 1997). Cultivars such as UFGold that set hi gh percentages of nodes with only flower buds could have difficulty supporting heavy fru it loads. Such cult ivars could set heavy fruit loads with very little foliage. These fruit will be reduced in size and quality, and may be damaged from excessive exposure to th e sun. With the lack of foliage to support vegetative growth, shoots will remain thin. Gr owth of the terminal vegetative buds, on these shoots the following year will produce l ong thin branches that can hang close to the ground, where the shoots and foliage could be damaged by herbicides. Lack of adequate foliage cover in the canopy can cause the exposed branches and scaffold limbs to sunburn. The damaged w ood can later serve as an entry way for pathogens and insects. Lack of foliage can also cause problems w ith pruning and training trees. Since these shoots have very few ve getative buds, the number of potential pruning locations is reduced. These shoots will have to be cut back to the main scaffold limb. This can be problematic in tr aining trees into the open-vase form, or when trying to keep trees compact. These problems may also occu r in genotypes that have high frequency of blind nodes. Differences for blind node percentages were observed during 2005 among locations and cultivars. The north-cen tral location had the lowest percentages of blind nodes across all four cultivars dur ing 2005. Warmer temperat ures during bud development were probably the cause of higher blind node s observed at the central and southwest locations. Blind nodes are generally cause d by high temperatures during a period of

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52 rapid shoot growth (Richards et al., 1994). Average temperat ures above 22C, as well as other stresses imposed on trees, have been shown to be critical for the development of blind nodes (Boonprakob and Byrne, 2003). Average temperatures above 22C are common in many areas of Florida, especially further south, during the summer months. However, genotypic differences appear to exist among cultivars. While cultivars had above 50% blind buds in central and southwes t Florida, TropicBeauty tended to have the highest percentage of blind nodes at al l locations. UFGold usually had a lower percentage of blind nodes than TropicBeauty . This is in agreement with published information for UFGold that states that fe w blind buds are set by this cultivar (Sherman and Lyrene, 1997). There were other stresses th at were imposed on the tree s at the central location. Effects other than temperature may play an im portant role in the re duction of certain bud types and the increase in blind nodes for some cultivars. There was a significant reduction in the percentage of nodes that had both vegetative and flower buds during 2005. As stated earlier, defoliation from b acterial spot was more pronounced in central Florida, and during the summ er and fall of 2004, several ma jor hurricanes passed through central Florida. The stresses from the above mentioned factors along with the effect of temperature during the critical period of bud formation in late August and September may have caused the higher incidence of blind nodes and lower incidences of nodes with both vegetative and flower buds observed in central Florida. Cultivars that exhibit a high percentage of blind nodes such as TropicBeauty need to be planted in areas that do not rece ive the high summer temperatures during bud

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53 development. It is important to test cu ltivars in areas that receive high summer temperatures to determine how the cultivars ar e affected by different climate conditions. Number of Buds per Node and Bud Density The number of vegetative buds and flower s per node were lower during 2005 for several cultivars at the central location compar ed to either the sout hwest or north-central locations. Vegetative bud counts per node di ffered between years at the central and southwest locations. Two factors may have c ontributed to this. Stresses imposed from the passage of three hurricanes and high incidence of bacterial spot may be causes of the low bud and flower counts per node observed. The shredding and tearing of the leaves from the passage of the hurricanes, as well as senescence of leaves from bacterial spot may have affected vegetative and flower bud growth and development during late August and September as well as overall health of the tree. Higher flower bud counts per node and lower densities of blind nodes at the northcentral location may be a resu lt of cooler temperatures during bud development in the summer and fall within this location compared to the central or southwest locations. There also may be genotype differences for different densities of nodes that are more prevent at different locations. Since bli nd nodes are caused by warmer temperatures, fewer blind nodes would be set at the north -central location and more flower or vegetative buds would be set. This would explain the higher flower bud counts per node. Higher flower and fruit densities observ ed in some peach cultivars may be the result of genetic tendencies in some cultivars for higher fruit densities or fruit set. This has been observed in apricot. Alburquerque et al. (2004) observed the effect of climatic conditions and cultivar differences on several ap ricot cultivars. They concluded that final fruit set was influenced more by cultivar than by climate. The higher fruit density

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54 observed in UFGold compared to Tropi cBeauty might be a result of a genetic tendency for UFGold to set high amounts of flowers and fruits and for TropicBeauty to set low amounts of flowers and fruits. General Conclusions Testing to determine the adaptation of diffe rent cultivars at multiple locations can help to determine where certain traits are more pronounced. Warmer locations may increase the prevalence of blind nodes in cultiv ars. Cultivars should be tested in warmer areas to see if they are prone to this condi tion. Genetic tendencies may also exist for blind nodes and nodes with only floral buds in certain cultivars. Genotypic differences may also exist among cultivars for fruit density. Stresses from environmental factors and diseases may have an effect on the number and type of buds set at a node. The results obtained here on the occurrence of blind nodes in different climatic regions and prevalence of nodes with floral buds provides valuable information to breeders, when selecting germplasm for re lease or future crosses.

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55 0 50 100 150 200 250 300 350 400 450 500 20042005 yearChill units (hours) North-Central Central Southwest Figure 1. Total chill unit accumulation for hours below 7.2 C among locations for the 2004 and 2005 seasons for four low-chill peach cultivars from early November to January 31 for each year.

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56Table 1. Mean date of full bloom for both 2004 and 2005 across three locations for four lo w-chill peach cultivars. 2004 Season 2005 Season Cultivar North-Central Central Southwest Location Significance North-Central Central Southwest Location Significance FlordaPrince 01-28-04bzAy 01-28-04bA 01-25-04aA 0.5758 02-02-05bB 02-24-05bA 01-30-05Ca <.0001 FlordaGlo 01-31-04bA 02-02-04bA 02-02-04aA 0.7274 02-05-05bB 02-28-05aA 02-02-05Ba <.0001 UFGold 02-13-04aA 02-09-04aA 01-31-04aB <0.0001 02-12-05aB 02-28-05aA 02-01-05aC <.0001 TropicBeauty 01-31-04bAB 01-28-04bB 02-01-04aA 0.0211 02-02-05bB 02-23-05bA 01-21-05aB <.0001 Cultivar Signif. <0.0001 <0.0001 0.0688 <0.0001 <0.0001 0.0431 z Means within location fo llowd by the same lowercase letter are not si gnificantly different accord ing to Tukeys Test < 0.05. y Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukey s Test < 0.05

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57 c a bc b 0 5 10 15 20 25 30 35 40 45 50 FlordaprinceFlordagloUFGoldTropicBeauty Cultivar% Figure 2. Main effects for the percentage of nodes with only vegetative buds during 2004 for four low-chill peach cultivars. Lowercase letters represent significant differences among cultivars using Tukeys Test P < 0.05. a b b 0 5 10 15 20 25 30 35 40 North-CentralCentralSouthwest Location% Figure 3. Main effects for the percentage of nodes with only vegetative buds during 2004 for three locations. Lowercase letters represent significant differences among locations using Tukeys Test P < 0.05.

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58 b ab ab a 0 2 4 6 8 10 12 14 16 18 20 FlordaprinceFlordagloUFGoldTropicBeauty Cultivar% Figure 4. Main effects for the percentage of nodes with only vegetative buds during 2005 for four low-chill peach cultivars. Lowercase letters represent significant differences among cultivars using Tukeys Test P < 0.05. a a a 0 2 4 6 8 10 12 14 16 18 North-CentralCentralSouthwest Cultivar% Figure 5. Main effects for the percentage of nodes with only vegetative buds during 2005 for three locations. Lowercase letters represent significant differences among locations using Tukeys Test P < 0.05.

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59 aAB aB aA aB aB aA bB aA bA abA aA bA 0 5 10 15 20 25 30 35 40 45 50 North-CentralCentralSouthwestLocations% Flordaprince Flordaglo UFGold TropicBeauty Figure 6. Percentage of nodes with both vege tative and flower buds for four low-chill peach cultivars during the 2004 season within three locations. Lower case letters represent significant differe nces among cultivars within a location using Tukeys Test P < 0.05. Uppercase letters represent significant differences among locations for each cultivar using Tukeys Test P < 0.05. aB aA aC aA aA abB aA aA bB bB aA aB 0 5 10 15 20 25 30 35 40 North-CentralCentralSouthwestLocations% Flordaprince Flordaglo UFGold TropicBeauty Figure 7. Percentage of nodes with both vege tative and flower buds for four low-chill peach cultivars during the 2005 season within three locations. Lower case letters represent significant differe nces among cultivars within a location using Tukeys Test P < 0.05. Uppercase letters represent significant differences among locations for each cultivar using Tukeys Test P < 0.05.

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60 c a b bc 0 5 10 15 20 25 30 35 40 FlordaprinceFlordagloUFGoldTropicBeauty Cultivar% Figure 8. Main effects for the percentage of nodes with only flower buds during 2005 for four low-chill peach cultivars. Lowe rcase letters represent significant differences among cultivars using Tukeys Test P < 0.05. a a 0 2 4 6 8 10 12 14 16 18 20 North-CentralCentral Location% Figure 9. Main effects for the percentage of nodes with only floral buds during 2005 between two locations. Lowercase letters represent significant differences between locations using Tukeys Test P < 0.05.

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61 bB abA bAB abA abA bA abA bAB bB aA aA aA 0 10 20 30 40 50 60 North-CentralCentralSouthwestLocations% Flordaprince Flordaglo UFGold TropicBeauty Figure 10. Percentage of blind nodes for four low-chill peach cult ivars during the 2004 season within three locations. Lowe r case letters represent significant differences among cultivars within a location using Tukeys Test P < 0.05. Uppercase letters represen t significant differences among locations for each cultivar using Tukeys Test P < 0.05. bA abA abB bA abA aB bA bA bB aA aB aC 0 10 20 30 40 50 60 70 80 90 North-CentralCentralSouthwestLocations% Flordaprince Flordaglo UFGold TropicBeauty Figure 11. Percentage of blind nodes for four low-chill peach cult ivars during the 2005 season within three locations. Lowe r case letters represent significant differences among cultivars within a location using Tukeys Test P < 0.05. Uppercase letters represen t significant differences among locations for each cultivar using Tukeys Test P < 0.05.

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62Table 2. Mean vegetative and flower buds per node for the 2004 season, for four low-chill peach cultivars within three differen t locations. Vegetative Buds/Node Flower Buds/Node North-Central Central Southwest North-Central Central Southwest Flordaprince 0.66azABy 0.561abB0.719aA 0.61abA 0.26bB 0.47abAB Flordaglo 0.66aA 0.56abA 0.64abA 0.68aA 0.45aB 0.49aB UFGold 0.75aA 0.67aAB 0.58abB 0.43bA 0.36abAB0.21bB TropicBeauty 0.47bA 0.44bA 0.48bA 0.47bA 0.33abA 0.41abA z Means within location followed by the same lo wercase letter are not significantly different according to Tukeys Test P < 0.05. y Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05. Table 3. Mean vegetative and flower buds per node for the 2005 season, for four low-chill peach cultivars within three differen t locations. Vegetative Buds/Node Flow er Buds/Node Flowers/Node NorthCentral Central Southwest NorthCentral Central Southwest NorthCentral Central Southwest Flordaprince 0.513azAy 0.256aB 0.445aA 0.708aA 0.249cbB0.310aB 0.475aA 0.052cbB ---x Flordaglo 0.476aA 0.234aB 0.423aA 0.620aA 0.299bB 0.317aB 0.423aA 0.116bB --UFGold 0.441aA 0.098bB0.490aA 0.781aA 0.430aB 0.402aB 0.423aA 0.202aB --TropicBeauty 0.491aA 0.244aB 0.163bB 0.825aA 0.181cB 0.100bB 0.549aA 0.031cB --z Means within location followed by the same lowercase letter ar e not significantly different ac cording to Tukeys Test P < 0.05. y Means for cultivars across loca tions followed by the same uppercase letter are not significantly different according to Tukey s Test P < 0.05. x Data unavailable.

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63Table 4.Vegetative bud, flower bud, and blind node density for f our low-chill peach cultivars for the 2004 season within three different locations. Vegetative Buds/ cm Shoot Le ngth Flower Buds/ cm Shoot Lengt h Blind Nodes/ cm Shoot Length NorthCentral Central Southwest NorthCentral Central Southwest NorthCentral Central Southwest Flordaprince 0.41bzAy 0.43abA 0.38aA 0.38abA 0.19bB 0.23aB 0.21bB 0.37abA 0.14bB Flordaglo 0.43abA 0.46abA 0.32abB 0.44aA 0.35aA 0.23aB 0.22bB 0.38abA 0.17bB UFGold 0.51aA 0.53aA 0.30abB 0.28bA 0.29abA 0.10bB 0.17bA 0.28bA 0.23abA TropicBeauty 0.32cAB 0.37bA 0.25bB 0.32abA 0.27abA 0.21abA 0.36aB 0.51aA 0.28aB z Means within location followed by the same lowercase letter are not significantly different according to Tukeys Test P < 0.05. y Means for cultivars across locations followed by the same uppercas e letter are not significantly different according to Tukey s Test P < 0.05. Table 5. Vegetative bud and blind node de nsity for four low-chill peach cultivars for the 2005 season within three different lo cations. Vegetative Buds/ cm Shoot Lengt h Blind Nodes/ cm Shoot Length North-Central Central Southwest North-Central Central Southwest Flordaprince 0.31azAy 0.26aA 0.32aA 0.21abC 0.66abA 0.42bB Flordaglo 0.35aA 0.27aA 0.32aA 0.27aB 0.67abA 0.50bA UFGold 0.30aB 0.11bC 0.41aA 0.17bB 0.59bA 0.45bA TropicBeauty 0.35aA 0.27aA 0.16bB 0.28aB 0.79aA 0.88aA z Means within location followed by the same lowercas e letter are not significant ly different according to Tukeys Test P < 0.05. y Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05.

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64Table 6. Flower bud and flower density for four low-chill peac h cultivars for the 2005 season with in three different locations. Floral Buds/ cm Shoot Lengt h Flowers/ cm Shoot Length North-Central Central Southwest North-Central Central Southwest Flordaprince 0.44azAy 0.27bcB 0.22abB 0.29aA 0.06bB ---x Flordaglo 0.45aA 0.34bAB 0.24aB 0.31aA 0.13bB --UFGold 0.52aA 0.49aA 0.35aB 0.28aA 0.24aA --TropicBeauty 0.58aA 0.21cB 0.10bC 0.39aA 0.04bB --z Means within location followed by the same lowercas e letter are not significantl y different according to Tukeys Test P < 0.05. y Means for cultivars across locations followed by the sa me uppercase letter are not significantly different according to Tukeys Test P < 0.05. x Data unavailable.

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65Table 7. Main effects of fruit and node density for four lowchill peach cultivars, and three different locations, for the 2004 and 2005 seasons. 2004 2005 Fruit/ cm Shoot Length Nodes/ cm Shoot Length Fruit/ cm Shoot Length Nodes/ cm Shoot Length Cultivar Flordaprince 0.06cz 0.64a 0.05b 0.81b Flordaglo 0.14b 0.66a 0.13a 0.89ab UFGold 0.23a 0.67a 0.16a 0.88ab TropicBeauty 0.05c 0.70a 0.06b 0.97a Location North-Central 0.11ay 0.66b 0.11a 0.69c Central 0.12a 0.83a 0.09a 1.13a Southwest ---x 0.52c --0.86b z Means across cultivars followed by the same lowercas e letter are not significantly different according to Tukeys Test P < 0.05. y Means across locations followed by the same uppercase le tter are not significantly different according to Tukeys Test P < 0.05. x Data unavailable.

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66 CHAPTER 4 FRUIT QUALITY AND YIELD OF FO UR LOW-CHILL PEACH CULTIVARS GROWN IN THREE LOCATIONS Introduction Several important fruit quality characterist ics of peach are affected by climate and cultural practices. Percent blush coverage can be affected by the prevailing climate in a production region. Rouse and Sherman (1989a) reported a higher blush in the Lower Rio Grande Valley of Texas than in Gainesville, Florida, for several cultivars of low-chill peaches. This was attributed to the warmer pr evailing temperatures in that area of Texas. However, Topp and Sherman (1989b) reporte d no correlation betw een temperature and red blush. Other characteristic s such as stylar tip (Topp a nd Sherman, 1989b; Salvador et al., 1998) and fruit development period (F DP) (Anderson and Sherman, 1994; Topp and Sherman, 1989b; Rouse and Sherman, 1989a; Wei nberger, 1948) can also be affected by temperature during development. Different cultural practices can also affect fruit quality and yield. Higher rates of nitrogen (N) have been shown to impose a greener ground color (Meheriuk et al., 1995), increase the length of the FDP (Saenz et al ., 1997), increase fruit yield (Shoemaker and Gammon, 1963), and increase astringency (Jia et al., 1999). Diffe rent tree training techniques, open vase or perpendicular Y, can increase light penetration and affect several quality attributes such as SSC, ground color, and flesh firmness (Farina et al., 2005). Fruit thinning can be important for some developmental aspects such as SSC (Corelli-Grappadelli and Coston, 1991) and fr uit size (Tukey and Einset, 1938). Light

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67 interception is also importan t in red blush development (Erez and Flore, 1986) and ground color development (Lewallen and Marini, 2003). Yield and some quality traits can also in teract with each other; a good example of this was reported by (Rowe and Johnson, 1992) who found a relationship between total yield and fruit size. They found that larger fruit were produced at the expense of total yield; in essence this means that more fruit on the tree reduces fruit size (Rowe and Johnson, 1992). The objective of this experiment was to observe fruit quality characteristics and yield of four low chill peach cultivars at three locations in Florida. Quality and developmental characteristics observed in cluded blush, L*, C*, h*, SSC, SSC/TA ratio, fruit shape, fruit size, and FDP. Total fru it weight and number were also determined. Materials and Methods Locations Three sites were chosen that represente d different locations and climates from north-central to south Florida. The northcentral site was located in Archer, Florida (Lake fine sand, 29.52N 82.53W), the second or central location was in Winter Garden, Florida (Calander fine sand, 28.57N 81.58W El ev. 32.0 m), and the third or southwest location was in Immokalee, Florida (I mmokalee fine sand, 26.43N 81.41W). Four cultivars (Flordaglo, Flordaprince, Tropi cBeauty, and UFGold) were planted at all three sites. All cultivars were grafted onto a greenleaf nematode re sistant peach rootstock (Fl 9-04). Trees were planted in February, 2002, at all locations using a north/south row orientation at a distance of 4.57 m between trees (346 trees/hectare) in a randomized complete block design, with five replications and single tree plots, within each location.

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68 Cultural Practices Overhead irrigation was used for frost pr otection at the northcentral site during bloom in 2004 and 2005. Neither the central or southwest locations received any frost protection. All trees were wint er pruned in early to mid-January each year. Trees were pruned to an open vase form and headed back to a height of ~2.5 meters. The trees were also summer pruned in early June of both y ears as needed. Trees at the north-central location received overhead irriga tion and trees were not water stressed at any time during either season. At the central location, trees were irrigated by microsprinkler emitters for 25 minutes each morning before dawn. During 2004, over a 2-week time span during mid to late March, a substantial leak occurred in the main irrigation line and the trees did not receive any irrigation at that during that period. Microsprinkler emitters were also used at the southwest location. Weeds were controlled at all locations by maintaining a herbicide band under the canopy of the trees and among trees. Weed c ontrol was accomplished at the north-central and central locations with glyphosate and a water condi tioning agent (blend of polyacrylic, hydroxyl carboxylic, and phosphoric aci ds). Applications were made with a five gallon backpack sprayer when needed. At the southwest lo cation glyphosate and paraquat were used. Fertilizer at the north-central location was applied by hand in three applications during the year, early February, early June, and late September. During both seasons, crossover fertilizer applications from an adjacent commercial bl ueberry field occurred eight times from a mechanical fertilizer spr eader on the east side of the trees. These times were: early February, early March, late March, late May, early July, late July, late August, and early September. When fer tilizer was hand broadcast, it was placed

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69 primarily under the west half of the tree to compensate for the unequal distribution of fertilizer from the crossover applications. Fertilizer application times at the central location were the same as at the north-centr al location. Reclaimed water was used for irrigation at the central loca tion. Total amount of N applied via reclaimed irrigation water was obtained by calculating an aver age N concentration of reclaimed water (.0072428 g N/L) between July 2005 and Janua ry 2006. Additionally, emitter output, line pressure, and irrigation schedule were used to determine total N applied per hectare from reclaimed water which was calculated at 33.86 kg/ha/season. Nitrogen fertilizer rates varied among locations. For 2004, th ey were 276 kg/ha at the north-central location, 103 kg/ha at the centr al location and 112 kg/ha at the southwest location. For 2005 these rates were 313 kg/ha at the north -central location, 114 kg/ ha at the central location and again 112 kg/ha at the southwest location. Paraffinic hydrocarbon oil was use to control white peach scale ( Pseudaulacaspis pentagona (Targioni Tozzetti)), as needed during the dormant season. Fruit were handthinned just prior to pit hardening to a dist ance of 15 cm between fruit. After thinning, phosmet and captan were applied to control plum curculio ( Conotrachelus nenuphar (Herbst)) and peach scab ( Cladosporium carpophilum (Thum.)), respectively. Postharvest sprays at the north-central lo cation, were a combination of copper sulfate (20% metallic Cu equivalent), a non-ionic surfactant (alkylphenol etozylate, sodium salts of soya fatty acids, and isopropyl alcohol), and phosphoric acid, which were applied every three weeks until mid-Octobe r to control bacterial spot ( Xanthomonas arboricola pv. pruni (= X. campestris pv. pruni )). At the central locati on trees were sprayed until late August and early July in 2004 and 2005, respectively. Ch lorothalonil or a

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70 combination of pyraclostroblin and boscalid wa s applied as needed to control peach rust ( Tranzschelia discolor (F. Chl.) Trans. and Litr.) at the north-central and central locations. For all pesticide applications tree s were sprayed early in the morning. Sprays were applied by using a hydraulic sprayer (John Bean sprayers, Modular Hydraulic Sprayer, Model DM10E200FERH, Hogansvill e, Ga), with a handgun, at 500 psi on all parts of the tree until run off occurred. At the southwest loca tion azoxystrobin and myclobutanil were used mont hly to manage peach rust. Fruit Development Period A visual estimation of the overall bl oom on the tree was done in 2004 and 2005. Bloom was rated twice each week (when appl icable) using a 10% to 100% scale, and the date of petal fall was recorded. FDP was de termined from 50% to 60% bloom to first commercial harvest. Harvest Total yield and weight During 2004, each tree was harvested individually and the numbers and weights of marketable and nonmarketable fruit were record ed. Nonmarketable fruit were delineated as those that were < 4.5 cm, showed signs of wind scaring, catf acing, bacterial spot, insect predation, split pits, deep sutured fruit, or rotten fruit. Fru it were harvested at a firm ripe stage of developmen t; harvest occurred twice each w eek at all locations. Fruit from the north-central locati on were counted and weighed di rectly in the field. Fruit from the central location were bought directly to the laboratory and counted and weighed. Marketable fruit were weighed and the weight and the number of fruit were recorded for each tree at each harvest date. The same pr ocedure was applied to the nonmarketable fruit.

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71 After marketable fruit were weighed a nd counted at the no rth-central location, eleven representative sub-samples from each tr ee for each harvest date were selected at random and placed in peach trays that were obtained from a local grocery store. The trays were then placed in plastic Rubbermaid containers for transpor t to the laboratory. Fruit from the central Florida location were harvested and transported to the laboratory, then weighed and eleven repres entative fruit samples were se lected as described above. During 2005, the procedure was changed slightly so that fruit from the central Florida location were weighed on site. Fruit se lection and transport were the same. At the north-central location, it appeared that the east sides of the trees had fewer fruit than the west sides of the trees. This looked to be true for all four cultivars. To determine if there was a difference in locat ion of fruit in the tree canopy, each tree was divided into two sectors, east and west, and fruit were counted and weighed as such. Trunk measurements Every six months after leaf fall and after fruit harvest, trunk circumference was measured. Readings were taken using a 150 cm dressmakers tape at a pre-determined spot 15 cm above the ground level. This was later used to calculate trunk cross-sectional area (TCA). Fruit size, weight, and blush Fruit sub-samples were placed in a walk-i n cooler (3 5C), where they were cooled to remove field heat. Prior to fruit quality measurem ents fruit were removed from the cooler the previous day and allowed to wa rm to room temperature. Ten fruit from each sub-sample were measured in three diffe rent orientations: blossom end to stem end, cheek to cheek, suture to side opposite sutu re. Each 10-fruit sample was weighed and each fruit was rated visually for the amount of red blush under fluorescent light.

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72 Chromicity values In 2005, at early (first commercial) harv est and mid harvest (greatest number of fruit removed per tree), a Konica Minolta CR 400/410 Chroma meter (Konica Minolta, Osaka, Japan) was used to test the chromi city values on the most blushed and least blushed surface areas of five fruit from each 10-fruit sub-sample. The chroma meter was calibrated using a standard calibration plate prior to each use. For post harvest measurements in 2005, the same five fruits th at were used for chromicity measurements were used for soluble solids concentrati on (SSC), titratable acidity (TA), pH, and pressure measurements. During 2004 five fru its were selected at random from the ten fruit sample for fruit size, weight, and blush at early and mid harvest. Blossom end During 2005, fruit blossom end tips were ra ted as either recessed, flattened, or extended. Thirty fruit were selected at random from the marketable fruit from each tree during peak harvest and rated in the field for blossom end tip. Fruit that would be damaged in shipping were considered extended tip fruit. Firmness, soluble solids concentrat ion, titratable acidity, and pH Flesh firmness was measured using a fi rmness tester (IFAS Firmness Tester, Gainesville, FL) fitted with a 6 mm probe. Tw o measurements per fruit were taken (from the center of each cheek) from 5-fruit samples. The epidermis was removed from the test area prior to measuring flesh firmness. Fr uit were peeled and flesh samples were collected from the cheek area of each fr uit (avoiding the points where pressure measurements were taken, and the suture, a nd opposite the suture). A composite flesh sample was obtained for each 5-fruit sub-sample Flesh samples were quick frozen in a 80C freezer and stored at -30C. Flesh samp les were removed from the freezer, allowed

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73 to thaw at room temperature, and homogenized in a blender. The slurry was centrifuged for 20 minutes at 14,000 rpm at 5C. The samp les were then filtered through two layers of cheese cloth into a 50 ml b eaker. Six g of supernatant di luted with 50 ml of deionized water was used to measure TA. Samples were titrated to an end point of 8.2 using an automatic titrimeter (Fisher Titrimeter II, No. 9-313-10, Pittsburg, Pa) and expressed as ml NaOH. The normality of NaOH used wa s 0.1N. The remainder of the undiluted supernatant was used to determine pH and SSC. A Digital Refractometer (Reichert-Jung, Mark Abbe II Refractometer, Model 10480, Depe w, NY) was used to measure the SSC of the undiluted sample and was expressed as Br ix. The pH of the sample was measured using a pH meter (Corning Scientific In struments, pH meter 140, Medfield, Ma). Statistical Analysis Statistical analysis was achieved using SA S 9.1 (SAS Institute Inc., Cary, NC). Means were determined using PROC GLM a nd means separations among and within the locations were by Tukeys HSD at the P 0.05 level. Results Due to higher rates of N applied at the north-central location, direct comparisons could not be made between this location and the central and so uthwest locations. Variables from this location were placed in sepa rate tables when significant interactions existed between location and cultivar. Sta tistical comparisons were used between the central and southwest locations. Fruit Development Period During 2004, UFGold had the shortest FD P at the north-central and central locations (Tables 8 and 9). In central Fl orida, the FDP was l onger for TropicBeauty than for the other three cultivars and longer than either Flordaprince or Flordaglo in

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74 southwest Florida. Flordaglo had a longer FDP within central Fl orida than southwest Florida. UFGold had a longer FDP at the southwest location compared to the central location. Statistical comparisons could not be made between the north-central location and other locations because of the higher nitrogen rates used in north-central Florida. However, in general FDP was generally l onger at this location than the other two locations. During 2005 within both north-central and central Florida, TropicBeauty had the longest FDP and UFGold th e shortest (Tables 10 and 11). At the southwest location Flordaprince had the shortest FDP. All cultivars had a si gnificantly shorter FDP at the central location then at the southwest location. Direct co mparisons could not be made between the north-central lo cation and the other locatio ns, however again FDP was longer in north-central Florida compared to the other locations A consistent pattern for cultivar FDP was observed at both the north -central and central locations during both years. Generally, UFGold had the s hortest FDP, followed by Flordaprince, Flordaglo, and TropicB eauty (Tables 8,9,10 and 11). Fruit Number, Weight, and Set No significant interactions were observe d between location and cultivar for fruit number adjusted for trunk cross-sectional ar ea (TCA), or for percent fruit set during 2004 and 2005. Therefore, only the main effects are presented for each variable. During 2004, the adjusted number of fru it was greater in UFGold than other cultivars (Table 13). Significant differen ces were not observed among locations. During 2005, the adjusted number of fruit was greate r in Flordaglo and UFGold than in Flordaprince or TropicBeauty. Greater values for adjusted fruit number were observed at the central location comp ared to the north-central location.

