Group Title: effects of certain growth regulating chemicals on the maturity of tomato (Lycopersicon esculentum mill.) /
Title: The Effects of certain growth regulating chemicals on the maturity of tomato (Lycopersicon esculentum mill.)
CITATION PDF VIEWER THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00097742/00001
 Material Information
Title: The Effects of certain growth regulating chemicals on the maturity of tomato (Lycopersicon esculentum mill.)
Physical Description: 132 leaves : ill. ; 28 cm.
Language: English
Creator: Southam, William James, 1944-
Publication Date: 1970
Copyright Date: 1970
 Subjects
Subject: Plants, Effect of chemicals on   ( lcsh )
Plant growth inhibiting substances   ( lcsh )
Plant growth promoting substances   ( lcsh )
Vegetable Crops thesis Ph. D
Dissertations, Academic -- Vegetable Crops -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis (Ph. D.)--University of Florida, 1970.
Bibliography: Includes bibliographical references (leaves 118-130).
Additional Physical Form: Also available on World Wide Web
General Note: Typescript.
General Note: Vita.
Statement of Responsibility: by William James Southam.
 Record Information
Bibliographic ID: UF00097742
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000560634
oclc - 37751342
notis - ACY6193

Downloads

This item has the following downloads:

PDF ( 6 MBs ) ( PDF )


Full Text







THE EFrFECTS OF CERTAiN GROWTH R.,SULATIN

















Py
CHEMNKALS CN TAV ;ATURTY CM T.MiTO

















WILLIAM J. SOUTHAI4














A DISSErilrOTi';.t lTRKSrTEDO rO TH' GR>.--'U..T COULD TJ. OF
TE-E UN'V2RSIT' ru.OO.PT0
IN PA.TI'. L FULFILLLMIENT OF THE .i:f.:I(4EM NTS', FO-I i2T ?
IDGPRjE OV DCC'TO? OF F P-LOSOPH.Y










U.NTV-? "' ''" I-.. '.A


1970




























TO MY WIFE, PARENTS AND FRIENDS--

THOSE FORCES WHICH HAVE MOLDED ,,MY

THOUGHT











AC KNOW'LEDGEMENTS


The author wishes to extend his sincere apprecic'ion and gr=iiude to Dr. V. F.

Nettles, Chairman o' t:h Supervisory Corminihtee a.~ w'PcFi;ssor cf Vectaible Crop;,

for his advice ard assistance throughout e the graduate program and vclucble criticism

of thi manuscript.

Appiociaticn is also expressed to Dr. B.D. DThcm:son, Professor of Vegetable

Crops, and Dr. D.D. Gull, Associate Professor of \/egetable Crops, for their counsel

in planning the laboratory phase of this project, devclopmeni of the graduate program

and suggesting improvenmenis in the manuscript. The author is especially grateful to

Dr. Thompson for his assistance in procuring an NDEIA Title !V pre-doctoil f&'lo'-

ship, enabling the completici of this project.

To ID. MA..R. Langhcom, Professor of Agricultural Economicsand Dr. T.E.

Hurmphrey,, FPofessor of Botany, who have provided invaluable guidance during thc

course /or k cs members of the Supervisory Committee and help in approaching certain

aspects cf this project, th e author extends his gratitude.

Advice in the dev!eopment of experimental techniques fro-m .'. R.H. eiggs,

Professor of Frjui Crops, Dr. H.H. Bryan, Assistant Professor or Vegeto ble Crops,

and Di. C.B. Hall, F',ofesor of Vegetable Crops, is very much ;ppreciatcd by !-.e

writer.

To the Departmenrt of Vegetable Crops for providing ass;stoaice in the field aOd

[i i





laboratory experiments, and for providing financial help in the form of an NDEA

Title IV grant, the author is grateful.

The help and cooperation of Mrs. E.J. Weiner, Computer Progiarnme'r, Dr. J.A.

Cornell, Assistant Professor of Statistics,and Mrs. Yvonne Dixo;i, Typist, is also

appreciated.

Finally, to Martha, whose long-suffering patience made the work much easier,

the author is forever indebted.











TABLE OF CONTENTS

Page
ACKNOWLEDGEMENTS . . . iv

LIST OF TABLES . .. .. .. .. .. xiii

LIST OF ILLUSTRATIONS xvil

ABSTRACT xviii

INTRODUCTION .. .... . 1

LITERATURE REVIEW . . . . 4

Morphology . . .. 4
Flower Production .. . . . 6
Flove, and Fruit Set .. .. ..... .. 7

Boron . . .. . . .10
Calcium .... 11

Abscission... ......... 11

Auxin-Ethylene Salance . .13
Auxin-Ethylene . . .13
Auxin Gicdiant . .14
Auxin Concentration . . 14
Aux!n-Auxin Bcalance . . 15
Auxin-Serecence Factoc 15
Me-ibrarc e ilte Iit . . . 15
Me hlionine-Auxin . . 15
Auxin-Gibbrellinr-Abscission Acce!erai-ing Hormone 15
Endogenous Abscissicn-Accelerating Su'stances . . 15
Tl'o--SIa e Theory . .. . . 16
Locci zed Celljulcr Senescence 16
Agiing-Eihylene . .. . . .16

Compounds Affectin: Abscission . . . 1
Field Appications . . .18






Auxins .
Gi bbereI lins . .
Ethylene .

MATERIALS AND METHODS .

Selection of Chemicals .

Fall 1968 . . .

Preliminary Field Screening .
Quality Eva!uation .
Statistical Evaluation

Spring 1969 .

Field Pos .
Quality Evaluation .

Bio-yield point .
Texture . .
Color .
Soluble solids . .
pH and titratable acidity .

Statistical Evaluation

Fall 1969 .

Field Plots .
Quality Evaluation
Statistical Evaluation
Bioassay of Auxins. in the Fruit

Experimental procedure
Isolation technique
Bioassay .

Spring 1970 .

Harvest Method Compaison .

Statement of the model
Generation of parameters

Costs .


I


1 1


Page
18
22
22

24

24

25

25
28
29

29

29


32
33
33
3A
34

34

36

36
33
38
38

38
39
39

40

40

40
44

.4


I I i I







Price ..
Acreage. .
Yields.. .
Labo; . .

Solution .
Parametric programming .

RESULTS .

Fall 1968 .

Fol ar Symptoms . .
Yield Data .

Single harvest .

Light red and ripe fruit .
Immature, mature green through

Quality Evaluation.....

Ripening characteristics
Handling characteristics. .

Spring 1969. .....

Fol ior Symptoms .. ...
Yield Data .

First harvest . . .

Light red and ripe fruit
Bireuker through pink fruit
Subtotl . .

Second hcrvesr..

Light red and ripe fruit
BrakVr through pink Fruit
Mature c;ru-i fruit
Inimathj,-u r~i ... .
Subtolcdt. ...

Grand total .


. . . . . .



. . . . . .

pinL fruit cand total yield .








. .
. . . . . .
. . . . . .












. . . . . .
. . . . . .

. . . .

. . . . . .

. . . . . .
......

.... .
.... ..


Page
44
44
45
45

45
45

47

47

47
47

47

47
47

50

50
50

50

50
50.

50

50
52
54

54

54
57
57
60
60

63






Page
Quality Evaluatio 63

Bio--yield point 63

First harvest . .. 63
Second harvest 63

Shear force 63

First harvest. . . .. 63
Second harvest . 67

Color . 67

First harves . .. 67
Second harvest 71

Soluble solids . 71

First harvest . .. 71
Second harvest . . ... .75

pH' . 75

First harvest .. . 75
Second harvest . 78

Titratable acidity .. . 78

First harvest . .78
Second harvest. .. . 81

Fall 1969 . .81

Foliar Symptoms 81
Yield Data..... .82

Single harvest . 82

Breaker through pink fruit 82
Mature green fruit .. ... .82
Immature fruit . 85
Total . .... 85

Quality Evc!uation 5






Ripening characteristics .
Handling characteristics .

Bioassay cf Auxins in the Fruit .

Effect of extract cn coleoptile sections
Effec'" of extract cn coleodt e sections


Spring 1970 .

Harvest Method Comparisc.n

Initial solution of model
Parametric programming

Restraint changes
Yield changes
Cost changes
Price changes

DISCUSSION . . .

Effects of Field Treatments

Single Applications

Ascorbic acid .
Boric acid .

Yield effects .
Quality effects

Calcium chloride

Yield effects
Quality effects

Duraset .

Yield effects
Quality effects .

Emery C-9 .
Ethrel .

Yield effects


Page
85
85

85


89

89
90

94
94
94,
95

96

96

96

96
96

96
97

99

99
99

100

100
101

102
102

102







Quality effects

Fatty acid ester .
Gibberellic acid

Yield effects
Quality effect .

IAA ... .
TIBA . ..

Combined Applications

Duraset-Eihrel .

Yield effects
Quality effects

Duraset-boric acid

Yield effects
Quality effects

Duraset-bcric acid-Ethrel

Yield effects .
Quality effects


: : :


Boric acid-Ethrel .

Yield effects ..
Quality effects .

Boric acid-calcium chloride.. . . . .

Yield effects . ...
Quality effects . .

TIBA-boric acid (simultaneous application)
TIBA-boric acid (split application) . .
TIBA-Ethrel .

Bioassay .. .. . .
Harvest Comparison . .


Page
. . .. 104

.. 104
. 104

. 104
. 105

. 105
S 106

S 106

.106

106
. . ... 107

S . . 107

S 107
S . 107

. . . 108

. 108
108


. . .


. .
.


: ::


..*




Pege
Initia Solution . . . .. . 112
Parametric Programming . . 112

SUMMARY AND CONCLUSIONS . . . . . . 115

SELECTED BIBLIOGRAPHY . 118

BIOGRAPHICAL SKETCH ...... .. .. 131












LIST OF TABLES


Table Page
1 CHEMICALS, CONCENTRATIONS AND TIMES OF APPLICATION
USED IN THE FALL 1963 EXPERIMENT . . . . 27

2 CHEMICALS, CONCENTRATIONS AND TIMES OF APPLICATiON
USED IN iHE SPRING 1969 EXPERIMENT . .... 31

3 CHEMICALS, CONCENTRATIONS AND TIMES OF APPLICATION
USED IN THE FALL 1969 EXPERIMENT . . . . 37

4 SCHEMATIC TABLEAU OF A MIXED INTEGER PROGRAMMING
MODEL FOR EVALUATION OF THREE TOMATO HARVESTING
METHODS . . .. . . . 43

5 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE NUMBER OF LIGHT RED
AND RIPE FRUIT PER PLOT, FALL 1968. . . . 48

6 EFFECT OF CHEMICAL., CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE NUMBER OF IMMATURE,
MATURE GREEN THROUGH PiNKAND TOTAL FRUIT PER PLOT,
FALL 1968 . . . .. ..... .49

7 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE YIELD OF LIGHT RED
AND RIPE FRUIT PER PLOT--FIRST HARVEST, SPRING 1969. 51

8 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE YIELD OF BREAKER
THROUGH P!N!K FRUIT PER PLOT--COMBIINED DATA--
FIRST HARVEST, SPRING 1969 . . . . . 53

9 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
TREATMENT ON THE AVERAGE TOTAL YIELD CF FRUIT PER
PLOT--FIRST HARVEST, SPRING 1969 . . . . 55

10 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF





Page


APPLICAi'lON ON THE AVERAGE YiELD OF LIGHT RED AND
RIPE FRUIT PER PLOT--SECOND HARVEST, SPRING 1969 . 56

11 EFFECT OF CHEMICAL, CONCENTRATION AND TIMF OF
APPLICATION ON THE AVERAGE YIELD OF BREAKER
THROUGH PINK FRUIT PER PLOT--COMBINED DATA--
SECOND HARVEST, SPRING 1969 . . . . 58

12 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE YIELD OF MATURE GREEN
FRUIT PER PLOT--SECOND HARVEST, SPRING 1969 . 59

13 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE YIELD OF IMMATURE
FRUIT PER PLOT--SECOND HARVEST, SPRING 1969 . 61

14 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE TOTAL YIELD OF FRUIT
PER PLOT--SECOND HARVEST, SPRING 1969. . . 62

15 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE TOTAL YIELD OF TWO
HARVESTS---COMBINED DATA, SPRING 1969 . . 64

16 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE BIO-YIELD POINT OF
WHOLE BREAKER FRUIT--FIRST HARVEST, SPRING 1969 .65

17 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE BIO-YIELD POINT OF
WHOLE BREAKER FRUIT--SECOND HARVEST, SPRING 1969 66

18 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE FORCE REQUIRED TO SHEAR
100 GRAMS OF EQUATORIAL SLICES TAKEN FROM CHAMBER
RIPENED FRUIT--FIRST HARVEST, SPRING 1969 . ... 68

19 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE FORCE REQUIRED TO SHEAR
100 GRAMS OF EQUATORIAL SLICES TAKEN FROM CHAMBER
RIPENED FRUIT---SECOND HARVEST, SPRING 1969. . 69

20 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE a/b COLOR RATIO OF LOCULAR
AND PE"ICARP AREAS OF CHAN"'E? RIPENED FRUIT--FIRST
HARv SF:'ING 1959. . . . . . 70


xiii




Tabie


21 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE q/b COLOR RATIO OF LOCULAR
AND PERICARP AREAS OF CHAMBER RIPENED FRUIT--
SECOND HARVEST, SPRING 1969 . . . .

22 EFFECT OF CHEMICAL, CONCENTRATION AN D TIME OF
APPLICATION ON THE AVERAGE SOLUBLE SOLIDS CON-
TENT OF LOCULAR AND PERICARP AREAS OF CHAMBER
RIPENED FRUIT--FIRST HARVEST, SPRING 1969 . .

23 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE SOLUBLE SOLIDS CON-
TENT OF LOCULAR AND PERICARP AREAS OF CHAMBER
RIPENED FRUIT---SECOND HARVEST, SPRING 1969. .

24 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE pH OF LOCULAR AND
PERICARP AREAS OF CHAMBER RIPENED FRUIT--FIRST
HARVEST, SPRING 1969 . . . . . .

25 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE pH OF LOCULAR AND
PERICARP AREAS OF CHAMBER RIPENED FRUIT--SECOND
HARVEST, SPRING 1969 . . . . . .


26 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE TITRATABLE ACIDITY OF
LOCULAR AND PERICARP AREAS OF CHAMBER RIPENED
FRUIT--FIRST HARVEST, SPRING 1969. . . .

27 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE TITRATABLE ACIDITY OF
LOCULAR AND PERICARP AREAS OF CHAMBER RIPENED
FRUIT--SECOND HARVEST, SPRING 1969 . . .

28 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE WEIGHT OF BREAKER
THROUGH PINK FRUIT PER PLOT--FALL 1969 .....

29 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE WEIGHT OF MATURE
GREEN FRUIT PER PLOT--FALL 1969 . . . .