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75 During 2005, the percent of fruit set was lower in TropicBeauty than in Flordaglo or UFGold. Diffe rences in the percentage of fruit set during 2005 were not significant among locations. During 2004, adjusted fruit yield was greater for UFGold than for Flordaprince or TropicBeauty within north-central Florid a (Table 13). A lower adjusted yield was observed in central Florida for Flordaprince compared to Flordaglo or UFGold. During 2004, site differences were only observe d in UFgold, a grea ter adjusted yield was observed at the north-centr al location than at the centr al location. During 2005, the adjusted yield was greater for UFgold than F lordaprince within north-central Florida. A greater adjusted yield was observed in cen tral Florida for Flordaglo and UFGold, than observed in Flordaprince or TropicB eauty. At the southw est location, a greater adjusted yield was observed for Flordaglo th an for Flordaprince or UFGold. During 2005, a greater adjusted yield wa s observed for TropicBeauty at the southwest location than the other locations. The adjusted yiel d was high in Flordaglo within the central Florida location. Fruit Blossom End No significant differences among cultivars were observed for the percent of fruit with flattened blossom ends in southwest Florida during 2005 (Fi gure 12). However, Flordaglo had less fruit with flattened blosso m ends than the other cultivars at both the central and north-central locations. The per centage of fruit that exhibited flattened blossom ends was similar at all three lo cations, and generally ranged from 40 70%. Differences among cultivars were observed for fruit that had recessed blossom end at all locations. TropicBeauty tended to have the lowest percent of fruit with this phenotype at all locations, although differences were not signifi cant for all cult ivars at all

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76 sites. Within central Florida, the percent of fruit with recessed blossom ends was higher for Flordaglo than for TropicBeauty. At the southwest loca tion UFGold had a higher percent of fruit with recessed blossom en ds than Flordaprince or TropicBeauty. There was a general trend for a reduction in the percentage of fruit that showed recessed blossom ends as the locations pr ogressed south for all cultivars. There were no differences observed among cultivars within both the north-central and central areas of Florida for fruit with extended blossom ends. A higher percent of fruit with extended blossom ends was obser ved for TropicBeauty than for the other cultivars at the southwest site In southwest Florida, U FGold had fewer fruit with extended tips than Flordaprinc e. Across locations there was a low percentage of fruit that exhibited extended blossom ends in northcentral Florida. Gene rally, percentages of fruit with extended blossom ends incr eased as locations progressed south. Post Harvest Quality Titratable Acidity. No significant differences for TA were observed among cultivars during 2004 in central Florida (Tab le 14). In the no rth-central location, TropicBeauty had a higher mean value for TA than UFGold or Flordaprince (Table 15). UFGold had a lower TA at the southwest site comp ared to the other cultivars (Table 14). Differences between the central and southwest locati ons were only observed for UFGold, which had a highe r TA at the central location. During 2005 interactions between location and cultivar for TA, were not significant. Therefore, only the main effect s are presented. Higher values for TA were observed in Flordaglo and T ropicBeauty than in Flordap rince or UFGold (Table 16). Lower TA values were observed at the southwest location than at the central or north-central locations.

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77 Soluble Solids Concentration. During 2004, there were no significant differences among cultivars for SSC at the southwest location (Table 14). In north-central Florida, TropicBeauty SSC values were higher than UFGold (Table 15). At the central Florida location, Flordaglo had lower SSC than either Flordaprince or UFGold (Table 14). A difference between the central and s outhwest locations was only observed for Flordaprince which had a higher SSC valu e at the central location. Although direct comparisons could not be made with the north-central location, several cultivars were observed to have lower SSC values at this lo cation relative to the other locations. (Tables 14 and 15). There were no significant differences observed among cultivars for SSC at either the north-central or central locations dur ing 2005 (Tables 17 and 18). In southwest Florida UFGold had a higher value for SSC than the other cultivars (Table 17). Differences were observed between the central and southwest locations for Flordaprince, Flordaglo, and UFGold. These cultivars had higher SSC values in Southwest Florida than in central Florida. Statistical comparisons could not be made with the north-central location; however, valu es were lower for all cultivars at this location compared to the other two locations (Tables 17 and 18). SSC:TA Ratio. During 2004, no significant interact ions were observed between location and cultivar. Therefore, only the main effects are presented for this year. The ratio was higher in UFGold compared to th e other cultivars. A lower SSC:TA ratio was observed in the north-central location th an the central or southwest locations. During 2005, Flordaglo had a lower SSC:TA ra tio than either Flordaprince or UFGold at the north-central location (Table18). At bot h the central and southwest

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78 locations UFGold had higher SSC:TA ratios than the other cultivars which were not different from one another (Table 17). Between the central and southwest locations, higher SSC:TA ratios were observed for all cu ltivars in the southwest location. Even though statistical comparisons were not made with the north-central location, SSC:TA ratios tended to be lower at this location compared to the other two locations (Tables 17 and 18). Pressure. During 2004, fruit pressure readings we re higher for UFGold than for either Flordaglo or Tropi cBeauty at both the north-centr al and central locations, and higher than Flordaprince at the central lo cation (Tables 14 and 15). Pressure readings in southwest Florida were higher for F lordaglo than for Flordaprince or TropicBeauty (Table 14). Between the centr al and southwest loca tions, fruit pressure readings were higher in UFGold and T ropicBeauty within the central location. During 2005, UFGold had higher pressure readings than the other cultivars at the north-central location (Table 18). In th e central Florida, higher pressure readings were observed for Flordaglo than for eith er UFGold or Tr opicBeauty and both of these were greater than Flordaprince (Table 17). Within the southwest site UFGold had a higher pressure reading than either F lordaglo or Flordaprince, and these were higher than TropicBeauty. Higher fruit pre ssure readings were obs erved in the central location than southwest location for Flord aprince, Flordaglo, and TropicBeauty. Color Percent blush During 2004, a trend was observed between nor th-central and cent ral Florida where higher percent blush values were observed fo r Flordaprince and Flordaglo than for UFGold and TropicBeauty (Table 20 and 21). However, in southwest Florida, higher

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79 values were observed for TropicBeauty th an for UFGold which had the least blush (Table 20). Blush values were higher acr oss all cultivars at the southwest location compared to the central location. Even though statistical comparisons could not be used for north-central Florida, it was observed that blush values tended to be lower at this location than at the other two locations (Tables 20 and 21). During 2005 UFGold had the least blush of any cultivar at all sites (Tables 22 and 23). Significant differences were observed am ong all cultivars at th e southwest location. Flordaprince had the hi ghest percent blush cover, followed by Flordaglo, TropicBeauty, and UFGold (Table 22). As in the previous year, blush values were highest for all cultivars at the southwest locat ion. Even though direct comparisons could not be used it was observed th at blush values tended to be lower at the north-central location than at the other locations (Tables 22 and 23). Colorimeter Colorimeter measurements were taken during 2005. Two measurements were taken representing the highest and lowe st blushed surfaces on each fruit. Light. L* values from the highest blushed surface of the fruit were lower in Flordaglo than in UFGold or TropicBeauty in north-c entral Florida (Table 24). Within the central location UFGold had highe r L* values on the highest blushed area for all cultivars. At the southwest location, significant differences were observed among all cultivars. UFGold had the greatest L* value on the highest blush surface of the fruit; followed by TropicBeauty, Flordaglo, and Flordaprince. L* values for the lowest blushed surface were higher for TropicBeauty than for the other cultivars in north-central Florida. Flordaglo and TropicBeauty had higher L* values on the lowest blushed surface than Flordaprince or UFG old at the central

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80 location. In southwest Florida, UFGold ha d higher L* values on the lowest blushed surface of the fruit than a ny of the other cultivars. Chroma. C* values on the highest blushed su rface of the fruit were higher in UFGold than in Flo rdaglo at the north-central loca tion. Within both the central and southwest locations, UFGold had a higher C* value than the other cultivars on the highest blush surface of the fruit. A trend for C* values on the lowest blushed surface of the fruit was observed for the cultivars at both north-central and central Florida locations. Si gnificant differences were observed among all cultivars. UFGold had the greatest C* value followed by TropicBeauty, Flordaprince, and Flord aglo. Within the southwest location UFGold had C* values that were higher th an the other cultivars and Flordaglo C* values were lowest. Hue. Hue values on the highest blushed su rface of the fruit were lower for Flordaglo than for UFGold or TropicBeauty at the no rth-central location. Within central Florida, UFGold had higher h* values than the other cultivars which were not different from one another. At the southw est location higher h* values were observed for UFGold and TropicBeauty than fo r Flordaprince or Flordaglo. On the lowest blushed surface of the fru it TropicBeauty had a higher h* value than Flordaprince. In central Florida, hi gher values were observed in Flordaglo and TropicBeauty than in Flordaprince or UFGold. Significant differences were observed among cultivars within the southwest location. At this lo cation UFGold had the highest h* value followed by TropicBeauty, Flordaglo, and finally Flordaprince.

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81 In general values for the highest blus hed location on the fruits were tightly clustered together when hue and croma values were graphed together for all cultivars at all locations indicating little va riation between cultivars and lo cations for this trait (Figure 13). Values for the lowest blushed location on the fruits tended to be more scattered for all cultivars within all locations indicating high variation for this trait among cultivars and locations. Individual Fruit Weight Differences were observed for i ndividual fruit weights during 2004. TropicBeauty had the greatest mean fruit wei ghts at the central and southwest locations and greater fruit weight than Flordaprince or UFGold in north-c entral Florida (Tables 20 and 21). Within the central location, all cu ltivars were significantly different from each other. TropicBeauty had the greatest fruit weight, followed by Flordaglo, Flordaprince, and UFGold (Table 20). Wh en the central and sout hwest locations were compared, fruit weights were greater for Flo rdaglo and TropicBeauty at the central location and higher for Flordaprince and F lordaglo at the sout hwest location. Even though direct statistical compar isons were not used, fruit we ights were generally greater in the north-central location compared to the other locations (Tables 20 and 21). During 2005 a trend was observed between nor th-central and central Florida where fruit weights were greatest for Tropi cBeauty, followed by Flordaprince and Flordaglo, with the least we ight for UFGold (Tables 22 an d 23). At the southwest site TropicBeauty fruit weight wa s greater than UFGold (Table 22). Between the central and southwest locations, across all cultivars, fruit weights were greater at the central location. Results at the northcentral location were similar to the previous year in that fruit weights tended to be higher than at the other two locations (Tables 22 and 23).

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82 Fruit Size Cheek Diameter. Average cheek diameter was unavailable from the north-central and central sites during 2004 due to measurem ent error. At the only locality in where data was available, the so uthwest location, TropicBeauty had the greatest cheek diameter (Table 20). This data was available from all thr ee locations during 2005. In north-central Florida TropicBeauty had a higher cheek diamet er than either Flo rdaglo or UFGold (Table 23). Higher cheek diameter was also observed in TropicBeauty than the other cultivars in central and sout hwest Florida (Table 22). UFGold tended to have the lowest cheek diameter at most locations. Between the central and southwest locations, cheek diameter was highest at the central loca tion for all cultivars. Cheek diameters at the north-central location were generally obs erved to be higher; however statistical comparisons were not used (Tables 22 and 23). Suture Diameter. Average suture diameter was larger for TropicBeauty than for UFGold during 2004 at the north-central locati on (Table 21). TropicBeauty also had a larger suture diameter than the other cultivar s in central and southwes t Florida (Table 20). Larger suture diameters were observed in s outhwest Florida than in central Florida for Flordaprince and UFGold. Suture diameter was larger at the central location for TropicBeauty than at the southwest location. Suture diameter was observed to be larger at the north-central location than at the central or southwest locations, but was not compared to these locations because of hi gher N rates applied th ere (Tables 20 and 21). During 2005, TropicBeauty had a larger suture diameter than Flordaprince or UFGold at the north-central location (Table 23). In central and southwest Florida a trend was observed with Tr opicBeauty again having a larger suture diameter than the

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83 other cultivars (Table 22). This was fo llowed by Flordaglo, Flordaprince, and UFGold. Suture diameters for Flordapri nce, Flordaglo, and TropicBeauty were generally larger in central Florida compared to southwest Florida. It was observed that the suture diameters at the north-central lo cation were larger than at the central or southwest locations; however direct statisti cal comparisons were not made (Tables 22 and 23). Fruit Length. During 2004, a trend was observed at all locations where UFGold had shorter fruit length than the other cul tivars (Tables 20 and 21). Fruit length was larger in southwest Florida for Flordaprince UFGold and TropicBeauty (Table 20). Comparisons with the north-central location could not be made, however it was observed that fruit length tended to be greate r at this location (Tables 20 and 21). No significant interactions between lo cation and cultivar were observed during 2005 for fruit length. Therefore only the main effects are presente d. Fruit length was less in UFgold compared to the other cultiv ars (Table 24). Fruit length was greater at the north-central location then at the southwest location. Discussion The yield and quality attributes of peache s, observed in this experiment, varied significantly within and among the different locations and cultivars. There are many factors that can affect fruit quality and yiel d. Cultural practices and climate at a given location can have a pronounced effect on fruit yield and quality. Cu ltural practices such as fertilizer rates and irriga tion programs, pruning and thinni ng, can all have a significant affect on quality attributes such as fruit size, blush, and sugar content. Genotypic differences are also important, and many cultivar s differ in their quality attributes. Some cultivars can have higher SSC or TA levels than other cultivars. Genetic, cultural, and

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84 climatic factors collectively can affect the final size, shape, color, as well as other quality indices. Fruit Development Period Similar patterns were found for fruit development for the same cultivars grown in different locations. A pattern for fruit development among cultivars was observed for both the north-central and cen tral locations during 2004 and 2005. TropicBeauty had the longest FDP followed by Flordaglo, Florda prince, and UFGold. This follows the release statements for length of FDP for the different cultivars. However in southwest Florida FDP of TropicBeauty and UFGold were similar. This may be because UFGold did not receive adequate chilling in southwest Florida thereby extending the bloom period and resulting in an error in th e estimation of full bloom. FDP of UFGold was about 6 to 7 days shorter in north-central than in southwest Florida both years. Information pertaining to different patterns in fruit development at different locations, can help growers determine what cultivars w ould be suitable for their location to have continuous production of peaches during the im portant April and May market window in Florida. Although the relative pattern for fru it development of the cu ltivars was the same at the different locations, length of the FDP was different between the two locations and between both years at the central location. The shorter FDP and later harvest in the cen tral location can be attributed to the delayed bloom experienced during 2005 and wa rmer temperatures du ring the first stage of fruit development. The FDP for 2005 was s horter in the central location than in the other locations or during the pr evious year for the same lo cation. The delayed bloom in 2005 may be attributed to several different fact ors, or a combination of factors, such as insufficient chilling, high incidence of b acterial spot, and the passage of several

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85 hurricanes through the region the previous fall, as discussed in the previous chapter. Temperatures can have a pronounced eff ect on fruit development. In central Florida, chilling was unusually low in 2005. Th is lead to a full bloom date that was one month later than the previous year. Yet ha rvest at the central lo cation was only delayed two weeks. Since bloom in 2005 was delayed nearly a month, the first stage of fruit development occurred at a time when temperatures were warmer resulting in an accelerated rate of development. The difference in temperature during the fi rst stage of fruit development between 2004 and 2005 probably accounts for the reduc tion in FDP observed. Temperatures during the early stages of development have been shown to affect the FDP of both peach (Batjer and Martin, 1965) and apricot (Li lleland, 1936). During 2004 within the central location, the length of the FDP followed the in formation released for each cultivar (Rouse and Sherman, 1989b; Sherman and Lyrene, 1997; Sherman and Lyrene, 1989; Sherman et al., 1982). In general, there was a ten da y difference observed in the FDP at the central location between 2004 and 2005. Topp and Sherman (1989a) reported that a 1C reduction in mean temperature over the entire FD P can result in a 5-day increase in FDP. Boonprakob et al. (1992) indicate d that using the average dail y temperature 30 to 45 days after full bloom was a good predictor for the leng th of the FDP. They reported a 2 to 6 day reduction in FDP for every 1C increase in mean temperature, depending on the cultivar. The 30 day period following full bloom would have been predominantly in the month of February, 2004, and March, 2005. Th e average temperature for the month of February, 2004, was 16.65C and the average te mperature for the month of March, 2005, was 18.13C. This is a 1.48C temperature di fference between the two years. This

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86 temperature difference most likely resulted in the reduction in FDP during 2005 at the central location. The increased length in FDP may also be attr ibuted to the higher rates of N applied. The amount of N applied during the course of a season can affect the FDP as well as many different fruit quality attributes. With in the north-central location, N application rates were more than twice that at the other locations. Higher N rates have been shown to affect the FDP of peaches (Saenz et al., 1997). The addition of higher N rates may have further contributed the longer FDP observe d in the cultivars at this location. The effect that the increased rates of N had at the north-central location was calculated for 2004 using the mean FDP of Flordaprince, Flordaglo, and TropicBeauty at the three different locations UFGold could not be used because of the longer FDP observed in the southwest lo cation may be attributed to insufficient chilling. The mean FDP of th e three cultivars for the th ree locations was used to determine the mean temperature during fruit development. The difference in FDP and mean temperature was determined between central and southwest Florida. The difference in FDP and mean temperature over fruit develo pment was used to calculate the increase in length of FDP for every 1C; this differe nce was a 4.4 day increase for a 1C decrease in mean FDP temperature. The difference in mean FDP temperature between the northcentral and southwest locations was 2.56C. This difference was multiplied by 4.4 to get an 11.3 day difference in FDP between the sout hwest and north-central locations. When the mean FDP at the north-central location was subtracted from the mean FDP at the southwest location the difference was 12.3 days. This shows only a one day increase in the length of FDP at the north-central locati on from the higher rates of N applied at that

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87 location. Therefore it is like ly that the longer FDP in north -central Florida resulted from to cooler temperatures at that location rather than the higher rates of N. Fruit Size, Shape, and Yield Fruit size and shape varied considerably among the different cultivars at the different locations. In some cases, fruit si ze and shape were differe nt from previously reported information. Mean fruit weight, ch eek diameter, suture diameter, and fruit length tended to be greater for TropicBeauty an d lesser for UFGold at all locations. It was previously reported that TropicBeau ty and UFGold produce peaches averaging 100 g and 110 g respectively (Rouse and Sherman, 1989b, Sherman and Lyrene, 1997). Results obtained in this experiment show ed that fruit average fruit weights of TropicBeauty were over 100 g at all locations and in some instances well over 100 g. The opposite was true for UFGold. UFGold fruit weights close to those in the release statement were only achieved at the north-central location wh ere the trees received higher N rates. In the central and southwest locati ons fruit weights were much less than the 110 g specified in the release statement. Competition among fruits may be one possi ble explanation for the reduced fruit size due to the higher fruit set in UFGold Generally there was a higher adjusted number of fruit per tree for UFGold than for TropicBeauty. More carbohydrates may have been available to the TropicBeauty fru it due to the lower fruit set, and this may have resulted in increased fruit size. It is also possible that hi gher N rates than were applie d in central or southwest Florida are needed to attain moderately la rge fruit for UFGold Higher rates of N fertilizer applied in north-central Florida ma y have resulted in the larger fruit observed there for all cultivars. Averag e fruit weights, dimensions, a nd lengths were all greatest in

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88 north-central Florida. It has been reported that fruit size a nd weight can be affected by N rates. Saenz et al. (1997) repor ted an increase in fruit mass at higher N rates. Rates of N fertilization at the north-cen tral location were at least 2.5 times higher than at the locations in central or southwes t Florida. The fertilizer was also spread out over several light applications. This may have resulted in more N being available for plant uptake and less N leached below the root zone compared to only tw o or three applications. Small fruit size for several cultivars in the central location during 2004 may be the result of water restriction from lack of i rrigation during stage III of growth. During 2004, in the central location, low fruit weights were observed for Flordaprince and UFGold but not for Flordaglo or TropicBeauty. Pr ior to harvest in 2004, th e irrigation line for the entire planting of trees at the central location was damaged and irrigation was not applied for two weeks. The break in the irrigation line occurred during the last two weeks of March, 2004. It has been shown that water restrictions during stage III of development can affect fruit size (Li et al ., 1989). Flordaprin ce and UFGold both have FDPs that are shorter than Flordaglo or TropicBeauty. Flordaprince and UFGold were probably furt her into stage III of fruit growth than Flordaglo or TropicBeauty during th e non-irrigated period. Harvest of Flordaprince and UFGold began two weeks after the irri gation line was repaired while harvest of Flordaglo and TropicBeauty began three to four weeks after the repair. Flordaglo and TropicBeauty which have longer FDPs proba bly received more water during stage III of fruit growth than either Flordaprince or UFGold. The low fruit weights for Flordaprince and UFGold during 2004 were likely a result of reduced irrigation during fruit growth.

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89 During 2004 it appeared that there may be a difference among the types of blossom end (i.e. recessed, flattened, or extended) amon g the cultivars and locations. This trait was observed during the 2005, season to de termine if a difference existed among locations or cultivars. Temperature di fferences among the locations during fruit development may be the cause of the differences observed in the percen tage of fruit with sunken and extended blossom ends. There appeared to be more fruit with recessed blossom ends at the north-central location a nd more fruit with extended blossom end at the southwest location. Peaches with extended blossom ends have been reported by various authors (Salvador et al., 1998; Topp and Sherman, 1989b). Pronounced blossom end development has been attributed to warmer temperatures in an area (Topp and Sherman, 1989b) and to inadequate chilli ng or prolonged dormancy (Byrne and Bacon, 1992; Campbell et al., 1995; Koffmann and Patten, 1992; Rouse and Sherman, 2002a; Rouse and Sherman, 1989a). Cultivar differences may exist for the per centage of fruit with extended blossom ends. Some of the cultivars in this experi ment such as Flordaglo and TropicBeauty had a higher percentage of fruit with a more pronounced tip in southwest Florida compared to other cultivars such as UFGol d. New low-chill cultivars and selections should be tested in warm areas to determine the prevalence of this condition prior to their release since fruit that exhibit pronounced tips are easily damaged in shipment. Cultivars that exhibit this trait would probably be bett er suited for producti on in cooler climates. Yield varied considerably among genotypes, locations, and years. It can be influenced by weather and cultural practices. Since yield is so vari able, it is difficult if not impossible to determine an average yiel d for each cultivar. Generally, Flordaglo

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90 and UFGold had higher adjusted yields than Flordaprince or TropicBeauty. One reason for the higher yields for these two cultivars is that gr eater amounts of flower buds were set in these two cultivars. This agr ees with the release statements by Sherman and Lyrene (1997; 1989). By setting higher numbe rs of flowers than other cultivars, yield losses from late spring frosts and freezes can be minimized and higher yields can be accomplished. However, this can lead to in creased costs from greater fruit thinning requirements. Higher rates of N at the north-central lo cation may have also contributed to the higher adjusted yield and adjusted fruit number at that location. It has been shown that higher N rates can affect yi eld (Saenz et al., 1997; Shoe maker and Gammon, 1963). This along with overall better health of the trees possibly contributed to the higher adjusted yield observed. Fruit size and weight were also greater at the north-central location. Larger fruit contributed to high yields obtained at the north-central location. Color Fruit color is important for market sale of peaches. Consumers want peaches that have a high blush and bright yellow ground color (Anderson and Sherman, 1994). Fruit color varied among the different cultivars and locations. Generally the highest blush was observed in Flordaprince a nd the lowest was observed in UFGold. However blush values at several of the locations were lower than what is stated in the cultivar release statements, only at the southwest location di d percent blush reach previously reported values for these cultivars. The release statem ents indicate that Flo rdaprince has a blush of approximately 80% and UFGold has a bl ush of about 70-90% (Sherman and Lyrene, 1997; Sherman et al., 1982). We observed fr uit blush values around 40 % for UFGold and around 60 % for Flordaprince within the north-central location during both years.

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91 Blush values in central Florida for UFG old were approximately 45% during 2004 and 60% during 2005, and values for Flordaprince were 60-65% during both seasons. Fruit blush values for Flordaprince and UFGol d appear to be lower than previously reported. Reduced blush in more northern locations and higher blush at the southwest location might be due to greater sunlight expos ure to the fruit at the southwest location. Generally blush values observed in southwes t Florida agreed with previously reported information (Rouse and Sherman, 1989b; Sherman and Lyrene, 1989; Sherman and Lyrene, 1997; Sherman et al., 1982). Highe r UV irradiance from sunlight has been shown to increase both red color development and concentration of anthocyanin (Kataoka and Beppu, 2004). In the Northern Hemisphere as locations progress further south, the intensity of solar radiation in creases. The trees within the southwest location probably had a higher intensity of sunlight than the trees at the north-central location. This higher intensity of sunlight would at least partia lly account for the increased blush observed at the southwest location. The amount of light entering the canopy is another factor which can have an effect on fruit quality. The dense canopy cover and excessive growth at the north-central location from the higher amounts of N fertili zer most likely contributed to the lower blush at that location. Trees at the central and southwest locations had less canopy cover and the fruit had greater expos ure to light. Several report s have shown that increased light exposure can cause a highe r red blush in peaches (Er ez and Flore, 1986; Lewallen and Marini, 2003; Kataoka and Beppu, 2004).

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92 Fruit Quality There were several fruit quali ty traits that differed among cultivars. TA values were lowest in UFGold across locations and the SSC:TA ratio wa s highest in this cultivar. SSC values for UFGold were sim ilar to the other cultivars. The higher value for the SSC:TA ratio for UFGold can be at tributed to the lower TA values. Also UFGold tended to be firmer than other cultiv ars. UFGold received some of is genetic background from clingstone germplasm and it is considered a nonmelting flesh peach. Nonmelting flesh peaches are firmer than melting flesh cultivars due to lower levels of endo-polygalacturonase. Differen ces in organic acids have been observed between peach and nectarine mutants, with higher levels re ported for nectarine (Wen et al., 1995). Also the composition of organic acids in melting fl esh peaches has been studied, with malic acid being the predominant acid (Byrne et al. 1991). Differences among the different maturity stages in nonmelting flesh peaches have also been studied, with lower levels of TA observed at more advanced maturity levels (Brooks, et al. 1993). However, information regarding differences between nonmelting and melting flesh peaches for levels of TA at the same stage of matu rity is not available in the literature. The lower values for SSC at the north-cen tral location may be a result of higher N rates used at this location. During both y ears it was observed that the north-central location generally had lower SSC and SSC:TA ratios than the other locations across all cultivars. Fruit quality can be affected by hi gh amounts of N. Jia et al. (1999) concluded high N rates inhibited sugar accumulation in peac h. This is similar to what we observed. The trees at the north-central location had higher N rates and generally had fruit with lower sugar content as measured in brix values. The increased rate of N probably contributed to lower overall brix values in the fruit.