30 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE WEIGHT OF IMM\ATURE


72




73




74


76


79




80


84






Table Page
FRUIT PER PLOT--FALL 1969 . . . . . 86

31 EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF
APPLICATION ON THE AVERAGE TOTAL WEIGHT OF FRUIT
PER PLOT--FALL 1969 . . . . . 87

32 LENGTH OF AVENA COLEOPTILE SECTIONS AFFER TWENTY-
FOUR HOURS IN MEDIA CONTAINING INDOLE EXTRACTS
OBTAINED FROM ETHREL TREATED AND UNTREATED FRUIT
DURING CHAMBER RIPENING . . . . . 88

33 INITIAL TABLEAU AND OPTIMAL SOLUTION OF A LINEAR
PROGRAM MODEL FOR EVALUATION OF THREE TOMATO
HARVEST METHODS .. ........ 91

34 CHANGES IN OPTIMAL SOLUTION DUE TO PARAMETRIC
PROGRAMMING OF CERTAIN PARAMETERS PRESENTED IN
TABLE 32. . . . . . . 92












LIST OF ILLUSTRATIONS


Figure

1 SCHEME OF ANALYSIS USED IN EVALUATING THE QUALITY OF
FRUIT OBTAINED IN THE SPRING 1969 EXPERIMENT . .


Poge


35






Abstract of Diss.rt..i:, P .,sen. d to Graduate Council at the University of Florida
in Part!ici F-':i.lment of the Requiremenl- for ihe Degree of
Doctor of Philosophy


THE EFFECTS OF CEPTAIN GROWTH REGULATING CHEMICALS ON
THE MATURITY OF TCMATO (Lycopersicon esculentum Mili.)


By

William J. Southam
August, 1970

Chairmor,: Dr. V. F. Nettles
Major Department: Vegetable Crops

The chemicals ascorbic acid, boric acid, calcium chloride, Duroset, Emery C-9,

Ethrel, fatty acid ester, IAA and TIBA were evaluated in field trials as to their activ-

ity in producing a uniform maturity in tomatoes (Lycopersicon esculentu.T Mill.). Times

of application, concentrations and effects on quality paramcners were also evalua'-d.

A labcraiory experiment was conducted to determine the effects of anr Ethr,! dip

on the auxin content of tomato fruit in storage.

A mixed integer programming made! was utilized in testing the economic signifi-

cance of the resu!is of the field trials as well as evaluating the precision of certain of

the values included :n the model.

The hteatments of TIbA-boric acid and T IBA-Ethrel in split applications showed the

only significant effects on the total yield by reducing it. The major effects of the ofher

treatments were to alter the yields within the various maturity classes.

Ethrel applied ct the time of the fifteenth inflorescence increased the percent yield

of the light rd thro-gh ripe fruit and rec'uced the percent yield of thle mature green

fruit in ith second harvest. Ethiel applied one week iater increased tHe percent 'ie:J

xvii






of the light red through ripe and breaker through pink fruit cf the first harvest and

reduced the percent yield of the mature green fruit of the second harvest. The boric

acid applied at the ninth internode followed by Ethrel applied at the. fifteenih in-

florescence produced an increase in the percent yield of light red through ripe cod

breaker through pink fruit of the first and second harvest and reduced the mature green

of the second harvest.

The effects on ihe quality parameters were erratic but generally supported the

thesis that the early application of Ethrel affected llhe later fruit and the later appli-

cation affected the early fruit and the boric acid-Ethrel combination affected both the

early and late fruit. The boric ocid-Ethrel treatment appears to be the only cne with

promise of an econom-ic application.

The laboratory experiment showed on increase in auxins due to Ethrel treatment

at 2 and 3 weeks'extRaction after treatment, and a natural increase in cuxin at a 1

week extraction that was not evident in the heated fruit.

The economic caalysiz demonstrated a 11.4 percent increase in yield over the

mechanical harvest :method alone i/as required for the utilization of a chemical method

with a cost of $132.67 per acre under a 50 acre and 3500 man-hour restriction and

with a price of $2.50 per crate. Thus the 2.5 percent increase of the boric acid-

Ethrel combination was not sufficient. However, if the price were increased to $3.34

per crate, the trea 'enl v,'ould be useful. In addition, a yield of 84.3 percent of the

hand har'..est was fc..,',nd' necessary for machine harvest vwilhout chemical treatment to

b. the only rne;hod e, ployed unncer the previous rescictions.


xv I i












INTRODUCTION


Tomatoes ore an important item in ihe diet of the United States' consumer. The

1968 per capital consumption of fresh tomatoes was twelve pounds, putting tomatoes

after lettuce and watermelons in total fresh vegetable use (165). The major winter

sources of fresh tomatoes for northern U.S. markets are the sub-tropical and tropical

areas of the western hemisphere, particularly Florida and Mexico (56).

In Florida, the value of the 1968 tomato crop was $92,159,000, comprising 31.3

percent of the total worth of the state's vegetable industry for that year (57).

Recently, Mexican competition has proven a serious threat to the FlordcWa industry

which once supplied the majority of tomatoes for the northern markets. In the 1968-69

season, Mexico shipped almost one half of the winter tomatoes; 15,132 carlot equiv-

alents compared to 15,290 carlot equivalents shipped from Florida during the same

period (27). The reason for this increase in Mexican shipments can be traced to a

gradual improvement in production techniques and a much lower production cost. The

primarry element in this low'r cost is labor.

Mexicon growers need only pay $2. 10 per day compared to the minimum level of

S1.15 per hour in Florida (56). Not only do Mexican grower; have the advantage of

lower labor cost, they have an alicst unliriicid labboi supply. The scarcity of domestic

farm labor in Florida ha; produced an inability to adequately harrvest the tomaio crop

during pcak prio:L.






Thus, it is imperative that the Florida grower examine all aspects of production

with the purpose of severely reducing labor requirements. As an example, it appears

necessary that the method of staking tomatoes, being a high labor requiring technique,

must be modified or eimiriated. However, harvest is still the phase of production with

the highest requirement for labor, requiring approximately 25 percent of the total labor

need of staked tomatoes and 50 percent of the total in ground tomatoes (26, 28).

Mechanization, whereby capital: is substituted for labor, is, of course, the ob-

vious answer. it has been found that mechanical harvesting could reduce the per ton

harvest cost of canning tomatoes from $17.19 to 59.84 (128). There are many prob-

lems associated with the development of mechanical harvesting techniques. Extensive

research in California has resulted in the mechanization of tomatoes harvested for

canning; however, only pilot work is being conducted or fresh market mechanical

harvest. The greater care required for handling of fresh market tomatoes has slowed

the development of mechanical methods. The Florida Agricultural Experiment Station,

realizing the urgency of the problem, has embarked on on extensive research project

to investigate all avenues available for the mechanization of fresh market tomatoes

(70). It was recognized early that one of the primary obstacles to mechanical harvest-

ing is the lack of uniform maturity for a once-over harvest.

There are several! approaches to the solution of this problem and the foremost is

the development of a suitable determinant variety (155). However, it is well known

that breeding proricrnms require long periods to incorporate all of the desired charac-

teristics into a variety. Therefore, it is necessary to examine oth-r methods of pro-

moting uniforri, mrnurity as an ancillary program to provide a temporary solution.

While it is ccceptfd that all phases of production exert scrne influences orn tih






uniformity of growth and maturity of tomatoes (48, 49, 78, 163), the area that has

received the most attention and claims of promise is the use of exogenously applied

growth regulators (104, 134, 154). The purpose of ihis study was to examine further

the use of synthetic plant growth regulators in 'his regard. The area of investigation

was limited to hose compounds exhibiting an effect on the floral zone, as the other

iypes of growth regulators are being examined under the auspices or Florida Agri-

cultural Experiment Station Project 1406. In addition, Ihe effects of these florca

zone regulators on the quality of the fruit were monitored.












LITERATURE REVIEW


Morphology

It has been stated that this investigation will concern itself primarily with the

floral development of the tomato. This area has been precisely defined (43). Follow-

ing this, the physiology of the floral zone and ways that have been suggested to

chemically modify its behavior are reviewed.

The inflorescence of the tomato is a racemous cyme type. In this case, the apex

of the main floral axis pedunclee) terminates in a flower, while six to eleven other

flowers arise on lateral branches (pcdicels) farther down the axis (43, 135).

Few of the flowers are open simultaneously; thus,the inflorescence is found with

a variation of immature flowers, mature flowers, and fruit of differing ages. The

tomato flower itself is perfect, hypogynous, regular, pendant and generally six-merous

and,when mature, the corolla lobes cre leflexed and of a yellow color. The stamens

are attached to the base of the corolla tube and are coalesced io form a cone around

the pistil. The pistil consists of an enlarged ovary, elongate style and stigma which

extends slightly beyond the apex of the androecium.

The pedicel is generally composed of a thick cortex, a ring of vascular tissue

and a central pith. Abcut one centimeter below the receptacle along the axis is the

abscission zone. There is a reduction in pedicel diameter at this point. In cross

section, the zone begins a; the epidermis and extends across the coitex to the

4






vascular tissue (it does not extend across the vascular tissue), then through the pith.

The cells of the abscission zone are small and flattened (43).

In ihe abscission zones of apple, gardenia and sweet pea flower buds, which are

similar to that of tomato (43, 73, 96, 109, 110, 151), much cellular modification has

been o'.tlied, and as most authorities consider all types of abscission in the same light

(2, 10, 16), there does not appear to be much danger in comparing these different

plant types. Collenchyma cells are in greater abundance than in normal sterns, oc-

cupying areas normally occupied by sclerenchyma. The cell walls of the collenchyvma

are thicker and the corners of the cells, normally square, are rounded and the middle

lamellae are more prominent. Sc!erenchymo tissue, its usual function structural, is

reduced in the area of the zone and not present in cortical areas. In the xylem a

number of fibers and vessels of the vascular cylinder are replaced by the modified

scalariform (elongate) type vith scalariform pits. The epidermal cells are elongate

and easily separated and the pith is enlarged. All of these modifications serve to

weaken 1he pedicel in the abscission zone.

Electron microscope examinations (86) have shown the indentation of the cuticle

has branches which extend through the abscission zone, following the middle lamellae,

Thus, separation occurs along these branches. Other ultrastructural details include

an increased amcJnt of invaginations of the plasmalemra, and within these invaoi-

nations are a nwyrber of apparent microbcdies v.ith crystalloid cores. Branched

plasmodesmata extending into the middle lamellar region and microtubles adjacent and

parallel to the plasmklemma arc also scen. Another unique structure reported was a

membrane encloseC I fnul component in r-irny of the chloroplasts of the absci'sic.n

zone. Aithoe nh func.-iLn: ocf Ihes-e pcriicular structures are not knovn, it ;s






speculated (50) that the microbodies contain hydrolytic enzymes.


Flower Production

Kraus and Kraybill (93) distinguished between flower production, flovier set and

fruit set (fruitfulness). The first tcrm was used in the context of an actual number of

flowers (or floral buds) initiated by the plant. In opposition, the second term, flower

set, was taken to represent the number of flowers that remained in the inflorescence

and did not ubscise. Finally, fruit set represented the production and maturation of

fruit, whether it was parthenocarpic (the ovary developed without fertilization),

normal or the immature fruit aborted.

Went, in a series of experiments investigating the effects of environmental

conditions on the growth, flowering and fruiting of tomatoes (174, 175), demonstrated

that variations of photoperiod, thermoperiod and light intensity within normal ranges

had little effect on flower production. It is well known (162) that aside from varietal

differences (92, 74), tomato flower production is generally insensitive to environ-

mental fluctuations. Only when the temperature is reduced to a constant 200C (174)

is the flower production affected.

Beginning with Kraus and Kraybill (93), the effects of nutrition, particularly

nitrogen, on tomato flowering have been widely discussed. However, their research

concerned the "fruitfulness" of tomatoes and did not deal directly with flower pro-

duction. They did point out that initiation of floral primorclia and blooming were not

governed by conclitins affecting fruit setting and that,within normal rangss of nutri-

tion, flower production of tomatoes is relatively constant. And as it became evident

thau cultural techniq, es affected primarily fiuit set, the emphasis of resecrcih ,i'

directed voword explcr inj this phenomenon.






Flower and Fruit Set

As alluded to above, the factors affecting flowie: and fluit set have been much

more clearly defined. Went, in the same series of experiments (174), showed that

tomato plants grovn at low night temperatures (15-20'C) and high day temperatures

(26.50C) had the highest fruit set. He also noted that artificial light during the cool

night period inhibits fruit formation entirely. He concluded that the cause of this

was the operation of two processes, each with a different optimumr temperature c",

one requiring dark.

Smith (152) in a study of aborted tomato flowers, listed a number of causes of

blossom drop and fruit set failure during anthesis. Among these causes were very

hot dry or very cold weather, hard rains, thrip injury, deficient soil moisture and

rapid vine growth resulting from excessive nitroges fertilization. Following a histo-

logical examination, Smith observed that the embryo sacs of aborting tomato pistils

never developed beyond a weak mature egg stfoge and that the embryo sac and ovules

had not developed any farther at 190 hours after anlhesis (pollination) than they had

ai onihesis. He then observed that the slow growth of the pollen tube leaves the

flower vulnerable tc weather conditions and undei adverse conditions the generative

nucleus is killed before pollination occurs. Another abnormality noted during his

examination was an excessive style elongation during periods of hot weather.

Along these same lines, style exsertion (extension of the style beyond the anthers,

thus preventing ad,- .; -' pollination) and pollen sterility aie the princry causes of

poor fruit set under cxt-emely low light intensities cr high ;jliht and hiih temperature

(87). In this review, Johnson also disco:sc; dormancy ;.. '..a cies resut!i from high

temperature and liaht. When these ovaries arc forced to develop : t! ut fci ';l;1atico.,







they are partheniccrpic. Dormancy of fertilized ovaries also occurs, as a result of

low or high temperatures accompanied by low light intensities, high temperature and

high light, or whMc.- there is large number of fruit aliedy set in the same or adjacent

clusters. AbsciE .on of norma! flowers, however, is judged to be the major cause o'

unfruilfulness and this in turn is at[ribuied to the tendency of vegetative plants to

limit fruit produc-ion.

Haas (65) fo'-nd under conditions of low humidity and high soil moisture tensions

that smaller oranr.;e fruits, due to their proportionately greater surface area, lose

moisture more rapidly and have a high abscission rate.

The above &observaiions parallel the familiar work of Kraus and Kraybil! (93) in

which the two act'hors describe four conditions of the tomato plant in reference to its

nutritional status... The four conditions described were:

1. High ni't.ogen, adequate water and minerals but low carbohydrate. This

plant is 'weakened and non-fruitful.

2. High nitrogen, water and minerals, and available carbohydrates. This plant

is barrerr (flowers fail to mature and abscise) and sterile.

3. Low nitrc-gen, high carbohydrate. This plant has increased fruitfulness,

fertility .znd is less vegetative.

4. Very low nitrogen, high carbohydrate. This plant is neither highly vegetative

nor fruitful.

Kraus and K-rzybill explained these conditions by postulating that the balance

of nitrogen and carbohydrates was more important than Ihe absolute amounts of either

and that an imban-rice between the two affected the plant's ability to set and mature

fruit.






In an attempt to explain the results of Kraus and Kraybill in cytological terms,

Howlett (79) found that carbohydrate deficiency resulted in the suppression of male

organs but nitrogen deficiency had little effect.

A valid criticism of nutritional studies of this type, however, is that they were

carried out at ,utrient levels beyond the range found under normal condition:. Work

by Arnon and Hcogland (12) under more optimal conditions failed to show a negative

correlation between vegetative growth (high nitrogen) and fruit set.

Leopold and Scott (?9), trying to delineate all factors governing fruit set of

tomatoes, found that the presence of mature leaves was of primary importance to the

development of an adequate fruit set. They also found, as did Went (175), that

carbohydrates, particularly fructose and sucrose, were able to substitute to a high

degree for the mature leaf in promoting fruit set of excised flowers. Isolating com-

pounds ihat perhaps were supplied by the mature leaf, they found five other cate-

gories of compounds thwich were capable of increasing fruit set. These were: organic

nitrogenous compounds, inorganic nitrogenous compounds, organic acids, reducing

substances and some inorganic ions. Aerobic conditions were also required. The

authors pointed out, however, that due to the large number of compounds acting in

this manner and the obvious role of many fumaricc acid, arginine, potassium dihydracen

phosphate) in respiration, that the compounds examined did not play a direct role in

fruit set.

Recently Addicott (9) has proposed a scheme whereby the indirect role of these

substrates is elucidated as they enter in different pathways of carbohydrate, amino

acid and protein metabolism.

Examining the technique of dk.floliation (pruning) Further, Aun (14) reached





10

simirir conclusions to those of Leopold and Scott, that the mature leaves exerted the

greatest influence on number of blossoms flowerr set) and fruit set. He also found

that removal of young oxilary buds greatly increased the htcl number of blossoms.


Boron

In examining methods that could be used tc enhance fertilization, it was Found

thoa boron played an essential role in pollen germination (8). The effect of boron

may b! three-fold (89). It promotes absorption and metabolism of sugars by forming

sugar-borate complexes, it increases oxygen uptake and is involved in the synthesis

of peciic material for the wall of the actively elongating pollen tube. It may also

play a role in the inactivation of germination inhibitors in tomato pollen. The effect

of boron is in excess of any other vitamin, hormone or chemical used in culture so!u-

tions due to ils generally low concentration in the pollen grain. In a comprehensive

review, Gauch and Dugger (61) discuss the application of boron as a foliar spray

and its importance in pollen physiology in a number of plants. In this and another

paper (60) they pos.ulate the role of boron in sugar translocaticn and propose the sugar-

borate complex mentioned by Johri and Vasi! (89). Not only is germination improved

with boron treatment, but tube length is significantly longer (161). Field applications

to pear trees (soil and foliar) have been found to increase fruit set (17), although under

admittedly sub-optimal growing conditions. The enhancement of sugar translocation

mentioned by Gauch and Dugger and others (39; 173) would be a beneficial factor in

promoting fruit set and maintaining a uniform growth rate throughout fruit maturation.

A partial substitution beiwveon boron and auxin has been suggested (53), indicating a

major role for bcron in hormone physiology.







Calcium

A similar rcle, but not as extensive as for boron, has been shown for calcium in

pollen germinc'ion (25). It appears that calcum,r also generally low in pollen tissue,

has a stimulative effect on the growth and germirntion of low density pollen popu-

lotions. Calcium is also necessary for mitosis (51). It is possible that calcium may

be the governing factor in chemotropism (89) or the growth of the pollen tube toward

the ovary. Finally, it is well known (51) that calcium functions as a constituent of

cell walls and middle lamella as calcium pectate. This could serve to strengilen the

abscission zone (147).

An interaction between boron and calcium in the soil has been shown (90, 133).

These workers shoved that an increase in calcium reduced boron toxicity sympic-ns acdi

actually reduced the bcrc,-i content of the tissue. Increasing calcium had ,ittic effect

on boron deficiency symptoms and boron was found to have no effect on cclciLum

metabolism.


Abscission

It is evident (37, 152) that the principal mechanism that limits the fruit set of

tomatoes is abscission and a good deal of research has accrued on this subject; un-

fortunately, the major reference concerning physiology is to cotton explants and

secondarily to apple fruit and tomato.

A usable definition of abscission would be that it is the morphological cutting

away of a modified branch of axis (110), such as u pedicel. Prior to abscission, the

cells along the zone elongant and the nuclei increase in size. The epidermal cells

become compressed cad, in s^,ne cases (23, 143), tlhe sta.ch content of the cells

increases, cell divi';-c i occ.- ac d. imnrzediately preceding c'kl-cissiEcn, the sftrch ir






the crea of sepacation is hyirolyzed.

At abscissica there is increased peciic enzyme activity (pectose) and dissolution

of the !oinelia a w. secondcrv cell wall. Soluble sugars and uronic acids are released

and with the sep.:rc::on of the surrounding cell layers the xylem vessels are physically

broken by the weo.h f of the flower, fruit or leaf. Finally, periderm formation on the

stu.nm occurs (73, 96, 132, 171).

In general, ithe healthy organ (flower, fruit, leaf) prevents abscission until it

senesces or is ac'ed upon by external factors.

Abscission, however, can occur at any period during the development of the Flower

or fruit; for conv'e.rience in discussion, three divisions as to physiological development

can be constructed (152). These divisions are: blossom drop, i.e., abscission before

fertilization, imnriaurie fruit drop, and mature fruit drop. The causes of blossom, a:nd

immature fruit drop can be listed generally as mechanica, general envircnmenr prior

to fertilization, v-egetative and fruiting stages of the plant and artificial factors (87, 152)

Mechanical r-.duction of abscission is merely the result of shear forces produced

by high velocity winds, rainfall or cultural disturbance. This process is a function of

pedicel length an.d need not be discussed further.

Environmental and plant stage causes of abscission have already been revie,,ed

under factors affecting failure of fruit set.

Several excellent reviews have been compiled on the physiology cf absci-s.on and

how abscission is affected by various exogenous factors (2, 3, 10, 44, 85, 140). Low

oxygen teilsions co: high carbon dioxide can prevent abscission; this points out that

respiration is requ-F.ed for cabscission to take place. Deficien- le;- cf nitrogen, zinc,

calcium, sulfur, r.:ngnesiu-n, potassium, boron and iron accelerate abscission cs do




13

excesses cf zinc, iron, chlorine end iodine. High salt or alkclir.e conditions also pro-

duce abscission.

The area that has received by far the greatest attention in abscission research,

however, is the effects of phytohormones, both naturally occurring and artificial.

Abeles (2) lists all of the current hypotheses of how abscission is regulated by

hormones (this author considers ethylene as a hormone).


Auxin-Ethylene Balance

As proposed by Hall (68), this theory states that since indoleacetic acid (IAA)

or other auxins can prevent abscission and ethylene induces absc;s.-;cn; it is the

proper balance between the two, maintained in the tissue, that prevents absc:~ion.

The absolute amount of either is not considered the important factor. Sone of the

effects of applied ethylene are to lower endogenous ouxin (5) and. increase the

activity of cellulose (4, 44). It is suggested (7) that ethylene is a hormone in t-ci

it stimulates RNA and protein synthesis in receptive (non-juv\en;!e) cc -a' ep:F'ans.

In this same work it was noted thai boih the effect of ethylene aci oLscissic.! wvcre

blocked by actinomycin D, which suggests that the proteins stinriulated by elhylene

are Ihe hydrolytic enzymes which cause akscission (76, 105, 122).


Auxin--Ethylne

Here (16) it is sucejsted that a continual supply) of auxin p,'events alscision;

when this supply falls Lblow a critical ltvel, abscission occurs. Exojenous appli-

cation to tl-.e distal (leaf or fruit) side ventsablcission. Ethylene is seen os t'-!

activator of abscission metabolis1n end c.,xin the inhibitc,-.






Auxin Gradient

This is perhaps the most widely known of the abscission regulating hypotheses.

Addicott and Lynch (11) propose that an auxin gradient exists across the abscission

zone. As long as the auxin concentration is higher on the distal side than on the

proximal (plant) side, there is no abscission. When the level of auxin on the distal

side equals that on the proximal or when exogenous, foliar applied auxin raises the

proximal level above that of the distal, abscission occurs. Radioactive tracer studies

have shown that IAA will not pass through the abscission zone (77). This interpreta-

tion has been used (87) in explaining the difference between foliar and inflorescence

application of growth regulators in tomatoes. Results from foliar sprays of the syn-

thetic auxin, parachlorophenoxyacetic acid (PCPA) were erratic. It was felt that

increased fruit set was due to reduction of vegetative growth or prevention of ab-

scission as this auxin moved into the abscission zone, maintaining an artificially high,

but still balanced,auxin level. The opposite effects also could occur, due to ab-

scission acceleration or mortality of the pollen or ovules. Blossom applications were

found to be more consistent in increasing fruit set (reducing abscission) by maintaining

the normal higher distal concentration. Since development of the ovary then occurred

without the necessity of pollination, many fruit were parthenocarpic, a condition

long associated with floral "hormone" sprays (64).


Auxin Concentration

In an attempt to explain the opposite effects of differing auxin concentrations,

Gaur and Leopold (62) suggest that a high auxin concentration (greater than 15 ppm)

inhibits abscission and a lower concentration promotes abscission. While proximal

applications were four to be more effective than distal, the some pattern is described






by other researchers (2 1, 22).


Auxin-Auxin Balance

In this proposal (85), it is felt theit the leaf supplies a sufficient amount of auxin

to prevent abscission until which time it can no longer produce enough, then auxin

from other leaves promotes abscission.


Auxin-Senescenct Factor

Although similar to the above theory, it is felt that some substance from the aging

leaf promotes abscission, rather than translocated auxin (127).


Membrane Integrity

Auxin is thought to act by maintaining the integrity of the membrane and, when

the ouxin level drops, a loss in ne:,ibraie integrity is followed by cell separation

(37, 142).


M- thionine-Auxin

Methionine is felt to act as o methyl donor, and,by methylating carboxyl groups

of pectin molecules, overcomes the auxi.- effect oicnd hastens abscission (183).


Auxir,-Gibberellin-Abscisiron Accelerating Hormone

A conjunciive meclaii sm is propcosd wV're gibberellin is an antagonist of auxin

and a third compound is affec-ed by the action of the two (24, 39, 100, 101).


Encdognc:,s Abscis~ion Acclerar.:g u:-_ta.ncs.

Abscisin is thl..., t o bt an abscission regulcting hormo.,ie, and is a product

of senescing tissue (3).






Two-Stage Theory

A two-stage action of abscission is said to exist and a high auxin concentration

inhibits abscission if the first stage of abscission is not completed. The second stage

allows aux^n promnoive abscission. The two-phase action o" auxin in the auxin con-

centralion theory is still proposed, and actions similar to that of auxin are claimed

for kinetin. Gibberellic acid was found to promote abscission at all concentrations,

and shorten the duration of the first stage (40, 139).


Localized Cellular Senescence

Abscissicn regulation is composed of two stages. In the first stage, a metcaol'c

difference develops between the cells on either side of the undeveloped abscissi;n

zone, giving a mobilization advantage to the proximal side. The second stage then

follows, with a mobilization of materials out of the distal tissue, suppression of

synthetic activities there, and a transition toward cell wall degradation. The actions

of the various growth regulators can be accommodated as preferential effects on the

two stages of development. Auxin and ethylene effects are on the second stage as

in the Two--Stage Theory (30, 98).

These last two theories, however, do not fit with 'he practice of thinning early

season apples with auxin sprays. Murneek and Teubner (123), preceding the develop-

ment of these theories, found that the early season treatment was lethal to the develop-

ing embryo. They felt that,perhaps with the death of the embryo, a continuous supply

of auxin to the abscission zone was lost. Later applications were found to prevent

abscission, once the embryo was mature and no longer supplied auxin.


Aging-Ethylene

Examining further the -elcationship between auxin and eth/,ene, it wa; firs;




17

suggested (1 i) that ethylene may influence the destruction of auxin. However, with

the knowledge thai auxin is transported polarly basipetally (150), the concept of

ethylene action, has been modified to that of an inhibitor (or at least a reducer) of

auxin transport. Burg and Burg (36) showed the capacity of the polar auxin transport

system is markedly reduced by ethylene. Abeles (1) did not find a transport eafect,

at least during the duration of a short treatment (three hours). He later (2) explained

the positional effect of auxin due to differential transport rates, allowing or pro-

hibiting the effect of endo;enous ethylene. Distally applied auxin is able to in-

hibit abscission, regardless of the accelerated rate of ethylene evolution, by being

rapidly transpc ted to the abscission zone. Auxin applied proximally stin:ri!c'es

abscission because it is unable to move as rapidly to the obscissioi zonr.cond the

ethylene effect becomes dominant. He proposed that the modo of action of othir

exogenously applied ;!scisslon accelerators (ibscissin, gibberellin, eic.) is by in-

creasing endogeno.s ethylene production. Noting that ethylene was found to bK r,.c:t

effective on ca.d tissues, he concluded that abscission rates are deterrrined by an

increase in sensitivity of the tissue and proposes !he Aging-Ethylene hypothesis.


Compounds Affecting Abscission

Although it is far fiom, reso:ved which of the above hypotheses is the correct inter-

pretation of abscission, valuable information can be gleaned as to which compounds

affect abscission. In surni a,y, ethylene, gibberellins, abscis-in, and many au>ins--

2, 4-dichlorophenoxy c:etic acid (2, A-D), 2, 4, 5-tric -iroacetic acid (2, /, 5-T),

napthaleneace. c .ci (t JAA), IA-, and PCPA--undr certain conditions,vwll pro; ote

abscission. Au'?.., p; t i'oloi !Ay cid PCPA\,cani in certLin in:tunces, prevent

abs~.ission Ev ....: : c nd in thi r- ~ or ;ciso : : ; cj iv:y by acting o. eIcr






ethylene or auxin (6, 111), it is found that 2, 3, 5-triiodobenzoic acid (TIBA) has

an abscission promoting effect (58, 176, 184). The mode of action of TIBA (often

called an "anti-auxin") appears to be through the blockage of transport of IAA from

its site of production (40, 81, 94, 124, 125), thus producing two effects: a reduction

of auxin in remote areas and an increase in local areas. Thus many varied effects can

be expected from TIBA application. Two of the effects that are of concern cre the

removal of apical dominance (as does gibberellic acid) and fasciation or flattened,

coalesced tissue. Many claims (81) have been made for the use of TIBA in promoting

a large single harvest by eliminating apical dominance and converting all vegetative

buds to floral buds. However, since all varieties intended for mechanical harvest-

ing at present (and those proposed) are determinant, apical dominance is not an

important factor. The problem of fasciation is of greater concern for if the frequency

of fasciated floral buds were to increase with TIBA treatment, the yield of mcrket-

able fruits would be affected (18, 177).

Another group of compounds that have been shown to have abscission activity,

but have not been widely researched under laboratory conditions, are the phlhalamic

acids. They have been shown to inhibit terminal growth and cause the development

of an abscission zone in beans (119) and inhibit auxin transport in corn (41). These

results suggest an action similar to that of TIBA.