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93 Higher brix values in the central lo cation during 2004 for three of the four cultivars may be the result of the break in th e irrigation that occurre d during stage III of fruit growth. Water restrictions during stag e III of development can increase the brix levels in fruit (Li et al., 1989). Since Flo rdaprince and UFGold were well into stage III of fruit growth, and Flordaglo and Tr opicBeauty were at the end of the second stage or the very beginni ng the third stage, brix ma y have been increased for Flordaprince and UFGold, but no t Flordaglo or TropicBeauty. General Conclusions The quality indices observed in this experime nt varied within the different locations and by the different cultural practices used. Hi gher blush values at the southwest location may be attributed to higher incidence of sun light at that particular location. The longer FDP observed at the north-central location can be attributed to cooler temperatures at that site compared to the other locations. Water re strictions during a critical growth stage at the central location during 2004 were probably the cause of the increase brix levels observed in some cultivars. Competition among fruits in UFGold may have been the cause of low fruit weights observed for this cul tivar compared to the other cultivars in the experiment. Testing cultivars in several locations can help to determine the adaptation of certain cultivars for different areas. The high N rates used in north-central Fl orida may provide valuable information on response of low-chill peach cultivars to hi gher than currently r ecommended nitrogen rates in Florida. It was observed that the hi gher rates of nitrogen w ithin the north-central location resulted in longer FD P, increased yield, larger fr uit size, and lower brix. Greater yields may be possible by in creasing nitrogen rates above current recommendations, or by applying nitrogen fert ilizers in small frequent applications.

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94 However, further testing need s to be done to determine th e optimum amount of nitrogen needed to increase yield and fruit size, without reducing br ix values, blush values, and increasing the FDP. Information on fruit development and on quali ty attributes such as brix and fruit shape can help growers in choosing cultiv ars to fulfill certain market windows and market niches such as white flesh or donut peaches. FDP is very important in areas such as Florida where the production window is confined to April and May. If this timeframe is missed, then the crop will be harvested at a time when competition from other regions, such as California or South Georgia, will have lowered market prices for Florida fruit.

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95 Table 8. Bloom dates, harvest dates, and fr uit development period (FDP) for four lowchill peach cultivars for the central and southwest locations for 2004. Bloom Date Harvest Date (first Commercial) FDPz (Days) Central Cultivar Flordaprince 01-28-04byAx 4-19-04cA 82.6bA Flordaglo 02-02-04bA 4-25-04abA 84.2bA UFGold 02-09-04aA 4-20-04bcA 72.0cB TropicBeauty 01-28-04bB 4-29-04aA 93.0aA Southwest Cultivar Flordaprince 01-25-04aA 4-15-04cB 80.8bA Flordaglo 02-02-04aA 4-29-04aA 79.4bB UFGold 01-31-04aB 4-20-04bA 87.2abA TropicBeauty 02-01-04aA 4-30-04aA 89.6aA z Fruit development period y Means within location followed by the same lowercase letter are not significantly different accord ing to Tukeys Test P < 0.05. x Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05. Table 9. Bloom dates, harvest dates, and fr uit development period (FPD) for four lowchill peach cultivars for the north-central location for 2004. Bloom Date Harvest Date (first Commercial) FDPz (Days) Cultivar Flordaprince 01-28-04by 4-26-04c 90.4a Flordaglo 01-31-04b 5-08-04a 97.8a UFGold 02-13-04a 5-03-04b 81.4b TropicBeauty 01-31-04b 5-11-04a 99.0a Significance <0.0001 <0.0001 0.0001 z Fruit development period y Means across cultivars followed by the same lowercase letter are not significantly different according to Tukeys Test P < 0.05.

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96 Table 10. Bloom dates, harvest dates, and fr uit development period (FPD) for four lowchill peach cultivars for the central and southwest locations for 2005. Bloom Date Harvest Date (first Commercial) FDPz (Days) Central Cultivar Flordaprince 02-24-05ayAx 5-5-05bA 71.2bB Flordaglo 02-28-05bA 5-13-05aA 74.0bB UFGold 02-28-05bA 5-3-05bA 65.0cB TropicBeauty 02-23-05aA 5-15-05aA 82.2aB Significance <0.0001 <0.0001 <0.0001 Southwest Cultivar Flordaprince 01-30-05aB 4-17-05bB 78.2bA Flordaglo 02-02-05aB 5-7-05aB 95.0aA UFGold 02-01-05aB 4-30-05abA 88.8aA TropicBeauty 01-21-05aB 4-26-05abB 94.8aA Significance 0.0431 0.0245 <0.0001 z Fruit development period y Means within location followed by the sa me lowercase letter are not significantly different according to Tukeys Test P < 0.05. x Means for cultivars across locations followed by the same uppercase letter are not significantly different accord ing to Tukeys Test P < 0.05. Table 11. Bloom dates, harvest dates, and fr uit development period (FPD) for four lowchill peach cultivars for the north-central location for 2005. Bloom Date Harvest Date (first Commercial) FDPz (Days) Cultivar Flordaprince 02-02-05by 5-02-05c 90.6b Flordaglo 02-05-05b 5-10-05b 94.6b UFGold 02-12-05a 5-03-05c 81.0c TropicBeauty 02-02-05b 5-14-05a 102.2a Significance <0.0001 <0.0001 <0.0001 z Fruit development period y Means across cultivars followed by the same lowercase letter are not significantly different according to Tukeys Test P < 0.05.

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97 Table 12. Main effects of percentage fru it set during 2005 and adjusted marketable number of fruit for both 2004 and 2005 for four low-chill peach cultivars and three locations. 2004 2005 2005 Number/TCAz Number/TCA Fruit Set (%) Cultivar Flordaprince 0.66cy 0.89b 49.8ab Flordaglo 1.79b 1.82a 60.8a UFGold 3.09a 2.32a 64.5a TropicBeauty 1.20bc 0.96b 31.9b Location North-Central 1.66ax 1.22b 35.1a Central 1.64a 1.75a 68.5a z Trunk cross-sectional area (cm2). y Means across cultivars followed by the same lowercase letter are not significantly different according to Tukeys Test P < 0.05. x Means across locations followed by the sa me uppercase letter are not significantly different according to Tukeys Test P < 0.05.

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98 Table 13. Adjusted yield for 2004 and 2005 for four low-chill peach cultivars within three locations. 2004 2005 Fruit Yield (kg)/TCAz Fruit Yield (kg)/TCA North-Central Cultivar Flordaprince 0.08byAx 0.12bA Flordaglo 0.21abA 0.17abB UFGold 0.37aA 0.22aA TropicBeauty0.18bA 0.13abB Central Cultivar Flordaprince 0.06bA 0.11bA Flordaglo 0.22aA 0.28aA UFGold 0.19aB 0.25aA TropicBeauty0.16abA 0.15bB Southwest Cultivar Flordaprince ---w 0.17bA Flordaglo --0.27aAB UFGold --0.16bA TropicBeauty--0.21abA z Trunk cross-sectional area (cm2). y Means within location followed by the same lowercase letter are not significantly different according to Tukeys Test P < 0.05. x Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05. w Data unavailable.

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99 aA abB bcB abA aA aA aB aB bA aA aAB abB bA bA aA aB aA bcA aA abA aA abA aA aA aA aA aA aA bA bAB cB aA aB aB aB aA 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 Recessed NC Recessed C Recessed SW Flattened NC Flattened C Flattened SW Extended NC Extended C Extended SW Blossom End% Flordaprince Flordaglo UFGold TropicBeauty Figure 12. Percentage of peach fruit with s unken, flattened, and extended blossom ends within the North-central (NC), Central (C), and Southwest (SW) locations. Lower case letters represent significant differences among cultivars for a certain trait within a location according to Tukeys Test P < 0.05. Uppercase letters represent significan t differences among locations for a certain trait for each cultivar using Tukeys Test P < 0.05.

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100 Table 14. Post harvest quality measurements for four low-chill peach cultivars during 2004, within the central and southwest locations, for measurements of TA, SSC, and Pressure. TAz SSCy (Brix) Pressure (N) Central Cultivar Flordaprince 0.951axAw 12.38aA 20.75cA Flordaglo 0.972aA 10.59bA 27.21bA UFGold 0.895aA 11.65aA 37.13aA TropicBeauty 1.010aA 11.47abA 20.71cA Southwest Cultivar Flordaprince 0.938aA 11.10aB 17.97bA Flordaglo 1.012aA 11.28aA 23.87aA UFGold 0.706bB 11.18aA 21.37abB TropicBeauty 0.898aA 10.84aA 8.07cB z Titratable acidity. y Soluble solids concentration. x Means within location followed by the same lowercase letter are not significantly different accord ing to Tukeys Test P < 0.05. w Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05. Table 15. Post harvest quality measurements for four low-chill peach cultivars during 2004, within the north-central location, fo r measurements of TA, SSC, and Pressure. TAz SSCy (Brix) Pressure (N) Cultivar Flordaprince 0.904bcx 10.29ab 19.05ab Flordaglo 1.122ab 09.79ab 16.53b UFGold 0.677c 09.17b 21.63a TropicBeauty 1.136a 11.16a 16.71b z Titratable acidity. y Soluble solids concentration. x Means across cultivars followed by the same lowercase letter are not significantly different accord ing to Tukeys Test P < 0.05.

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101 Table 16. Main effects for TA for four lowchill peach cultivars and three locations during 2005. Cultivar TAz Flordaprince 0.880by Flordaglo 1.028a UFGold 0.819b TropicBeauty 0.969a Location North-Central 0.984ax Central 0.970a Southwest 0.826b z Titratable acidity. y Means across cultivars followed by the same lowercase letter are not significantly different according to Tukeys Test P < 0.05. x Means across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05. Table 17. Post harvest quality measurements for four low-chill peach cultivars during 2005, within the central and southwest lo cations, for measurements of SSC, Ratio, and Pressure. SSCz (Brix) Ratio (SSC/TA) Pressure (N) Central Cultivar Flordaprince 11.52ayBx 12.96bB 19.55cA Flordaglo 11.89aB 11.04bB 38.82aA UFGold 11.95aB 14.92aB 29.29bA TropicBeauty12.03aA 11.56bB 26.62bA Southwest Cultivar Flordaprince 12.80bA 15.56bA 13.47bB Flordaglo 12.91bA 14.60bA 13.67bB UFGold 14.37aA 20.17aA 31.24aA TropicBeauty12.29bA 14.75bA 7.89cB z Soluble solids concentration. y Means within location followed by the same lowercase letter are not significantly different accord ing to Tukeys Test P < 0.05. x Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05.

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102 Table 18. Post harvest quality measurements for four low-chill peach cultivars during 2005, within the north-central location, fo r measurements of SSC, Ratio, and Pressure. SSCz (Brix) Ratio (SSC/TA) Pressure (N) Cultivar Flordaprince 9.70ay 10.64a 16.45b Flordaglo 9.44a 8.61b 19.78b UFGold 9.48a 10.73a 30.24a TropicBeauty 10.28a 10.09ba 15.78b z Soluble solids concentration. y Means across cultivars followed by the same lowercase letter are not significantly different accord ing to Tukeys Test P < 0.05. Table 19. Main effects for the ratio of SSC :TA for four low-chill peach cultivars and three locations during 2004. Cultivar Ratio (SSC/TA) Flordaprince 12.21bz Flordaglo 10.42c UFGold 14.43a TropicBeauty 11.32bc Location North-Central 11.05by Central 12.17a Southwest 13.05a z Means across cultivars followed by the same lowercase letter are not significantly different according to Tukeys Test P < 0.05. y Means across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05.

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103 Table 20. Fruit blush, weight, and dimension measurements for four low-chill peach cultivars during 2004 within the central and southwest locations. Blush (%) Individual Weight (g) Cheek Diameter (cm) Suture Diameter (cm) Fruit Length (cm) Central Cultivar Flordaprince 66.71azBy 87.65cB ---x 5.13cB 5.52bB Flordaglo 69.89aB 111.65bA --5.80bA 5.71baA UFGold 58.89bB 73.54dB --4.92cB 5.09cB TropicBeauty 57.00bB 138.28aA --6.30aA 5.93aB Southwest Cultivar Flordaprince 95.33baA 93.88bA 5.45b 5.63baA 5.85bA Flordaglo 91.47bcA 94.44bB 5.48b 5.60bA 5.74bA UFGold 90.53cA 91.07bA 5.51b 5.63baA 5.45cA TropicBeauty 98.20aA 113.24aB 5.97a 5.83aB 6.08aA z Means within location followed by the sa me lowercase letter are not significantly different according to Tukeys Test P < 0.05. y Means for cultivars across locations follo wed by the same uppercase letter are not significantly different accord ing to Tukeys Test P < 0.05. x Data unavailable. Table 21. Fruit blush, weight, and dimension measurements for four low-chill peach cultivars during 2004 within the north-central location. Blush (%) Individual Weight (g) Cheek Diameter (cm) Suture Diameter (cm) Fruit Length (cm) Cultivar Flordaprince 57.18az 153.20b ---y 6.41bc 6.20ba Flordaglo 60.00a 157.25ba --6.65ba 6.25a UFGold 43.79b 132.81c --6.24c 5.96b TropicBeauty 41.05b 163.96a --6.71a 6.25a z Means across cultivars followed by the same lowercase letter are not significantly different according to Tukeys Test P < 0.05. y Data unavailable.

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104 Table 22. Fruit blush, weight, cheek diameter, an d suture diameter measurements for four low-chill peach cultivars during 2005 within the centra l and southwest locations. Blush (%) Individual Weight (g) Cheek Diameter (cm) Suture Diameter (cm) Central Cultivar Flordaprince 62.20azBy 131.34bA 6.32bA 5.91bA Flordaglo 52.90bB 129.42bA 6.26bA 5.95bA UFGold 46.25cB 94.95cA 5.80cA 5.41cA TropicBeauty 47.50cbB 152.86aA 6.69aA 6.47aA Southwest Cultivar Flordaprince 89.80aA 86.26bcB 5.22cbB 5.59bB Flordaglo 79.15bA 100.53baB 5.37bB 5.63bB UFGold 62.25dA 75.16cB 5.08cB 5.28cA TropicBeauty 72.45cA 107.61aB 5.72aB 5.98aB z Means within location followed by the same lowercase letter are not significantly different accord ing to Tukeys Test P < 0.05. y Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05. Table 23. Fruit blush, weight, cheek diameter, an d suture diameter measurements for four low-chill peach cultivars during 2005 within the north-central location. Blush (%) Individual Weight (g) Cheek Diameter (cm) Suture Diameter (cm) Cultivar Flordaprince 57.20az 160.58b 7.02ba 6.63b Flordaglo 59.18a 156.02b 6.83b 6.72ba UFGold 37.40c 118.48c 6.37c 6.15c TropicBeauty 45.80b 171.68a 7.13a 6.90a z Means across cultivars followed by the same lowercase letter are not significantly different accord ing to Tukeys Test P < 0.05.

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105 Table 24. Main effects for fruit length for f our low-chill peach cu ltivars and for three locations during 2005. Cultivar Fruit Length Flordaprince 6.17az Flordaglo 6.09a UFGold 5.32b TropicBeauty 6.18a Location North-Central 6.14ay Central 5.89ab Southwest 5.81b z Means across cultivars followed by the same lowercase letter are not significantly different according to Tukeys Test P < 0.05. y Means across locations followed by the same uppercase letter are not significantly different according to Tukeys Test P < 0.05.

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106 Table 25. Colorimeter measurement values fo r the 2005 harvest season for both the most blushed and least blushed location on each fruit, for L*,C*h* values at three different locations for four low-chill peach cultivars. L* C* h* Most Least Most Least Most Least North-Central Cultivar Flordaprince 36.60baz 64.18b 34.28ba 47.45c 28.66ba 76.37c Flordaglo 35.82b 64.01b 31.59b 32.69d 27.72b 83.12ba UFGold 39.05a 65.52b 35.28a 52.88a 31.59a 80.86bc TropicBeauty 38.64a 68.56a 32.94ba 50.28b 31.90a 88.07a Significance 0.0030 <0.0001 0.0441 <0.0001 0.0018 <0.0001 Central Cultivar Flordaprince 33.32b 65.91b 30.66b 49.36c 25.91b 75.63b Flordaglo 34.85b 69.24a 32.29b 32.66d 27.14b 88.58a UFGold 38.86a 63.90b 37.44a 55.82a 31.35a 74.31b TropicBeauty 35.35b 69.42a 32.12b 52.72b 28.03b 85.86a Significance <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 Southwest Cultivar Flordaprince 30.45d 54.67c 25.90c 49.08b 23.08c 52.01d Flordaglo 32.11c 59.53b 29.24b 34.85c 25.39b 57.74c UFGold 36.61a 64.93a 34.96a 56.18a 28.94a 74.50a TropicBeauty 33.74b 61.46b 25.20c 49.94b 27.95a 76.26b Significance <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 z Means within location followed by the sa me lowercase letter are not significantly different according to Tukeys Test P < 0.05.

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107 FG TB FP UFG FP FG TB UFG TB FP FG UFG UFG FP TB FG TB FP UFG FG TB FP UFG FG0 10 20 30 40 50 60 70 80 90 100 0102030405060 CromaHue highest nc highest c highest sw lowest nc lowest c lowest sw Red Yellow Figure 13. Hue and croma chart for the highest and lowest blushed locations on four lowchill peach cultivars at three locations in Florida.

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108 CHAPTER 5 CONCLUSIONS In this experiment trees planted in more southern locations produced trees with more blind nodes and fruit with more pronounced blossom ends, and higher blush values. A reduction in FDP attributed to an increas e in the average temperature during fruit development was detected between north-centr al Florida and southwest Florida. Lower percentages of blind nodes and higher amounts of fruit with recessed blossom ends were observed in north-central Florid a. UFgold tended to set more fruit and had more nodes with only flower buds compared to the othe r cultivars. Genera lly higher amounts of blind nodes were observed in TropicBeauty comp ared to the other three cultivars. Both environmental and disease factors may have c ontributed to the lower percentage of nodes with vegetative and flower buds and highe r amounts of blind nodes observed in central Florida. Higher rates of N applied at the north-central location pr obably contributed to the higher fruit weights, lower blush values, lower SSC, and higher adjusted fruit number and yield at that location. The time during which peach fruit mature in Florida has important economic considerations in Florida. Fruit ripening typically occurs during April/May when there are relatively few domestic peaches on the mark et and imports have stopped. This is a period when high prices can be achieved from quality fruit. Identifying suitable cultivars and locations in Florida to target this window is vital. Generall y, there was an earlier harvest, shorter FDP, and higher blush in the southwest Florida location. The shorter FDP and earlier harvest can be attributed to warmer temperatures during fruit

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109 development in this area compared to more northern locations. The higher percent blush in the southwest location is most likely do to higher UV irradian ce at this location. Higher UV irradiance has been shown to increase both red color development and concentration of anthocyani n (Kataoka and Beppu, 2004). Ar eas such as the southwest location would be good regions to start production to target the early/mid April market while prices are still high. Flordaprince generally wa s one of the earliest-ripening peaches followed by UFGold. Flordaprin ce would be a good peach to start the early market window because it is one of the earliest to mature and has a high blush coverage, followed by UFGold which has high fruit set, yield, and high SSC:TA ratio. Fruit with extended blossom ends can be easily damaged during harvest and shipment. This trait is generally more pr onounced in warmer areas. New cultivars and selections should be tested in southern areas for prevalence of fruit with this trait. Testing in warm areas will keep cultivars out of the market that are prone to this condition which can limit the amount of ma rketable fruit available for sale. Trees with large amounts of blind nodes ar e difficult to prune because fewer nodes are capable of sprouting. Fr uit born on shoots with blind nodes may also lack size due to insufficient photosynthates. It is importa nt to know which genotypes are the most capable of producing high numbers of both vegetative and floral buds, and those more prone to producing blind nodes. This w ould allow the culling of genotypes with a propensity towards blind nodes. Greater dens ities of floral and vegetative buds are an advantage in areas such as northern Florida or southern Georgia that are prone to late spring freezes which can kill swelling or ope n flowers or shoots (Werner et al., 1988).

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110 Stresses imposed on trees during bud forma tion, in late summer/early fall, from high temperatures or severe weather ma y reduce the number of buds per node and increase the likely hood of blind nodes. Highe r temperatures in the southwest location resulted high amounts of blind nodes at that location, and probably contributed to the increased amounts of blind nodes at the central location. Another contributing factor at the central location was the passage of th ree hurricanes. Defoliation and wind damage, along with higher temperatures probably re sulted in the reduced number of buds and flowers observed. This could be detrimental to tree survival if there are few vegetative buds are set and to crop yields if few flower buds are set. The delayed bloom that was observed in 2005 in central Florida was probably a result of early defoliation from diseases a nd hurricanes. This caused a late season growth flush to occur that may have delayed the onset of dormancy and chill accumulation. Reliable spray programs need to be developed in order to combat disease problems such as bacterial spot and rust, especially in areas with a monsoonal climate, and which produce a heavy layer of dew on the leaves in th e morning. If diseases are not controlled, the resulting defoliation can increase the like lihood of a delayed bloom such as the one experienced in the spring of 2005. If this occurs the early market window may be missed, or low fruit set may occur from fruit being set under warmer temperature conditions (Rouse and Sherman, 2002b). Fertilizer recommendations for some areas of Florida may need to be increased. Greater amounts of nitrogen fertilizer may be needed or more applications may be needed throughout the growing season. It was observed in north-central Florida that fruit size and weight was larger than othe r locations and yields were hi gher. Nitrogen rates were at

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111 least two times higher in north-central Florida, compared to central or southwest Florida, and were probably the cause of the high fruit weights and yields observed. By applying nitrogen to the soil several times and at lo w rates, losses to leaching are reduced, and more is available for the plan t to take in during the year. Higher amounts of nitrogen fertilizer ma y also cause problems. At the northcentral location lower percent blush values lower SSC, and lower SSC:TA ratios were observed, compared to central or southwest Florida. The higher rates of nitrogen fertilizer at this location caused the trees to have excessive growth which probably reduced blush values. It has been reported that trees which have excessive growth during fruit development tend to have fruit which ha ve less red blush due to excessive shading from foliage (Erez and Flore, 1986). Higher ni trogen rates have also been shown inhibit sugar accumulation and the reduction of organi c acids (Jia et al., 1999). Higher nitrogen fertilizer rates need to be tested in order to get an equal balance between increased fruit size and adequate qualit y for market sale. Information obtained through this stu dy can help growers, breeders, and researchers in testing and eval uating different cultivars of pe aches. Testing in several locations and optimizing cultural practices for new cultivars, can ensure optimum yields and quality.

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115 Faragher, J.D. 1983. Temperature Regulation of Anthocyanin Accumulation in Apple Skin. J. Exp. Bot. 34: 1291 -1298. Farina, V., R. Lo Bianco, and P. Inglese. 2005 Vertical Distribution of Crop Load and Fruit Quality within Vaseand Y-shaped Canopies of Elegant Lady Peach. Hortsci 40: 587 -591. Faust, M. and B. Timon. 1995. Origin and Dissemination of Peach. Hort. Rev. 17: 331 379. Francis, F.J. 1970. Color Measurements in Plant Breeding. Hortsci. 5: 102 -106. George, A.P., R.J. Nissen and R.J. Collins. 1994. Effects of Temperature and Pollination on Growth, Flowering and Fruit Set of the Non-Astringent Persimmon Cultivar Fuyu Under Controlled Temperatures. J. of Hort. Sci. 69: 225 -230. Gurdian, R.J. and R.H. Biggs. 1964. Effect of Low Temperatures on Terminating Bud Dormancy of Okinawa, Flordawon, Flordahome, and Nemaguard Peaches. Proc. Fla. State Hort. Soc. 77: 370 -379. Hall, I.V. and R.Stark. 1972. Anthocyanian Pr oduction in Cranberry Leaves and Fruit, Related to Cool Temperatures at a Low Light Intensity. Hort. Res. 12: 183 -186. Hilgeman, R.H. 1966. Effect of Climate of Florida and Arizona on Grapefruit Enlargement and Quality; Apparent Tran spiration and Internal Water Stress. Proc. Fla. State Hort. Soc. 79: 99 -106. Iglesias, I., J. Graell, G. Echeverra, and M. Vendrell. 1999. Differences in Fruit Development, Anthocyanin Content, Yield and Quality of Seven Delicious Apple Strains. Fruit Varieties Journal 53:133 -145. Iglesias, I., J. Salvia, L. Torguet, C. Cabs. 2002. Orchard Cooling with Overtree Microsprinkler Irrigation to Improve Fruit Color and Quality of Topred Delicious Apples. Scientia Hort. 93: 39 -51. Islam, M.S. and S. Khan. 2000. Changes in Quality Characteristics of Three Tomato Cultivars Maturing at Seven Different Sowing Times. Trop. Agric. 77: 236 -243. Iwasaki, N., C. Oogaki, M. Iwamasa, J. Ma tsushima, K. Ishihata. 1986. Adaptability of Citrus Species Based on the Relationships Between Climatic parameters and Fruit Quality Characteristics. J. Japan. Soc. Hort. Sci. 55: 153 -168. Jia, H-J., K. Hirano, and G. Okamoto. 1999. Effects of Fertilizer Levels on Tree Growth and Fruit Quality of Hakuho Peaches ( Prunus persica ). J. Japan. Soc. Hort. Sci. 68: 487 -493.

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118 Okie, W.R. and D.J. Werner. 1996. Genetic In fluence on Flower Bud Density in Peach and Nectarine Exceeds that of Environment. Hortsci. 31: 1010 -1012. Polowick, P.L. and V. K. Sawhney. 1985. Te mperature Effects on Male Fertility and Flower and Fruit Development in Capsicum Annum L. Scientia Hort. 25: 117 -127. Pressey, R. and J.K. Avants. 1978. Differen ce in Polygalacturonase Composition of Clingstone and Freestone Peaches. J. of Food Sci. 43: 1415 -1417, 1423. Priv, J-P., J.A. Sullivan, J.T.A. Proctor, and O.B. Allen. 1993. Climate Influences Vegetative and Reproductive Components of Primocane-fruiting Red Raspberry Cultivars. J. Amer. Soc. Hort. Sci. 118: 393 -399. Porter, G.W., G.D. Richards, B.L. T opp, and W.B. Sherman. 1996. Low-Chill, Nonmelting Flesh Peaches with Fresh Market and Export Potential. Acta Hort. 374: 53 -60. Ragland, C.H. 1934. The Development of the Pe ach Fruit, With Sp ecial Reference to Split-Pit and Gumming. Proc. Amer. Soc. Hort. Sci. 31: 1 -21. Reay, P.F. 1999. The Role of Low Temperatures in the Development of the Red Blush on Apple Fruit (Granny Smith). Scientia Hort. 79: 113 -119. Reay, P.F. and J.E. Lancaster. 2001. Accu mulation of Anthocyanins and Quercetin Glycosides in Gala and Royal Gala Apple Fruit Skin with UV-B-Visible Irradiation: Modifying Effects of Fruit Maturity, Fruit Side, and Temperature. Scientia Hort. 90: 57 -68. Reuther, W., G.K. Rasnussen, R.H. Hilg eman, G.A. Cahoon, and W.C. Cooper. 1969. A Comparison of Maturation and Composition of Valencia Oranges in some Major Subtropical Zones of the United States. J. Amer. Soc. Hort. Sci. 94: 144 -157. Richards, G.D., G.W. Porter J. Rodriguez-A, and W.B. Sherman. 1994. Incidence of Blind Nodes in Low-chill Peach and Nectarine Germplasm. Fruit Varieties Journal 48: 199 -202. Richardson, A.C., K.B. Marsh, E.A. MacRae. 1997. Temperature Effectrs on Satsuma Mandarin Fruit Development. The Journal of Horticultural Science 72: 919 -929. Richardson, E.A., S.D. Seeley, and D.R. Walker. 1974. A Model for Estimating the Completin of Rest for Redhave n and Elberta Peach Trees. Hortsci. 9: 331 -332. Rouse, R.E. and W.B. Sherman. 2002a. P eaches for Subtropical South Florida. Journal America Pomological Society 56: 179 -184. Rouse, R.E. and W.B. Sher man. 2002b. High Night Temperat ures During Bloom Affect Fruit Set in Peach. Proc. Fla. State Hort. Soc. 115: 96 -97.