Field Applications

Auxins

Since Gustafson (64-) showed that synthetic auxins, applied to the style, could

cause the development of ionato ovaries without fertilization (and prevent abscission),

the use of auxin treatments to increase yield has been widely expounded. However.






other than common uscge in the San Diego, early market production area of Cali-

fornia (172), the urse of hormcse sprays has had little grower acceptance. There could

be many reasons far this: confusion over correct compound and dosage; time, numbers

and method of application; and fear of reducing quality.

Many compounds have been screened as to activity in promotion of fruit set

and prevention of cbscission (13, 35, 85, 185). It appeals that any compound meeting

the crite ia of cuxin activity (38) has activity in this regard. Among the more success-

ful are IAA, NAA and PCPA (114, 172, 180). All of these compounds applied at

25ppm have the desired effect of increased fruil set. Unfortunately, at this concen-

tration, these chemicals produce abnormal folincgo symptoms when applied as whole

plant foliar sprays, and,us a result, only single blossom sprays are recommended (114,

148). This limits t0-e application of these chemicals to areas where the expected

higher price for early yields warranis the high labor cost involved in blossom appli-

cations. This fact, as was discussed in the introduction, would preclude this specific

technique in Florida.

Artificial fruit set is rnos! successful under conditions of low night temperatures

(winter or early spring crops) (126) or high temperatures (greater than 900F) and high

light intensities (8/"). Thes conditions are typically those conducive to lov fertility

and high abscission rates, as has already been discussed.

Thus it was shc,.'n that cny fruit that is forced to develop under these conditions

will be seedless or p:-thenocarpic (S3). Parthenocarpy per se may not be an unde-

sirable churacteritc, but cocomitcnl developments lead to the unsuitability cf

parthenocorpic fruit: far :.arkct, especially when these fruit are handled mechanically.

Parth2nocarpic fruit, ',,i: hav:g i same color and flesh characteristics as normal




20

fruit, have only partially filled locules (113). The fruit is typically puffy (air filled),

pointed and subject to premature breakdown (172). This early breakdown is most

likely due to premature softening (80). Therefore, fruit set with auxin treatments

would certainly handle poorly under the more severe conditions of mechanical harvest.

Consequently, any program that is designed to use auxins in promoting on increased

yield for a single mechanical harvest in Florida must attempt to avoid the foliar

symptoms in the whole plant treatment required by labor cost and unavailability and

also to avoid the excessive production of parthenocarpic fruit. The success of this

type of program seems improbable with the present knowledge of these compounds.

Although TIBA and the phthalamic acids cannot be defined precisely as auxins,

they are included in the same context due to many similarities (158).

Since its development (75), the compound N-meta-toly phthcialamic acid (NMT,

Duraset*) has been foliarly applied to tomatoes with success (121, 156, 157, 158,

168) in increasing a single (early) yield and total yield. These experiments were

carried out in northern areas under admitted (121) low night temperatures. This

suggests an activity similar to auxin. Research in a southern area (54) failed to show

on increase in total number of fruit and indicated a softening of the treated fruit. A

definite auxin-like activity is found in the ability of the N-arylphthalamic acids to

promote parthenocarpic fruit (157, 158). Even though auxin activity is strongly

suspected, the higher rates (200 ppm) and foliar sprays without foliar symptoms indi-

cate a much lower activity and possible practical applications. In fact, the material

Duroset is available for commercial use.

NMT may not behave er:nirely as an auxin, though there are indications that it

*Ncaugatuck Chemical Division, I .S. Rubber Cc., Naugatuck, Conn.







has characteristics in common with TIBA. The results that show increased flower

production (75, 157) were conducted primarily with indeterminant and semi-deter-

minant varieties. This would implicate NMT in cancelling apical dominance, an

action also attributed to TIBA. This is not a clear-cut response, however, for some

varieties that did demonstrate an increased number of flowers were determinant.

In many of the above experiments, increasing early yield was the primary

objective instead of increasing uniformity. Therefore, it is necessary at this point

to make a distinction between early yield and uniform yield and clarify the relation-

ship between the two. Early yield refers to the fruit harvested first, early in the

season. It is important, especially in winter and early spring production areas,

because the early fruit brings the highest market price. The fruits harvested for

the early market are obviously those from the first cluster and typically the yield is

small. Chemical techniques designed to increase the early yield are aimed at in-

creasing the fruit set of the first cluster.

Uniform yield, on the other hand, refers to the amount of fruit of the same

physiological age. Already stated, the goal in artificially increasing the size of

the uniform yield is to increase the number of fruit set at any one particular time

and carrying this fruit load through to harvest. Therefore, techniques devised for

increasing the early yield could also be applicable to increasing uniform yield.

Little field work hics been conducted with TIBA applications on tomato; however,

to reiterate the remarks made under effects on abscission, TIBA has an anti-auxin

effect in promoting a ciYe;ion and causes increased flower production in non-

det:rminant varieties (81, 184). Problems that could arise w.vih field application

would be exp-ctcd foliar synmp'oms. Symptoms such as r.dctiioi of le~af area,




22

reduced iniernode length and fasciation could seriously impair the yield and quality

of the treated fruit.


Gibberellins

Gibberellins generally hove a wide spectrum of growth responses (181). Among

the flowering responses is promoting the fruit set of tomatoes. Rappaport (131)

found with twice weekly applications of 100 and 200 micrograms per plant (foliar

application) that stem elongation was increased. Flowering was hastened by three

to six days without affecting number of nodes with 25-100 micrograms and normal

and parthenocarpic fruit set was increased by 1-500 micrograms per ml. The flower-

ing response, then, is very similar to that of auxins. The increased parthenocarpy

could well be due to the heterostylus (style exsertion) condition found by Bukovac

and Honma (31) after gibberellin treatments. Other gibbereilin effects are not

similar to auxin. Although gibberellins have been found to have an opposing effect

to that of ethylene in delaying senescence (suppress fruit ripening) (52, 144), they

still accelerate abscission (138). Prior research in Florida (59) has failed to show

any beneficial effects from gibberellin treatments on tomatoes, and, in fact, a yield

reduction was reported.


Ethylene

Since ethylene is a gas, obvious application difficulties have prevented field

experiments. Now, a liquid formulation is available that produces much the same efio.:

as ethylene gas (42, 141, 169) and does, in fact, accelerate the ripening of tomatoes

(141) parollei to the manner of ethylene. This material, 2-chloroethylphosphonic






acid (CEPHA, AmChem 66-329, Ethrel), has been shov/n (170) to evolve ethylene

gas on an almost one to one molar ratio when titrated with NaGH. With a material

such as this it is possible to make field applications as foliar sprays. Ethrel was

found not to initiate growth of emasculated flowers or increase the growth rate of

pollinated or parthenocarpic tomato fruit. The only flowers that were induced to

abscise were unpollinated, mature flowers (84). However, some fruit abscission-

inducing chericals,such as ascorbic acid, have been thought to act through a re-

sultant increased emission of ethylene (45). Ethrel did not have any effect on fruit

size but accelerated ripening by five to six days. Whole plant sprays of 1000 ppm

applied to five--leaf stage plants caused inhibition of terminal bud growth and arrested

growth for two weeks followed by abnormal growth of many lateral buds. When

applied to later slages, these effects were not observed, and only the typical ethy-

lene symptoms of epinasty were seen (107, 136, 149).

Further evidence of the ethylene-gibberellin antagonism is presented by Robin-

son, Shannon and De La Guardia (137) when Ethrel treatments were seen to modify

andromonecious cucumber line by initating the production of perfect or female flowers.

Ethrel applications would then have two-fold effects. By hastening the ripening

of mature green tomatoes, ease of sorting could be increased; those fruit too mature

for shipment to fresh market could be used in canning operations. Secondly, by

thinning those blossoms which were at anthesis, a more uniform yield could be obtained.

The treatments will have little effect on the immature fruit since it has been dem-

onstrated (106, 129) that ethylene treatments will not ripen immature fruit, only force

color development. Difficulties thai arise re e te tendency to "shatter" or abcise

prematurely, during hi-rnst crnd Ihe pocr hca dling :harccteristics of th. riper fruit (19).


1 AmCherr Prci'c. 1 ,c., Ambler, Pa.













MATERIALS AND METHODS


Selection of Chemica!s

In order to present The development of this project designed to produce a

temporary method, with present varieties, of promoting uniform fruit set and main-

taining that set through to a uniform maturity, the criteria of selecting materials are

outlined below.

I The techniques explored were in the area of chemical growth regulators

directly affecting the fruit set or obscission process.

II The chemicals tested have shown promise in this regard.

III The desired characteristics of the chemicals include:

A. Desired results

1. Sigrificanfly increase single yield

a. increase fruit set at any one time

b. ,Reduce fruit set at other times

B. Ease of application


1. Low kabor requirement

2. Broca application period

3. No special equipment requirements

C. Ease of procurement

1. Commercial availability (registered for use)

24







2. Low cost

D. No deleterious effects

1. FoliGr symptoms

2. Quality of fruit

a. Handling

b. Consumption

The materials selected for testing were:

Ascorbic Acid (vitamin C)

Boron (boric acid, H3BO3)

Calcium (calcium chloride. CaCL2)

Duraset (N-meto toylphthalamic acid)

Ethrel (chloroethylphosphonic acid)

Gibberellin (gibberellic acid, GA3)

[AA (indoleacetic acid)

TIBA (2, 3, 5-tri-iadobenzoic acid)

Also included were two compounds submitted for testing by Dr. H. H. Bryan,

Subtropical Experiment Station, Homestead, Florida:

Emery C-91 (formula not known)

Fatty Acid Fster2 (formula not known)


Fall 1968

Preliminary Field Screening

On August 15, greenhouse groin transplants of 1he vcriety Florid'e were


1 Emery !ndush'ies, Inc., crC'.' Ccrew lTover, Cincinnat- i, Ohio.
2 Procter cnd Gamble Co., 301 E. Sixth St., Cinci:r, til, Ohio.







mechanically transplanted into single ro.vs in the field at the Horticultural Unit

experimental farm of the University of Florida, Gainesville. The row spacing was

6 feet center-to-center. The beds vere raised 3 feet wide with 18 inches for the

in-row spacing. The soil type was an Arrendondo fine sand with a pH of about 5.0

to 5.5. Prior to planting the land was fumigated with 20 gallons per acre of D-D

and 1,200 pounds per acre of 6-8-8 fertilizer with 40 pounds per ton of FTE 503

were applied in bands. The rnicroe!ement analysis of this fertilizer was then 3.0

percent B, 3.0 percent Cu, 18.0 percent Fe, 7.5 percent Mn, 0.2 percent Mo and

7.0 percent Zn. About midway in the season the crop was sidedressed with an addi-

tional 800 pounds per acre of 15-0-15 fertilizer. Overhead irrigation was used to

supplement natural rainfall which was generally heavy. Weekly applications of a

Sevin-Zineb combination at 1.25 pounds per 100 gallons and 2.0 pounds per 100

gallons respectively were made. These applications were made with a tractor drawn

sprayer of the blower type at a rate of 100 gallons per acre. Cultivation was accom-

plished by hand and mechanical means. The plants vere not staked.

The treatment plots were 30 feet long in the row and replicated three times in a

random pattern. The chemical treatments were applied with a 1 gallon stainless steel

Hudson pneumatic sprayer. A 4 liter mix of the chemical was made for the three

replicates with 0.1 milliliter Triton b-1956 per liter as a surfactant. Application

was made by spraying to foliar run-off according to the rates and times appearing in

Table 1.

As this experiment was meant only for initial exploration, no combinations were

used; the experimental design was a five x two x two facioria! with five chemicals,

two rates and two times of application. The concentrations were chosen to brocket

those used in previously reported works (87, 172, 179, 180). The tmnes of applicci;ci






Table 1
CHEMICALS, CONCENTRATIONS AND TIMES OF APPLICATION USED IN THE
FALL 1968 EXPERIMENT


First Bloom Second Bloom

Duraset (100 parts per million)* Duraset (100 parts per million)

Duraset (300 ppm) Duraset (300 ppm)

Emery C-9 (0.5 pe: cent)** Emery C-9 (0.5 per cent)

Emery C-9 (1.5 per cent) Emery C-9 (1.5 per cent)

Ethre! (200 ppm)** Ethrel (203 ppm)

Eihrel (600 ppm) Ethrel (600 ppm)

Fatty Acid Ester (0.5 per cent)** Fatty Acid Ester (0.5 per cent)

Fatty Acid Ester (1.5 per cent) Fatty Acid Ester (1.5 per cent

IAA (10 ppm)* IAA (10 ppm)

IAA (30 ppm) IAA (30 ppm)

Control--no applica-ions

* Weight by Volume determination
** Volume by Vol'mn determination
-- Solutions prepared b, c'isolving 10 and 30 milligrams IAA in 10 and 30 milliliters
of 95 percent ethyl alcohol respectively anc then bringing to 1 liter volume with
top water




28

were chosen, following the recommendations of Johnson (87) and Singletory (148), as

when the majority of flowers had developed in the first end second inflorescences: or

at about twvo and four weeks after transplanting. Lack of space prohibited the screening

of all materials selected at this time, and although the activity of IAA was well defined

(87) it was included as a treatment for a check on application methods and times.

The fruit was harvested prematurely on November 5 in order to avoid a pre-

dicted frost. The original criterion for harvest was for 10-20 percent of the control

fruit to be ripe. All fruit were harvested and a count was made of the number of fruit

from each treatment in each of the following classes:

1. Green

2. Mature Green through Pink

3. Light Red and Ripe

These classes were according to the categories as described by the United States

Department of Agriculture (164). The discrimination between green (immature) and

mature green fruit was made on the basis of size (fruit smaller than 2 inches in diam-

eter were excluded) and subjective maturity measures, such as firmness (overly firm

fluit, suggesting inadequate internal jell formation,were excluded) and skin develop-

ment. An informal check of the reliability of these criteria by observing ripening

ability proved this method workable and consistent with others (46, 103, 182).

A subsample of 20 fruit of U.S. Number 1 grade and uniform in size and maturity

(breaker stage as defined by the U.S. D.A. (164) from category 2 above) was taken

from each treatment. These subsamples were treated with 50 parts per million of

Chlorine (as Sodium Hypochlorite) and removed for quality evaluation.

Quality Evaluation
Eight of the chlorine trcated fruit were selected from each subsample, place







in one gallon glass containers and an airflow of 13-15 liters per hour was directed

into each container. The containers were placed in a darkened room and on attempt

was made to maintain a constant temperature of 68F but 100F fluctuations were

noted. Ripening characteristics and ripe fruit quality were monitored only by ob--

servations.


Statistical Evaluation

Yield data of each category and toial were analysed using a one--way analysis

of variance, and individual mean differences among treatments for each category and

total were determined with the Duncan's Multiple range test as described by Steel

and Torrie (153).


Spring 1969

Field Plots

The variety Tropi-Gro was direct seeded in the field on March 12. 1he row

spacing was again 6 feet center-to-center on raised, 3 feet wide beds. However,

in this experiment the beds were covered with a black polyethylene mulch and

planting was accomplished by cutting holes in the plastic at 15 inch intervals and

placing two to three seeds per hill. The soil type used in this experiment was a Leon

fine sand with a pH of 4.5-5.0 on the Horticultural Unit of the University of Florida.

Preplant fumigation and initial fertilization vere carried out as before, although side-

dressing was done vwih 1000 pounds per acre of 6-8-8 fertilizer. Insect and disease

control and irrictc.-io wver 0 as in the fall 1968 experiment but supplemental irrigation

was more frequent during rihIs season due to the normally low rainfall.

The exprirentc! 'c.~ -; were plcts 50 feet long in the row under a completely







random experimental design and replicated three times.

Treatment applications were made as before with the hand carried sprayer. For

this experiment,however, Triton X-100 was used as the surfactant. In addition, it

was found that about 1.2 liters of solution per plotwere sufficient for complete wetting

of the plants in early stages; later on, 2.0 liters were required.

The chemicals, concentrations and times of application appear in Table 2. Be-

sides the Ireatmenis appearing in Tabie 2, non-replicated applications of gibberellic

acid (35 ppm) and ascorbic acid (10,000 ppm) were made at third bloom plus one

week for observational trials. The terms first, second and third bloom are for con-

venience; a more precise definition of these periods was made. First bloom cor;e-

sponded to the fourth to fifth internode; the flowers of the first inflorescence were

formed but not open. The second bloom was defined as occurring at the eighth to

ninth internode. Finally, the third bloom was considered as when the fifteenth in-

florescence was mature (the sixteenth inflorescence was open but not mature) or about

two weeks after the second bloom. The treatment made one week following the third

bloom corresponded to the time when this variety ceased its bush-like appearance

and became more prostrate.

In order to alleviate the problem of differentiating immature green from mature

green, two harvests were made. The first harvest was carried out when an estimated

10 percent of the fruit were completely ripe. This harvest was conducted on June 16,

and the only fruit harvested were those between the breaker stage and ripe. The

fruit were then sorted into the following three categories:

1. Breaker

2. Pink

3. Light red and ripe







Table 2

CHEMICALS, CONCENTRATIONS AND TIMES OF APPLICATION USED IN THE
SPRING 1969 EXPERIMENT


First Bloom


Second Bloom


Third Bloom


Third Bloom plus
1 week


Duraset (200 ppm)*

Durasef (200 ppm)

Duraset (200 ppm)

Duraset (200 ppm)


Ethrel (1,250 ppm)**


Boric Acid (20 ppm)*

Boric Acid (20 ppm)

Boric Acid (20 ppm)


Ethrel (1,250 ppm)

Ethrel (1,250 ppm)

Ethrel (1,250 ppm)


Ethrel (1,250 ppm)


Boric Acid (20 ppm)

Calcium Chloride (20 ppm)*

Boric Acid (20 ppm)
plus
Calcium Chloride (20 ppm)

Control--no applications


* Weight by Volume determination
** Volume by Volume determination


C~_ _I~~ I~C __







The weight of fruit in each one of these categories was then taken. Twenty-five

fruit, U.S. Number 1, and of uniform size and maturity were subsampled from the

breaker class, dipped in 50 ppm chlorine and placed in a dark ripening room at 680F

and 80 percent relative humidity. The fruit were later removed for quality evaluation.

Eight days after the first harvest, a second harvest was conducted; this time all

fruit were harvested. Since this harvest did require the separation of mature green

from immature green, the criteria used in the fall 1968 experiment were again em-

ployed to separate tho fruit into the following categories:

1. Immature green

2. Mature green

3. Breakers

4. Pink

5. Light red and ripe

The weight of fruit in each class was taken and the subsomple of twenty-five fruit in

class three was taken and treated as in the first harvest.


Quality Evaluation

Bio--yield point

After 12 hours in the ripening room, five fruit were removed and the bio-yield

point,as described by Keener (91), of the whole fruit was determined with an Instron

stress-strain analyser equipped with a tip constructed to the dimensions of those

found on the Magness-Tayler pressure tester (112). The fruit was positioned in a

shallow dish filled with moist, fine sand that offered good support. This dish was

then placed on the Icad cell anvil and the cross-.head was allowed to descend at a

speed of one inch per hour. When the bio-yield point was evidenced by c; peak cn







the chart, the cross-head was reversed. In order Io get an estimate of skin strength,

an area on the tomato, slightly larger than the cross-sectional area of the penetrating

tip (seven sixteenths inches), was peeled and the difference between the bio-yield

force of lhe peeled section and the bio-yield force of an unpeeled section 1800

opposed on the same fruit was taken to represent the skin strength. This method

was used instead of the puncture method evaluated by Voisey and Lyoll (167)

in order to avoid the laborious procedure of providing a satisfactory sample of

skin.

The remaining fruit were allowed to ripen fo," 7 days at which time they were

removed for further analysis.


Texture

Three fruit were rcndomly selected and sliced at right angles to the central axis

with a parallel bladed knife. A 100 gram sample of one fourth inch slices selected

from only the equatorial area was then placed with the slice at right angles to the

grid cell of a Kramer shear press equipped with the 2500 pound proving ring and

operated at the 10 percent range. Three readings were taken from different samples

of the resistance of the flesh to shear forces, giving a measure of the firmness or

texture of the tomato flesh (160).


Color

According to the methods used by Hall (68) and McCollum (103), equal and

opposite quarter sections were obtained for testing by cutting parallel to the central

axis in two planes, 900 opposed. Thus only one half of the fruit v.'as used in anotysis.

The locular jell and seeds were separated from the pericarp and indccpiident analysis






was conducted on each sample (see Figjre 1),. Each sample was hc-nogenized in a

blender for 1 minute at low speed and filt-~red ihr-ugh a single layer of cheese cloth.

One hundred milliliter aliquots were taken from each filtrate. Approximately 0.1

milliliter antifoaming agent (DowFcam)iri was then added to the aliquots which were

evacuated for 20 minutes. The a/b color racio was then determined through the use

of a Hunter color-difference meter (145).


Soluble solids

The remaining cheese cloth filtrate was then filtered through commercial! paper

towels cut to fit Buchner funnels. The filtrate was frozen for later analysis. Upon

thawing, soluble solids content as percent was measured with a Bauch and Lombe

Abbe 13L table model refractometer by placing two drops of the filtrate on the prism

and making the readings. Each reading was duplicated and corrected for temperature

variations.


pH and titratable acidity

From the thawed samples two 10 mili! iter aliquots were diluted with 40 mill--

liters of distilled wa-er and pH deteiminasions were made with c: Fisher pH meter.

The samples were then titrated to a pH of 8.0 vwiTh 0. 1N NaOH on a Fisher

titrimeter (71).


Statistical Evaluation

The yield results for each category and total as raw data and as percent of the

overall treatment totals and the results from a!l quality evaluations were analysed

with a one-way analysis of variance and individual mean differences were determined

with the Duncnn's Multiple range test.






Figure 1

SCHEME OF ANALYSIS USED IN EVALUATING THE QUALITY OF FRUIT OBTAINED
IN THE SPRING 1969 EXPERIMENT


Horvest


Subslnple 25 breaker stage fruit

Chl rine dip (50 ppm for 30 seconds)

Ripening room (680F, 80 per cent RH, dark)

7 days

12 hours Ripe fruit
v - i Slice 3 fruit into one fourth inch slices
Bio-yield point V
determination of 5 fruit Select 100 grams of equatorial slices

Texture determination

Cut equal and opposite sections

Outer and inner pericarp < >Locular jell and seeds
4, ____________________
Blender (1 minute)

Filter through cheese cloth

Filtrate

Take 100 milliliter oliquots Filter thro gh paper towel

Add antifoam agent Freeze

Vacuum (20 minutes) Thaw

Color determination Soluble solids determination
V
Two Samples of 10 milliliters plus
40 milliliters of distilled water

Titratable acidity and pH determinations







Fall 1969

Field Plots

Plants of the variety Tropi.-Gru were transplanted into the field at the Horti-

cultural Unit on August 21. The transplanting was done by hand using plants grown

in peat pots filled with commercial potting mix. The sail type was an Arredondo

fine sand with a pH of about 5.5-6.0. The row spacing and plant density were as

in the spring and the rows were again covered with a black polyethylene mulch.

Fertilization, insect and disease control and irrigation were also carried out as in

the spring 1969 experiment. Treatments were made as before with the hand carried

pneumatic sprayer on triplicate 30 feel long plots under a completely random design.

The chemicals used, their concentrations and times of application appear in

Table 3. The times of application were as defined in the previous experiment. The

rates of boric acid and Ethrel were reduced somewhat in order to determine if less

material could be used with the same results.

On November 17, following a killing frost, all fruit were harvested and sorted

into the following categories:

1. Immature green

2. Mature green

3. Breaker and pink

4. Light red and ripe

Since a Chi-square test of the results of the spring experiment in the classes

of breaker and pink showed no difference in variance and thus that the vwo popu-

lations were the same, these two categories were combined in this experiment. The

weights were taken from each class and the fruit was discarded due to frost damage.







Table 3

CHEMICALS, CONCENTRATIONS AND TIMES OF APPLICATION USED IN THE
FALL 1969 EXPERIMENT


First Bloom


Second Bloom


Third Bloom


TIBA (15 ppm)*~l

TIBA (15 ppm)

TIBA (15 ppm)


Boric Acid (10 ppm)*


Ethrel (1,000 ppr.)W*


* Weight by Volume determination
** Volume by Volume determination
- Solutions prepared by disolving 15 milligrams TIBA in 15 milliliters of 95 per--
cent ethyl alcohol and bringing to 1 liter volume with tap water







Quality Evaluation

The fruit were compared only by observation for any abnormalities that could have

been caused by the chemical treatments. No other evaluation was made due to ihe

fact that not enough undamaged fruit were available for valid comparison.


Statistical Evaluation

Yield data for each category and total were analysed according to the analysis

of variance, and differences between the means of classes within treatments were

compared with the Duncan's Multiple range test.


Bioassay of Auxins in the Fruit

In order to investigate the auxin--ethylene relationship further, an experiment

was conducted to isolate and compare by the Avena coleoptile straight growth test

the auxins produced in tomato fruit over time with and without treatment by 400

ppm Ethrel.


Experimental procedure

Forty mature green tomato fruit of uniform size and appearance were chosen

from the guard rows of the fall 1969 experimental plot. After the usual 50 ppm

chlorine dip, 15 fruit were treated by a 30 second dip in 400 ppm Ethrel (the con-

centration was reduced from that used in the field experiment because it was felt

that under these conditions the field rate would be excessive). All fruit were then

placed under standard ripening conditions. After an initial extraction, samples of

five fruit each were selected at one week intervals for four weeks and the indole

auxin components were isolated for assay with the Avena straight growth test.







Isolaticn technique

The technique used for extracting the indole auxins was a modification of the

ethyl alcohol extraction procedure presented by V\iios and Meudt (166). The juice

of whole fruit was expressed by a hand press through cheese cloth into a sufficient

volume of 95 percent ethyl alcohol to produce a final concentration of 80 percent

alcohol. This solution was then filtered through Whatman number 5 filter papel in

a Buchner funnel. The filtrate was evaporated to dryness. The residue was then

redissolved in 100 milliliters of acetonitrile (an indole ring solvent) and this solution

was washed three times in a separatory funnel with hexane which was discarded.

The acetonitrile fraction was then evaporated and the residue dissolved in 2 milli-

liters of 100 percent isopropyl alcohol. This fraction was stored in brown glass at

400F until Ihin layer chromatographic plating could be done. The plating was done

by spotting 50 microliters of the propanol fraction onto Avicel coated thin layer

plates and developed for 5 hours in 80 percent propanol. The Rf value was deter-

mined with a 10-3 Molar standard of IAA and locating the spot with a 50:1 mixture

of 5 percent perchloric acid and 0.5 M ferric chloride. After drying, five hundrcdi:s

of a gram sample of the thin layer material from the Rf area was scraped off and

dissolved in the Avena coleoptile test buffer.


Bioassay

A typical Avena straight growth test for auxin activity as described by Leopold

(97) was then conducted. The results were analysed using the t statistic (117) to

test for ao increase in coleoptile length for the extracts from treated and untreated

samples.






Spring 1970

Harvest Method Comparison

In order to economically compare hand harvest with machine harvest and machine

harvest of chemically treated fruit, a mixed integer programming model (66) was de-

vised with the help of Dr. M. R. Langham, Department of Agricultural Economics,

institute of Food and Agricultural Sciences, University of Florida, Gainesville,

Florida.

The purpose of this model was to evaluate the economic significance of the data

obtained in the previous experiments and to provide the grower with an aid in their

tomato harvest decisions. The model was designed to compare the variable costs per

acre of each harvest method plus the fixed cost per year required if a mechanical

harvester was purchased, the unit yield from all of the methods and the price per

unit. The limits placed on the model were yield from each method, labor available

and acres available.


Statement of the model

The goal of the model was to maximize the following, linear, revenue function

(Z).

Z alX1 -a2X2 -a3X3-FC(Q) -4- PX4

Where:

al = variable cost per acre fcr hand harvest method

X1 = number of acres to be hand harvested

a2 = variable cost per acre for machine harvest method

X2 = number of acres to be machine harvested





41

a3 = variable cost per acre for machine harvest method and chemical treatment

X3 = number of acres to be machine harvested and chemically treated

FC fixed cost per year of machinery

Q = a variable which takes on the value 0 or 1

P = price per 40 pound crate

X4 = amount sold, in 40 pound crates, from the 3 methods

Certain assumptions were made regarding the above function and are as follows:

1. The variable cost functions are linear over the range of values considered.

2. There are no other sources of revenue.

3. Only field costs are pertinent and shed and shipping costs need not be
considered.

4. All of the yield is sold at the same price.

Certain restraints were placed on the revenue (objective) function. The first

of these provided that the sum of the acres used for all methods could not exceed a

designated maximum.

X1 X2 +-X3 4-X5 =A

X2 -A (Q) LE* 0

X3 -A(Q) LE 0
Q LE 1
Q GE** 0
Q aninteger
*Less than or equal to
**Greater than or equal to

Where:

A = maximum acres available for cultivation

X5 "slack" or unuseu acres






It can be seen that the first two restraints containing the Q term will never be

effective but they require that Q be nonzero if either or both X2 and X3 are nonzero,

and since Q was restricted to be an integer, if either or both X2 or X3 were positive,

Q would take on the value 1 and assure that the fixed charge (FC) was incurred.

A balanced equation required that the amount produced must equal the amount

sold.

Y1'1 4 Y2X2 4- Y3X3 = X4

Where:

Y1 = yield (40 pound crates) expected per acre from hand harvest

Y2= yield (40 pound crates) expected per acre from machine harvest

Y3 "- yield (40 pound crates) expected per acre from machine harvest of
chemically treated fruit.

Finally a labor restriction was placed on the objective function. This restriction

required that the sum of the man-hours of labor used in each method could not exceed

a maximum amount available.