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123 BIOGRAPHICAL SKETCH Todd Walter Wert was born in Valparaiso, I ndiana, and was raised in Crown Point, Indiana. He graduated from Crown Point High School in the spring of 1999 and starting in the fall of 1999 he began his undergraduate studies at Purdue University Calumet, a satellite campus of Purdue University. The following fall he transferred to Purdue University in West Lafayette, and obtained his Bachelor of Science degree in the spring of 2003 in horticultural science. In the fa ll of 2003 Todd applied to the University of Florida as a masters student in the Hortic ultural Sciences Department, and he obtained his Master of Science degr ee in the summer of 2006.


Permanent Link: http://ufdc.ufl.edu/UFE0016200/00001

Material Information

Title: Evaluation of Four Low-Chill Peach (Prunus persica L. Batsch) Cultivars in Three Climatic Zones in Florida
Physical Description: Mixed Material
Copyright Date: 2008

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Title: Evaluation of Four Low-Chill Peach (Prunus persica L. Batsch) Cultivars in Three Climatic Zones in Florida
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0016200:00001


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Table of Contents
    Title Page
        Page i
        Page ii
    Dedication
        Page iii
    Acknowledgement
        Page iv
    Table of Contents
        Page v
        Page vi
        Page vii
        Page viii
    List of Tables
        Page ix
        Page x
    List of Figures
        Page xi
        Page xii
    Abstract
        Page xiii
        Page xiv
    Literature review
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
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        Page 25
        Page 26
    Materials and methods
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
    Evaluation of vegetative and flower bud development, and fruiting of four different cultivars of low-chill peach
        Page 36
        Page 37
        Page 38
        Page 39
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        Page 62
        Page 63
        Page 64
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    Fruit quality and yield of four low-chill peach cultivars grown in three locations
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
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        Page 105
        Page 106
        Page 107
    Conclusions
        Page 108
        Page 109
        Page 110
        Page 111
    References
        Page 112
        Page 113
        Page 114
        Page 115
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        Page 122
    Biographical sketch
        Page 123
Full Text












EVALUATION OF FOUR LOW-CHILL PEACH (Prunuspersica L. Batsch)
CULTIVARS IN THREE CLIMATIC ZONES IN FLORIDA

















By

TODD WALTER WERT


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA


2006

































Copyright 2006

by

Todd Walter Wert

































This thesis is dedicated to my parents Kermit and Irene Wert and to my brother Terry
Wert for the love and support they have given me.















ACKNOWLEDGMENTS

I would first like to thank my parents Kermit and Irene Wert and my brother Terry

Wert for all the love, support, and encouragement they have given me. I would also like

to thank all of my friends down here and at home for their support through thick and thin,

good and bad. For the immense amount of help they have provided me throughout this

process, I am indebted to my committee members, Dr. Jeffery Williamson, Dr. Jose

Chaparro, and Dr. Robert Rouse. For their help and support, a most sincere thank you

goes to Paul and Donna Miller; without their help I do not think this would have been

possible. I would also like to thank my harvesting crew for helping me pick and process

endless quantities of peaches. I thank all the people in Fifield Hall who took peaches off

of my hands when I needed to get rid of them.















TABLE OF CONTENTS



A C K N O W L E D G M E N T S ................................................................................................. iv

LIST OF TABLES ..................................... .. .......... ...................................... ix

LIST OF FIGURES ........................................ .............. xi

ABSTRACT ............................................ ............. ................. xiii

CHAPTER

1 LITER A TU R E R EV IEW .................................................................................1...

G general Inform ation....... .. ................................... ...............................................1.
H history and Im portation .. ...................................................................... ...............3...
L ow -C hill P each M arket............................................ ........................... .............. .4...
Tem perature Effects on O their Fruits ....................................................... ...............6...
Red Skin Color and Anthocyanin Concentration............................................7...
Titratable A cidity and Soluble Solids............................................. ................ 10
Fruit D evelopm ent Period (FD P) ....................... ...........................................11
F ruit Size, Y ield, and Shape ........................................................... ............... 13
Floral D evelopm ent ...... ... ................. .................................. ............... 15
Other A aspects of D evelopm ent ................ ...... ....... ................ 16
Climate and Temperature and Their Effect on Peaches ........................................17
Endodorm ancy, Chilling, and Bloom ............................................. ............... 18
Fruit Development Period (FDP) and Fruit Size............................................20
F ru it S h a p e ........................................................................................................... 2 1
Y field .................... .......... .... ................................................................ ........ 2 2
Post H arvest Q quality Characteristics.............................................. ................ 22
B lin d N o d e s ......................................................................................................... 2 3
O their A aspects .................... ....... ...... .. .. ............ ............... 23
Factors Other Than Temperature That Affect Fruit Quality .................................24
T h in n in g .............................................................................................................. 2 4
C anopy P position ... ... ........................................... ....................... .. ........ ... .. 24
H ig h N itro g en ...................................................................................................... 2 5
L eight .......................................................................................... . .... 26

2 M A TERIALS AND M ETH OD S .......................................................... ................ 27

Locations ............................................................................... 27


v









Cultural Practices ..... .... ............. .. ........... ...............................27
Frost Protection and Pruning ........................ .............................................. 27
Irrigation ....................................................................................................... 28
W eed C control .................................................................................................. 28
F fertilization .................................................................................................... 28
T em perature ................................................................................................... 29
D ise a se C o n tro l ...................................................................................................2 9
M easurem ents ....................................................................................................... 30
Shoot M easurem ents ........................................................................................ 30
Trunk M easurem ents ........................................................................................ 31
Bloom and Flow er Counts................................................................................31
Fruit Set M easurem ents and Thinning .............................................................31
Harvest ................................................ .................................. 32
T total Y field ........................................................................................................... 32
Fruit Size, W eight, and Blush...........................................................................33
C hrom city ...........................................................................................3.. . 33
B lossom E nd ....................................................................... ..............................34
Firmness, Soluble Solids Concentration, Titratable Acidity, and pH .................34
Statistical A analysis ................................................................................................ 35

3 EVALUATION OF VEGETATIVE AND FLOWER BUD DEVELOPMENT,
AND FRUITING OF FOUR DIFFERENT CULTIVARS OF LOW-CHILL
P E A C H ....................................................................................................................... 3 6

Introduction ................................................................................... ...................... 36
M materials and M ethods ............................................................................................37
L locations .............................................................................................................37
C cultural P practices .............................................................................................. 38
T em perature ................................................................................................... 39
B ud D ata C collection .........................................................................................39
B loom ................................................................................. ...............39
Node Characterization and Bud Density ........................................................ 40
Statistical A naly sis ........................................................................................... 40
R results ........................................... .................. .....................40
C hilling and B loom ..........................................................................................40
Bud Percentage..................................................42
Nodes with only vegetative buds .................. ....................................42
Nodes with vegetative and flower buds ....................................................42
N odes w ith only flow er buds ....................................................................43
B lind nodes ................................................................................................ 43
B uds per N ode ............................................................................................... 44
V egetative buds .........................................................................................44
Flower buds............................ ............................44
F low ers ................................................................................................... 45
B ud D density .......................................................................................... . 45
V egetative buds .........................................................................................45
Flow er buds ............... ........ .. ....... ......................... 46









F low ers ................................................................................................... 46
Fruit ............................................................................................. . 47
B lind nodes ................................................................................................ 47
N odes ............................................................................................. . 48
D iscu ssion ................................................................................... ...................... 48
Chilling and B loom ........................................................................................48
Percentage of Vegetative, Floral, and Blind Nodes ....................... ............... 50
Number of Buds per Node and Bud Density....................................................53
G general C onclu sion s ............................................ ....................... .. ........... .. 54

4 FRUIT QUALITY AND YIELD OF FOUR LOW-CHILL PEACH
CULTIVARS GROWN IN THREE LOCATIONS..............................................66

Introduction ................................................................................... ...................... 66
M materials and M ethods .. ..................................................................... ................ 67
L locations .............................................................................................................67
Cultural Practices.................................................................... 68
Fruit D evelopm ent Period ........................................................ 70
H harvest ..................................................................................................... .......70
T otal yield and w eight............................................................. ................ 70
T runk m easurem ents ...................................... ...................... ................ 7 1
Fruit size, w eight, and blush.................................................... ................ 71
C hrom city values .............. ............. ............................................ 72
B lossom end ............................................................................................72
Firmness, soluble solids concentration, titratable acidity, and pH ............72
Statistical A analysis .............. .... ............. ................................................ 73
R results ........................... .. ........... ................ ....................73
Fruit D evelopm ent Period ........................................................ 73
Fruit N um ber, W eight, and Set....................................................... ................ 74
Fruit Blossom End ... .. ................................ ........................................ 75
P ost H harvest Q quality ......................................... .. ....................... .... ........... 76
C o lo r ....................................................................................................................7 8
P percent blu sh ............................................................................................. 78
C olorim eter ................................................................................................ 79
Individual Fruit W eight .................................................................................... 81
Fruit Size .............................................................................................................82
D discussion ........................... .. ........... ................ ....................83
Fruit Development Period ...............................................................84
Fruit Size, Shape, and Y ield .............................................................................87
Color ............................................ ................................. 90
F ru it Q u a lity ........................................................................................................9 2
G general C conclusions .........................................................................................93

5 C O N C L U S IO N S ......................................................................................................10 8









LIST O F R EFEREN CE S ... ................................................................... ............... 112

BIOGRAPH ICAL SKETCH .................. .............................................................. 123















LIST OF TABLES


Table page

1 Mean date of full bloom for both 2004 and 2005 across three locations for
four low -chill peach cultivars ........................................................... ................ 56

2 Mean vegetative and flower buds per node for the 2004 season, for four low-
chill peach cultivars within three different locations........................ ................ 62

3 Mean vegetative and flower buds per node for the 2005 season, for four low-
chill peach cultivars within three different locations........................ ................ 62

4 Vegetative bud, flower bud, and blind node density for four low-chill peach
cultivars for the 2004 season within three different locations .............................63

5 Vegetative bud and blind node density for four low-chill peach cultivars for
the 2005 season within three different locations .............................................. 63

6 Flower bud and flower density for four low-chill peach cultivars for the 2005
season w within three different locations ............................................. ................ 64

7 Main effects of fruit and node density for four low-chill peach cultivars, and
three different locations, for the 2004 and 2005 seasons..................................65

8 Bloom dates, harvest dates, and fruit development period (FDP) for four low-
chill peach cultivars for the central and southwest locations for 2004...............95

9 Bloom dates, harvest dates, and fruit development period (FPD) for four low-
chill peach cultivars for the north-central location for 2004...............................95

10 Bloom dates, harvest dates, and fruit development period (FPD) for four low-
chill peach cultivars for the central and southwest locations for 2005...............96

11 Bloom dates, harvest dates, and fruit development period (FPD) for four low-
chill peach cultivars for the north-central location for 2005...............................96

12 Main effects of percentage fruit set during 2005 and adjusted marketable
number of fruit for both 2004 and 2005 for four low-chill peach cultivars and
th ree lo catio n s. ....................................................................................................... 9 7









13 Adjusted yield for 2004 and 2005 for four low-chill peach cultivars within
th ree lo catio n s. ....................................................................................................... 9 8

14 Post harvest quality measurements for four low-chill peach cultivars during
2004, within the central and southwest locations, for measurements of TA,
SSC and Pressure.. ............. ................ .............................................. 100

15 Post harvest quality measurements for four low-chill peach cultivars during
2004, within the north-central location, for measurements of TA, SSC, and
P re ssu re ........................................................................................................... . 1 0 0

16 Main effects for TA for four low-chill peach cultivars and three locations
d u rin g 2 0 0 5 .......................................................................................................... 10 1

17 Post harvest quality measurements for four low-chill peach cultivars during
2005, within the central and southwest locations, for measurements of SSC,
Ratio, and Pressure .. ............................................................................... 101

18 Post harvest quality measurements for four low-chill peach cultivars during
2005, within the north-central location, for measurements of SSC, Ratio, and
P re ssu re ........................................................................................................... . 1 0 2

19 Main effects for the ratio of SSC:TA for four low-chill peach cultivars and
three locations during 2004 ....................................................... ............... 102

20 Fruit blush, weight, and dimension measurements for four low-chill peach
cultivars during 2004 within the central and southwest locations .................... 103

21 Fruit blush, weight, and dimension measurements for four low-chill peach
cultivars during 2004 within the north-central location..................................103

22 Fruit blush, weight, cheek diameter, and suture diameter measurements for
four low-chill peach cultivars during 2005 within the central and southwest
lo c atio n s .............................................................................................................. 1 0 4

23 Fruit blush, weight, cheek diameter, and suture diameter measurements for
four low-chill peach cultivars during 2005 within the north-central location. ....104

24 Main effects for fruit length for four low-chill peach cultivars and for three
locations during 2005 ..................................................................................... 105

25 Colorimeter measurement values for the 2005 harvest season for both the
most blushed and least blushed location on each fruit, for L*,C*h* values at
three different locations for four low-chill peach cultivars. ............................. 106















LIST OF FIGURES


Figure page

1 Total chill unit accumulation for hours below 7.2 C among locations for the
2004 and 2005 seasons for four low-chill peach cultivars from early
N ovem ber to January 31 for each year ............................................. ................ 55

2 Main effects for the percentage of nodes with only vegetative buds during
2004 for four low -chill peach cultivars............................................. ................ 57

3 Main effects for the percentage of nodes with only vegetative buds during
2004 for three location s ......................................... ........................ ................ 57

4 Main effects for the percentage of nodes with only vegetative buds during
2005 for four low -chill peach cultivars............................................. ................ 58

5 Main effects for the percentage of nodes with only vegetative buds during
2005 for three locations. ............. ............. ............................................... 58

6 Percentage of nodes with both vegetative and flower buds for four low-chill
peach cultivars during the 2004 season within three locations...........................59

7 Percentage of nodes with both vegetative and flower buds for four low-chill
peach cultivars during the 2005 season within three locations...........................59

8 Main effects for the percentage of nodes with only flower buds during 2005
for four low -chill peach cultivars...................................................... ................ 60

9 Main effects for the percentage of nodes with only floral buds during 2005
b etw een tw o location s ........................................ .. ....................... ... ........ .... 60

10 Percentage of blind nodes for four low-chill peach cultivars during the 2004
season w within three locations .................................... ..................... ................ 61

11 Percentage of blind nodes for four low-chill peach cultivars during the 2005
season w within three locations. ........................................................ 61

12 Percentage of peach fruit with sunken, flattened, and extended blossom ends
within the North-central (NC), Central (C), and Southwest (SW) locations.........99









13 Hue and croma chart for the highest and lowest blushed locations on four
low-chill peach cultivars at three locations in Florida .................................107















Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

EVALUATION OF FOUR LOWCHILL PEACH (Prunus persica L.Batsch)
CULITIVARS IN THREE CLIMATIC ZONES IN FLORIDA

By

Todd Walter Wert

December 2006

Chair: Robert E. Rouse
Cochair: Jeffrey G. Williamson
Major Department: Horticultural Sciences

Four low-chill peach cultivars ('Flordaprince', 'Flordaglo', 'UFGold', and

'TropicBeauty') were grown in three different locations in Florida. These locations were

in north-central, central, and southwest Florida. The effects of different climatic

conditions were observed on vegetative and reproductive growth, and on fruit quality and

yield. Climate was observed to have an effect on the different cultivars within each

location.

'TropicBeauty' was observed to have greater fruit weight and size; however, it also

had longer fruit development period (FDP), lower blush, and higher amounts of blind

nodes than other cultivars. 'UFGold' had lower mean fruit weight and smaller fruit size,

but had a higher SSC:TA ratio, higher yields, and set higher amounts of floral buds than

other cultivars. Blush values were higher for 'Flordaprince' than for the other cultivars.

In several cultivars fruit weights were higher, and blush values were lower than

previously reported.









Differences among the locations were observed for amounts of fruit blush, SSC:TA

ratios, blind nodes, and blossom end ratings. Generally higher blush values and SSC:TA

ratios were observed in southwest Florida along with fruit with more pronounced

blossom ends. Higher amounts of blind nodes were also observed in southwest Florida,

and chilling accumulation was lowest at this location. The length of the FDP was

influenced by mean temperature during fruit development at all three locations. A longer

FDP was observed in north-central Florida where temperatures were lowest, and a shorter

FDP was observed in southwest Florida where temperatures were highest.

There was an accidental application of excess fertilizer at the north-central Florida

location. Rates were at least 2.5 times greater at this location. This higher rate of

nitrogen may have affected fruit quality and development. Mean blush values were

lower, fruit weights were higher, SSC values were lower, and the SSC:TA ratio was

lower compared to the other two locations. Fruit yield adjusted for trunk cross-sectional

area (TCA) was also higher in north-central Florida compared to the other locations.

It could be recommended that cultivars which exhibit large numbers of blind nodes

and greater percentage of fruit with extended tips be grown in locations further north.

Cultivars that do not have these problems should be planted further south to acquire the

higher blush values and SSC:TA ratios that are preferred in the market provided their

chilling requirement is met. Through the higher nitrogen rates applied at the north-

central location it could be concluded that current recommendations for amounts of

nitrogen fertilizer are too low for production in Florida and rates probably need to be

increased. Further research needs to be done in nitrogen rates in peach to determine the

optimum amount needed to increase fruit size and yield without sacrificing fruit quality.














CHAPTER 1
LITERATURE REVIEW

General Information

The peach is classified as a member of the genus Prunus and a member of the

species persica. Other common members of the Prunus genus include Japanese plum

(Prunus salicina), European plum (Prunus domestica, nectarine (Prunus persica),

apricot (Prunus armeniaca), almond (Prunus dulcis), sour cherry (Prunus cerasus), and

sweet cherry (Prunus avium). The peach was first classified by Carolus Linneaeus in

1753; the present name of Prunus persica was given to the peach by August Johann

Georg Batsch in 1801 (Faust and Timon, 1995) and has been used since.

The peach fruit has a double sigmoid growth curve, with three distinct stages of

growth (Connors, 1919). The first stage occurs after bloom and lasts until initiation of pit

hardening. Rapid fruit growth occurs during this stage and it is generally associated with

cell division (Addoms et al., 1930; Ragland, 1934). The beginning of pit hardening starts

the second stage of growth, or lag phase, in which the diameter of the fruit increases very

little but dry weight of the fruit increases due to endocarp lingification (Tukey, 1933).

This stage has also been associated with a rapid increase in the development of the

embryo (Tukey, 1933). Once pit hardening is complete the third stage of growth occurs

in which a rapid increase in fruit diameter continues until harvest. This stage is generally

associated with cell expansion (Ragland 1934).

There are many types and combinations of types of peaches grown today. There

are fruits that can have yellow, white, or red flesh, with yellow being the most common.









Fruits can have either melting or nonmelting flesh, the difference being the amount of

endo-polygalacturonase enzyme between the types. Nonmelting flesh peaches contain

very low levels of endo-polyglacturonase, and the flesh remains firm (Pressey and

Avants, 1978). Melting flesh peaches have normal levels of endo-polygalacturonase,

allowing the flesh to soften and "melt" from the pit. The nonmelting trait is particularly

useful for processing. Melting flesh types tend to fall apart during processing, while

nonmelting flesh peaches maintain their integrity and stay firm. The majority of cultivars

on the market are generally round, though there are peaches which are flat, these are

called 'Peento' peaches and are usually named in the market as "saucer peaches." The

adherence of the pit or stone to the flesh is classified as clingstone or freestone. The pit

of a freestone peach is easily removed from the flesh, with little or no flesh adhering to

the pit, once the peach becomes soft ripe; for the clingstone peach it is not possible to

cleanly separate the pit from the adjoining flesh. There are types which fall between the

two; these are called either semifree or semicling, again depending on adhesion of the

flesh to the pit at the soft ripe stage. Peaches can also be classified as to the amount of

acidity at harvest. Low acid types are generally called "honey" peaches; these peaches

generally have a high amount of sugar and, as the name implies, low amounts of acid.

High acid types are, as the name implies, higher in acid. The higher acid cultivars are

generally found in the U.S. market and low acid types are preferred by the Asian market

(Byrne et al., 2000).

The nectarine is a peach without fuzz. A single gene is the difference between the

two, but this gene affects several different characteristics (Byrne et al., 2000). Nectarines

are generally smaller, rounder, redder, higher brix, have a higher acid content, and are









denser (Byrne et al., 2000). Nectarines and peach can be prone to a condition called skin

speckles or sugar speckles. Skin speckles have been shown to vary with the amount of

sugar within the flesh of the nectarine or peach (Topp and Sherman, 2000; Wu et al.,

2003). Generally, nectarines are two brix units higher than peaches. The higher brix in

nectarines makes them more prone to skin speckles. Skin speckles appear as rough spots

lacking pigment on the cheeks and tip of the fruit (Topp and Sherman, 2000). Skin

speckling has been associated with increased transpiration rates in the parts which

contained the speckles (Wu et al., 2003).

History and Importation

The generic name of Prunus is Latin for Plum (Faust and Timmon, 1995). The

Romans acquired the peach from Persia, so it was thought the origin of the peach was

from there (Faust and Timmon, 1995); hence it was given the specific namepersica. It is

now thought that the cultivated peach is native to China (Yu-lin, 1985). The peach

probably made its way to Persia, from China, in the first or second century B.C., by way

of caravans (Faust and Timmon, 1995). It was not long after the importation of the peach

to Persia that Romans acquired it; from there it spread throughout Europe. During the

Spanish conquest of the Americas, the Spaniards brought the peach to Mexico, and also

introduced it into what is now the state of Florida. From Mexico the peach spread into

what are now the states of New Mexico, California, and Arizona (Faust and Timmon,

1995). Importation into Florida was about 1565 in the area around Saint Augustine.

From the importation into Florida it spread North and West to what are now the states of

Louisiana, Arkansas, Georgia, the Carolinas, New Jersey and New York during the

1600's, 1700's, and 1800's (Faust and Timmon, 1995).









During the mid 1800's there were a few direct imports from China to the U.S.

These peaches were commonly given the name of Chinese Cling (Faust and Timmon,

1995). It is believed that one of these Chinese Cling peaches may have been pollinated

by an 'Early Crawford' peach tree to give rise to the modern American peach genotypes

'Elberta' and 'Georgia Belle' (Faust and Timmon, 1995).

Three importations of peaches with low-chill genes from South Asia came into the

United States during the mid 20th century, and have been used extensively in the

University of Florida peach breeding program. One group was imported into Charleston,

South Carolina; the second group was imported into Hawaii (Hawaiian group); and the

third group was imported as seed from Okinawa (Sherman and Lyrene, 2003).

Low-Chill Peach Market

The low-chill peach in the state of Florida fills a market window that would

otherwise be devoid of peaches. The time period between April and May has relatively

few peaches in the market. During this time period importations from the southern

hemisphere have declined, and domestic peaches have not matured. The early blooming

peaches with short fruit development periods (FDP) developed by the University of

Florida peach breeding program could fill this market window. There is a negative

correlation between the temperature and the length of the FDP (Topp and Sherman,

1989a). Therefore, cultivars planted in the southern portions of the state should ripen

earlier than the same cultivars in the northern portions of the state. Rouse and Sherman

(2002a) demonstrated that cultivars which normally ripen in the Gainesville area of

Florida around early to mid May ripened in mid to late April in South Florida. This

early-ripening germplasm could fill the April to May market window keeping a constant









flow of peaches in the market between the end of importations and the start of domestic

production in other sections of the country.

Peaches have a large amount of variation for chilling requirement. A chilling unit

as defined by Weinberger (1950a) is one hour at 450F (7.20C) or below. Peach cultivars

are known that have chilling requirements varying from -50 cu ('Red Ceylon') to more

than 1100 cu ('Mayflower') (Okie, 1998). Within Florida, cultivars are classified as

being low-chill (<300 cu), medium-chill (300 to 525 cu), or high-chill (>525 cu)

(Williamson et al., 2005). Chilling requirement is essential to the survival and

reproduction of peach trees. Dormancy prevents the tree from growing during transient

warm periods that are favorable for growth during the winter when subsequent frosts and

freezes could kill developing flower buds and cambium (Weinberger, 1950b). Once

chilling is satisfied trees must acquire the appropriate amount of heat units to initiate

growth. As defined by Mufioz et al. (1986, p. 520), a heat unit is "the time needed for the

completion of a developmental process weighted by the prevailing temperature above a

base temperature." In this case we are talking about initiation of growth after

endodormancy. Peaches with the lowest chilling generally flower first. Peach cultivars

with a high chilling requirement from northern areas are not adapted to subtropical areas

like Florida because they are not exposed to enough chilling to break endodormancy

(Sherman and Lyrene, 2003).

In the state of Florida, the chilling can vary from 700 chill units in the western part

of the panhandle to as few as 50 chill units or less in areas of the southern tip of the state.

This means that cultivars with different chilling requirements need to be developed to fill

each of these climatic zones. The low-chill peach breeding program at the University of









Florida was started by R.H. Sharpe in 1953. His goal for the program was to "develop

commercially acceptable peach and nectarine cultivars ripening in sequence from late

April until early June for the 100 to 600 chill unit zones" (Sherman and Rodriguez -

Alcazar, 1987, p. 1235). By "commercially acceptable" he meant that the peach cultivars

had to be low-chill, have a FDP of 70 100 days, be firm, yellow-fleshed, and be of at

least moderate size (Sharpe, 1961). Another criteriaon used in the Florida peach breeding

program is a high amount of red over color or "blush". This along with a bright yellow

ground color is desired by U.S. consumers (Anderson and Sherman, 1994). The genes

for low-chilling were obtained from the South Asian and Hawaiian peach germplasm

mentioned previously. The peaches imported during the mid 1500's by the Spanish were

not used in the University of Florida peach breeding program because they ripened too

late in the season and were of moderate chilling.

Temperature Effects on Other Fruits

Temperature can have major effects on many different aspects of the development

of fruit crops. Of the various environmental factors, temperature can have the greatest

effect on fruit growth (Correlli-Grappadelli and Lakso, 2004). It can affect the color as

well as its perceived sweetness. Effects on fruit shape and size have also been noted.

Work done in Ireland on apple has shown that the two environmental factors which

seamed to be the most important in the growth of the fruit were sunlight and night

temperature (Blanpied and Kennedy, 1967). But temperature affects more than just

quality parameters. There have been several reports on effects on floral buds and fruit

development. Reductions in yields have also been reported. The problem with

determining the effects of temperature on development of fruit and other aspects of tree









development is that, it can be confused with rootstock and soil effects (Monselise and

Goren, 1987).

Red Skin Color and Anthocyanin Concentration

Anthocyanins are a class of pigments responsible for the red coloration of some

flowers and fruits. The six major groups of anthocyanidins are: pelargonidin, cyanidin,

peonidin, delphinidin, petunidin, and malvidin, with cyanidins being the most common

type of anthocyanin. Cyanidin glycosides are typically responsible for the scarlet reds,

pelargonidin glycosides for orange-red colors, and delphinidin glycosdes for bluish-red

colors (Lancaster, 1992).

Some of the most documented effects of temperature on growth and development

have been in relation to the development of red skin color and synthesis of anthocyanins.

Temperature can have a major effect on the synthesis of anthocyanin and subsequently

fruit color. During the last month of fruit maturation, the red pigmentation in the skin,

which is important for consumer acceptance in several different types of fruit, increases

with cooler night temperatures rather than warmer night temperatures (Sherman et al.,

2003).