L1X1 4- L2X2 4- L3X3 Jr X6 SL

Where:

L1 = labor (man-hours) required per acre for hand harvest

L2 labor (man-hours) required per acre for machine harvest

L3 = labor (man-hours) required per acre for machine harvest of chemically
treated fruit

X6 "slack" or unused labor

SL = maximum labor (man-hours) available

The objective function and restraints are arranged in a tableau in Table 4.














4-

C
.- 0


Ct


- c' ) c
-JI






- CNJ C
-J





-JI


C )
u-
o)



u_


_1









U i II L
UJ


0.



(




C o

O o
1 0


LUJ
LU
0:


SU
u.
LL
I


0
'0--
0
X c
o




LO
E




X
o





0
C)
0

X u
o


0
E o
<


coc






c







C -
2-
-C II
uo


- u
.


-0

o
0 cO
-1


o
> 0

0 c
^L
0


, _







Generation of parameters

Costs

The variable cost per acre for hand harvest was taken as the 1968-1969 picking

expense for growers in the Immokalee-Lee area of Florida (57). This figure, $218.13,

is representative of harvest costs for ground-grown, mature green tomatoes in Florida.

The costs for machine harvest had to be interpolated from California data (128). Using

the hourly requirements for machine harvest of tomatoes in California and labor costs

for Florida (29) of $2.50 per hour for supervisors, $2.00 per hour for harvester operator,

$1.30 per hour for sorters, $1.65 per hour for trailer drivers and fork lift operators,

$2.00 per hour for miscellaneous labor and a $21.92 per acre machine cost, a per

acre variable cost of $114.64 was obtained. The variable cost per acre for the machine

harvest of chemically treated tomatoes included the above cost plus an arbitrary $15.00

per acre material cost and a $3.03 per acre application cost (three-fcurths of an hour

per acre at $1.65 per hour for labor and $1.80 per acre for equipment) (26) for using

some type of chemical treatment. The fixed cost per year of machine harvesting was

taken as $6,574.00 (128) and no fixed costs were assigned to hand harvest methods.


Price

The initial price used was $2.50 per 40 pound crate but this was to be increased

in $.25 steps to $5.00 per crate.


Acreage

An initial limit of 50 acres was set to be later varied at 25 acre intervals to

4,000 acres.







Yields

Using the 1968-1969 yield average from the Immokalee--Lee area as a basis (28),

experimental yields were converted to compare to a normal yield. Thus YI and Y2

were obtained by multiplying the expected hand harvest yield (Y1 = 264 40 pound

crates) for the Immokalee-Lee area by the percent of normal yield obtained from

treating the spring 1969 experimental yields as a once-over harvest and eliminating

the light red through ripe category of the first harvest and the immature category of

the second harvest.


Labor

1he labor requirements used for hand harvest were 117.9 man-hours per acre (28);

57.93 man-hours for machine harvest and 58.68 man-hours for machine harvest and

chemical treatment (128). A total available labor limit was arbitiari!y set at 3,500

man-hours but was to be varied at 300 man-hour intervals to a maximum of 20,000

man-hours.


Solution

The assembled data were then transferred to a Hollerith card data deck for sub-

mission to the International Business Machine Model 360 computer at the Computing

Center, University of Florida,for solution under the Mathematical Programming System

(MPS) 360 control program (115).


Parametric programming

The sub-routines available within the MPS 360 program that allow.vd the para-

meters (cocfficients and restraint,) to be varied in discree, steps were utilized to

evaluate the sensitivity of tha model (72, 115). The pcrametcrs which wer of doubtful




46

accuracy or validity thai were varied were the variable cost of the machine harvest

of chemically treated fruit, price, acreage restraints, yields from both mechanical

harvesting methods and labor restraints.













RESULTS


Fall 1968

Foliar Symptoms

The only foliar symptom noted was some leaf roll in the early IAA treatments,

especially at 30 ppm.


Yield Data

Single harvest

Light red and ripe fruit

The effects of ihe treatments on the single yield of light red and ripe fruit cre

presented in Table 5. It is evident from the data that the later applications of

Duraset at 100 ppm and Fatty Acid Ester at 1.5 percent gave the highest yield of

ripe fruit. Also higher than control yields were obtained with both applications of

IAA at 10 ppm, Emery C-9 at 1.5 percent and Ethrel at 600 ppm applied at the

second bloom.


Immature, mature crcen through pink fruit and total yield

There was no srtnificont difference between the single harvest yields of any

treatment on inrrifui c, nature green through pink fruit or total yield (see Table







Table 5

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON
THE AVERAGE NUMBER OF LIGHT RED AN D RIPE FRUIT PER PLOT,
FALL 1968


Chemical Concentration

Duraset 100 ppm

Duraset 300 ppm

Emery C-9 0.5 %

Emery C-9 1.5 %

Ethrel 200 ppm

Ethrel 600 ppm

F. A. Ester 0.5 %

F. A. Ester 1.5 %

IAA 10 ppm

IAA 30 ppm

None

*Those numbers follovied by the
percent level.


Time of Application
First Bloom Second Bloom
(2 weeks after transplant) (4 weeks after transplant)
Number


5.6 fgh*

6.3 efgh

4.6 gh

13.0 bcde

4.6 gh

1.6 h

1.3 h

5.6 fgh

16.0 abc

7.3 efgh


21.6 a*

9.6 bcdefg

8.0 defgh

20.0 ab

9.3 cdefg

12.0 cdef

3.0 gh

21.0 a

15.3 abcd

7.3 efgh


4.3 gh

same letters) are not significantly different at the 5


--







Table 6

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON
THE AVERAGE NUMBER OF IMMATURE, MATURE GREEN THROUGH PINK
AND TOTAL FRUIT PER PLOT*
FAIL 1968


Time of Application_
First Bloom Second Bloom
Immature MG--pink Total Immature MG--pink Total
Chemical Concentration Number


Duraset

Durasef

Emery C-9

Emery C-9

Ethrel

Ethrel

F. A. Estei

F. A. Estei

IAA

IAA


100 ppm

300 ppm

0.5%

1.5%

200 ppm

600 ppm

0.5 %

1.5%

10 ppm

30 ppm


103.0

90.6

99.3

123.0

129.6

79.3

99.6

115.3

113.3

117.6


55.6

57.0

55.3

72.6

70.3

32.3

53.6

84.6

81.0

54.6


164.3

154.0

159.3

207.6

224.6

113.3

154.6

205.6

210.3

179.6


80.0

99.6

119.9

121.0

55.0

73.0

132.6

124.0

148.6

103.6


65.3

77.6

68.3

75.0

31.6

39.3

67.0

96.0

89.0

64.6


182.6

231.3

189.6

216.0

96.0

124.3

203.3

241.0

253.0

208.3


Immature MG--pink Total

None 121.3 62.0 187.6

*A one-way analysis of variance was unable to detect any significant difference at the
5 percent level.


r

r







Quality Evaluation

Ripening characteristics

No externally evident differences were noted in the mature green fruit as they

ripened; however,the later Ethrel applications wcre fully ripe one to two days earlier

than the other treatments. Increasing the Ethrel concentration from 200 ppm to 600

ppm irnreased the early ripening tendency.


Handling characteristics

The IAA and second bloom Duraset treated fruit showed a tendency to break

down more rapidly as was evidenced by an increased amount of bacterial soft rot in

these fruit. Some parthenocarpy was noted in the IAA treatments.


Spring 1969

Foliar Symptoms

The Ethrel treatments were the only ones showing definite foliar symptoms.

These symptoms were epinosty, increased formation of adventitious rools and an

early tendency for the vines to lose their bush-like appearance and become postrate.

Some blossom drop was apparent. The foliar symptoms were not permanent and new

growth was unaffected, the plants treated at the third bloom having lost all symptoms

by harvest.


Yield Data

First harvest

Light red and ripe fruit

The effect of the chemical, concentration and time of application on the yield

of light red and ripe fruit appears in Table 7. Here it is shown that the greatest






Table 7

EFFECT' OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON
THE AVERAGE YIELD OF LIGHT RED AND RIPE FRUIT PER PLOT--FIRST HARVEST
SPRING 1969


Time of Application and Chemical Average Yield 4-
Third Bloom Per Cent of
First Bloom Second Bloom Third Bloom plus 1 week Pounds Total
Duraset* 5.33 d 2.88 de
Duraset Ethrel** 7.96 cd 4.45 cde
Duraset Boric Acid*** 3.43 d 2.00 e
Duraset Boric Acid Ethrel 13.83 b 7.93 b
Boric Acid Ethrel 12.13 bc 7.73 bc
Ethrel 5.60 d 3.56 de
Ethrel 19.80 a 12.33 a
Boric Acid 5.40 d 2.38 de
Calcium Chloride*** 5.46 d 3. 15 de
Boric Acid
Plus
Calcium Chloride 8.86 bcd 5.50 bcd
Control 4.96 d 2.84 de

200 ppm
*1,250 ppm
*** 20 ppm
4- Numbers followed by the same letters) are not significantly different at the 5 percent
level.






effect on the early yield of ilhese fruit wcs produced by the later Ethrel application.

The absolute yield (expressed as pounds) and relative yield (expressed as percent of

the grand total of the various classes and harvests within the treatments) were both

much higher than the control. Similar, though not as extensive, effects were also

shown by the Duraset-boric acid-Ethrel combination and the boric acid-Ethrel corm-

bination. Finally, the Duraset-Ethrel treatment produced a higher absolute yield

the the control but did not demonstrate a significantly different relative yield.

In addition, the gibberellic acid and ascorbic acid treatments, applied at third

bloom plus one week, produced yields of 4. 17 pounds and 6.55 pounds, respectively.

Since these trials were not replicated, they cannot be compared directly with the

other treatments but the yields are comparable with treatments that did not differ

significantly from the control.


Breaker through pink fruit

Although the raw data were taken on the two separate classes of fruit, breaker

and pink, a Chi-square test (117) of the replicate totals of both classes showed no

difference between the two populations, indicating that the sorting procedure for

separating these two classes was not valid. Thus the two categories were combined

for treatment comparison and the results appear in Table 8.

When expressed as absolute yields, the only treatment significantly higher than

the control was the boric acid-Ethrel combination. However, a reduction in yield is

seen wilh the Duraset-Ethrel and boric acid plus calcium chloride treatments.

The relative yields still show the boric acid-Ethrel combination to be higher than

control but the later application of Ethrel also produced a higher percent of breaker through

pink fruit in the first harvest. No treatments show a retivo've yield lower than the control.






Table 8

EFFECT OF CHEMICAL, CONCENTRATiON AND TIME OF APPLICATION ON
THE AVERAGE YIELD OF BREAKER THROUGH PINK FRUIT PER PLOT--COMBINED
DATA--FIRST HARVEST, SPRING 1969


Time of Application and Chemical
Third Bloom
First Bloom Second Bloom Third Bloom plus 1 week


Average Yield 4-
Percent of
Pounds Total


Duraset*
Duraset
Durcset
Duraset


Ethrel**


Boric Acid*"*
Boric Acid
Boric Acid


Ethrel
Ethrel
Ethrel


Ethre!


Boric Acid
Calcium Chloride***
Boric Acid
Plus
Colcium Chloride


Control


16.60 c
19.80 bc
17.30 bc
20.73 abc
27.13 a
15.93 c
24.30 ab
18.93 b
17.36 bc


9.37 c
11.23 bc
10.46 c
12.21 bc
17.40 a
11.60 bc
15.13 ab
8.65 c
10.51 c


16.36 c 10.11 c
17.97 b 10.15 c


200 ppm
**1,250 ppm
*** 20 ppm

-- Numbers follo.,-ed by the same letier(s) are not significantly different at t ,. 5 percent
level.


__ ____ __I_ __ __




54

The gibberellic acid and ascorbic acid treatments yielded 15.45 pounds and 8.58

pounds as an absolute yield, and it appears that the ascorbic acid treatment would be

significantly lower than control, but since these are only observations, no definite

conclusions can be drawn.


Subtotal

Many of the same effects produced by chemical, concentration and time of appli-

cation appear in the first harvest total yie!d, Table 9, as are seen in the ripe and

breaker through pink yields. The highest early total yields were the result of the later

Ethrel treatment, the Duraset-boric acid-Ethrel combination and the boric acid--Ethrel

combination. Also significantly higher than control yields were obtained by the

Duraset-Ethrel treatment, the early application of Ethrel, the boric acld treatment

and the boric acid plus calcium chloride treatment.

When converted to percent of treatment totals, however, some of the increased

early yield is not as evident. The late application of Ethrel still produced the highest

relative yield, followed by the boric acid-Ethrel combination. The Duraset-boric

acid-Ethrel combination was the only other treatment that produced a yield signifi-

cantly greater than the control.


Second harvest

Light red and ripe fruit

The only treatment that showed a significantly greater absolute yield of light red

ond ripe fruit is boric acid alone (Table 10). Although not significant, the much

higher yields of Duraset-boric acid--Ethrel, boric acid-Ethrel, early Ethrel and calcium

chloride treatmenTs could prove to be of importance in later trials. One treatment,

Duraset-Ethrel, showed a significantly lower yield.

An interesting shift in significance become apparent upon conversion to percent.







Table 9

EFFECT OF CHEMICAL, CONCENTRATION ANDTIME OF TREATMENT ON THE
AVERAGE TOTAL YIELD OF FUI!T PER PI.OT--FIRST HARVEST, SPRING 1969


Time of Application and Chemical
Third Bloom
First Bloom Second Bloom Third Bloom plus 1 week


Average Yield !-
Percent of
Pounds Total


Duraset*
Duroset
Duraset
Duraset


Ethrel**


Boric Acid***
Boric Acid
Boric Acid


Ethrel
Ethrel
Ethrel


Ethre


Boric Acid
Calcium Chloride***
Boric Acid
Plus
Colcium Chloride


Control


200 ppm
**1,250 ppm
*** 20 ppm

4- Numbers followed by the same letters) are noi significantly different at the 5 percent
level.


21.96 d
27.70 c
20.76 d
34.56 abc
39.26 ab
28.90 bc
44. 16 c
24.33 c
22.83 d


25.23 c
22.93 d


12.26
15.69
12.46
20.15
25.14
17.83
27.47
11.05
13.00


15.62 cde
13.00 de


~~~~_~


_____ ~_







Table 10

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON
THE AVERAGE YiELD OF LIGHT RED AND RIPE FRUIT PER PLOT--
SECOND HARVEST, SPRING 1969


Time of Application and Chemical Average Yield 4-
Third Bloom Percent of
Firsr Bloom Second Bloom Third Bloom plus 1 week Pounds Total

Duraset* 34.33 b 19.24 abc
Duraset Ehfre!** 23.00 c 13.28 c
Duraset Boric Acid*** 31.06 b 17.02 abc
Duraset Boric Acid Elthrel 38.30 ab 22.46 abc
Boric Acid Ethrel 44.76 ab 28.14 a
Ethrel 40.76 ob 25.38 ab
Ethrel 30.96 b 19.04 abc
Boric Acid 59.33 a 26.33 ab
Calcium Chloride*** 46.93 ab 26.27 ab
Boric Acid
Plus
Calcium Chloride 34.30 b 2'.35 abc
Control 26.60 b 16.67 bc

200 ppm
**1,250 ppm
*** 20 ppm
4- Numbers followed by the some letler(s) are not significantly different at the 5 percent
level.




57

The highest relative yield was that of the boric acid-Ethrel combination. No other

treatment was significantly greater than the control on a percent basis.

The gibberellic acid trial produced a yield of light red and ripe fruit of 44.88

pounds and the ascorbic acid trial produced a yield of 35. 16 pounds, and apparently

neither of which was significantly different from the control.


Breaker through pink fruit

The data for this category were originally taken as two separate classes. How-

ever, as in the data for the first harvest, no significant difference was found between

the classes, thus the data were combined for analysis and appear in Table 11. A Chi-

square test for population differences between the breaker, pink and mature green

classes was significant; therefore,these classes could not be combined.

As can be seen in Table 11 the-only treatment to produce an absolute yield

greater than the control was the boric acid treatment. There were no differences

evident in the relative yields of any treatment.

The yields of the gibberellic acid and ascorbic acid trials, 56.99 pounds and

40.66 pounds respectively, were again not apparently significant although the ascorbic

acid yield was lower than the control.

Mature green fruit

In this category, tle. boric acid teiatmeni is seen (Table 12) to he the one that

resulted in a significantly higher thsn control absolute yield. On the other hand,

several treatments reduced the yield of mature green fruit. The boric acid-Fthlel,

early and late Ethrel and boric acid plus calcium chloride treatments all showed

significantly lower yields.

In reference to relative yields, i" is seen tat Ihe control, Dur.set-Ethrcl cnd







Toble 11

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON
THE AVERAGE YIELD OF BREAKER THROUGH PINK FRUIT PER PLOT--COMBINED
DATA---SECOND HARVEST, SPRING 1969


Time of Application and Chemical


First bloom Second Bloom


Third Bloom


Third Bloom
plus 1 week


Average Yield
Percent of
Pounds 4- Total 4- 4-


Duraset*
Durase t1
Duraset
Duraset


Ethrel'**


Boric Acid***
Boric Acid
Boric Acid


Ethrel
Ethrel
Ethrel


Ethrel


Boric Acid
Calcium Chloride***
Boric Acid
Plus
Calcium Chloride


Control


200 ppm
**1,250 ppm
*** 20 ppm

Numbers followed by the same letters) are no- significantly different at the 5 percent
level.
4-+-The one-way analysis of variance was unable to detect any significant difference
at the 5 percent level.


59. 70 ab
52.40 abc
49.70 bc
48.40 bc
43,80 c
51.26 abc
45.23 c
63.46 a
50.50 bc


55.36 abc
51.46 abc


34.47
29.99
29.30
28.23
28.04
31.77
28.05
28.69
28.24


34.09
29.81


--


""--I"-~-'-


--II-`- '--- -`----~~-I







Table 12

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON
THE AVERAGE YIELD OF MATURE GREEN FRUIT PER PLOT--SECOND HAPVES1,
SPRING 1969


Time of Application and Chemical Average Yield -
Third Bloom Percent of
First Bloom Second B!oom Third Bloom plus 1 week Pounds Total

Duroset* 38.40 abcd 21.27ab
Durasei- Ethrel** 50.13 ob 28.35 a
Duraset Boric Acid*** 48.30 ab 28.45 3
Duraset Boric Acid Ethrel 36.13 abcd 20.5! cb
Boric Acid Ethrel 18.26 d 1i.20 c
Ethrel 26.83 cd 16.54 bc
Ethrel 28.50 cd 17.74 bc
Boric Acid 55. 16 a 24.6S cb
Calcium Chloride*** 40.03 abc 21.87 ab
Boric Acid
Plus
Calcium Chloride 30.46 bcd 18.62 bc
Control 47.36 ab 27.67 a

200 ppm
**1,250 ppm
*** 20 ppm

4- Numbers followed by the same letters) are not significantly different at the 5 percent
level.




60

Duraset-boric acid produced the highest percent of mature green fruit in the second

harvest. Also not significantly different from the control were the Duraset, Duraset-

boric acid-Ethrel, boric acid and calcium chloride treatments. The remainder of

treatments were lower than the control.

The gibbereilic acid and ascorbic acid trials followed much the same pattern as

before. The gibberellic acid yield, 39.38 pounds, did not appear significantly

different while the ascorbic acid yield, 20.48 pounds, did not seem to be lower than

the control.


Immature fruit

There was no effect from any of the treatments on either the absolute or relative

yield of immature fruit as can be seen in able 13.

The gibberellic acid, 25.74 pounds, and ascorbic acid, 16.20 pounds, yields

also did not seem to be significant.


Subtotal

The one treatment that resulted in an increase in the absolute total yield of the

second harvest is evident in Table 14 as the boric acid treatment. No other treat-

ment differed significantly from the control.

Upon conversion to percent, the increased yield of the boric acid treatment

was no longer evident. In relation to relative yield, the only significant effects were

those lower then control. The early and late applications of Ethrel, the Duraset-

boric acid-Ethrel combination and the boric acid-Ethrel combinations showed re-

duced yields. Duraset, Duraset-Ethrel, Duraset-boric acid, boric acid, calcium

chloride and boric acid plus calcium chloride treatments did not differ from the

con rol.






Table 13

EFFECT OF CHEMICAL, CONCENTRATION AND TiME OF APPLICATION ON
THE AVERAGE YIELD OF IM4MATURE FRUIT PER PLOT--SECOND HARVEST,
SPRING 1959


Time of Application and Chemical


First Bloom

Duraset*
Duraset
Duraset
Duraset


Second Bloom


Third Bloom


Third Bloom
plus 1 week


Ethie i**


Boric Acid***
Boric Acid
Boric Acid


Ethrel
Ethre!
Ethrel


Ethrel


Boric Acid
Calcium Chloride***
Boric Acid
Plus
Calcium Chloride


Control


Average Yield 4
Percent of
Pounds Total


22.56
22.90
19.30
15.23
11.73
13.66
12.16
20.53
20.10


16.93
22.45


12.77
12.68
12.73
8.61
7.45
8.46
7.69
9.11
10.61


10.25
12.89


200 ppm
**1,250 ppm
*** 20 ppm

--The one-way analysis of variance was unable to detect any significant difference
at the 5 percent level.


-- --I---------"







Table 14

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON THE
AVERAGE TOTAL YIELD OF FRUIT PER PLOT--SECOND HARVEST, SPRING 1969


Time of Application and Chemical Average Yield -
Third Bloom Percent of
First Blocm Second Bloom Third Bioarn plus 1 week Pounds Total

Duraset* 155.00 ab 87.74 a
Duraset Ethrel** 148.43 b 84.30 ab
Duraset Boric Acid*** 150.03 b 87.53 a
Duraset Boric Acid Ethrel 138.06 b 79.85 b
Boric Acid Ethrel 118.16 b 74.85 bcd
Ethrel 132.53 b 82.16 b
Ethrel 116.86 b 72.53d
Boric Acid 198.50 a 88.95 a
Calcium Chloride*** 157.06 ab 86.99 a
Boric Acid
Plus
Calcium Chloride 137.06 b 84.37 cb
Control 149.63 b 88.65 a

200 ppm
**1,250 ppm
*** 20 ppm
-- Numbers followed by the same letters) are not significantly different at the 5 percent
level.






Grand total

No significant difference was found due to any of the treatments cn the grand

total as is shown in Table 15.


Quality Evaluation

Bio-yield point

First harvest

The effect of chemical, concentration and time of application on the average

bio--yield point of chamber ripened fruit from the first harvest is shown in Table 16.

The only significantly different treatment v/as that of the gibberellic acid. This treat-

ment shows a much more firm fruit than the others.

The skin strength measures proved to have too great a variation, ranging from

2.9 to 8.0 pounds in the same replicates. It is felt a much larger sample would be

required to show significant differences,and there may be some question as to this

being a valid measure of skin strength since there was difficulty in removing a uni-

form layer of skin.


Second harvest

No differences were found among the treatments in the second harvest (Table 17)

and since there was not enough fruit fi om the gibberellic acid and ascorbic acid

treatments for a complete quality analysis, these treotmeits were left out of this parti-

cular test.


Shoar force

First ho r/vest

1he effect of chemical, concentration and time of application on the ;:






Table 15

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON THE
AVERAGE TOTAL YIELD OF TWO HARVESTS--COMBINED DATA, SPRING 1969


Time of Application and Chemical
Third Bloom Average Yield
First Bloom Second Bloom Third Bloom plus 1 week (pounds) -L

Durfset* 176.96
Durasei Ethrel** 176.13
Duraset Boric Acid*** 170 79
Duraset Boric Acid Ethrel 172.62
Boric Acid Ethrel 157.42
Ethrel 161.43
Ethrel 161.02
Boric Acid 222.83
Calcium Chloride*** 179.89
Boric Acid
Plus
Calcium Chloride 169.29
Control 172.56

200 ppm
**1,250 ppm
*** 20 ppm
+The one-way analysis of variance was unable to detect a significant difference
at the 5 percent level.







Table 16

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON THE
AVERAGE BIO-YIELD POINT OF WHOLE BREAKER FRUIT--FIRST HARVEST,
SPRING 1969


Time of Application and Chemicul
Third Bloom Bio-Yield Point
First Bloom Second Bloom Third Bloom plus 1 week (pounds) -

Duraset* 7.56 bc
Duraset Ethrel** 7.70 bc
Duraset Boric Acid*** 8.33 bc
Duraset Boric Acid Ethre! 7.16 bc
Boric Acid Ethrel 6.96 bc
Eihrel 5.63 bc
Ethre! 6.30 bc
Boric Acid 6.00 be
Calcium Chloride*** 6.16 bc
Br ic Acid
Plus
Calcium Chloride 5.26 c
GA3 (35 ppm) 14.60 a
Ascorbic Acid 8.86 b
(10,000 ppm)
Control 6.30 bc

200 ppm
**1,250 ppm
*** 20 ppm
4- Numbers followed by the same letters) are not significantly different at the 5
percent level.







Table 17

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON THE
AVERAGE BIO-YIELD POINT OF WHOLE BREAKER FRUIT--SECOND HARVEST,
SPRING 1969


Time of Application and Chemical
Third Bloom Bio-Yield Point
First Bloom Second Bloom Third Bloom plus I week (pounds) +-

Duraset* 6.50
Duraset Ethrel** 7.46
Duraset Boric Acid*** 6.80
Duraset Boric Acid Ethrel 8.30
Boric Acid Ethrel 7.73
Ethrel 6.46
Ethrel 8.10
Boric Acid 8.06
Calcium Chloride*** 8.00
Boric Acid
Pius
Calcium Chloride 9.43
Control 8.16

200 ppm
**1,250 ppm
*** 20 ppm

-The one-way analysis of variance was unable to detect any significant difference
at the 5 percent level.




67

force required to shear a 100 grnm sample of slices taken from chamber ripened fruit

of the first harvest is shown in Table 18. Here it can be seen that the single Duraset

treatment shews a significant difference from the control although the Duraset-boric

acid and Duraset-boric acid-Ethrel treated fruit have higher values.

In the evaluation of the Ethrel treated fruit, care was taken to avoid the one:

that were beyond the stage comparable with the other treatments.

The gibberellic acid and ascorbic acid treated fruit were no] compared in this

analysis due to there noi being enough fruit available for adequate replicaiion.

However, the measurements made, 112.5 pounds and 102.5 pounds for the gibbesellic

acid and ascorbic acid respectively, compared with those treatments that were higher

but not significantly different.


Second harvest

The same pattern appears in this test as is seen in Ihe previous one (see Table 19).

The data show only the Duraset treatment produced significantly firmer fruit.

Enough of the gibberellic acid and ascorbic acid treated fruits were available

to provide adequate replication and,as is evident in the table, they did not differ

significantly from the control.


Color

First harvest

No difference in the color of the fruits from the various treatments as represented

by the a/b ratio was evident. The data are presented in Table 20. Although no

stc;ts!ical comparison was made, the p-ricarp fraction appeared to have a grenrally

hij-her a/b ratio : the locale.







Table 18

EFFECT OF CHE1j.M!CAL, CONCENTRATION AND TIME OF APPLICATION ON THE
AVERAGE FORC-E REQUIRED TO SHEAR 100 GRAMS OF EQUATORIAL SLICES
TAKEN FROM. CHAMBER RIPENED FRUIT--FIRST HARVEST, SPRING 1969


Time of Application and Chemical
Third Bloom Shear Force
First Bloom Second Sloom Third Bloom plus 1 week (pounds) 4-

Duraset* 131.6 a
Duraset Ethrel** 91.6 b
Duraset Boric Acid*** 110,0 ab
Duraset Bcric Acid Ethrel 112.5 ob
c.ric Acid Ethrel 101.6 b
Ethrel 97.5 b
Elhrel 97.5 b
EBcsic Acid 95.0 b
Cglcium Chloride*** 90.0 b
Braric Acid
Plus
C icium Chloride 95.8 b
Control 95.8 b

200 ppm
**1,250 ppm
*** 20 ppm

-- Numbers followed by the same letters) are not significantly different at the 5
percent level






Tab e 19

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPi.CATION ON THE
AVERAGE FORCE REQUIRED TO SHEAR 100 GRAiMAS OF EQUATORIAL SLICES
TAKEN FROM CHAMBER RIPENED FRUIT--SECOND- HARVEST; SPR.!NG 1969

Time of Applica ion and Chemiccl
Third Bloom Shoar Force
First Bloom Second Bloom Third Bloom plus 1 week (pounds) 4-

Duraset* 112.5 c
Duraset Ethrel** 98.3 abcd
Duraset Boric Acid*** 99.1 abcd
Duraset Boric Acid Ethrel 107.5 ab
Boric Acid Ethrel 69.1 d
Ethrel 79. I abcd