There has been considerable work done in apples in relation to changes in skin

coloration, concentration of anthocyanins in the apple peel, and the relationship between

the two with temperature. Fruit maturity in apple orchards can be influenced by several

factors including temperature and environmental conditions during development

(Warrington et al., 1999). Night temperatures coincide better with coloration than day

temperatures (Uota, 1952). It was concluded that the pigments responsible for the

formation of anthocyanin are affected by temperatures during the late part of the growing

season. Color development can be prompted by even a small number of cool night









temperatures and warm sunny days (Curry, 1997). A similar result was found in which

skin coloration was decreased by warm night temperatures (Blankenship, 1987).

In contrast Arakawa (1991) observed that as temperatures increased during fruit

development, the amount of anthocyanin increased as well. Similar results were obtained

by Reay and Lancaster (2001) in 'Gala' and 'Royal Gala' apples where they observed

that anthocyanin accumulation increased less at 100C than at 200C but only for early

harvests. Alternating temperatures have also shown to have an effect on skin coloration

and anthocyanin accumulation. It was observed in detached 'Granny Smith' apples that

alternating temperatures, at which there was a period of low temperature followed by a

period of high temperature, favored the accumulation of anthocyanin (Reay, 1999). A

similar effect was observed in 'Crisps Pink' apple (Marais et al., 2001). But this is

contrasted by Tromp (1999) who reports, temperature difference during the harvest

period had little if any effect on the development of 'Elstar' and 'Cox's Orange Pippin'

skin color. Similar results were found by Fragher (1983) in ripe apples.

Climate effects on skin color and anthocyanin accumulation in apple have been

reported by several other authors. It has been observed that when the prevailing weather

conditions are cooler and moister, anthocyanin content in the skin can be higher at

harvest (Igelesias et al., 2002). A similar result was found in which apples grown in a

semi-arid, cool, and high irradiant climate favored the accumulation of anthocyanins

more than if they were grown in a moist, warm, and low irradiant climate (Li et al.,

2004).

Different cultivars and strains of cultivars can have different reactions to

temperature. Iglesias et al. (1999) reported significant differences among seven strains of









'Delicious' apple for fruit coloration. When the seven strains were tested for three

seasons, the apples achieved the highest coloration during the season where weather

conditions were cooler and moister.

Red pigmentation in the skin of different pear cultivars has been observed to be

affected by the passage of cold fronts during the end of fruit development (Steyn et al.,

2004a). As with apples, cultivar differences were observed. The cultivar 'Rosemarie'

developed better color while 'Bon Rouge' had no response to temperature change (Steyn

et al., 2004a). It was concluded that cold fronts passing through the area during fruit

development helped the development of red coloration in the pears. Other observations

indicate an interaction of both the synthesis and degradation of anthocyanin occurs at

different temperatures, and this interaction determines the color of red pear fruit (Steyn et

al., 2004b). One factor which could reduce the rate of anthocyanin synthesis and hence

final coloration of the organ could be substrate limitation. If substrate limitation reduces

the rate of anthocyanin synthesis than coloration of the organ would occur at lower

temperatures (Steyn et al., 2004b).

High temperatures can have a major effect on anthocyanin accumulation and

subsequent coloration in grape skins. Anthocyanin accumulation in 'Merlot' grape was

observed to be deterred by abnormally high temperatures (Spayd et al., 2002). This

confirms an earlier report by Kliewer (1970) using 'Cardinal' grapes which showed a

marked difference between those that ripened at low verses high temperature. He

reported that color formation in grapes was more uniform at lower temperatures.

Varying effects have also been observed in other fruits. Flesh and surface

coloration of strawberries can be darker and redder when grown at warmer temperatures









(Wang and Camp, 2000). Blackberry juice color increased when fruits were grown at

lower temperatures (Naumann and Wittenburg, 1980). A similar result was found in

pomegranate (Shulman et al., 1984). For cranberries, colorimeter readings of red color

intensity were higher in cooler areas (Hall and Starke, 1972).

Many reports have been published regarding the influence of both temperature and

climate on fruit coloration and anthocyanin development. Conflicting reports abound in

the literature, among fruits and cultivars. In apples alone, increased coloration has been

observed at higher temperatures, lower temperatures, and alternating temperatures. There

appears to be no one single answer for the effect of temperature and climate on coloration

in fruit.

Titratable Acidity and Soluble Solids

Soluble solids concentration (SSC) can be used as an estimate of sugar content. In

addition to sugars, the components that make up the SSC can include organic acids,

amino acids, phenolic compounds, and soluble pectins (Mitcham et al., 1996). SSC is

measured using a refractometer and is expressed in terms of Brix or percent SSC.

Titratable Acidity (TA) is a measure of the amount of acid found within a commodity.

An estimation of TA is generally determined by taking a known volume of juice and

titrating it to a pH of 8.2 (Mitcham et al., 1996). Depending on the fruit, TA is expressed

as either the percent of malic, citric, or tartaric acid (Mitcham et al., 1996). The ratio

between both the SSC and TA can give a good estimation of the perceived sweetness of

an organ. For a given SSC value, fruit with lower TA are perceived as being sweeter and

those with a higher TA are perceived as being tarter.

Both TA and SSC can be affected by high and low temperatures. A reduction in

TA at locations with higher temperatures has been observed for several different types of









fruit. A decrease in TA has been observed in strawberry (Wang and Camp, 2000), grape

(Kliewer, 1968; Spayd et al., 2002), blackberry (Naumann and Wittenburg, 1980), and

pomegranate (Shulman et al., 1984) at warmer temperatures. In citrus, juice sacks had

lower levels of TA at harvest and higher TA levels during early fruit development for

fruit grown at warmer temperatures (Richardson et al., 1997).

The SSC of the whole fruit of Satsuma mandarin was reported to be greater when

grown at warmer temperatures (Richardson et al., 1997). A later article reported that the

increase in SSC was evident at early stages of citrus fruit development (Marsh et al.,

1999). Both pomegranate (Shulman et al., 1984) and persimmon (Mowat et al., 1997)

had higher SSC in warmer regions compared to cooler regions. Similar results were

observed in apple (Warington et al., 1999).

Conversely Islam and Khan (2000), Kano (2004), Nauman and Wittenburg (1980),

Tromp (1999), and Tukey (1952) all reported higher fruit SSC as temperatures decreased

for various fruits (tomatoes, watermelon, blackberry, apple, and cherry, respectively). An

early report in tomato may explain why higher temperatures reduce SSC in some fruits.

It was concluded that when night temperatures were low, translocation of sugar out of the

leaves and into the fruit was higher, and that these sugars were not being used for growth,

thus fruit were sweeter (Went and Cosper, 1945).

Fruit Development Period (FDP)

The FDP is the period from the peak time of bloom to the peak harvest time. There

are several factors which can affect the FDP. Included in this is the prevailing

temperature in the area and the genetic tendencies of the cultivar. Each cultivar has a

characteristic FDP. However, this can be affected by the temperatures during fruit

development. Tufts in (1929) observed three different apricot orchards in California with









cool, intermediate, and warm temperatures. He noticed that apricots of the same variety

ripened earlier at the warmest site. The difference was six to eight day's between warm

and intermediate sites, and two to three weeks between the warm and cool sites (Tufts,

1929). Like peach, apricot and cherry, have double sigmoidal growth curves with three

distinct stages of development. Any one of these stages can be affected by temperatures.

Tukey (1952, p. 162) stated that "warm temperatures immediately following full bloom

(during stage I) decrease the number of day's until fruit maturity. However, warm

temperatures late in the season (stage III) noticeably lengthen the number of days to

maturity." A similar finding for apricot was also observed (Baker and Brooks, 1944).

Another study in apricot in which a shelter was built around a limb, and heated at night to

200F above the outside ambient temperature; it was observed that the warmer

temperatures within the shelter shortened the first phase of fruit development by 22 day's

(Lilleland, 1936). Lilleland concluded that this decrease in the length of the first growth

phase of the apricot was in response to its environment, presumably the warmer night

temperatures in the shelter. The length of the entire FDP decreased for fruits within the

shelter compared to fruits outside of the shelter. In another shelter containing a spur with

only fruit the FDP was reduced by twenty eight days compared to fruit outside of the

shelter. Lilleland (1936) concluded that fruit growth can be affected independently from

the rest of the tree by exposure of only fruits to fluctuations in temperature. Later Baker

and Brooks (1944) reported that this reduction in the FDP is due to additional heat units

early in the season.

Stone fruit are not the only fruits which can be affected by warmer temperatures.

Usually warmer temperatures reduce the number of days to fruit maturity from full









bloom, but it has been shown that this is not always the case. Harvest began one month

earlier for figs grown in warmer areas than figs grown in cooler areas (Botti et al., 2003).

In grapes it was observed that higher temperatures during the day increased the number

of degree days for ripening of 'Pinot noir' fruits from veraison to fruit maturity,

compared to lower day time temperatures (Kliewer and Torres, 1972). Cooler

temperatures can also have an effect on ripening of fruits. Premature ripening of 'Bartlet'

pears has been reported when temperatures were cool one month prior to normal ripening

(Wang et al., 1971).

The FDP, of any fruit can be affected by several different things including bloom

time, temperature during fruit development, and genetic influence. Stone fruit can be

affected at all three stages of development. Increased temperature during the first stage

of growth can shorten the FDP considerably, while during the third stage it can lengthen

it. Higher temperatures during later developmental stages have also increased the FDP of

other fruits such as grapes.

Fruit Size, Yield, and Shape

Several effects of temperature on fruit size (both weight and diameter) have been

reported. Effects on fruit size can in turn have an effect on harvestable yield.

Environment can influence several factors related to raspberry fruit size, including; ovule

number and durpelet set and weight (Dale, 1986). Significant increases in fig weight and

diameter have been observed at warmer locations (Botti et al., 2003). Sour cherry fruits

that received a very high temperature treatment, (250F above the average outdoor night

temperature), had the smallest fruits compared to a medium (10F) and high (200F)

temperatures treatments (Tukey, 1952). Reuther et al. (1969) found that citrus fruit

grown in warmer areas generally were larger than those in cooler areas. Warm









springtime temperatures have also been reported to affect citrus fruit enlargement

(Cooper et al., 1963). In a production study for cranberry in five regions in the U.S. the

number of days needed to accumulate 0.5 g of fresh mass was determined (DeMoranville

et al., 1996). It was shown that in New Jersey high temperatures limited growth of the

fruit and that the opposite was true in Oregon and in Washington where low temperatures

limited fruit growth.

Documented effects in yield of several commodities have been observed. In

cranberry fruit yield was affected the most by temperature (Degaetano and Shulman,

1987). They found that temperatures above 32.20C during the time period when flowers

were opening and during berry formation were detrimental to yields. Raspberry yield has

been observed to be affected by the interaction of cultivar and above ground temperatures

(Prive et al., 1993). Citrus yields can be adversely affected by the maximum temperature

during the time of June drop (Jones and Cree, 1965).

Several reports have been published for different commodities concerning climatic

and temperature effects on the shape of fruit. Higher temperatures generally produce

rounder fruit and lower temperatures produce fruit that are more elongated (Sherman et

al., 2003). Several studies on peppers have shown that low night temperature can affect

the shape of the developing fruits. More flattened pepper fruits have been observed at a

lower night temperature of 120C verses fruit grown at a temperature of 180C (Aloni et al.,

1999). They also found that at the lower temperature the fruits were parthenocarpic.

Both deformed fruits and parthenocarpic fruits were also observed at lower temperatures

in an earlier study by Rylski and Spiglman (1982) who also worked with peppers.

Seedless pepper fruits were again observed at lower temperatures and larger fruits at









higher temperatures by Polwick and Sawheney (1985). Conversely, apple fruit shape was

not directly affected by environment but was affected by the number of seeds per fruit

(Tromp, 1990).

Citrus fruit shape has been observed to be influenced by temperature. The

condition of "sheepnosing" or "stem end tapering" in grapefruit is reported to be an effect

of low temperatures. In a controlled environment study by Wutscher (1976) where

grapefruit plants were exposed to a fixed day temperature and three different night

temperatures, the lower the night temperatures resulted in greater fruit elongation.

Temperature effects have also been seen in Valencia oranges and mandarins. Fruit grown

in warmer areas were rounder compared to those grown in cooler areas which were flatter

(Nauer et al., 1974). Similar effects were also reported for navel oranges (Nauer et al.,

1972), and grapefruit and lemons (Nauer et al., 1975).

Fruit size, yield, and shape can all be affected by temperature. In several reports

fruit size was increased under warmer temperature conditions. In contrast there are

several reports where fruit size was reduced at warmer temperatures. Reduction in fruit

size due to unfavorable temperatures during growth can lead to reduced yields. Lower

temperatures have been shown to produce flattened pepper fruits and "sheepnosing" in

citrus fruits. Warmer temperatures have produced larger pepper fruits and citrus fruits

which were rounder.

Floral Development

Development of flowers and floral buds can be affected by the prevailing

temperature in an area. In work with persimmon George et al. (1994) found that larger

flowers were produced at lower temperatures. Abnormalities in floral development at

lower temperatures have also been reported in pepper. They include abnormal









development of the petals, stamens, and gynoecia (Polwick and Sawhney, 1985). On the

other hand, it has been found in some flowers that increased temperatures promote

flowering. Higher day temperatures promoted flowering of 'Elegance' chrysanthemum,

but higher night temperatures delayed flowering (Cockshull et al.,1981). Winter

temperatures in different areas can also play a role in the development of flower buds in

blackberry. Continuous floral bud development occurred during the winter at sites that

were above 20C (Oregon), but not at sites with winter temperatures below 20C (West

Virginia and Arkansas) (Takeda et al., 2002).

Bud failure in almonds is a genetic disorder which is passed on through

vegetatively propagated material, and is influenced by high temperatures (Kester and

Asay, 1978). It is similar to blind wood in peaches. Bud failure is due to higher

temperatures during the previous summer (Kester and Asay, 1978). They state: "that bud

failure potential increased as one shifts from a low temperature location to a high

temperature location, however shifting from a high temperature location to a low

temperature location did not decrease the bud failure potential, but masked the

symptoms."

Other Aspects of Development

There are many other aspects of plant development which can be affected by

temperature and climate. It has been reported in cranberry that bud formation and

production of non-fruiting stems are favored by warmer temperatures (Degaetano and

Shulman, 1987). Coagulation of soluble tannins in persimmon fruit has been reported to

occur throughout the fruit development period in warm climates verses twenty three

weeks after full bloom in cool climates (Mowat et al., 1997). Temperatures during fruit









development have also been reported to effect the development of fruit translucency in

pineapple (Chen and Paull, 2001).

Increased temperatures have also been shown to affect the development of shoots

and leaves. Apricot limbs which were placed in a heated shelter had more growth than

those which were not in the shelter (Lilleland, 1936). High night temperatures have been

shown to affect the coloration of sour cherry leaves, with leaves grown at warmer

temperatures having less green color than at cooler temperatures (Tukey, 1952).

Numerous reports have been documented for temperature effects on citrus.

Variations in peel thickness have been associated with variations in temperature and have

been reported by several authors (Cohen et al., 1972; Hilgeman, 1966; Iwasaki et al.,

1986; and Young et al., 1969). Temperature also affects peel color of citrus. Orange peel

color in citrus is mainly due to the accumulation of carotenoids in the peel. The effect of

temperature on carotenoid accumulation in citrus peel was demonstrated in a controlled

environment experiment by Young and Erickson (1961). They found that 120C soil

temperature, 70C night temperature and 200C day temperature produced highly colored

fruits. They also observed an increase in any one of these temperature parameters caused

a reduction in the orange color of the peel. Similar results were obtained in 'Redblush'

grapefruit by Young et al. (1969). This was substantiated in the field by Reuther et al.

(1969) when it was reported that when night temperatures were higher during the months

of December to February, color development in the peel occurred at a slower rate.

Climate and Temperature and Their Effect on Peaches

Fruit color, size, shape, firmness, and taste are some of the characteristics which are

most important in determining fruit value (Porter et al., 1996). Effects of temperature on

the development of different parts of the peach tree have been documented. Time of









bloom, length of the FDP, fruit size, fruit shape, proportion of blind nodes, as well as

other aspects of fruit and tree development can be influenced by the prevailing

temperatures in the localities where peaches are grown.

Endodormancy, Chilling, and Bloom

As stated earlier different cultivars of peaches have different chilling requirements

to release them from endodormancy. This limits where certain cultivars of peaches can

be grown. Higher chill cultivars in the 700+ range are more suited to traditional peach

growing areas like central Georgia and South Carolina. When grown in areas like Florida

where the winters are mild, these cultivars will not receive adequate chilling and will not

flower. Low-chill cultivars which receive < 300 chill units (Williamson et al., 2005) are

more suited to subtropical areas like Florida. A chill unit has been defined as one hour at

450F (7.20C) or below (Weinberger, 1950a). Other models have been developed in an

attempt to obtain better estimates of chilling for different regions. Another model uses

the amount of hours between 320F (0C) and 450F (7.20C), and the Utah model

developed by Richardson et al. (1974) categorizes the hours even more thoroughly.

Richardson et al. (1974) proposed that one chill unit is accumulated when temperatures

are 37F (2.50C) to 480F (9.1C), one half of a chill unit is accumulated when

temperatures are 35F (1.50C) to 36F (2.40C) or 490F (9.20C) to 540F (12.40C); below

340F (1.40C) no chill units are accumulated. They also proposed the idea of negative

chill units or chilling negation, where between 610F (160C) and 650F (180C) a half of a

unit is lost and at temperatures above 650F (180C) a whole chill unit is lost (Richardson

et al., 1974). It has been reported that a condition of secondary dormancy can be induced

when temperatures are 200C or greater (Erez and Lavee, 1971). On the other hand

Maxwell and Lyons (1969) did not find chilling negation at temperatures above 70F









(21.10C). They also observed that temperatures of 50F (100C) can satisfy the cold

requirement for peaches with South Asian parentage. Rest breaking ability has also been

reported in temperatures above 450F by several other authors (Erez and Lavee, 1971;

Gurdian and Biggs, 1964). Another model reported by Sherman et al. (1978) seems to

give a good estimate of chilling in the southeast U.S. Their model uses the number of

hours below 7.20C during the coldest month in the winter season at a location, and this

number is multiplied by 2.5. Other models have reported success using

December/Janurary (Weinberger, 1956) and Janurary (Sharpe, 1969) mean temperatures.

If for some reason adequate amounts of chilling are not accumulated in an area in

the spring a condition called "prolonged dormancy" can occur. As defined by

Weinberger (1950b, p. 129) "prolonged dormancy of peaches is a condition in which leaf

and flower buds are delayed beyond the usual time of opening in the spring, even though

favorable growing temperatures occur." Effects of prolonged dormancy are a delay in

bloom, a period of bloom which is spread out several weeks, buds on the tips of shoots

blooming long before those at the base of the shoot, vegetative buds breaking in the

center of the tree first and then laterals, and in severe cases flower buds abscise before

opening (Couvillon, 1995; Sherman et al., 2003; Weinberger, 1950b). Other problems

with prolonged dormancy of peaches can include reduced fruit set and fruit that have a

pronounced tip (Byrne and Bacon, 1992, Campbell et al., 1995, Koffmann and Patten,

1992; Rouse and Sherman, 2002a; Rouse and Sherman, 1989a). It has been suggested

that the effect of temperature on the pronounced tip is more attributed to higher

temperatures during early development of the fruit rather than prolonged dormancy









(Sherman and Rodriguez-Alcazar, 1994). Other problems with lack of chilling are that

the fruit may have a greener ground color or reduced firmness (Byrne and Bacon, 1992).

Bloom period can be affected by temperature. Rouse and Sherman (1989a)

reported that bloom in the area around the Lower Rio Grande Valley of Texas was earlier

by 7 to 10 day's as compared to Gainesville Florida. This area is warmer than

Gainesville. Similar results were reported by Topp and Sherman (1989a). Floral

development can be affected adversely by high temperatures. Kozai et al. (2004)

reported that flower development was suppressed at temperatures above 250C.

Fruit Development Period (FDP) and Fruit Size

The FDP or period of time between peak bloom to peak harvest differs among

cultivars. The FDP can be highly temperature dependent (Anderson and Sherman, 1994).

Generally speaking peaches with a longer FDP usually have larger fruit and peaches with

a short FDP have smaller fruit. It is difficult to breed a large peach with a short FDP

(Porter et al., 1996). The effect of temperature on the FDP of peach is cultivar specific

and differs among the cultivars (Boonprakob et al., 1992).

Night temperature can have a substantial effect on maturity of 'Early Redhaven'

peach (Batjer and Martin, 1965). During early development, warmer temperatures

accelerated fruit maturity and cooler temperatures delayed it. It has also been reported

that low temperatures following bloom can prolong the FDP, this was also observed to be

cultivar specific (Blake, 1930).

Topp and Sherman (1989a) observed that a decrease of IC in the mean

temperature during the growing season increased the FDP by 5 day's. They also reported

that temperatures two months following full bloom were the most important. Similar

results were obtained by Boonprakob et al. (1992) for 30 to 45 days after full bloom, and









by Rouse and Sherman (1989a). The quickest time from bloom to harvest for peaches

has been observed at a night temperature above 100C and day temperatures below 38C

(Sherman et al., 2003).

Since fruit size and the FDP are correlated there should be a reduction in fruit size

in warmer locations verses cooler locations, which was also reported by Topp and

Sherman (1989b) where they observed that a 1C increase in mean monthly FDP

temperature caused a decrease in the diameter of the fruit by 0.7 mm. The date of the

first commercial harvest at a location can be more variable than the date of full bloom,

this is due to temperature fluctuations during fruit development (Topp and Sherman,

1989a).

Fruit set is another component which can be affected by the prevailing temperatures

in an area. Exposure of trees to several different temperature regimes, for three weeks

resulted in a complete reduction in fruit set at 21 290C (day/night) and a reduction in the

FDP at 15 230C verses 12 200C (Erez et al., 2000). The accumulated temperatures

during the FDP can be defined in terms of heat units. The growth during fruit

development is dependent on the accumulation of these heat units; the more units

accumulated, the faster the growth (Sherman et al., 2003).

As was reported earlier for sour cherries (Tukey, 1952) and apricot (Baker and

Brooks, 1944) that high temperature increased the FDP, an increase of the FDP was also

reported by Batjer and Martin (1965) for peaches. Trees subjected to a 700F (21.10C)

night temperature late in the season had a four day increase in FDP.

Fruit Shape

The stylar tip on the fruit can also be affected by temperature. It has genetic

tendencies in some cultivars and can be more pronounced in some areas. Generally,









more pronounced tips have been observed in warmer locations, and rounder tips in cooler

locations (Topp and Sherman, 1989b; Salvador et al., 1998).

Yield

There are two main components which can determine fruit yield, the total number

of fruit which are set and the final size of these fruit (Campbell et al., 1995). Fruit set can

be affected by temperature during early states of fruit development right after bloom or at

the time of bloom. Night temperature seems to be particularly important. Different

cultivars can react differently to higher temperatures. Some low-chill peach cultivars like

'Flordaprince' and 'TropicBeauty' have a high tolerance to high night temperatures and

have the ability to set a full crop almost every year, while other cultivars which are not

heat tolerant can have little or no crop set (Rouse and Sherman, 2002b). The effect of

temperature on fruit set can be very important in areas where low-chill peaches are

grown. It has been stated that stone fruits can't be grown in tropical areas because year

round warm conditions can cause a reduction in fruit set (Diaz, 1992). This was shown

by Kozai et al. (2004) where they reported that temperatures above 250C had a significant

effect on set of 'Hakuho' peach.

Post Harvest Quality Characteristics

The various post harvest quality characteristics such as red blush, ground color,

firmness, SSC, and TA, can all be affected by temperatures within a region or locality.

One of the characteristics most affected is the degree of red blush. The red pigments

comprising surface blush of peaches are composed of anthocyanins. More intense blush

has been observed in the Lower Rio Grande Valley of Texas compared to Gainesville

Florida for several cultivars of low-chill peaches (Rouse and Sherman, 1989a). This

difference was attributed to the warmer prevailing temperatures in that area. On the other









hand it has been reported that there is no correlation between temperature and red blush

(Topp and Sherman, 1989b). But Topp and Sherman (1989b) did find that firmness

increased as temperatures increased. Greater surface blush coverage in warmer areas and

lower TA in cooler areas has also been observed by Salvador et al. (1998).

Blind Nodes

A blind node as defined by Boonprakob and Byrne (1990) is the "condition in

which a node has no obvious vegetative or reproductive buds." It is generally associated

with higher temperatures during bud formation during the late summer months and is

more prevalent in warmer peach producing areas verses cooler peach producing areas.

Some cultivars of peach have a genetic tendency for blind nodes and this condition is

expressed in areas which have high temperatures during shoot growth (Sherman and

Rodriguez-Alcazar, 1994). High daily temperatures seem to favor the formation of blind

nodes (Boonprakob and Byrne, 1990). In particular mean temperatures above 220C have

been reported to favor high amounts of blind nodes (Boonprakob and Byrne, 2003).

Other Aspects

There are other aspects of development which can be altered by the prevailing

temperature in a given area where peaches are grown. Peach pubescence can be longer

for the same varieties when grown in areas with warmer temperatures during fruit growth

compared to areas with cooler temperatures (Sherman et al., 2003). Another aspect of

growth that can be affected by temperature is vegetative growth of the tree. Vegetative

growth can be ten times higher for the low-chill versus the high-chill genotypes

(Campbell et al., 1995). Since vegetative growth occurs during the same time that the

fruit are maturing, excessive growth can shade out fruit and reduce coloration of the skin

of the fruit in the interior portions of the canopy. Furthermore, more labor is required to









prune vigorous trees, either during the summer or winter. Buds also have a tendency to

be laid down closer to the terminals of the shoots. If these buds are set higher up in the

canopy prior to pruning because of excessive growth they may be pruned off

In some areas where the temperatures are high during the fall the trees do not

defoliate as they normally would in cooler locations. When this occurs, zinc sulphate is

sprayed on the trees to induce leaf fall (Diaz et al., 1986).

Factors Other Than Temperature That Affect Fruit Quality

There are factors other than temperature that can affect the quality of fruit. Levels

of fertilizer, light interception, thinning, and location of the fruit within the canopy can all

affect the final size, color and flavor of the fruit.

Thinning

Fruit thinning generally takes place just prior to or at the beginning of the second

stage of fruit growth referred to as "pit hardening". It was reported by Tukey and Einset

(1938) that fruit thinning early during stage one of growth resulted in the largest size, best

red color, and least reduction in yield compared to other treatments where, either no

thinning was done, or thinning was done at other stages of growth. Wider spacing of the

fruit on shoots resulted in larger fruit with greater SSC (Corelli-Grappadelli and Coston,

1991). Most likely this was due to reduced competition for assimilates among fruits.

Forty leaves per fruit gave the best fruit size and quality in a leaf area study conducted by

Weinberger (1931) in which the amount of leaf area in relation to the size of the fruits

was observed.

Canopy Position

Location of the fruit within the canopy has an effect on various quality parameters.

Significant differences in fruit weight, blush color, SSC, and firmness were all compared









between the upper and lower portions of the canopy (Farina et al., 2005). Fruit from the

upper portions were significantly larger, redder, and had a higher SSC than those at the

bottom of the canopy. Redder fruit were also reported in the upper canopy as compared

to the lower canopy (Bible and Singha, 1993). Dry weight and SSC of fruits have also

been shown to be higher in the upper portions of the canopy (Dann and Jerie, 1988).

High Nitrogen

Several authors have shown that high levels of nitrogen can have an effect on both

yield and color of fruit. The effect of nitrogen on yield has been reported by Shoemaker

and Gammon (1963). They reported that the highest yield was recorded with the highest

nitrogen concentration and the lowest yield was recorded with the lowest nitrogen

concentration. They also reported that the trees which received the highest nitrogen level

had the highest amounts of red color, they concluded that this was from the increased

crop load opening up the tree to more light. Similar results were observed by Saenz et al.

(1997), who also reported larger fruit. High nitrogen treatments have been shown to

decrease Brix, increase TA, decrease anthocyanin, and increase green ground color (Jia

et al., 1999). They also reported in sensory tests that fruit from the high nitrogen

treatment were rated as being, sour, bitter and astringent. Greener fruit with higher

nitrogen rates were observed by Meheriuk et al. (1995). They also reported that the

increased nitrogen rates did not increase fruit weight or red blush. Increased rates of

nitrogen fertilization can increase the FDP of the peach. Trees with higher nitrogen rates

had a 7 to 12 day delay in harvest (Saenz et al., 1997). This confirms an earlier report

that on average a 6.5 day increase in FDP was observed with a heavy application of

nitrogen (Blake, 1930).









Light

The amount of light which the fruit receives can have a pronounced effect on the

amount of red blush. Reflective mulch was used to increase light levels and shade cloth

to reduce light levels in peach trees (Lewallen and Marini, 2003). The reflective mulch

increased the amount of red blush on the fruits; they also reported more fruit with an

orange ground color with the reflective much and more fruits with a yellow to yellowish

green ground color in the shaded trees. In an experiment where peach fruits were

covered with aluminum foil, the development of anthocyanin was markedly increased

when the foil was removed and the fruit were exposed to short periods of direct sunlight

(Erez and Flore, 1986). They also reported a reduction in the color of the fruit when trees

were shaded with shade cloth.














CHAPTER 2
MATERIALS AND METHODS

Locations

Three sites representing different climates from north-central to south Florida were

chosen to grow several cultivars of low-chill peach trees. The north-central site was

located in Archer, Florida (Lake fine sand, 29.52N 82.53W), the second or central

location was in Winter Garden, Florida (Calander fine sand, 28.57N 81.58W Elev. 32.0

m), and the third or southwest location was in Immokalee, Florida (Immokalee fine sand,

26.43N- 81.41W). Four cultivars, ('Flordaglo', 'Flordaprince', 'TropicBeauty', and

'UFGold') were planted at each site. All trees were grafted onto a greenleaf nematode

resistant rootstock (Fl 9-04). Trees were planted in February, 2002, at all locations using

a north/south row orientation at a distance of 4.57 m between trees (346 trees/hectare) in

a randomized complete block design, with five replications and single tree plots, within

each location.

Cultural Practices

Frost Protection and Pruning

Overhead irrigation was used for frost protection at the north-central site during

bloom in 2004 and 2005. Neither the central or southwest locations received any frost

protection. All trees were winter pruned in early to mid-January each year. Trees were

pruned to an open vase form and headed back to a height of -2.5 meters. The trees were

also summer pruned in early June of both years as needed.









Irrigation

Trees at the north-central location received overhead irrigation and they were not

water stressed at any time during either season. Within the central location, trees were

irrigated by microsprinkler emitters for twenty five minutes each morning before dawn.

During 2004, over a two-week period between mid to late March, a substantial leak

occurred in the main irrigation line and the trees did not receive any irrigation during that

period. Microsprinkler emitters were also used at the southwest location. There were two

microsprinkler emitters per tree at the central location, and one per tree at the southwest

location.

Weed Control

Weeds controlled at all locations by maintaining a herbicide band under the canopy

of the trees and among trees in the row. The application band was three to four meters

wide. Weed control was accomplished at the north-central and central locations with

glyphosate and a water conditioning agent (blend of polyacrylic, hydroxyl carboxylic,

and phosphoric acids). Applications were made with a five gallon backpack sprayer

when needed. At the southwest location, both glyphosate and paraquat were used.

Fertilization

Fertilizer at the north-central location was applied by hand in three applications

during the year, early February, early June, and late September. During both seasons,

crossover fertilizer applications from an adjacent commercial blueberry field occurred

eight times from a mechanical fertilizer spreader on the east side of the trees. These

times were: early February, early March, late March, late May, early July, late July, late

August, and early September. When the fertilizer was hand broadcast it was primarily

placed under the west half of the tree to compensate for the unequal distribution of









fertilizer from the mechanical applications. Fertilizer application times at the central

location were the same as at the north-central location. Within the central location,

reclaimed water was used for irrigation. Total amount of nitrogen applied via reclaimed

irrigation water was obtained by calculating an average N concentration of reclaimed

water (.0072428 g N/L) between July, 2005, and January, 2006. Additionally, emitter

output, line pressure and irrigation schedule were used to determine total N applied from

reclaimed water which was calculated at 33.86 kg/ha/season. Nitrogen fertilizer rates

varied among locations. For 2004, they were 276 kg/ha at the north-central location, 103

kg/ha at the central location and 112 kg/ha at the southwest location. For 2005, N rates

were 313 kg/ha at the north-central location, 114 kg/ha at the central location and again

112 kg/ha at the southwest location.

Temperature

The temperature was recorded at the north-central and central locations with a

HOBO H8 Pro Series temperature sensor (Onset Computer Corporation, Bourne, MA)

starting the first week in November and ending in the last week of May. At the southwest

location, temperatures were obtained from a FAWN (Florida Automated Weather

Network) station. Chilling was determined at each location from early November to

January 31.

Disease Control

Paraffinic hydrocarbon oil was use to control white peach scale (Pseudaulacaspis

pentagon (Targioni Tozzetti)), as needed during the dormant season. Fruit were hand-

thinned just prior to pit hardening to a distance of 15 cm between fruit. After thinning,

phosmet and captain were applied to control plum curculio (Conotrachelus nenuphar

(Herbst)) and peach scab (Cladosporium carpophilum (Thum.)), respectively.









Postharvest sprays at the north-central location, were a combination of copper sulfate

(20% metallic Cu equivalent), a non-ionic surfactant (alkylphenol etozylate, sodium salts

of soya fatty acids, and isopropyl alcohol), and phosphoric acid, which were applied

every three weeks until mid-October to control bacterial spot (Xanthomonas arboricola

pv. pruni (= X campestrispv. pruni)). At the central location, trees were sprayed until

late August and early July in 2004 and 2005, respectively. Chlorothalonil, or a

combination of pyraclostroblin and boscalid, was applied as needed to control peach rust

(Tranzschelia discolor (F. Chl.) Trans. and Litr.) at the north-central and central

locations. For all pesticide applications trees were sprayed early in the morning. Spray

was applied by using a hydraulic sprayer (John Bean sprayers, Modular Hydraulic

Sprayer, Model DM10E200FERH, Hogansville, Ga), with a handgun, at 500 psi on all

parts of the tree until run off occurred. At the southwest location, azoxystrobin and

myclobutanil were used monthly to manage peach rust.

Measurements

Shoot Measurements

Three, one-year-old, shoots of average length were selected at random from each

tree at a height between 1.5 to 2 m during mid-January of both years. This was after the

completion of winter pruning, but prior to bud break. A 150 mm dial caliper (Spi 31-

414) was used to measure the shoot diameter at the shoot base, and a 150 cm measuring

tape was used to measure the length of each shoot from the base to the tip. Each node on

each shoot was observed and determined to be vegetative only, vegetative with one floral

bud, vegetative with two floral buds, or blind (neither vegetative nor floral buds present).

The total number of each bud type was determined for all selected shoots on each tree.

During the spring of 2005, it was noted that several nodes had groupings with either









single, double, or triple floral buds without vegetative buds. The procedure was changed

slightly to account for these node classifications.

Trunk Measurements

Every six months after leaf fall, and after fruit harvest, trunk circumference was

measured. Readings were taken using a 150 cm dressmaker's tape at a pre-determined

spot 15 cm above the soil surface. This information was used to calculate trunk cross-

sectional area (TCA).

Bloom and Flower Counts

A visual estimation of the overall progress of bloom on each tree was done in 2004

and 2005. Bloom was rated twice each week (when applicable) using a 10% to 100%

scale, and the date of petal fall was recorded. In 2004, biweekly flower counts were

made on tagged shoots (when applicable). Flowers were considered open when both the

anthers and stigmata were visible. The number of open flowers and fruitlets were

counted on each shoot and recorded together. In 2004, the number of aborted flowers

was not recorded, which gave only the number of flowers which set fruit. The procedure

was changed slightly during 2005 to take into account the number of aborted flowers so

the total number of open flowers on the selected shoots could be determined. Each node

on each shoot was observed weekly to determine whether the flowers set or aborted.

Both open flowers and fruitlets were recorded together. The date of 50 to 60% bloom or

full bloom and first commercial fruit harvest was used to calculate the fruit development

period (FDP).

Fruit Set Measurements and Thinning

During fruit development in late March of both 2004 and 2005 the numbers of fruit

on the tagged shoots were counted to determine percent fruit set. Thinning was done









manually and fruit were thinned to a distance of 10 to 15 cm. The number of fruit on

each shoot was counted prior to thinning to determine fruit set, and the number of fruit

removed in thinning was also recorded. During 2005, the number of fruit on tagged

shoots were counted again prior to harvest to determine if pre-harvest fruit drop occurred.

Harvest

Total Yield

During the 2004 harvest, each of the trees were harvested individually, and the

number and weight of both marketable and nonmarketable fruit were recorded.

Nonmarketable fruit were delineated as those which were <4.5 cm, showed signs of wind

scaring, catfacing, bacterial spot, insect predation, split pits, deep sutured fruit, or rotten

fruit. Fruit were harvested at a firm ripe stage of development; harvest occurred twice

each week at all locations. Fruit from the north-central location were counted and

weighed directly in the field. Fruit from the central location were bought directly to the

laboratory and counted and weighed. Marketable fruit were weighed, and the weight and

the number of fruit were recorded for each tree at each harvest date. The same procedure

was applied to the nonmarketable fruit.

After marketable fruit were weighed and counted at the north-central location,

eleven representative fruit from each tree for each harvest date were selected at random

and placed in peach trays that were obtained from a local grocery store. The trays were

then placed in plastic Rubbermaid containers for transport to the laboratory. Fruit from

the central Florida location were harvested and transported to the laboratory, then

weighed, and samples of eleven representative fruit were selected as described above.

During 2005, the procedure was changed slightly so that fruit from the central

Florida location were weighed directly on site. Fruit selection and transport were the









same. At the north-central location the east sides of the trees appeared to have fewer fruit

than the west sides of the trees. This looked to be true for all four cultivars. To

determine if there was a difference in location of fruit in the tree canopy, each tree was

divided into east and west sectors, and counted and weighed as such.

Fruit Size, Weight, and Blush

Fruit sub-samples were placed directly into a walk in cooler (3 50C) to remove

field heat. Prior to fruit quality measurements fruit were removed from the cooler and

allowed to warm to room temperature. Ten fruit from each sub-sample were measured in

three different orientations: blossom end to stem end, cheek to cheek, suture to opposite

suture side. Each 10-fruit sample was weighed and each fruit was rated for a visual

estimation of the amount of red blush under fluorescent light.

Chromicity

In 2005, at early (first commercial) harvest and mid harvest (greatest number of

fruit removed per tree), a Konica Minolta CR 400/410 Chroma meter (Konica Minolta,

Osaka, Japan) was used to test the chromicity values on the most blushed and least

blushed area of five fruit from each 10-fruit sub-sample. The chroma meter was

calibrated using a standard calibration plate prior to each use. The colorimeter measured

three variables; L*, a*, and b*, where L* is the lightness of the object, -a* is the degree

of greenness, +a* is the degree of redness, -b* is the degree of blueness and +b* is the

degree of yellowness on a CIELAB color chart (Francis, 1970). The values of hue angle

(h*) and chroma (C*) were computed from both a* and b*, where h* is a measure of the

color of the sample and C* is a measure of the intensity of that color. The same five

fruits that were used for chromicity measurements during 2005 were used for soluble

solids concentration (SSC), titratable acidity (TA), pH, and pressure measurements.









During 2004 the five fruits were selected at random from the ten fruit sample for fruit

size, weight, and blush at early and mid-harvest.

Blossom End

During the 2005 season, fruit blossom end tips were rated as recessed, flattened, or

extended. Thirty fruit were selected at random from the marketable fruit for each tree

during peak harvest and rated in the field for blossom end tip. Fruit which would be

damaged in shipping were considered extended tip fruit.

Firmness, Soluble Solids Concentration, Titratable Acidity, and pH

Flesh firmness was measured using a penetrometer (McCormick Fruit Tech,

Yakima, Wa) with a 6 mm probe attached to a drill press stand. Two measurements per

fruit were taken (from the center of each cheek) from 5-fruit samples. The epidermis was

removed from the test area prior to measuring flesh firmness. Fruit were peeled and flesh

samples were collected from the cheek area of each fruit (avoiding the points were

pressure measurements were taken, and the suture and opposite the suture). A composite

flesh sample was obtained for each 5-fruit sub-sample. Flesh samples were quick frozen

in a -800C freezer and stored at -300C. Flesh samples were removed from the freezer,

allowed to thaw at room temperature, and homogenized in a blender. The slurry was

centrifuged for twenty minutes at 14,000 rpm at 50C. The samples were then filtered

through two layers of cheese cloth into a 50 ml beaker. Six g of supernatant diluted with

50 ml of deionized water was used to measure TA. Samples were titrated to an end point

of 8.2 using an automatic titrimeter (Fisher Titrimeter II, No. 9-313-10, Pittsburg, Pa),

and expressed as ml NaOH. The normality of NaOH used was 0. IN. The remainder of

the undiluted supernatant was used to test both the pH of the sample and the SSC. A

Digital Refractometer (Reichert-Jung, Mark Abbe II Refractometer, Model 10480,






35


Depew, NY) was used to measure the SSC of the undiluted sample and expressed in

Brix. The pH of the sample was measured using a pH meter (Coming Scientific

Instruments, pH meter 140, Medfield, Ma).

Statistical Analysis

Statistical analysis was achieved using SAS 9.1 (SAS Institute Inc., Cary, NC).

Means were determined using PROC GLM and means separations among and within

locations were by Tukey's HSD at the P<0.05 level.














CHAPTER 3
EVALUATION OF VEGETATIVE AND FLOWER BUD DEVELOPMENT, AND
FRUITING OF FOUR DIFFERENT CULTIVARS OF LOW-CHILL PEACH

Introduction

Climate is one of several factors that can greatly influence growth and development

of reproductive organs, which in turn can affect crop yield. George et al. (1994) reported

that larger flowers were produced at lower temperatures in persimmon. Floral

abnormalities from low temperatures have been reported in pepper (Polwick and

Sawhney, 1985). Cockshull et al. (1981) reported that higher day temperatures promoted

flowering for 'Elegance' chrysanthemum, but they also reported that higher night

temperatures delayed it. Bud failure in almond is a condition where buds fail to emerge

in the spring. This condition has been attributed to environmental factors such as warm

temperatures (Kester and Asay, 1978).

Peaches initiate their floral and vegetative buds in the summer and fall prior to

flowering. Generally a node with a single vegetative bud is flanked on both sides by a

floral bud. However, different combinations of flower and vegetative buds can occur;

nodes with a vegetative bud only, nodes with only one floral bud, or nodes that are blind.

A blind node is a condition where there is no obvious vegetative or reproductive bud.

Blind nodes are generally associated with higher temperatures during bud formation

during the late summer months (Boonprakob and Byrne, 1990). This condition is more

prevalent in subtropical or tropical regions, verses temperate regions. Boonprakob et al.

(1996) concluded that blind node formation was due to failure of buds to differentiate.









Flower bud densities have been documented in peach and other stonefruit.

Genotype has a greater effect on the floral bud density than the environment in areas that

receive the same amount of chilling (Okie and Werner, 1996). Werner et al (1988) also

observed the genotypic differences in floral bud density in peach, in that peach genotypes

released from eastern breeding programs generally had more flower buds than those from

western breeding programs. Alburquerque et al (2004) observed genotypic differences in

apricot where early flowering varieties had the highest flower bud density and highest

percentage of fruit set.

The objective of this experiment was to evaluate the performance of four low chill

peach cultivars at three different locations in Florida with respect to several vegetative

and reproductive characteristics. These included: 1) the relative amount of different bud

types; 2) bud, flower, and fruit densities; and 3) dates of full bloom.

Materials and Methods

Locations

Three sites were chosen that represented different locations and climates from

north-central to south Florida. The north-central site was located in Archer, Florida

(Lake fine sand, 29.52N 82.53W), the second or central location was in Winter Garden,

Florida (Calander fine sand, 28.57N 81.58W Elev. 32.0 m), and the third or southwest

location was in Immokalee, Florida (Immokalee fine sand, 26.43N 81.41W). Four

cultivars, ('Flordaglo', 'Flordaprince', 'TropicBeauty', and 'UFGold') were planted at all

three sites. All trees were grafted onto a greenleaf nematode resistant rootstock (Fl 9-04).

Trees were planted in February, 2002, at all locations using a north/south row orientation

at a distance of 4.57 m between trees (346 trees/hectare) in a randomized complete block

design, with five replications and single tree plots.









Cultural Practices

General horticultural practices were used to control weeds, insects, and diseases.

Trees were winter pruned in early January and summer pruned after harvest in early June

as needed. Fertilizer at the north-central location was applied by hand in three

applications during the year: early February, early June, and late September. Crossover

applications of fertilizer from an adjacent commercial blueberry field occurred eight

times from a mechanical fertilizer spreader on the east side of the trees. These times

were: early February, early March, late March, late May, early July, late July, late

August, and early September. When the fertilizer was hand broadcast at the north-central

location, it was placed primarily under the west half of the tree to compensate for the

unequal distribution of fertilizer from the mechanical applications.

Fertilizer application times at the central location were the same as at the north-

central location. Within the central location reclaimed water was used for irrigation.

Total amount of nitrogen applied via reclaimed irrigation water was obtained by

calculating an average nitrogen (N) concentration of reclaimed water (0.0072 g N/L)

between July 2005 and January 2006. Additionally, emitter output, line pressure, and

irrigation schedule were used to determine total nitrogen applied per acre from reclaimed

water that was calculated at 33.86 kg/ha/season. Nitrogen fertilizer rates varied among

locations. For 2004, they were 276 kg/ha at the north-central location, 103 kg/ha at the

central location and 112 kg/ha at the southwest location. For 2005, N rates were 313

kg/ha at the north-central location, 114 kg/ha at the central location and again 112 kg/ha

at the southwest location.









Temperature

Temperatures were recorded at the north-central and central location with a

HOBO H8 Pro Series temperature sensor (Onset Computer Corporation, Bourne, MA)

starting the first week in November and ending in the last week of May. At the southwest

location, temperatures were obtained from a FAWN (Florida Automated Weather

Network) station. Chilling was determined at each location from early November to

January 31.

Bud Data Collection

Three one-year-old shoots of average length were selected at random from each

tree at a height between 1.5 to 2 m. during mid-January of both years. This was after the

completion of winter pruning, but prior to bud break. A 150mm dial caliper (Spi 31-414)

was used to measure the diameter of the shoot at the base, and a 150 cm measuring tape

was used to measure the length of each shoot from the base to the tip. Each node on each

shoot was observed and determined to be vegetative only, vegetative with one floral bud,

vegetative with two floral buds, or blind (neither vegetative nor floral buds present). The

total number of each bud type was determined for all selected shoots on each tree.

During the spring of 2005, it was noted that several nodes had groupings with

either single, double, or triple floral buds without vegetative buds. The procedure was

changed slightly to account for these node classifications.

Bloom

A visual estimation of the overall bloom on each tree was done in 2004 and 2005.

Bloom was rated twice each week (when applicable) using a 10% to 100% scale, and the

date of petal fall was recorded. In 2004, biweekly flower counts were made on tagged

shoots (when applicable). Flowers were considered open when both the anthers and









stigmata were visible. The number of open flowers and fruitlets were counted on each

shoot and recorded together. The number of aborted flowers was not recorded, which

gave only the number of flowers that set fruit. The procedure was changed slightly during

2005 to take into account the number of aborted flowers so the total number of open

flowers on the selected shoots could be determined. Each node on each shoot was

observed weekly to determine whether the flowers set or aborted. Both open flowers and

fruitlets were recorded together. Information regarding numbers of open flowers was

unavailable from the southwest location for both years. After bloom, but before thinning,

fruits were counted on each of the selected shoots to determine fruit set.

Node Characterization and Bud Density

From the information collected the following variables were calculated: percentage

of nodes with vegetative buds, percentage of nodes with vegetative and floral buds,

percentage of nodes with floral buds only (2005), percentage of blind nodes, vegetative

buds/node (VB/N), floral buds/node (FB/N), flowers/node (FL/N), vegetative buds/cm

(VB/cm), floral buds/cm (FB/cm), flowers/cm (FL/cm), fruit/cm (FT/cm), blind

nodes/cm (BN/cm), and nodes/cm (N/cm).

Statistical Analysis

Statistical analysis was achieved using SAS 9.1 (SAS Institute Inc., Cary, NC).

Means were determined using PROC GLM and means separation among and within the

locations were by Tukey's HSD at the P<0.05 level.

Results

Chilling and Bloom

Chilling was significantly different among locations. However, the numbers of

chilling hours recorded during both years, were very similar for each location. The









greatest number of chill hours was observed in north-central Florida followed by central

and then southwest Florida (Figure 1).

In 2004, 'UFGold' bloomed later than the other cultivars at the north-central and

central Florida locations. However, 'UFGold' bloomed earlier (January 31) at the

southwest location than in central (February 9) or north-central (February 13) Florida

(Table 1). Conversely, 'TropicBeauty' bloomed earlier at the central location (January

28) than at the southwest location (February 1). No significant differences for bloom

date were observed among cultivars at the southwest site.

During 2005, significant differences in bloom period were observed among

cultivars and sites. 'Flordaprince' bloomed earlier (January 30) in southwest Florida then

in north-central (February 2) or central (February 14) Florida. 'UFGold' had an earlier

bloom (February 1) at the southwest location compared to the north-central (February 12)

and central (February 28) locations. Bloom in central Florida for both 'Flordaglo' and

'TropicBeauty' was later than for the other two locations.

Bloom of all cultivars at the central location during 2005 was delayed nearly one

month compared to the previous year. Full bloom dates for 'TropicBeauty',

'Flordaprince', 'Flordaglo', and 'UFGold' were the 23rd, 24th, 28th, and 28th of February,

respectively. 'Flordaprince' and 'TropicBeauty' bloomed earlier than either 'Flordaglo'

or 'UFGold'. At the north-central location, 'UFGold' bloomed later than the other

cultivars. No significant differences were observed for bloom date among cultivars at the

southwest site.









Bud Percentage

Nodes with only vegetative buds

No significant interactions between location and cultivar were found in either year

for the percent of nodes with only vegetative buds. Therefore only the main effects are

presented. During 2004, the percentage of nodes with only vegetative buds was

significantly higher in 'UFGold' than in the other cultivars (Figure 2). There were a

higher percentage of nodes with vegetative buds at the southwest location compared to

the north-central and central locations (Figure 3). During 2005, a higher percentage of

nodes with only vegetative buds were observed in 'Flordaprince' than 'TropicBeauty'

(Figure 4). There were no differences observed among locations during 2005 (Figure 5).

Nodes with vegetative and flower buds

During 2004, the percentage of nodes with both vegetative and flower buds was

greater for 'Flordaprince' and 'Flordaglo' than for either 'UFGold' or 'TropicBeauty' in

north-central Florida; and greater than 'UFGold' in southwest Florida (Figure 6).

Significant differences were not observed among cultivars at the central site. A higher

percentage of nodes with vegetative and flower buds were observed at the north-central

location than the central location for 'Flordaprince'. A higher percentage of nodes with

both vegetative and flower buds were observed at the north-central location for

'Flordaglo' compared to the other locations. The percentage of nodes with vegetative

and flower buds was lowest for 'UFGold' at the southwest location.

During 2005, there were no significant differences observed among cultivars at the

north-central location (Figure 7). Within the central location, 'Flordaprince' had a larger

percentage of nodes with vegetative and flower buds than 'UFGold', and at the southwest

location 'TropicBeauty' had a smaller percentage than the other cultivars. In general,









lower percentages of nodes with vegetative and flower buds were observed at the central

location compared to other locations.

Nodes with only flower buds

Nodes that had only flower buds were only measured during 2005 and only in

north-central and central Florida. There were no significant interactions between location

and cultivar. Therefore, only the main effects are presented. A higher percentage of

nodes with only flower buds were observed for 'UFGold' than for the other cultivars

(Figure 8). No differences were observed between locations (Figure 9). 'TropicBeauty'

had a lower percentage of nodes with only flower buds than 'UFGold' or 'Flordaglo'.

Blind nodes

During 2004 the percentage of blind nodes was greater for 'TropicBeauty' than for

the other cultivars at all locations (Figure 10). Similarly, the percentage of blind nodes

was greater for 'TropicBeauty' than for 'UFGold' in central Florida and greater than

'Flordaprince' in southwest Florida. A higher percentage of blind nodes were observed

in the central than the southwest location for 'Flordaprince'. A higher percentage of

blind nodes were observed in 'UFGold' at the southwest location compared to the north-

central location.

During 2005, at the north-central location, more blind nodes were observed for

'TropicBeauty' and 'Flordaglo' than for 'UFGold' (Figure 11). 'TropicBeauty' also had

a larger percentage of blind nodes than 'UFGold' in central Florida and a larger

percentage than all other cultivars at the southwest location. A lower percentage of blind

nodes were observed in the north-central location than the other locations.









Buds per Node

Vegetative buds

During 2004, the number of vegetative buds per node was significantly less for

'TropicBeauty' than for the other cultivars at the north-central location (Table 2).

Similarly they were less for 'TropicBeauty' than for 'UFGold' in central Florida, or for

'Flordaprince' at the southwest location. The number of vegetative buds per node was

higher in southwest Florida than central Florida for 'Flordaprince'. Higher values were

observed at the north-central location than at the southwest location for 'UFGold' during

2004. During 2005 no significant differences were observed among the cultivars in

north-central Florida (Table 3). However, 'UFGold' had fewer vegetative buds per node

than the other cultivars at the central location and 'TropicBeauty' had fewer than the

other cultivars at the southwest location. The number of vegetative buds per node was

generally lowest for 'Flordaprince', 'Flordaglo', and 'TropicBeauty' in central Florida.

Flower buds

During 2004, more flower buds per node were observed for 'Flordaglo' than for

either 'UFGold' or 'TropicBeauty' in north-central Florida, or for 'UFGold' at the

southwest location (Table 2). 'Flordaglo' had a higher amount of flower buds per node

than 'Flordaprince' in central Florida. Location differences were observed for several

cultivars during 2004. The number of flower buds per node for 'Flordaprince' was

higher in north-central Florida than in central Florida. Flower buds per node for

'Flordaglo' were also higher at the north-central location than at the other locations.

'UFGold' had higher flower bud counts per node at the north-central location than at the

southwest location.









During 2005 significant differences among cultivars were not observed at the

north-central location (Table 3). In central Florida more flower buds per node were

observed for 'UFGold' than for 'Flordaglo' or 'TropicBeauty'. 'TropicBeauty' had the

least flower buds per node at the southwest site. Among locations the number of flower

buds per nodes was higher for all cultivars at the north-central location.

Flowers

The number of flowers per node was not observed during 2004 and only at the

north-central and central locations during 2005. Significant differences were not detected

in north-central Florida (Table 3). In central Florida, more flowers per node were

observed for 'UFGold' than for 'Flordaglo' or 'TropicBeauty'. Between the two

locations, the number of flowers per node was higher in north-central Florida than in to

central Florida.

Bud Density

Vegetative buds

Vegetative bud density (buds/cm shoot length) during 2004 was greater for

'UFGold' than for 'Flordaprince' or 'TropicBeauty' at the north-central location, and

greater than 'TropicBeauty' in central Florida (Table 4). At the southwest location

'Flordaprince' had a greater vegetative bud density than 'TropicBeauty'. A lower density

of vegetative buds was observed at the southwest location than to the other locations in

both 'Flordaglo' and 'UFGold'. Lower densities were observed for 'TropicBeauty' in

southwest Florida compared to central Florida during 2004.

Significant differences were not observed during 2005 among cultivars at the north-

central site (Table 5). However, lower values were observed for 'UFGold' than for the

other cultivars at the central location, or for 'TropicBeauty' at the southwest location.









Higher densities of vegetative buds were observed at the southwest location for 'UFGold'

followed by the north-central and central locations. Lower densities were observed for

'TropicBeauty' in southwest Florida compared to north-central or central Florida.

Flower buds

During 2004, greater flower bud density (flower buds/cm shoot length) was

observed for 'Flordaglo' than for 'UFGold' in north-central Florida (Table 4). Within the

central location, 'Flordaglo' had greater flower bud density than 'Flordaprince'. Flower

bud density was less for 'UFGold' than for 'Flordaprince' or 'Flordaglo' at the southwest

location. The north-central location had a higher flower bud density for 'Flordaprince'

than the central or southwest locations. Lower values for flower bud density were

observed in 'Flordaglo' and 'UFGold' at the southwest location compared to the other

locations.

During 2005, significant differences were not observed in the north-central site

(Table 6). At the central location 'UFGold' had higher flower bud densities than either

'Flordaglo' or 'TropicBeauty'. In southwest Florida 'TropicBeauty' had lower values

than 'Flordaglo' or 'UFGold'. High values for flower bud density were observed for

'Flordaprince' at the north-central location, and low values were observed at the

southwest location for 'UFGold'. Higher flower bud densities were observed in north-

central Florida for 'Flordaglo' than in southwest Florida. Flower bud density was highest

for 'TropicBeauty' at the north-central location followed by the central and southwest

locations.

Flowers

Flower density (flowers/cm shoot length) was not observed during 2004. During

2005 flower density was observed at the north-central and central locations. No









differences were observed among cultivars at the north-central location (Table 6). There

were higher flower densities observed in 'UFGold' in central Florida compared to the

other cultivars. Higher flower densities were observed in north-central Florida for

'Flordaprince', 'Flordaglo', and 'TropicBeauty' than in central Florida.

Fruit

No significant interactions were found between location and cultivar during either

2004 or 2005 for fruit density (fruit/cm shoot length). Therefore, only the main effects

are presented. During 2004, higher fruit density was observed for 'UFGold' than for the

other cultivars (Table 7). During 2005, higher fruit densities were observed for

'Flordaglo' and 'UFGold' than for 'Flordaprince' or 'TropicBeauty'. There were no

significant differences observed between the two locations during either year.

Blind nodes

During 2004, significant differences in the frequency of blind nodes (blind

nodes/cm shoot length) were observed among cultivars at all locations. Blind node

frequency at the north-central location was greatest for 'TropicBeauty' (Table 4). In

central Florida, frequencies were greater for 'TropicBeauty' than for 'UFGold'. At the

southwest location, blind node frequencies were higher for 'TropicBeauty' than for

'Flordaprince' or 'Flordaglo'. Blind node frequencies for 'Flordaprince', 'Flordaglo',

and 'TropicBeauty' were highest at the central location.

During 2005, the frequency of blind nodes was lower for 'UFGold' than for either

'Flordaglo' or 'TropicBeauty' in north-central Florida (Table 5). Higher values were

observed for 'TropicBeauty' than for 'UFGold' at the central location, and at the

southwest site values for 'TropicBeauty' were higher than for all other cultivars. Lower









amounts of blind nodes were observed in north-central Florida than in central or

southwest Florida.

Nodes

No significant interactions for node density were observed between locations and

cultivars during either year. Therefore, only main effects are reported. Significant

differences were not detected among the cultivars during 2004 (Table 7). During 2005 a

higher density of nodes was observed in 'TropicBeauty' than in 'Flordaprince'. During

both years node density was higher in central Florida than at the other locations.

Discussion

Chilling and Bloom

The location where trees are grown can affect many aspects of development.

Temperatures in an area can affect when bloom occurs and the development of buds

during the summer and fall. There have also been several reports on the effect of

temperature on fruit set of peach (Edwards, 1987; Erez et al., 2000; Rouse and Sherman,

2002b) and apple and pear (Tromp and Borsboom, 1994).

Chilling hours accumulated during the late fall and winter are important in breaking

endodormancy of peaches (Weinberger, 1950a). The amount of chilling required varies

by cultivar (Weinberger, 1950a) as well as by bud type (Scalabrelli and Couvillon, 1986).

The cultivars observed in this experiment were low-chill, and require only 150 200

hours of chilling (Rouse and Sherman, 1989b; Sherman and Lyrene, 1997; Sherman and

Lyrene, 1989; Sherman et al., 1982).

A delay in bloom at the central location was observed during 2005. This delay in

bloom was probably the result of early defoliation from bacterial spot combined with

severe winds from several hurricanes in the summer, 2004. During summer, 2004, the









incidence of bacterial spot was very high at the central Florida location. Infection and

defoliation had already begun in May, 2004. The trees were not sprayed at this time

because fruit were still being harvested. The disease was already well established within

the orchard and on several nearby plum trees when a spray program was initiated in early

June. Wind and rain aid in the spread of this disease. During 2004, several major

hurricanes (Category 2 or higher prior to landfall) passed through the area. Hurricanes

Charley, Frances, and Jeanne all affected crops within the area. Leaf shredding and

tearing was common at all three orchard site; however, the central location was directly

hit by all three hurricanes. These storms likely increased the spread of bacterial spot

within each tree and among trees. The high sustained winds and strong gusts shredded

leaves and caused partial defoliation. The damaged leaves were likely points of infection

for bacterial spot and some trees were completely defoliated from both bacterial spot and

tropical storm force winds by the end of September. The early defoliation in 2004

resulted in a late summer/early fall growth flush that may have delayed the onset of

dormancy and chill accumulation. Early defoliation from the combined affect of three

major hurricanes, high incidence of bacterial spot, and late summer growth probably

resulted in the marked delay in bloom experienced at the central location during 2005.

Such a delay in bloom can be very detrimental to fruit set. Low yields may result when

flowering and fruit set occur under warmer temperature conditions (Rouse and Sherman,

2002).

The progressive delay in bloom observed for 'UFGold' as the locations progressed

further north may have resulted from this cultivar accumulating the necessary heat units

for bloom at a faster rate at the southwest location. There was a twelve day difference









between the north-central and southwest locations for date of full bloom in 'UFGold'.

Generally full bloom was within about three days of each other for 'Flordaprince',

'Flordaglo', and 'TropicBeauty' between north-central Florida and southwest Florida.

Chilling in 'UFGold' may have been satisfied at all three locations at approximately the

same time. However, in the southwest location, more heat units may have been

accumulated in a shorter period of time than at the central or north-central locations

resulting in earlier bloom in southwest Florida. Weinberger (1948) reported a two day

delay in full bloom for 'Elberta Peach' between the Fort Valley area of Georgia (central

GA.), and areas in northern Georgia. This earlier bloom may facilitate an earlier harvest

in more southern locations. However it has been reported that the temperatures following

bloom can be important in reducing FDP (Boonprakob et al., 1992; Topp and Sherman,

1989a; Weinberger, 1948).

Percentage of Vegetative, Floral, and Blind Nodes

The percentage of vegetative, floral, and blind nodes can indicate how well adapted

cultivars are to different climatic zones, and indicate which cultivars have a high

cropping potential. This can give an indication of what conditions are favorable or

unfavorable for development of certain types of nodes, mainly blind nodes. A blind node

is a condition where there is no vegetative or floral bud located at a node (Boonprakob et

al., 1996). This can be caused by high temperatures during bud development

(Boonprakob and Byrne, 1990).

During 2005, there were some nodes without vegetative buds that had at least one

flower bud. There appeared to be a greater percentage of these node types set for

'UFGold' than for the other cultivars. The percentage of flower bud only nodes in

'UFGold' ranged form 31% at the north-central location to 39% at the central location.









Percentages ranged from 8% to 18% among the other three cultivars. This data supports

the cultivar release information which states that 'UFGold' tends to set high amounts of

flower buds (Sherman and Lyrene, 1997).

Cultivars such as 'UFGold' that set high percentages of nodes with only flower

buds could have difficulty supporting heavy fruit loads. Such cultivars could set heavy

fruit loads with very little foliage. These fruit will be reduced in size and quality, and

may be damaged from excessive exposure to the sun. With the lack of foliage to support

vegetative growth, shoots will remain thin. Growth of the terminal vegetative buds, on

these shoots the following year will produce long thin branches that can hang close to the

ground, where the shoots and foliage could be damaged by herbicides.

Lack of adequate foliage cover in the canopy can cause the exposed branches and

scaffold limbs to sunburn. The damaged wood can later serve as an entry way for

pathogens and insects. Lack of foliage can also cause problems with pruning and training

trees. Since these shoots have very few vegetative buds, the number of potential pruning

locations is reduced. These shoots will have to be cut back to the main scaffold limb.

This can be problematic in training trees into the open-vase form, or when trying to keep

trees compact. These problems may also occur in genotypes that have high frequency of

blind nodes.

Differences for blind node percentages were observed during 2005 among locations

and cultivars. The north-central location had the lowest percentages of blind nodes

across all four cultivars during 2005. Warmer temperatures during bud development

were probably the cause of higher blind nodes observed at the central and southwest

locations. Blind nodes are generally caused by high temperatures during a period of









rapid shoot growth (Richards et al., 1994). Average temperatures above 220C, as well as

other stresses imposed on trees, have been shown to be critical for the development of

blind nodes (Boonprakob and Byrne, 2003). Average temperatures above 220C are

common in many areas of Florida, especially further south, during the summer months.

However, genotypic differences appear to exist among cultivars. While cultivars had

above 50% blind buds in central and southwest Florida, 'TropicBeauty' tended to have

the highest percentage of blind nodes at all locations. 'UFGold' usually had a lower

percentage of blind nodes than 'TropicBeauty'. This is in agreement with published

information for 'UFGold' that states that few blind buds are set by this cultivar (Sherman

and Lyrene, 1997).

There were other stresses that were imposed on the trees at the central location.

Effects other than temperature may play an important role in the reduction of certain bud

types and the increase in blind nodes for some cultivars. There was a significant

reduction in the percentage of nodes that had both vegetative and flower buds during

2005. As stated earlier, defoliation from bacterial spot was more pronounced in central

Florida, and during the summer and fall of 2004, several major hurricanes passed through

central Florida. The stresses from the above mentioned factors along with the effect of

temperature during the critical period of bud formation in late August and September

may have caused the higher incidence of blind nodes and lower incidences of nodes with

both vegetative and flower buds observed in central Florida.

Cultivars that exhibit a high percentage of blind nodes such as 'TropicBeauty' need

to be planted in areas that do not receive the high summer temperatures during bud









development. It is important to test cultivars in areas that receive high summer

temperatures to determine how the cultivars are affected by different climate conditions.

Number of Buds per Node and Bud Density

The number of vegetative buds and flowers per node were lower during 2005 for

several cultivars at the central location compared to either the southwest or north-central

locations. Vegetative bud counts per node differed between years at the central and

southwest locations. Two factors may have contributed to this. Stresses imposed from

the passage of three hurricanes and high incidence of bacterial spot may be causes of the

low bud and flower counts per node observed. The shredding and tearing of the leaves

from the passage of the hurricanes, as well as senescence of leaves from bacterial spot

may have affected vegetative and flower bud growth and development during late August

and September as well as overall health of the tree.

Higher flower bud counts per node and lower densities of blind nodes at the north-

central location may be a result of cooler temperatures during bud development in the

summer and fall within this location compared to the central or southwest locations.

There also may be genotype differences for different densities of nodes that are more

prevent at different locations. Since blind nodes are caused by warmer temperatures,

fewer blind nodes would be set at the north-central location and more flower or

vegetative buds would be set. This would explain the higher flower bud counts per node.

Higher flower and fruit densities observed in some peach cultivars may be the

result of genetic tendencies in some cultivars for higher fruit densities or fruit set. This

has been observed in apricot. Alburquerque et al. (2004) observed the effect of climatic

conditions and cultivar differences on several apricot cultivars. They concluded that final

fruit set was influenced more by cultivar than by climate. The higher fruit density









observed in 'UFGold' compared to 'TropicBeauty' might be a result of a genetic

tendency for 'UFGold' to set high amounts of flowers and fruits and for 'TropicBeauty'

to set low amounts of flowers and fruits.

General Conclusions

Testing to determine the adaptation of different cultivars at multiple locations can

help to determine where certain traits are more pronounced. Warmer locations may

increase the prevalence of blind nodes in cultivars. Cultivars should be tested in warmer

areas to see if they are prone to this condition. Genetic tendencies may also exist for

blind nodes and nodes with only floral buds in certain cultivars. Genotypic differences

may also exist among cultivars for fruit density. Stresses from environmental factors and

diseases may have an effect on the number and type of buds set at a node. The results

obtained here on the occurrence of blind nodes in different climatic regions and

prevalence of nodes with floral buds provides valuable information to breeders, when

selecting germplasm for release or future crosses.












500
450
400
350
300
250
200
150
100
50
0-


2004


* North-Central
* Central
o Southwest


2005


year

Figure 1. Total chill unit accumulation for hours below 7.2 C among locations for the
2004 and 2005 seasons for four low-chill peach cultivars from early
November to January 31 for each year.













Table 1. Mean date of full bloom for both 2004 and 2005 across three locations for four low-chill peach cultivars.
2004 Season 2005 Season
Location Location
Cultivar North-Central Central Southwest Significance North-Central Central Southwest Significance
FlordaPrince 01-28-04bzAy 01-28-04bA 01-25-04aA 0.5758 02-02-05bB 02-24-05bA 01-30-05Ca <.0001
FlordaGlo 01-31-04bA 02-02-04bA 02-02-04aA 0.7274 02-05-05bB 02-28-05aA 02-02-05Ba <.0001
UFGold 02-13-04aA 02-09-04aA 01-31-04aB <0.0001 02-12-05aB 02-28-05aA 02-01-05aC <.0001
TropicBeauty 01-31-04bAB 01-28-04bB 02-01-04aA 0.0211 02-02-05bB 02-23-05bA 01-21-05aB <.0001
Cultivar Signif. <0.0001 <0.0001 0.0688 <0.0001 <0.0001 0.0431
z Means within location followed by the same lowercase letter are not significantly different according to Tukey's Test < 0.05.
Y Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukey's Test < 0.05






















30


25


20

15

10

5


0Flordaprince
Flordaprince


C


Flordaglo


UFGold TropicBeauty


Cultivar


Figure 2. Main effects for the percentage of nodes with only vegetative buds during 2004
for four low-chill peach cultivars. Lowercase letters represent significant
differences among cultivars using Tukey's Test P < 0.05.


25


20


15

10

5


0 North-Central
North-Central


Central
Location


Southwest


Figure 3. Main effects for the percentage of nodes with only vegetative buds during 2004
for three locations. Lowercase letters represent significant differences among
locations using Tukey's Test P < 0.05.













20
ab
18 -

16 ab

14

12

S10

8

6

4

2

0
Flordaprince Flordaglo UFGold TropicBeauty
Cultivar

Figure 4. Main effects for the percentage of nodes with only vegetative buds during 2005
for four low-chill peach cultivars. Lowercase letters represent significant
differences among cultivars using Tukey's Test P < 0.05.





a
16-

14

12

10

8--

6

4

2

0
North-Central Central Southwest
Cultivar

Figure 5. Main effects for the percentage of nodes with only vegetative buds during 2005
for three locations. Lowercase letters represent significant differences among
locations using Tukey's Test P < 0.05.












50 aA
45

40 -

35 aB
bA bA aABaB
30 b h -C Flordaprince
u 25abA Flordaglo
2 O UFGoId
20 0 TropicBeauty

15 -
10 -

5

0
North-Central Central Southwest
Locations

Figure 6. Percentage of nodes with both vegetative and flower buds for four low-chill
peach cultivars during the 2004 season within three locations. Lower case
letters represent significant differences among cultivars within a location
using Tukey's Test P < 0.05. Uppercase letters represent significant
differences among locations for each cultivar using Tukey's Test P < 0.05.



40

35 a aA

30

25 *-A 0 Flordaprince
Flordaglo
S20 -] UFGold
[O TropicBeauty
15 -

10 abB aB

5

0
North-Central Central Southwest
Locations

Figure 7. Percentage of nodes with both vegetative and flower buds for four low-chill
peach cultivars during the 2005 season within three locations. Lower case
letters represent significant differences among cultivars within a location
using Tukey's Test P < 0.05. Uppercase letters represent significant
differences among locations for each cultivar using Tukey's Test P < 0.05.







60




40
a
35

30

25

20

15 bc

10 -





Flordaprince Flordaglo UFGold TropicBeauty
Cultivar

Figure 8. Main effects for the percentage of nodes with only flower buds during 2005 for
four low-chill peach cultivars. Lowercase letters represent significant
differences among cultivars using Tukey's Test P < 0.05.



20 -

18

16

14

12

10

8

6

4
2

0
North-Central Central
Location

Figure 9. Main effects for the percentage of nodes with only floral buds during 2005
between two locations. Lowercase letters represent significant differences
between locations using Tukey's Test P < 0.05.







61



60 aA
aA aA
50
abA abA ab

40 -
bAB bA AE m Flordaprince

P 30 b m Flordaglo
3 bB / UFGold
o1 TropicBeauty
20


10 -


0
North-Central Central Southwest
Locations

Figure 10. Percentage of blind nodes for four low-chill peach cultivars during the 2004
season within three locations. Lower case letters represent significant
differences among cultivars within a location using Tukey's Test P < 0.05.
Uppercase letters represent significant differences among locations for each
cultivar using Tukey's Test P < 0.05.


90 aA

80

70 aB

60 abbA A bA
bA bA m Flordaprince
50 Flordaglo
40 aC 3 UFGold
O3 TropicBeauty
30

20

10-

0
North-Central Central Southwest
Locations

Figure 11. Percentage of blind nodes for four low-chill peach cultivars during the 2005
season within three locations. Lower case letters represent significant
differences among cultivars within a location using Tukey's Test P < 0.05.
Uppercase letters represent significant differences among locations for each
cultivar using Tukey's Test P < 0.05.












Table 2. Mean vegetative and flower buds per node for the 2004 season, for four low-chill peach cultivars within three different
locations.
Vegetative Buds/Node Flower Buds/Node
North-Central Central Southwest North-Central Central Southwest
Flordaprince 0.66azABY 0.561abB 0.719aA 0.61abA 0.26bB 0.47abAB
Flordaglo 0.66aA 0.56abA 0.64abA 0.68aA 0.45aB 0.49aB
UFGold 0.75aA 0.67aAB 0.58abB 0.43bA 0.36abAB 0.21bB
TropicBeauty 0.47bA 0.44bA 0.48bA 0.47bA 0.33abA 0.41abA
z Means within location followed by the same lowercase letter are not significantly different
according to Tukey's Test P < 0.05.
Y Means for cultivars across locations followed by the same uppercase letter are not significantly
different according to Tukey's Test P < 0.05.


Table 3. Mean vegetative and flower buds per node for the 2005 season, for four low-chill peach cultivars within three different
locations.
Vegetative Buds/Node Flower Buds/Node Flowers/Node
North- North- North-
Central Central Southwest Central Central Southwest Central Central Southwest
Flordaprince 0.513azAy 0.256aB 0.445aA 0.708aA 0.249cbB 0.310aB 0.475aA 0.052cbB ---x
Flordaglo 0.476aA 0.234aB 0.423aA 0.620aA 0.299bB 0.317aB 0.423aA 0.116bB ---
UFGold 0.441aA 0.098bB 0.490aA 0.781aA 0.430aB 0.402aB 0.423aA 0.202aB ---
TropicBeauty 0.491aA 0.244aB 0.163bB 0.825aA 0.181cB 0.100bB 0.549aA 0.031cB ---
z Means within location followed by the same lowercase letter are not significantly different according to Tukey's Test P < 0.05.
Y Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukey's
Test P < 0.05.
x Data unavailable.












Table 4.Vegetative bud, flower bud, and blind node density for four low-chill peach cultivars for the 2004 season within three
different locations.
Vegetative Buds/ cm Shoot Length Flower Buds/ cm Shoot Length Blind Nodes/ cm Shoot Length
North- North- North-
Central Central Southwest Central Central Southwest Central Central Southwest
Flordaprince 0.41bzAy 0.43abA 0.38aA 0.38abA 0.19bB 0.23aB 0.21bB 0.37abA 0.14bB
Flordaglo 0.43abA 0.46abA 0.32abB 0.44aA 0.35aA 0.23aB 0.22bB 0.38abA 0.17bB
UFGold 0.51aA 0.53aA 0.30abB 0.28bA 0.29abA 0.10bB 0.17bA 0.28bA 0.23abA
TropicBeauty 0.32cAB 0.37bA 0.25bB 0.32abA 0.27abA 0.21abA 0.36aB 0.51aA 0.28aB
z Means within location followed by the same lowercase letter are not significantly different according to Tukey's Test P <
0.05.
Y Means for cultivars across locations followed by the same uppercase letter are not significantly different according to Tukey's
Test P < 0.05.


Table 5. Vegetative bud and blind node density for four low-chill peach cultivars for the 2005 season within three different locations.
Vegetative Buds/ cm Shoot Length Blind Nodes/ cm Shoot Length
North-Central Central Southwest North-Central Central Southwest
Flordaprince 0.3 lazAy 0.26aA 0.32aA 0.21abC 0.66abA 0.42bB
Flordaglo 0.35aA 0.27aA 0.32aA 0.27aB 0.67abA 0.50bA
UFGold 0.30aB 0.1 IbC 0.41aA 0.17bB 0.59bA 0.45bA
TropicBeauty 0.35aA 0.27aA 0.16bB 0.28aB 0.79aA 0.88aA
z Means within location followed by the same lowercase letter are not significantly different according
to Tukey's Test P < 0.05.
Y Means for cultivars across locations followed by the same uppercase letter are not significantly
different according to Tukey's Test P < 0.05.












Table 6. Flower bud and flower density for four low-chill peach cultivars for the 2005 season within three different locations.
Floral Buds/ cm Shoot Length Flowers/ cm Shoot Length
North-Central Central Southwest North-Central Central Southwest
Flordaprince 0.44azAy 0.27bcB 0.22abB 0.29aA 0.06bB ---x
Flordaglo 0.45aA 0.34bAB 0.24aB 0.31aA 0.13bB ---
UFGold 0.52aA 0.49aA 0.35aB 0.28aA 0.24aA ---
TropicBeauty 0.58aA 0.21cB 0.lObC 0.39aA 0.04bB ---
z Means within location followed by the same lowercase letter are not significantly different according to
Tukey's Test P < 0.05.
Y Means for cultivars across locations followed by the same uppercase letter are not significantly different
according to Tukey's Test P < 0.05.
x Data unavailable.












Table 7. Main effects of fruit and node density for four low-chill peach cultivars, and three different locations, for the 2004 and 2005
seasons.
2004 2005
Fruit/ Nodes/ Fruit/ Nodes/
cm Shoot Length cm Shoot Length cm Shoot Length cm Shoot Length
Cultivar
Flordaprince 0.06cz 0.64a 0.05b 0.81b
Flordaglo 0.14b 0.66a 0.13a 0.89ab
UFGold 0.23a 0.67a 0.16a 0.88ab
TropicBeauty 0.05c 0.70a 0.06b 0.97a
Location
North-Central 0.11 ay 0.66b 0.11 a 0.69c
Central 0.12a 0.83a 0.09a 1.13a
Southwest --- ___0.52c --- 0.86b
zMeans across cultivars followed by the same lowercase letter are not significantly different according to
Tukey's Test P < 0.05.
Y Means across locations followed by the same uppercase letter are not significantly different according to
Tukey's Test P < 0.05.
x Data unavailable.














CHAPTER 4
FRUIT QUALITY AND YIELD OF FOUR LOW-CHILL PEACH CULTIVARS
GROWN IN THREE LOCATIONS

Introduction

Several important fruit quality characteristics of peach are affected by climate and

cultural practices. Percent blush coverage can be affected by the prevailing climate in a

production region. Rouse and Sherman (1989a) reported a higher blush in the Lower Rio

Grande Valley of Texas than in Gainesville, Florida, for several cultivars of low-chill

peaches. This was attributed to the warmer prevailing temperatures in that area of Texas.

However, Topp and Sherman (1989b) reported no correlation between temperature and

red blush. Other characteristics such as stylar tip (Topp and Sherman, 1989b; Salvador et

al., 1998) and fruit development period (FDP) (Anderson and Sherman, 1994; Topp and

Sherman, 1989b; Rouse and Sherman, 1989a; Weinberger, 1948) can also be affected by

temperature during development.

Different cultural practices can also affect fruit quality and yield. Higher rates of

nitrogen (N) have been shown to impose a greener ground color (Meheriuk et al., 1995),

increase the length of the FDP (Saenz et al., 1997), increase fruit yield (Shoemaker and

Gammon, 1963), and increase astringency (Jia et al., 1999). Different tree training

techniques, open vase or perpendicular Y, can increase light penetration and affect

several quality attributes such as SSC, ground color, and flesh firmness (Farina et al.,

2005). Fruit thinning can be important for some developmental aspects such as SSC

(Corelli-Grappadelli and Coston, 1991) and fruit size (Tukey and Einset, 1938). Light









interception is also important in red blush development (Erez and Flore, 1986) and

ground color development (Lewallen and Marini, 2003).

Yield and some quality traits can also interact with each other; a good example of

this was reported by (Rowe and Johnson, 1992) who found a relationship between total

yield and fruit size. They found that larger fruit were produced at the expense of total

yield; in essence this means that more fruit on the tree reduces fruit size (Rowe and

Johnson, 1992).

The objective of this experiment was to observe fruit quality characteristics and

yield of four low chill peach cultivars at three locations in Florida. Quality and

developmental characteristics observed included blush, L*, C*, h*, SSC, SSC/TA ratio,

fruit shape, fruit size, and FDP. Total fruit weight and number were also determined.

Materials and Methods

Locations

Three sites were chosen that represented different locations and climates from

north-central to south Florida. The north-central site was located in Archer, Florida

(Lake fine sand, 29.52N 82.53W), the second or central location was in Winter Garden,

Florida (Calander fine sand, 28.57N 81.58W Elev. 32.0 m), and the third or southwest

location was in Immokalee, Florida (Immokalee fine sand, 26.43N 81.41W). Four

cultivars ('Flordaglo', 'Flordaprince', 'TropicBeauty', and 'UFGold') were planted at all

three sites. All cultivars were grafted onto a greenleaf nematode resistant peach rootstock

(Fl 9-04). Trees were planted in February, 2002, at all locations using a north/south row

orientation at a distance of 4.57 m between trees (346 trees/hectare) in a randomized

complete block design, with five replications and single tree plots, within each location.









Cultural Practices

Overhead irrigation was used for frost protection at the north-central site during

bloom in 2004 and 2005. Neither the central or southwest locations received any frost

protection. All trees were winter pruned in early to mid-January each year. Trees were

pruned to an open vase form and headed back to a height of -2.5 meters. The trees were

also summer pruned in early June of both years as needed. Trees at the north-central

location received overhead irrigation and trees were not water stressed at any time during

either season. At the central location, trees were irrigated by microsprinkler emitters for

25 minutes each morning before dawn. During 2004, over a 2-week time span during

mid to late March, a substantial leak occurred in the main irrigation line and the trees did

not receive any irrigation at that during that period. Microsprinkler emitters were also

used at the southwest location.

Weeds were controlled at all locations by maintaining a herbicide band under the

canopy of the trees and among trees. Weed control was accomplished at the north-central

and central locations with glyphosate and a water conditioning agent (blend of

polyacrylic, hydroxyl carboxylic, and phosphoric acids). Applications were made with a

five gallon backpack sprayer when needed. At the southwest location glyphosate and

paraquat were used.

Fertilizer at the north-central location was applied by hand in three applications

during the year, early February, early June, and late September. During both seasons,

crossover fertilizer applications from an adjacent commercial blueberry field occurred

eight times from a mechanical fertilizer spreader on the east side of the trees. These

times were: early February, early March, late March, late May, early July, late July, late

August, and early September. When fertilizer was hand broadcast, it was placed









primarily under the west half of the tree to compensate for the unequal distribution of

fertilizer from the crossover applications. Fertilizer application times at the central

location were the same as at the north-central location. Reclaimed water was used for

irrigation at the central location. Total amount of N applied via reclaimed irrigation

water was obtained by calculating an average N concentration of reclaimed water

(.0072428 g N/L) between July 2005 and January 2006. Additionally, emitter output,

line pressure, and irrigation schedule were used to determine total N applied per hectare

from reclaimed water which was calculated at 33.86 kg/ha/season. Nitrogen fertilizer

rates varied among locations. For 2004, they were 276 kg/ha at the north-central

location, 103 kg/ha at the central location and 112 kg/ha at the southwest location. For

2005 these rates were 313 kg/ha at the north-central location, 114 kg/ha at the central

location and again 112 kg/ha at the southwest location.

Paraffinic hydrocarbon oil was use to control white peach scale (Pseudaulacaspis

pentagon (Targioni Tozzetti)), as needed during the dormant season. Fruit were hand-

thinned just prior to pit hardening to a distance of 15 cm between fruit. After thinning,

phosmet and captain were applied to control plum curculio (Conotrachelus nenuphar

(Herbst)) and peach scab (Cladosporium carpophilum (Thum.)), respectively.

Postharvest sprays at the north-central location, were a combination of copper sulfate

(20% metallic Cu equivalent), a non-ionic surfactant (alkylphenol etozylate, sodium salts

of soya fatty acids, and isopropyl alcohol), and phosphoric acid, which were applied

every three weeks until mid-October to control bacterial spot (Xanthomonas arboricola

pv. pruni (= X campestrispv. pruni)). At the central location trees were sprayed until

late August and early July in 2004 and 2005, respectively. Chlorothalonil or a









combination of pyraclostroblin and boscalid was applied as needed to control peach rust

(Tranzschelia discolor (F. Chl.) Trans. and Litr.) at the north-central and central

locations. For all pesticide applications trees were sprayed early in the morning. Sprays

were applied by using a hydraulic sprayer (John Bean sprayers, Modular Hydraulic

Sprayer, Model DM10E200FERH, Hogansville, Ga), with a handgun, at 500 psi on all

parts of the tree until run off occurred. At the southwest location azoxystrobin and

myclobutanil were used monthly to manage peach rust.

Fruit Development Period

A visual estimation of the overall bloom on the tree was done in 2004 and 2005.

Bloom was rated twice each week (when applicable) using a 10% to 100% scale, and the

date of petal fall was recorded. FDP was determined from 50% to 60% bloom to first

commercial harvest.

Harvest

Total yield and weight

During 2004, each tree was harvested individually and the numbers and weights of

marketable and nonmarketable fruit were recorded. Nonmarketable fruit were delineated

as those that were < 4.5 cm, showed signs of wind scaring, catfacing, bacterial spot,

insect predation, split pits, deep sutured fruit, or rotten fruit. Fruit were harvested at a

firm ripe stage of development; harvest occurred twice each week at all locations. Fruit

from the north-central location were counted and weighed directly in the field. Fruit

from the central location were bought directly to the laboratory and counted and weighed.

Marketable fruit were weighed and the weight and the number of fruit were recorded for

each tree at each harvest date. The same procedure was applied to the nonmarketable

fruit.









After marketable fruit were weighed and counted at the north-central location,

eleven representative sub-samples from each tree for each harvest date were selected at

random and placed in peach trays that were obtained from a local grocery store. The

trays were then placed in plastic Rubbermaid containers for transport to the laboratory.

Fruit from the central Florida location were harvested and transported to the laboratory,

then weighed and eleven representative fruit samples were selected as described above.

During 2005, the procedure was changed slightly so that fruit from the central

Florida location were weighed on site. Fruit selection and transport were the same. At

the north-central location, it appeared that the east sides of the trees had fewer fruit than

the west sides of the trees. This looked to be true for all four cultivars. To determine if

there was a difference in location of fruit in the tree canopy, each tree was divided into

two sectors, east and west, and fruit were counted and weighed as such.

Trunk measurements

Every six months after leaf fall and after fruit harvest, trunk circumference was

measured. Readings were taken using a 150 cm dressmakers tape at a pre-determined

spot 15 cm above the ground level. This was later used to calculate trunk cross-sectional

area (TCA).

Fruit size, weight, and blush

Fruit sub-samples were placed in a walk-in cooler (3 50C), where they were

cooled to remove field heat. Prior to fruit quality measurements fruit were removed from

the cooler the previous day and allowed to warm to room temperature. Ten fruit from

each sub-sample were measured in three different orientations: blossom end to stem end,

cheek to cheek, suture to side opposite suture. Each 10-fruit sample was weighed and

each fruit was rated visually for the amount of red blush under fluorescent light.









Chromicity values

In 2005, at early (first commercial) harvest and mid harvest (greatest number of

fruit removed per tree), a Konica Minolta CR 400/410 Chroma meter (Konica Minolta,

Osaka, Japan) was used to test the chromicity values on the most blushed and least

blushed surface areas of five fruit from each 10-fruit sub-sample. The chroma meter was

calibrated using a standard calibration plate prior to each use. For post harvest

measurements in 2005, the same five fruits that were used for chromicity measurements

were used for soluble solids concentration (SSC), titratable acidity (TA), pH, and

pressure measurements. During 2004 five fruits were selected at random from the ten

fruit sample for fruit size, weight, and blush at early and mid harvest.

Blossom end

During 2005, fruit blossom end tips were rated as either recessed, flattened, or

extended. Thirty fruit were selected at random from the marketable fruit from each tree

during peak harvest and rated in the field for blossom end tip. Fruit that would be

damaged in shipping were considered extended tip fruit.

Firmness, soluble solids concentration, titratable acidity, and pH

Flesh firmness was measured using a firmness tester (IFAS Firmness Tester,

Gainesville, FL) fitted with a 6 mm probe. Two measurements per fruit were taken (from

the center of each cheek) from 5-fruit samples. The epidermis was removed from the test

area prior to measuring flesh firmness. Fruit were peeled and flesh samples were

collected from the cheek area of each fruit (avoiding the points where pressure

measurements were taken, and the suture, and opposite the suture). A composite flesh

sample was obtained for each 5-fruit sub-sample. Flesh samples were quick frozen in a -

800C freezer and stored at -300C. Flesh samples were removed from the freezer, allowed









to thaw at room temperature, and homogenized in a blender. The slurry was centrifuged

for 20 minutes at 14,000 rpm at 50C. The samples were then filtered through two layers

of cheese cloth into a 50 ml beaker. Six g of supernatant diluted with 50 ml of deionized

water was used to measure TA. Samples were titrated to an end point of 8.2 using an

automatic titrimeter (Fisher Titrimeter II, No. 9-313-10, Pittsburg, Pa) and expressed as

ml NaOH. The normality of NaOH used was 0. IN. The remainder of the undiluted

supernatant was used to determine pH and SSC. A Digital Refractometer (Reichert-Jung,

Mark Abbe II Refractometer, Model 10480, Depew, NY) was used to measure the SSC

of the undiluted sample and was expressed as Brix. The pH of the sample was measured

using a pH meter (Coming Scientific Instruments, pH meter 140, Medfield, Ma).

Statistical Analysis

Statistical analysis was achieved using SAS 9.1 (SAS Institute Inc., Cary, NC).

Means were determined using PROC GLM and means separations among and within the

locations were by Tukey's HSD at the P<0.05 level.

Results

Due to higher rates of N applied at the north-central location, direct comparisons

could not be made between this location and the central and southwest locations.

Variables from this location were placed in separate tables when significant interactions

existed between location and cultivar. Statistical comparisons were used between the

central and southwest locations.

Fruit Development Period

During 2004, 'UFGold' had the shortest FDP at the north-central and central

locations (Tables 8 and 9). In central Florida, the FDP was longer for 'TropicBeauty'

than for the other three cultivars and longer than either 'Flordaprince' or 'Flordaglo' in









southwest Florida. 'Flordaglo' had a longer FDP within central Florida than southwest

Florida. 'UFGold' had a longer FDP at the southwest location compared to the central

location. Statistical comparisons could not be made between the north-central location

and other locations because of the higher nitrogen rates used in north-central Florida.

However, in general FDP was generally longer at this location than the other two

locations. During 2005 within both north-central and central Florida, 'TropicBeauty' had

the longest FDP and 'UFGold' the shortest (Tables 10 and 11). At the southwest location

'Flordaprince' had the shortest FDP. All cultivars had a significantly shorter FDP at the

central location then at the southwest location. Direct comparisons could not be made

between the north-central location and the other locations, however again FDP was

longer in north-central Florida compared to the other locations. A consistent pattern for

cultivar FDP was observed at both the north-central and central locations during both

years. Generally, 'UFGold' had the shortest FDP, followed by 'Flordaprince',

'Flordaglo', and 'TropicBeauty' (Tables 8,9,10 and 11).

Fruit Number, Weight, and Set

No significant interactions were observed between location and cultivar for fruit

number adjusted for trunk cross-sectional area (TCA), or for percent fruit set during 2004

and 2005. Therefore, only the main effects are presented for each variable.

During 2004, the adjusted number of fruit was greater in 'UFGold' than other

cultivars (Table 13). Significant differences were not observed among locations. During

2005, the adjusted number of fruit was greater in 'Flordaglo' and 'UFGold' than in

'Flordaprince' or 'TropicBeauty'. Greater values for adjusted fruit number were

observed at the central location compared to the north-central location.









During 2005, the percent of fruit set was lower in 'TropicBeauty' than in

'Flordaglo' or 'UFGold'. Differences in the percentage of fruit set during 2005 were not

significant among locations.

During 2004, adjusted fruit yield was greater for 'UFGold' than for 'Flordaprince'

or 'TropicBeauty' within north-central Florida (Table 13). A lower adjusted yield was

observed in central Florida for 'Flordaprince' compared to 'Flordaglo' or 'UFGold'.

During 2004, site differences were only observed in 'UFgold', a greater adjusted yield

was observed at the north-central location than at the central location. During 2005, the

adjusted yield was greater for 'UFgold' than 'Flordaprince' within north-central Florida.

A greater adjusted yield was observed in central Florida for 'Flordaglo' and 'UFGold',

than observed in 'Flordaprince' or 'TropicBeauty'. At the southwest location, a greater

adjusted yield was observed for 'Flordaglo' than for 'Flordaprince' or 'UFGold'. During

2005, a greater adjusted yield was observed for 'TropicBeauty' at the southwest location

than the other locations. The adjusted yield was high in 'Flordaglo' within the central

Florida location.

Fruit Blossom End

No significant differences among cultivars were observed for the percent of fruit

with flattened blossom ends in southwest Florida during 2005 (Figure 12). However,

'Flordaglo' had less fruit with flattened blossom ends than the other cultivars at both the

central and north-central locations. The percentage of fruit that exhibited flattened

blossom ends was similar at all three locations, and generally ranged from 40 70%.

Differences among cultivars were observed for fruit that had recessed blossom end

at all locations. 'TropicBeauty' tended to have the lowest percent of fruit with this

phenotype at all locations, although differences were not significant for all cultivars at all









sites. Within central Florida, the percent of fruit with recessed blossom ends was higher

for 'Flordaglo' than for 'TropicBeauty'. At the southwest location 'UFGold' had a

higher percent of fruit with recessed blossom ends than 'Flordaprince' or 'TropicBeauty'.

There was a general trend for a reduction in the percentage of fruit that showed recessed

blossom ends as the locations progressed south for all cultivars.

There were no differences observed among cultivars within both the north-central

and central areas of Florida for fruit with extended blossom ends. A higher percent of

fruit with extended blossom ends was observed for 'TropicBeauty' than for the other

cultivars at the southwest site. In southwest Florida, 'UFGold' had fewer fruit with

extended tips than 'Flordaprince'. Across locations there was a low percentage of fruit

that exhibited extended blossom ends in north-central Florida. Generally, percentages of

fruit with extended blossom ends increased as locations progressed south.

Post Harvest Quality

Titratable Acidity. No significant differences for TA were observed among

cultivars during 2004 in central Florida (Table 14). In the north-central location,

'TropicBeauty' had a higher mean value for TA than 'UFGold' or 'Flordaprince' (Table

15). 'UFGold' had a lower TA at the southwest site compared to the other cultivars

(Table 14). Differences between the central and southwest locations were only observed

for 'UFGold', which had a higher TA at the central location.

During 2005 interactions between location and cultivar for TA, were not

significant. Therefore, only the main effects are presented. Higher values for TA were

observed in 'Flordaglo' and 'TropicBeauty' than in 'Flordaprince' or 'UFGold' (Table

16). Lower TA values were observed at the southwest location than at the central or

north-central locations.









Soluble Solids Concentration. During 2004, there were no significant differences

among cultivars for SSC at the southwest location (Table 14). In north-central Florida,

'TropicBeauty' SSC values were higher than 'UFGold' (Table 15). At the central Florida

location, 'Flordaglo' had lower SSC than either 'Flordaprince' or 'UFGold' (Table 14).

A difference between the central and southwest locations was only observed for

'Flordaprince' which had a higher SSC value at the central location. Although direct

comparisons could not be made with the north-central location, several cultivars were

observed to have lower SSC values at this location relative to the other locations. (Tables

14 and 15).

There were no significant differences observed among cultivars for SSC at either

the north-central or central locations during 2005 (Tables 17 and 18). In southwest

Florida 'UFGold' had a higher value for SSC than the other cultivars (Table 17).

Differences were observed between the central and southwest locations for

'Flordaprince', 'Flordaglo', and 'UFGold'. These cultivars had higher SSC values in

Southwest Florida than in central Florida. Statistical comparisons could not be made

with the north-central location; however, values were lower for all cultivars at this

location compared to the other two locations (Tables 17 and 18).

SSC:TA Ratio. During 2004, no significant interactions were observed between

location and cultivar. Therefore, only the main effects are presented for this year. The

ratio was higher in 'UFGold' compared to the other cultivars. A lower SSC:TA ratio was

observed in the north-central location than the central or southwest locations.

During 2005, 'Flordaglo' had a lower SSC:TA ratio than either 'Flordaprince' or

'UFGold' at the north-central location (Tablel8). At both the central and southwest









locations 'UFGold' had higher SSC:TA ratios than the other cultivars which were not

different from one another (Table 17). Between the central and southwest locations,

higher SSC:TA ratios were observed for all cultivars in the southwest location. Even

though statistical comparisons were not made with the north-central location, SSC:TA

ratios tended to be lower at this location compared to the other two locations (Tables 17

and 18).

Pressure. During 2004, fruit pressure readings were higher for 'UFGold' than for

either 'Flordaglo' or 'TropicBeauty' at both the north-central and central locations, and

higher than 'Flordaprince' at the central location (Tables 14 and 15). Pressure readings

in southwest Florida were higher for 'Flordaglo' than for 'Flordaprince' or

'TropicBeauty' (Table 14). Between the central and southwest locations, fruit pressure

readings were higher in 'UFGold' and 'TropicBeauty' within the central location.

During 2005, 'UFGold' had higher pressure readings than the other cultivars at

the north-central location (Table 18). In the central Florida, higher pressure readings

were observed for 'Flordaglo' than for either 'UFGold' or 'TropicBeauty' and both of

these were greater than 'Flordaprince' (Table 17). Within the southwest site 'UFGold'

had a higher pressure reading than either 'Flordaglo' or 'Flordaprince', and these were

higher than 'TropicBeauty'. Higher fruit pressure readings were observed in the central

location than southwest location for 'Flordaprince', 'Flordaglo', and 'TropicBeauty'.

Color

Percent blush

During 2004, a trend was observed between north-central and central Florida where

higher percent blush values were observed for 'Flordaprince' and 'Flordaglo' than for

'UFGold' and 'TropicBeauty' (Table 20 and 21). However, in southwest Florida, higher









values were observed for 'TropicBeauty' than for 'UFGold which had the least blush

(Table 20). Blush values were higher across all cultivars at the southwest location

compared to the central location. Even though statistical comparisons could not be used

for north-central Florida, it was observed that blush values tended to be lower at this

location than at the other two locations (Tables 20 and 21).

During 2005 'UFGold' had the least blush of any cultivar at all sites (Tables 22 and

23). Significant differences were observed among all cultivars at the southwest location.

'Flordaprince' had the highest percent blush cover, followed by 'Flordaglo',

'TropicBeauty', and 'UFGold' (Table 22). As in the previous year, blush values were

highest for all cultivars at the southwest location. Even though direct comparisons could

not be used it was observed that blush values tended to be lower at the north-central

location than at the other locations (Tables 22 and 23).

Colorimeter

Colorimeter measurements were taken during 2005. Two measurements were

taken representing the highest and lowest blushed surfaces on each fruit.

Light. L* values from the highest blushed surface of the fruit were lower in

'Flordaglo' than in 'UFGold' or 'TropicBeauty' in north-central Florida (Table 24).

Within the central location 'UFGold' had higher L* values on the highest blushed area

for all cultivars. At the southwest location, significant differences were observed among

all cultivars. 'UFGold' had the greatest L* value on the highest blush surface of the fruit;

followed by 'TropicBeauty', 'Flordaglo', and 'Flordaprince'.

L* values for the lowest blushed surface were higher for 'TropicBeauty' than for

the other cultivars in north-central Florida. 'Flordaglo' and 'TropicBeauty' had higher

L* values on the lowest blushed surface than 'Flordaprince' or 'UFGold' at the central









location. In southwest Florida, 'UFGold' had higher L* values on the lowest blushed

surface of the fruit than any of the other cultivars.

Chroma. C* values on the highest blushed surface of the fruit were higher in

'UFGold' than in 'Flordaglo' at the north-central location. Within both the central and

southwest locations, 'UFGold' had a higher C* value than the other cultivars on the

highest blush surface of the fruit.

A trend for C* values on the lowest blushed surface of the fruit was observed for

the cultivars at both north-central and central Florida locations. Significant differences

were observed among all cultivars. 'UFGold' had the greatest C* value followed by

'TropicBeauty', 'Flordaprince', and 'Flordaglo'. Within the southwest location

'UFGold' had C* values that were higher than the other cultivars and 'Flordaglo' C*

values were lowest.

Hue. Hue values on the highest blushed surface of the fruit were lower for

'Flordaglo' than for 'UFGold' or 'TropicBeauty' at the north-central location. Within

central Florida, 'UFGold' had higher h* values than the other cultivars which were not

different from one another. At the southwest location higher h* values were observed for

'UFGold' and 'TropicBeauty' than for 'Flordaprince' or 'Flordaglo'.

On the lowest blushed surface of the fruit 'TropicBeauty' had a higher h* value

than 'Flordaprince'. In central Florida, higher values were observed in 'Flordaglo' and

'TropicBeauty' than in 'Flordaprince' or 'UFGold'. Significant differences were

observed among cultivars within the southwest location. At this location 'UFGold' had

the highest h* value followed by 'TropicBeauty', 'Flordaglo', and finally 'Flordaprince'.









In general values for the highest blushed location on the fruits were tightly

clustered together when hue and croma values were graphed together for all cultivars at

all locations indicating little variation between cultivars and locations for this trait (Figure

13). Values for the lowest blushed location on the fruits tended to be more scattered for

all cultivars within all locations indicating high variation for this trait among cultivars

and locations.

Individual Fruit Weight

Differences were observed for individual fruit weights during 2004.

'TropicBeauty' had the greatest mean fruit weights at the central and southwest locations

and greater fruit weight than 'Flordaprince' or 'UFGold' in north-central Florida (Tables

20 and 21). Within the central location, all cultivars were significantly different from

each other. 'TropicBeauty' had the greatest fruit weight, followed by 'Flordaglo',

'Flordaprince', and 'UFGold' (Table 20). When the central and southwest locations were

compared, fruit weights were greater for 'Flordaglo' and 'TropicBeauty' at the central

location and higher for 'Flordaprince' and 'Flordaglo' at the southwest location. Even

though direct statistical comparisons were not used, fruit weights were generally greater

in the north-central location compared to the other locations (Tables 20 and 21).

During 2005 a trend was observed between north-central and central Florida where

fruit weights were greatest for 'TropicBeauty', followed by 'Flordaprince' and

'Flordaglo', with the least weight for 'UFGold' (Tables 22 and 23). At the southwest site

'TropicBeauty' fruit weight was greater than 'UFGold' (Table 22). Between the central

and southwest locations, across all cultivars, fruit weights were greater at the central

location. Results at the north-central location were similar to the previous year in that

fruit weights tended to be higher than at the other two locations (Tables 22 and 23).









Fruit Size

Cheek Diameter. Average cheek diameter was unavailable from the north-central

and central sites during 2004 due to measurement error. At the only locality in where

data was available, the southwest location, 'TropicBeauty' had the greatest cheek

diameter (Table 20).

This data was available from all three locations during 2005. In north-central

Florida 'TropicBeauty' had a higher cheek diameter than either 'Flordaglo' or 'UFGold'

(Table 23). Higher cheek diameter was also observed in 'TropicBeauty' than the other

cultivars in central and southwest Florida (Table 22). 'UFGold' tended to have the

lowest cheek diameter at most locations. Between the central and southwest locations,

cheek diameter was highest at the central location for all cultivars. Cheek diameters at

the north-central location were generally observed to be higher; however statistical

comparisons were not used (Tables 22 and 23).

Suture Diameter. Average suture diameter was larger for 'TropicBeauty' than for

'UFGold' during 2004 at the north-central location (Table 21). 'TropicBeauty' also had a

larger suture diameter than the other cultivars in central and southwest Florida (Table 20).

Larger suture diameters were observed in southwest Florida than in central Florida for

'Flordaprince' and 'UFGold'. Suture diameter was larger at the central location for

'TropicBeauty' than at the southwest location. Suture diameter was observed to be larger

at the north-central location than at the central or southwest locations, but was not

compared to these locations because of higher N rates applied there (Tables 20 and 21).

During 2005, 'TropicBeauty' had a larger suture diameter than 'Flordaprince' or

'UFGold' at the north-central location (Table 23). In central and southwest Florida a

trend was observed with 'TropicBeauty' again having a larger suture diameter than the









other cultivars (Table 22). This was followed by 'Flordaglo', 'Flordaprince', and

'UFGold'. Suture diameters for 'Flordaprince', 'Flordaglo', and 'TropicBeauty' were

generally larger in central Florida compared to southwest Florida. It was observed that

the suture diameters at the north-central location were larger than at the central or

southwest locations; however direct statistical comparisons were not made (Tables 22

and 23).

Fruit Length. During 2004, a trend was observed at all locations where 'UFGold'

had shorter fruit length than the other cultivars (Tables 20 and 21). Fruit length was

larger in southwest Florida for 'Flordaprince', 'UFGold' and 'TropicBeauty' (Table 20).

Comparisons with the north-central location could not be made, however it was observed

that fruit length tended to be greater at this location (Tables 20 and 21).

No significant interactions between location and cultivar were observed during

2005 for fruit length. Therefore only the main effects are presented. Fruit length was

less in 'UFgold' compared to the other cultivars (Table 24). Fruit length was greater at

the north-central location then at the southwest location.

Discussion

The yield and quality attributes of peaches, observed in this experiment, varied

significantly within and among the different locations and cultivars. There are many

factors that can affect fruit quality and yield. Cultural practices and climate at a given

location can have a pronounced effect on fruit yield and quality. Cultural practices such

as fertilizer rates and irrigation programs, pruning and thinning, can all have a significant

affect on quality attributes such as fruit size, blush, and sugar content. Genotypic

differences are also important, and many cultivars differ in their quality attributes. Some

cultivars can have higher SSC or TA levels than other cultivars. Genetic, cultural, and









climatic factors collectively can affect the final size, shape, color, as well as other quality

indices.

Fruit Development Period

Similar patterns were found for fruit development for the same cultivars grown in

different locations. A pattern for fruit development among cultivars was observed for

both the north-central and central locations during 2004 and 2005. 'TropicBeauty' had

the longest FDP followed by 'Flordaglo', Flordaprince', and 'UFGold'. This follows the

release statements for length of FDP for the different cultivars. However in southwest

Florida FDP of 'TropicBeauty' and 'UFGold' were similar. This may be because

'UFGold' did not receive adequate chilling in southwest Florida thereby extending the

bloom period and resulting in an error in the estimation of full bloom. FDP of 'UFGold'

was about 6 to 7 day's shorter in north-central than in southwest Florida both years.

Information pertaining to different patterns in fruit development at different locations,

can help growers determine what cultivars would be suitable for their location to have

continuous production of peaches during the important April and May market window in

Florida. Although the relative pattern for fruit development of the cultivars was the same

at the different locations, length of the FDP was different between the two locations and

between both years at the central location.

The shorter FDP and later harvest in the central location can be attributed to the

delayed bloom experienced during 2005 and warmer temperatures during the first stage

of fruit development. The FDP for 2005 was shorter in the central location than in the

other locations or during the previous year for the same location. The delayed bloom in

2005 may be attributed to several different factors, or a combination of factors, such as

insufficient chilling, high incidence of bacterial spot, and the passage of several









hurricanes through the region the previous fall, as discussed in the previous chapter.

Temperatures can have a pronounced effect on fruit development. In central

Florida, chilling was unusually low in 2005. This lead to a full bloom date that was one

month later than the previous year. Yet harvest at the central location was only delayed

two weeks. Since bloom in 2005 was delayed nearly a month, the first stage of fruit

development occurred at a time when temperatures were warmer resulting in an

accelerated rate of development.

The difference in temperature during the first stage of fruit development between

2004 and 2005 probably accounts for the reduction in FDP observed. Temperatures

during the early stages of development have been shown to affect the FDP of both peach

(Batjer and Martin, 1965) and apricot (Lilleland, 1936). During 2004 within the central

location, the length of the FDP followed the information released for each cultivar (Rouse

and Sherman, 1989b; Sherman and Lyrene, 1997; Sherman and Lyrene, 1989; Sherman

et al., 1982). In general, there was a ten day difference observed in the FDP at the central

location between 2004 and 2005. Topp and Sherman (1989a) reported that a 1C

reduction in mean temperature over the entire FDP can result in a 5-day increase in FDP.

Boonprakob et al. (1992) indicated that using the average daily temperature 30 to 45 days

after full bloom was a good predictor for the length of the FDP. They reported a 2 to 6

day reduction in FDP for every 1C increase in mean temperature, depending on the

cultivar. The 30 day period following full bloom would have been predominantly in the

month of February, 2004, and March, 2005. The average temperature for the month of

February, 2004, was 16.650C and the average temperature for the month of March, 2005,

was 18.130C. This is a 1.480C temperature difference between the two years. This









temperature difference most likely resulted in the reduction in FDP during 2005 at the

central location.

The increased length in FDP may also be attributed to the higher rates of N applied.

The amount of N applied during the course of a season can affect the FDP as well as

many different fruit quality attributes. Within the north-central location, N application

rates were more than twice that at the other locations. Higher N rates have been shown to

affect the FDP of peaches (Saenz et al., 1997). The addition of higher N rates may have

further contributed the longer FDP observed in the cultivars at this location.

The effect that the increased rates of N had at the north-central location was

calculated for 2004 using the mean FDP of 'Flordaprince', 'Flordaglo', and

'TropicBeauty' at the three different locations. 'UFGold' could not be used because of

the longer FDP observed in the southwest location may be attributed to insufficient

chilling. The mean FDP of the three cultivars for the three locations was used to

determine the mean temperature during fruit development. The difference in FDP and

mean temperature was determined between central and southwest Florida. The difference

in FDP and mean temperature over fruit development was used to calculate the increase

in length of FDP for every 1C; this difference was a 4.4 day increase for a 1C decrease

in mean FDP temperature. The difference in mean FDP temperature between the north-

central and southwest locations was 2.560C. This difference was multiplied by 4.4 to get

an 11.3 day difference in FDP between the southwest and north-central locations. When

the mean FDP at the north-central location was subtracted from the mean FDP at the

southwest location the difference was 12.3 day's. This shows only a one day increase in

the length of FDP at the north-central location from the higher rates of N applied at that