Ethrel 73.3 d
Boric Acid 77.5 bcd
Calcium Chloride*** 105.0 abc
Boric Acid
Plus
Calcium Chloride 73.3 cd
GA3 (35 ppm) 79.1 abcd
Ascorbic Acid 106.6 ab
(10,000 ppm)
Control 95,0 abcd

200 ppm
** 1,250 ppm
*** 20 ppm

4-Numbers followed by the some letters) are no$ significantly ditfer.nt oi the 5
percent level.







Table 20

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON THE
a/b COLOR RATIO OF LOCULAR AND PERICARP AREAS OF CHAMBER RIPENED
FRU!T--FIRST HARVEST, SPRING 1969


lTime of Application and Chemical
Third Bloom a/b Ratio 4
First Bloom Second Bloom Third Bloom plus 1 week Locule Pericarp

Durcset* 1,50 2.78
Duraset Ethrel** 1.42 2.22
Duraset Boric Acid*** 1.16 1.96
Duraset Boric Acid Ethrel 1,31 2.11
Boric Acid Ethrel 1,07 2.22
Ethrel 1.10 1.83
E threl 1.18 1.92
Boric Acid 1.15 1.98
Calcium Chloride*** 1.02 1.81
Boric Acid
Plus
Calcium Chloride 1.27 1.74
GA3 (35 ppm) 1.33 2.22
Ascorbic Acid 1.22 2.04
(10,000 ppm)
Conh ro_ 1.28 2.19

200,ppm
**1,250 ppm
*** 20 ppm
4-The one-way analysis of variance was unable to detect any significant difference
at the 5 percent level.







Second harvest

Similar to the first h-,rvest, the second harvest showed no difference in color cs

a result of the treatments (see Table 21). Here the higher a/b ratio of the pericarp

was even more marked.


Soluble solids

The effect of chemical, concentration and time of application on the average

soluble solids content of the locular and pericarp fractions of chamber ripened fruit

from the first and second harvests is presented in Tables 22 and 23.


First harvest

Locule.-- As presented in Table 22, the highest soluble solids content of the locular

area was the result of the later application of Fthrel. The next highest percent soluble

solids was produced by the boric acid-Ethrel and Duraset-boric ocid-Ethrel combinations.

Following this, the Duraset and boric acid treated fruit were still higher in soluble

solids than the ccnlrol. The last treatment to be significantly higher than control is

the Duraset-Ethrel combination. Finally, the gibberellic acid and ascorbic acid

treatments produced fruit with locular areas that were significantly lowe., in soluble

solids than the control.

Pericarp.-- In this fraction the differences were not quite as marked (see Table

22), although the pericarp area was generally higher in soluble solids than the locular

area. Here no treatment was different than the control yet there were differences

among the various t'ca tmens. The gibberellic acid and Duraset-boric acid treatments

were higher than tl-, boric acid-Ethrel, urcsa t and Duroset-boric acid-Ethrel

treatments.







Table 21

EFFECT OF CHEMICAL, CONCENTRATION AND T!ME OF APPLICATION ON THE
a/b COLOR RATIO OF LOCULAR AND PERICARP AREAS OF CHAMBER RIPENED
FRUIT---SECOND HARVEST, SPRING 1969


Time of App!icaticn and Chemical
Third Bloom c/b Ratio -
First Bloom Second Bloom Third Bloom plus 1 week Locule Pericarp

Durcset* 1.20 2.03
Durcset Ethrel** 1.49 2.17
Durao t Boric Acid*** 1.28 2.37
Duraz.et Boric Acird Ethrel 1.51 2.30
Boric Acid Ethrel 1.40 2.05
Ethrel 1.43 2.45
Ethrel 1.70 2.74
Boric Acid 1.70 2.46
Calcium Chloride*** 1.49 2.23
Boric Acid
Plus
Calcium Chloride 1.58 2.50
GA3(35ppm) 1.64 2.13
Ascorbic Acid 1.57 2.33
(10,000 ppm)
Con tro!_ 1.82 2.41

200 ppm
** 1,25 ppm
*** 20 ppm
The cn-v/way analysis of variance v/as unable to detect any significant difference
at the 5 percent level.







Table 22

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON THE
AVERAGE SOLUBLE SOLIDS CONTENT OF LOCULAR AND PERICARP AREAS OF
CHAMBER RIPENED FRUIT--FIRST HARVEST, SPRING 1969


Time of Application and Chemicda Soluble Solids
Third Bloom (percent) 4-
First Bloom Second loorn Third Bloom plus 1 week Locule Pericarp

Duraset* 3.62 c 3.85 cd
Duraset Ethrel** 3.32 de 4.30 abc
Duraset Boric Acid*** 2.02 h 4.50 a
Duraset Boric Acid Ethrel 4.02 b 3.70 d
Boric Acid Ethrel 4.10 ab 4.00 bcd
Ethrel 3.42 d 4.17 abcd
Ethre! 4.25 a 4.37 ab
Boric Acid 3.50 cd 4.37 ab
Calcium Chloride*** 2.50 h 4.27 abc
Boric Acid
Plus
Calcium Chloride 3. 17 ef 4.07 abcd
GA3(35ppm) 2.82 g 4.51 a
Ascorbic Acid 2.77 a 4.17 abcd
(10,000 ppm)
Control 3.07 f 4.07 abcd

200 ppm
**1,250 ppm
*** 20 ppm

-I- Numbers followed by the same letters) are not significantly different at the 5 percent
level.







Table 23

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON THE
AVERAGE SOLUBLE SOLIDS CONTENT OF LOCULAR AND PERICARP AREAS OF
CHAMBER RIPENED iFUIT--SECOND HARVEST, SPRING 1969


Time of Application and Chemical Soluble Solids
Third Bloom (percent) 4-
First Bloom Second Bloom Third Bloom plus 1 week Locule Periccrp


Duraset*
Duraset
Duraset
Duraset


Ethrel**


Boric Acid***
Boric Acid
Boric Acid


Ethrel
Ethre!
Ethrel


Ethrel


Boric Acid
Calciurn Chloride***
Boric Acid
Plus
Calcium Chloride


GA3 (35 ppm)
Ascorbic Acid
(10,000 ppm)


Control


4.05g 4.22 e
4.37 bc 4.62 cd
4.42 b 5.02 ab
4.42 b 5.02 ab
4.27 cde 4.62 cd
4.90 a 5,25 a
4.25 cde 4.50 cde
4.30 bcde 4.70 bcd
4.20 ef 4.35 de


4.10 fg 4.55 cde
4.22 def 4.60 cd
4.35 bcd 4. 85 bc

4.22 def 4.82 bcd


200 ppm
**1,250 ppm
*** 20 ppm

-- Numbers followed by the same letters) are not significantly different at the 5 percent
level.


_ __I_________ ~__ __ ___


__ _I~___






Second harvest

Locule.--- The pattern of significant differences was not quite the same as in

the first harvest. In this harvest, the highest locular soluble solids are apparent in

Table 23 as those from fru-t treated with Ethrel at the second bloom. Next in solu-

ble solids percent are the Duraset-boric acid, Duraset-boric acid-Ethrei and Durcset-

Ethrel treatments. The remaining treatments, except for Duraset, did not vary signi-

ficantly from the control although the ascorbic acid and boric acid treatments tended

to higher soluble solids content. The Duraset treated fruit showed a significantly

lower soluble solids content.

Pericarp.-- The same differences existed in the pericarp area as in the !ocular

area (see Table 23), although not as vell defined. The early Ethrel treatment is the

only treatment that produced significantly higher soluble solids, clbhough the Dur'aset-

boric acid and Duraset-boric acid-Elhrel treatments were considerably higher than

the coniro!. As in the locular area, the pericarp area of the Duraset treated fruit

was significantly lower in soluble solids.


pH

The effect of chemical, concentration and time of application on the average pH

of locular and pericarp fractions of chamber ripened fruii from the first and second

harvest is shown in Tobles 24 and 25.


First harvest

Locule.-- Tha effect of chemical, concentration and time of application on the

first harvest average locular pH is presented in Table 24. In Table 24 it car be seen

that four treocannts--Dura;et, gibb1rellic acid, th lato, applicotio- of Ethrcl end







Table 24

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON THE
AVERAGE pH OF LOCULAR AND PERICARP AREAS OF CHAMBER RIPENED FRUIT--
FIRST HARVEST, SPRING 1969


Time of Application and Chemical
Third Bloom pH
First Bloom Second Bloom Third Bloom plus 1 week Locule-l- Pericarp4- -

Duraset* 4.38 a 4.37
Duraset Ethre!** 4.30 ab 4.31
Duraset Boric Acid*** 4.30 ab 4.30
Durcset Boric Acid Ethre! 4.20 c 4.29
Boric Acid Ethrel 4.21 c 4.26
Ethrel 4.29 bc 4.32
Ethrel 4.37 a 4.28
Boric Acid 4.12 d 4.23
Calcium Chloride*** 4.27 bc 4.30
Boric Acid
Plus
Calcium Chloride 4.28 bc 4.26
GA3(35ppm) 4.38 a 4.27
Ascorbic Acid 4.36 a 4.45
(10,000 ppm)
Control 4.26 bc 4.26

200 ppm
**1,250 ppm
*** 20 ppm
4- Numbers followed by the same letters) are not significantly different at the 5
percent level.
-r- -The one-way analysis of variance was unable to detect any significant difference
at the 5 percent level.






Table 25

EFFECT OF CHEMICAL, CONCENTRATION AND TiM.E OF APPLICATION ON THE
AVERAGE pH OF LOCULAR AND PERICARP AREAS OF CHAMBER RIPENED FRUIT--
SECOND HL-VEST, SPRING 1969


Time of Application and Chemical
Third Bloom pH i-
First Bloom Second Bloom Third Bloom plus 1 week Locule Pericarp

Durasct* 4.34 de 4.38 abc
Dura:et Ethre!** 4.45 bcd 4.21 bcd
Duraset Boric Acid*** 4.40 de 4.35 abcd
Duraset Boric Acid Ethrel 4.44 bcd 4.34 abcd
Boric Acid Ethrel 4.55 ab 4.50 a
Ethrel 4.52 abc 4.43 a
Ethrei 4.41 cde 4.44 a
Boric Acid 4.61 a 4.47 a
Calcium Chloride*** 4.20 f 4.17 cd
Boric Acid
Plus
Calcium Chloride 4.26 f 4.19 cd
GA3(35ppm) 4.52 abc 4.41 ab
Ascorbic Acid 4.45 bcd 4.31 abcd
(10,000 ppm)
Control 4.30 ef 4.15 d

200 ppm
**1,250 ppm
*** 20 ppm
4- Numbers followed by the same letters) are not significantly different at the 5 percent
level.




78

asco.lic acid--produced a significantly higher pH of the locular area. Also in this

table the significant lowering of the pH by the boric acid application is seen.

Pericarp.-- No significant effect can be seen due to the treatments on the pH

of th, pericarp area.


Second harvest

Locule.--- An almost complete reversal of the effects noted in the first harvest

is se':n in Table 25. The boric acid treatment became the one with the highest pH.

Also significantly y higher were the boric acid-Ethrel, early Ehl'el and gibberellic

acid applications. Finally, the Duraset-Ethrel, Duraset-boric acid-Ethrel and

ascoibic acid treatments had the significantly lowest pH, oiher than the control.

Pcricarp.-- In this case, significant effects among the treatments were no'ed in

the p-,icarp areas (see Table 25). The boric acid-Eihrei combination, early and

late ul'plications of Ethrel and boric acid all showed the highest pl-. Others not as

high, hut significantly higher than control values, v/re the Duraset and ascorbic

acid lic tments.


Titruliec acidity

ihl effect of chemical, concentration and time of application on the average

titrail,,lc acidity of the locular and pericarp portions of chamber ripened fruit from

the fii:.i and second harvest is presented in Tables 26 and 27.


First h %.!e\ st

I '.'ulo.-- The treatment effects on the titrateable acidity of the locular area

are .w|,,) in Table 26. Duraset and Duraset--boric acid-Ethrel produced the highest

titrcai,!.!; acidity expressed as milliliters of one-tenth Normal sodium hydroxide






Table 26

EFFECT OF CHEMICAL, CONCENTRATION AND T!ME OF APPLICATION ON THE
AVERAGE TITRATABLE ACiDITY OF LOCULAR AND PERICARP AREAS OF
CHAMBER RIPENED FRUIT--FIRST HARVEST, SPRING 1969


Time oF Application arid Chemical Titratable Acidity 4-
Third Bloom (milliliters of.l1 NNaOH)
First Bloom Second B;oom Third Bloom plus 1 week Locufe Pericarp

Duraset* 8.65 a 5.20 e
Duraset Ethrel** 7.15 bc 6.85 o
Duraset Boric Acid*** 4.15 f 5.50 c
Boric Acid Ethrel 8.45 a 5.50 c
Boric Acid Ethrei 8.20 ab 5.50 c
Ethre! 7.10 bc 5.20
Ethrel 6.90 cd 5.20 e
Boric Acid 7.85 abc 5.95 b
Calcium Chloride*** 5.70 de 5.50c
Boric Acid
Plus
Calcium Chloridc 7.00 bc 5.80 b
GA3(35ppm) 4.45 f 5.95 b
Ascorbic Acid 4,6 e 5.30d
(10,000 ppm)
Control 6.65 cd 5.85 b

200 ppm
**1,250 ppm
*** 20 ppm

+-Numbers followed by the same letters) are noi significantly different at the 5
percent level.






Table 27

EFFECT OF CHEMICAL, CONCENTRATION AND TIME OF APPLICATION ON THE
AVERAGE TITRATABLE ACIDITY OF LOCULAR AND PERICARP AREAS OF
CHAMBER RIPENED FRUIT--SECOND HARVEST, SPRING 1969


Time of Application and Chemical Titratoble Acidity 4-
_- -- 'Third Bloom (millili ers of .1 N NaOH)
First Bloom Second Bloom Third Bloom plus 1 week LoTule Pericarp

Duraset* 6.55 g 4.75 f
Duraset Ethrei** 9.55 b 7.05 a
Duraset Boric Acid*** 7.70 ef 5.35 e
Duraset Boric Acid Ethrel 8.35 d 5.70 cd
Boric Acid Ethre! 7.75 e 4.60 c
Ethrel 8.45 d 5.80 c
Ethrel 9.27 c 5.65 d
Boric Acid 7.65 ef 5.80 c
Calcium Chloride*** 8.25 d 5.30 e
Boric Acid
Plus
Calcium Chloride 7.50 f 5.60 d
GA3(35ppm) 8.45 d 4.55g
Ascorbic Acid 7.75 e 4.75 f
(10,000 ppm)
Control 9.85 a 6, 5 b

200 ppm
**1,250 ppm
*** 20 ppm
Number followed by the same letters) are not significantly different at the 5 percent
level.




81

required to titrate a given volume of diluted extract to pH 8.0. No other treatments

produced a significantly higher tilrainble acidity hut the Duraset-boric acid,

gibberellic ocid and ascorbic acid treatments significantly reduced the titratable

acidity.

Pericarp.-- Although generally lower (see Table 26),the titratable acidity of

the pericarp areas from the treated fruit did not parallel that of the locular fraction.

Here the highest titratable acidity was produced by the Duraset-Ethrel combination.

All other effects were manifested as lower than control titratable acidity. The

Duraset treatment and the two Ethrel treatments produced the lowest acidity followed

by the ascorbic acid treatment and then the Duraset-boric acid, Duraset-boric acid-

Ethrel, boric acid-Fthrel and calcium chloride treatments.


Second harvest

Locule.-- The effects on the locular area of the fruit from this harvest were

demonstrated as all treatments producing a lower titratable acidity than the control

(see Table 27). The lowest titratable acidity was the result of the Duraset treatment.

Pericarp.-- One treatment, as shown in Table 27, demonstrated an increase

over the ccnlrol. The Duiaset-Ethrel combination produced the highest titratable

acidity in the psricarp fraction of the fruit in the second harvest. All other treat-

menis reduced thc acidity and the gibberellic acid and the boric acid-Ethrel treat-

merits reduced it the most.


Fall 1969

Fol ior Syrnptorns

Severe folicr s -CT- wcre observed with the TI BA applications. Thlse




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs