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Nutrient Requirements of Warm-Season Putting Green Cultivars during Grow-In and Their Drought Resistance Once Established

Permanent Link: http://ufdc.ufl.edu/UFE0041085/00001

Material Information

Title: Nutrient Requirements of Warm-Season Putting Green Cultivars during Grow-In and Their Drought Resistance Once Established
Physical Description: 1 online resource (188 p.)
Language: english
Creator: Rowland, John
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: bermudagrass, fertilizer, greens, growin, nitrogen, paspalum, potassium, seashore, zoysiagrass
Soil and Water Science -- Dissertations, Academic -- UF
Genre: Soil and Water Science thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Bermudagrasses Cynodon dactylon (L.) Pers. x C. transvaalensis Burt Davy were the primary warm-season species used on golf greens until improved varieties of seashore paspalum (Paspalum vaginatum Swartz) and zoysiagrass (Zoysia spp.), with claims of reduced fertilizer and water requirements, became available. Nitrogen is normally applied at 4.9 g N m?superscript two wk?superscript one during warm-season putting green establishment to ensure rapid turfgrass cover. Potassium, which reduces turfgrass growth, quality, and tolerance to environmental stresses when deficient, is often applied at rates equal to or greater than N in an attempt to increase its benefits. TifDwarf (TD) and TifEagle (TE) bermudagrasses, SeaDwarf (SD) seashore paspalum, and PristineFlora (PF) zoysiagrass Zoysia japonica Stued. by Zoysia tenuifolia (L.) Merr. had varied levels of N, K, and irrigation applied to compare nutrient and water use requirements. Cultivars were sprigged at 36.6 msuperscript three ha?superscript one on a USGA-specified sand research green in Sept. 2008 and July 2009. Fertilizer treatments included 1.2, 2.4, 3.7, or 4.9 g N m?superscript two wk?superscript one, and a one-time application of polymer-coated urea (PCU) at 39.1 g N m?superscript two. Each N treatment coincided with four N to K fertilization ratios (N:K): 1N:1K, 1N:2K, 1N:3K, or 1N:4K. Within cultivar grow-in rate was similar for SD,TD, and TE in both years, and PF in year 2 with 2.4, 3.7, or 4.9 g N m?superscript two wk?superscript one; 1.2 g N m?superscript two wk?superscript one was similar for SD in year 2. There were no significant effects among N:K. The 2.4 g N m?superscript two wk?superscript one rate was generally considered best for rapid establishment of all cultivars. Although 1.2 g N m?superscript two wk?superscript one was usually slower to grow-in, it often provided a more desirable putting surface than 3.7, or 4.9 g N m?superscript two wk?superscript one. One application of PCU provided sufficient cover for all cultivars in 2009. The USGA green was then fertilized with N at 4.9 g m?superscript two 30d?superscript one, and K at 1N:1K, 1N:2K, 1N:3K, or 1N:4K and irrigated at 25, 50 or 100% of potential evapotranspiration (ETo), as determined by the Blaney-Criddle equation. Treatments were initiated in April (experiment 1) and Oct. (experiment 2) 2009. All cultivars had objectionable wilting at 25% ETo, although PF and SD generally had less in exp. 2. TifDwarf and TE had objectionable wilting at 50% ETo in both exp. s, while PF was objectionable in exp. 2. Wilting did not become objectionable at 100% ETo. There were no beneficial effects for increasing N:K. SeaDwarf appeared to tolerate deficit irrigation the best. A second water use study, which used identical irrigation treatments and lysimeters to measure evapotranspiration (ET), was conducted with PF, SD, and TD sodded on Hallandale fine sand (Siliceous, hyperthermic Lithic Psammaquent). All cultivars had objectionable wilting at 25, 50, and 100% ETo. SeaDwarf had less wilting than PF in both exp., and TD in exp. 2 at 25% ETo. TifDwarf wilted most at 50% ETo in exp. 2. PristineFlora had the highest ET, and SD the lowest. Irrigation at 100% ETo was insufficient for all cultivars on the native soil. PristineFlora and SD provided high quality putting surfaces and had better drought resistance than TD and TE bermudagrass. SeaDwarf required the least N during establishment.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by John Rowland.
Thesis: Thesis (Ph.D.)--University of Florida, 2010.
Local: Adviser: Cisar, John L.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041085:00001

Permanent Link: http://ufdc.ufl.edu/UFE0041085/00001

Material Information

Title: Nutrient Requirements of Warm-Season Putting Green Cultivars during Grow-In and Their Drought Resistance Once Established
Physical Description: 1 online resource (188 p.)
Language: english
Creator: Rowland, John
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: bermudagrass, fertilizer, greens, growin, nitrogen, paspalum, potassium, seashore, zoysiagrass
Soil and Water Science -- Dissertations, Academic -- UF
Genre: Soil and Water Science thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Bermudagrasses Cynodon dactylon (L.) Pers. x C. transvaalensis Burt Davy were the primary warm-season species used on golf greens until improved varieties of seashore paspalum (Paspalum vaginatum Swartz) and zoysiagrass (Zoysia spp.), with claims of reduced fertilizer and water requirements, became available. Nitrogen is normally applied at 4.9 g N m?superscript two wk?superscript one during warm-season putting green establishment to ensure rapid turfgrass cover. Potassium, which reduces turfgrass growth, quality, and tolerance to environmental stresses when deficient, is often applied at rates equal to or greater than N in an attempt to increase its benefits. TifDwarf (TD) and TifEagle (TE) bermudagrasses, SeaDwarf (SD) seashore paspalum, and PristineFlora (PF) zoysiagrass Zoysia japonica Stued. by Zoysia tenuifolia (L.) Merr. had varied levels of N, K, and irrigation applied to compare nutrient and water use requirements. Cultivars were sprigged at 36.6 msuperscript three ha?superscript one on a USGA-specified sand research green in Sept. 2008 and July 2009. Fertilizer treatments included 1.2, 2.4, 3.7, or 4.9 g N m?superscript two wk?superscript one, and a one-time application of polymer-coated urea (PCU) at 39.1 g N m?superscript two. Each N treatment coincided with four N to K fertilization ratios (N:K): 1N:1K, 1N:2K, 1N:3K, or 1N:4K. Within cultivar grow-in rate was similar for SD,TD, and TE in both years, and PF in year 2 with 2.4, 3.7, or 4.9 g N m?superscript two wk?superscript one; 1.2 g N m?superscript two wk?superscript one was similar for SD in year 2. There were no significant effects among N:K. The 2.4 g N m?superscript two wk?superscript one rate was generally considered best for rapid establishment of all cultivars. Although 1.2 g N m?superscript two wk?superscript one was usually slower to grow-in, it often provided a more desirable putting surface than 3.7, or 4.9 g N m?superscript two wk?superscript one. One application of PCU provided sufficient cover for all cultivars in 2009. The USGA green was then fertilized with N at 4.9 g m?superscript two 30d?superscript one, and K at 1N:1K, 1N:2K, 1N:3K, or 1N:4K and irrigated at 25, 50 or 100% of potential evapotranspiration (ETo), as determined by the Blaney-Criddle equation. Treatments were initiated in April (experiment 1) and Oct. (experiment 2) 2009. All cultivars had objectionable wilting at 25% ETo, although PF and SD generally had less in exp. 2. TifDwarf and TE had objectionable wilting at 50% ETo in both exp. s, while PF was objectionable in exp. 2. Wilting did not become objectionable at 100% ETo. There were no beneficial effects for increasing N:K. SeaDwarf appeared to tolerate deficit irrigation the best. A second water use study, which used identical irrigation treatments and lysimeters to measure evapotranspiration (ET), was conducted with PF, SD, and TD sodded on Hallandale fine sand (Siliceous, hyperthermic Lithic Psammaquent). All cultivars had objectionable wilting at 25, 50, and 100% ETo. SeaDwarf had less wilting than PF in both exp., and TD in exp. 2 at 25% ETo. TifDwarf wilted most at 50% ETo in exp. 2. PristineFlora had the highest ET, and SD the lowest. Irrigation at 100% ETo was insufficient for all cultivars on the native soil. PristineFlora and SD provided high quality putting surfaces and had better drought resistance than TD and TE bermudagrass. SeaDwarf required the least N during establishment.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by John Rowland.
Thesis: Thesis (Ph.D.)--University of Florida, 2010.
Local: Adviser: Cisar, John L.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041085:00001


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1 NUTRIENT REQUIREMENTS OF WARM-SEASON PUTTING GREEN CULTIVARS DURING GROW-IN AND THEIR DROUGH T RESISTANCE ONCE ESTABLISHED By JOHN HUDSON ROWLAND A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2010

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2 2010 John H. Rowland

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3 To my family

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4 ACKNOWLEDGMENTS I would like to thank Dr. John Cisar for pr oviding me the opportunity to obtain my doctorate, and my additional adviso rs for their expertise, time, and devotion to the process. I would like to thank Pamela Michels and my fami ly for their never-ending support, as well as everyone at the Fort Lauderdale Research and Education Center who helped with my research project, particularly Brian St einberg. Donations of sod from Wayne Hanna and Environmental Turf, fertilizer from Raymond Snyder of Harrells chemicals from Bayardo Herrera of UAP, sand from John Swaner of Golf Agronomics, so il sensors from Charlie of Toro, and lasergrading by Kevin Hardy of Ballpark Maintenance were greatly appreciated. Funding from the Calvin L. Korf Turfgrass Research Endowme nt helped make this research possible.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ............................................................................................................... 4 LIST OF TABLES ...........................................................................................................................7 LIST OF FIGURES .........................................................................................................................9 LIST OF ABBREVIATIONS ........................................................................................................ 17 ABSTRACT ...................................................................................................................... .............18 CHAPTER 1 INTRODUCTION .................................................................................................................. 20 Rationale ..................................................................................................................... ............20 Turfgrass Nutrition .................................................................................................................20 Fate of Nutrients .....................................................................................................................21 Water Requirements ............................................................................................................ ...22 Water Sources ................................................................................................................. ........22 Watering Practices ..................................................................................................................23 Water Quality ................................................................................................................. .........25 2 ESTABLISHMENT OF WARM-SEASO N PUTTING GR EEN CULTIVARS AS AFFECTED BY NITROGEN/POT ASSIUM FERTILIZATION .......................................... 27 Introduction .................................................................................................................. ...........27 Materials and Methods ...........................................................................................................29 Experimental Site ............................................................................................................ 29 Experimental Design and Statistical Analysis ................................................................. 30 Fertilizer Treatments ....................................................................................................... 30 Measurements .................................................................................................................. 30 Results and Discussion ........................................................................................................ ...31 Turfgrass Cover ...............................................................................................................31 Chlorophyll ................................................................................................................... ...32 Thatch Development ....................................................................................................... 32 Root Development ........................................................................................................... 33 Surface Compressibility and Ball Roll ............................................................................34 Mower Scalping ...............................................................................................................34 Quality and Recovery ...................................................................................................... 35 Algae ......................................................................................................................... .......36 3 DROUGHT RESISTANCE OF NEWL Y-ESTABLISHED WARM-SEASON PUTTING GREE N CULTIVARS AS AFFEC TED BY NITROGEN/POTASSIUM FERTILIZATION ................................................................................................................. ..63

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6 Introduction .................................................................................................................. ...........63 Materials and Methods ...........................................................................................................65 Experimental Site ............................................................................................................ 65 Measurements .................................................................................................................. 66 Statistical Analysis .......................................................................................................... 68 Results and Discussion ........................................................................................................ ...68 Turfgrass Wilting .............................................................................................................68 Soil Moisture ...................................................................................................................69 Turfgrass Quality .............................................................................................................70 Chlorophyll Levels .......................................................................................................... 71 Normalized Difference Vegetative Index ........................................................................ 71 Drought Resistance Characteristics .................................................................................72 4 DROUGHT RESISTANCE OF WARM-SEA SON PUTTING GREEN CULTIVAR S SODDED ON SANDY NATIVE SOIL ............................................................................... 104 Introduction .................................................................................................................. .........104 Materials and Methods .........................................................................................................106 Experimental Site .......................................................................................................... 106 Measurements ................................................................................................................ 107 Statistical Analysis ........................................................................................................ 108 Results and Discussion ........................................................................................................ .108 Turfgrass Wilting ...........................................................................................................108 Soil Moisture .................................................................................................................109 Evapotranspiration .........................................................................................................111 Turfgrass Quality ...........................................................................................................111 Chlorophyll Levels ........................................................................................................ 112 Normalized Difference Vegetative Index ...................................................................... 113 5 CONCLUSIONS .................................................................................................................. 149 APPENDIX CHAPTER 2 DATA ................................................................................................................ ....153 CHAPTER 3 DATA ................................................................................................................ ....166 CHAPTER 4 DATA ................................................................................................................ ....180 LIST OF REFERENCES .............................................................................................................182 BIOGRAPHICAL SKETCH .......................................................................................................188

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7 LIST OF TABLES Table page 2-1 Anova table for turfgrass cover of a USGA -specified research green in experime nt 1 at week 13 on 1 January 2009. ........................................................................................... 39 2-2 Anova table for turfgrass cover of a USGA -specified research green in experime nt 2 at week 9 on 23 September 2009. ...................................................................................... 43 2-3 Anova table for chlorophyll index of a US GA-specified research green in experime nt 1 at week 17 on 29 January 2009. ......................................................................................45 2-4 Anova table for chlorophyll index of a US GA-specified research green in experime nt 2 at week 6 on 3 September 2009. ..................................................................................... 46 2-5 Anova table for thatch depth of a USGAspecified research green at the end of experime nt 1................................................................................................................... ....47 2-6 Anova table for thatch depth of a USGAspecified research green at the end of experime nt 2................................................................................................................... ....48 2-7 Anova table for root length of a USGA -specified research green at the end of experime nt 1................................................................................................................... ....49 2-8 Anova table for root length of a USGA -specified research green at the end of experime nt 2................................................................................................................... ....50 2-9 Anova table for surface compressibility of a USGA-specified research green in experime nt 1 at week 15 on 13 January 2009. ................................................................... 51 2-10 Anova table for surface compressibility of a USGA-specified research green in experime nt 2 at week 10 on 3 October 2009. .................................................................... 52 2-11 Anova table for ball roll di stance of a USGA-specified re search green in experime nt 1 at week 24 on 20 March 2009. ........................................................................................53 2-12 Anova table for ball roll di stance of a USGA-specified re search green in experime nt 2 at week 11 on 9 October 2009. .......................................................................................54 2-13 Anova table for mower scalping of a USGA-s pecified research green in experime nt 1 at week 20 on 19 February 2009. .......................................................................................55 2-14 Anova table for mower scalping of a USGA-s pecified research green in experime nt 2 at week 10 on 1 October 2009. .......................................................................................... 56 2-15 Anova table for quality of a USGA-specified research green at the end of experime nt 1..........................................................................................................................................57

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8 2-16 Anova table for quality of a USGA-specified research green at the end of experime nt 2..........................................................................................................................................58 2-17 Anova table for recovery of a USGA-s pecified research green at the end of experime nt 1................................................................................................................... ....59 2-18 Anova table for recovery of a USGA-s pecified research green at the end of experime nt 2................................................................................................................... ....60 2-19 Anova table for algae on a USGA-specified re search green in experime nt 1 at week 7 on 24 November 2008. .......................................................................................................61 2-20 Anova table for algae on a USGA-specified re search green in experime nt 2 at week 4 on 22 August 2009. ............................................................................................................62 3-1 Physical properties of USGA-specified soil. ..................................................................... 73 3-2 Canopy characteristics of warm-season putting green cultivars. ....................................... 73 3-3 Thatch depth and root length of warm-season putting green cultivars. ............................. 73 4-1 Physical properties of Hallandale fine sand. .................................................................... 114 A-1 Effect of potassium on turfgrass cover. ...........................................................................155 A-2 Effect of potassium on chlorophyll index. .......................................................................156 A-3 Effect of potassium on thatch depth. ................................................................................157 A-4 Effect of potassium on root length. ..................................................................................158 A-5 Effect of potassium on surface compressibility. ..............................................................159 A-6 Effect of potassium on ball roll. ....................................................................................... 160 A-7 Converted modified stimpme ter ball roll distances. ........................................................ 161 A-8 Effect of potassium on mower scalping. .......................................................................... 162 A-9 Effect of potassium on turfgrass quality. .........................................................................163 A-10 Effect of potassium on turfgrass recovery. ...................................................................... 164 A-11 Effect of potassium on algal cover. ..................................................................................165

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9 LIST OF FIGURES Figure page 2-1 Trends of weekly means for turfgrass cover during grow-in of a USGA-specified research green in experime nt 1 fr om 2 October 2008 16 April 2009. ............................ 37 2-2 Trends of weekly means for turfgrass cover as affected by N fertilization during grow-in of a USGA-specified research gr een in experime nt 1 from 2 October 2008 16 April 2009. ....................................................................................................................38 2-3 Effect of grass*Nitrogen (N) on turfgrass cover of a USGA-specified research green in experime nt 1 at week 13 on 1 January 2009. ................................................................. 39 2-4 Trends of weekly means for turfgrass c over, as affected by N/ K fe rtilization ratio during grow-in of a USGA-specified research green in experiment 1 from 2 October 2008 16 April 2009. ........................................................................................................40 2-5 Trends of weekly means for turfgrass cover during grow-in of a USGA-specified research green in experime nt 2 from 30 July 4 November, 2009. .................................. 41 2-6 Trends of weekly means for turfgrass cover as affected by N fertilization during grow-in of a USGA-specified research gr een in experime nt 2 from 30 July 4 November, 2009. ................................................................................................................42 2-7 Effect of grass*N on turfgrass coverage of a USGA-specified research green in experime nt 2 at week 9 on 23 September 2009. ................................................................ 43 2-8 Trends of weekly means for turfgrass cover as affected by N/K fertilization ratio during grow-in of a USGA-specified research green in experiment 2 from 30 July 4 November, 2009. ................................................................................................................44 2-9 Effect of grass*N on chlorophyll index of a USGA-specified research green in experime nt 1 at week 17 on 29 January 2009. ................................................................... 45 2-10 Effect of grass*N on chlorophyll index of a USGA-specified research green in experime nt 2 at week 6 on 3 September 2009. .................................................................. 46 2-11 Effect of grass*N on thatch depth of a USGA-specified research green at the end of experime nt 1................................................................................................................... ....47 2-12 Effect of grass*N on thatch depth of a USGA-specified research green at the end of experime nt 2................................................................................................................... ....48 2-13 Effect of grass*N on root length of a USGA -specified research green at the end of experime nt 1................................................................................................................... ....49

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10 2-14 Effect of grass*N on root length of a US GA-specified research green at the end of experime nt 2................................................................................................................... ....50 2-15 Effect of grass*N on surface compressibility, as measured with a Volkm eter, of a USGA-specified research green in expe riment 1 at week 15 on 13 January 2009. ........... 51 2-16 Effect of grass*N on surface compressibil ity, as measured with a Volkm eter, of a USGA-specified research green in expe riment 2 at week 10 on 3 October 2009. ............ 52 2-17 Effect of grass*N on ball roll distance of a USGA-specified research green in experime nt 1 at week 24 on 20 March 2009. ..................................................................... 53 2-18 Effect of grass*N on ball roll distance of a USGA-specified research green in experime nt 2 at week 11 on 9 October 2009. .................................................................... 54 2-19 Effect of grass*N on mower scalping of a USGA-specified research g reen in experiment 1 at week 20 on 19 February 2009. ................................................................. 55 2-20 Effect of grass*N on mower scalping of a USGA-specified research gr een in experiment 2 at week 10 on 1 October 2009. .................................................................... 56 2-21 Effect of grass*N on quality of a USGA-specified research green two weeks after verticutting at the end of experime nt 1. ............................................................................. 57 2-22 Effect of grass*N on quality of a USGA-specified research green two weeks after verticutting at the end of experime nt 2. ............................................................................. 58 2-23 Effect of grass*N on recovery of a USGA-specified research green two weeks after verticutting at the end of experime nt 1. ............................................................................. 59 2-24 Effect of grass*N on recovery of a USGA-specified research green two weeks after verticutting at the end of experime nt 2. ............................................................................. 60 2-25 Effect of grass*N for algae on a USGA-specified research green in experime nt 1 at week 7 on 24 November 2008. ..........................................................................................61 2-26 Effect of grass*N for algae on a USGA-specified research green in experime nt 2 at week 4 on 22 August 2009.................................................................................................62 3-1 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in e xperiment 1 from 2 May 16 May 2009. ..........................................................................................................74 3-2 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in e xperiment 1 from 5 May 16 May 2009. ..........................................................................................................75

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11 3-3 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experim ent 1 from 5 May 16 May 2009. ..........................................................................................................76 3-4 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in e xperiment 2 from 18 October 30 October 2009. ...............................................................................................77 3-5 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in e xperiment 2 from 18 October 28 October 2009. ...............................................................................................78 3-6 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experim ent 2 from 18 October 28 October 2009. ...............................................................................................79 3-7 Soil moisture of a USGA-specified research green under 25% ETo irrigation in experime nt 1 from 30 April 12 May 2009. ..................................................................... 80 3-8 Soil moisture of a USGA-specified research green under 50% ETo irrigation in experime nt 1 from 30 April 12 May 2009. ..................................................................... 81 3-9 Soil moisture of a USGA-specified research green under 100% ETo irrigation in experime nt 1 from 30 April 12 May 2009. ..................................................................... 82 3-10 Soil moisture of a USGA-specified research green under 25% ETo irrigation in experime nt 2 from 19 October 24 October 2009. ........................................................... 83 3-11 Soil moisture of a USGA-specified research green under 50% ETo irrigation in experime nt 2 from 19 October 24 October 2009. ........................................................... 84 3-12 Soil moisture of a USGA-specified research green under 100% ETo irrigation in experime nt 2 from 19 October 24 October 2009. ........................................................... 85 3-13 Quality of recently established warm -season putting green cultiva rs on a USGAspecified research green unde r 25% ETo irrigation in experiment 1 from 2 May 16 May 2009. ..........................................................................................................................86 3-14 Quality of recently established warm -season putting green cultiva rs on a USGAspecified research green unde r 50% ETo irrigation in experiment 1 from 2 May 16 May 2009. ..........................................................................................................................87 3-15 Quality of recently established warm -season putting green cultiva rs on a USGAspecified research green under 100% ETo i rrigation in experiment 1 from 2 May 16 May 2009. .....................................................................................................................88

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12 3-16 Quality of recently established warm -season putting green cultiva rs on a USGAspecified research green unde r 25% ETo irrigation in expe riment 2 from 19 October 29 October 2009. ........................................................................................................... 889 3-17 Quality of recently established warm -season putting green cultiva rs on a USGAspecified research green unde r 50% ETo irrigation in expe riment 2 from 19 October 29 October 2009. ............................................................................................................ .90 3-18 Quality of recently established warm -season putting green cultiva rs on a USGAspecified research green unde r 100% ETo irrigation in expe riment 2 from 19 October 29 October 2009. ............................................................................................................ .91 3-19 Chlorophyll index of recently establis hed warm-season putting green cultivars on a USGA-specified research green under 25% irrigation in experim ent 1 from 2 May 12 May 2009. .....................................................................................................................92 3-20 Chlorophyll index of recently establis hed warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in e xperim ent 1 from 2 May 12 May 2009. ..........................................................................................................93 3-21 Chlorophyll index of recently establis hed warm-season putting green cultivars on a USGA-specified research green under 100% ET o irrigation in experiment 1 from 2 May 12 May 2009. ..........................................................................................................94 3-22 Chlorophyll index of recently establis hed warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in e xperim ent 2 from 19 October 25 October 2009. ...............................................................................................95 3-23 Chlorophyll index of recently establis hed warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in e xperim ent 2 from 19 October 25 October 2009. ...............................................................................................96 3-24 Chlorophyll index of recently establis hed warm-season putting green cultivars on a USGA-specified research green under 100% ET o irrigation in experiment 2 from 19 October 25 October 2009. ...............................................................................................97 3-25 Normalized difference vegetative index (NDVI) of recently established wa rm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 1 from 2 May 12 May 2009. .................................................... 98 3-26 Normalized difference vegetative index (NDVI) of recently established wa rm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 1 from 2 May 12 May 2009. .................................................... 99 3-27 Normalized difference vegetative index (NDVI) of recently established wa rm-season putting green cultivars on a USGA-speci fied research green under 100% ETo irrigation in experiment 1 from 2 May 12 May 2009. .................................................. 100

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13 3-28 Normalized difference vegetative index (NDVI) of recently established wa rm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 2 from 19 October 25 October 2009. ..................................... 101 3-29 Normalized difference vegetative index (NDVI) of recently established wa rm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 2 from 19 October 25 October 2009. ..................................... 102 3-30 Normalized difference vegetative index (NDVI) of recently established wa rm-season putting green cultivars on a USGA-speci fied research green under 100% ETo irrigation in experiment 2 from 19 October 25 October 2009. ..................................... 103 4-1 Wilting ratings of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 25 Septem ber to 31 October 2009. ................................ 115 4-2 Wilting ratings of sodded warm-season putting green cultivars under 50% ETo irrigation in experime nt 1 from 26 September to 1 November 2009. .............................. 116 4-3 Wilting ratings of sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 1 from 31 Septem ber to 31 October 2009. ................................ 117 4-4 Wilting ratings of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 14 Novem ber to 10 December 2009. ............................ 118 4-5 Wilting ratings of sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 2 from 14 Novem ber to 9 December 2009. .............................. 119 4-6 Wilting ratings of sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 2 from 14 Novem ber to 10 December 2009. ............................ 120 4-7 Soil moisture for sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 Septem ber to 30 October 2009. ................................ 121 4-8 Soil moisture for sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 1 from 20 Septem ber to 30 October 2009. ................................ 122 4-9 Soil moisture for sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 1 from 20 Septem ber to 30 October 2009. ................................ 123 4-10 Soil moisture for sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 12 Novem ber to 10 December 2009. ............................ 124 4-11 Soil moisture for sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 2 from 12 Novem ber to 10 December 2009. ............................ 125 4-12 Soil moisture for sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 2 from 12 Novem ber to 10 December 2009. ............................ 126

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14 4-13 Evapotranspiration of sodded warm-season putting green cultivars in experime nt 1 from 29 September to 30 October 2009. .......................................................................... 127 4-14 Evapotranspiration of sodded warm-season putting green cultivars in experime nt 2 from 12 November to 9 December 2009. ........................................................................128 4-15 Comparison of evapotranspiration (ET) calculation me thods in experiment 1 from 29 September to 30 October 2009. ....................................................................................... 129 4-16 Comparison of evapotranspiration (ET) calculation me thods in experiment 2 from 12 November to 9 December 2009. ......................................................................................130 4-17 Quality ratings of sodded warm-season putting gr een cultivars under 25% ETo irrigation in experiment 1 from 20 September to 31 October 2009. ................................ 131 4-18 Quality ratings of sodded warm-season putting gr een cultivars under 50% ETo irrigation in experiment 1 from 20 September to 31 October 2009. ................................ 132 4-19 Quality ratings of sodded warm-season putting gr een cultivars under 100% ETo irrigation in experiment 1 from 20 September to 31 October 2009. ................................ 133 4-20 Quality ratings of sodded warm-season putting gr een cultivars under 25% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ............................ 134 4-21 Quality ratings of sodded warm-season putting gr een cultivars under 50% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ............................ 135 4-22 Quality ratings of sodded warm-season putting gr een cultivars under 100% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ............................ 136 4-23 Chlorophyll index of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 Septem ber to 30 October 2009. ................................ 137 4-24 Chlorophyll index of sodded warm-seas on putting green cultivars under 50% ETo irrigation in experiment 1 from 20 Septem ber to 30 October 2009. ................................ 138 4-25 Chlorophyll index of sodded warm-seas on putting green cultivars under 100% ETo irrigation in experiment 1 from 20 Septem ber to 30 October 2009. ................................ 139 4-26 Chlorophyll index of sodded warm-seas on putting green cultivars under 25% ETo irrigation in experiment 2 from 12 Novem ber to 10 December 2009. ............................ 140 4-27 Chlorophyll index of sodded warm-seas on putting green cultivars under 50% ETo irrigation in experiment 2 from 12 Novem ber to 10 December 2009. ............................ 141 4-28 Chlorophyll index of sodded warm-seas on putting green cultivars under 100% ETo irrigation in experiment 2 from 12 Novem ber to 10 December 2009. ............................ 142

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15 4-29 Normalized difference vegetative in dex (NDVI) of sodded warm-season putting green cu ltivars under 25% ETo irrigation in experiment 1 from 20 September to 30 October 2009. ...................................................................................................................143 4-30 Normalized difference vegetative in dex (NDVI) of sodded warm-season putting green cu ltivars under 50% ETo irrigation in experiment 1 from 20 September to 30 October 2009. ...................................................................................................................144 4-31 Normalized difference vegetative in dex (NDVI) of sodded warm-season putting green cu ltivars under 100% ETo irrigation in experiment 1 from 20 September to 30 October 2009. ...................................................................................................................145 4-32 Normalized difference vegetative in dex (NDVI) of sodded warm-season putting green cu ltivars under 25% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ............................................................................................................... 146 4-33 Normalized difference vegetative in dex (NDVI) of sodded warm-season putting green cu ltivars under 50% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ............................................................................................................... 147 4-34 Normalized difference vegetative in dex (NDVI) of sodded warm-season putting green cu ltivars under 100% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ............................................................................................................... 148 A-1 Actual and historical mean air temperatur es (C) in experime nt 1 from 20 October 2008 16 April 2009. ......................................................................................................153 A-2 Actual and historical mean air temperatures (C) in experime nt 2 from 23 July to 4 November 2009. ...............................................................................................................154 B-1 Comparison of theta meter with grass in place, and removed for direct reading of volum etric water content. ................................................................................................. 166 B-2 Comparison of theta meter with grass in place and the gravime tric method of determining volumetri c water content. ............................................................................ 167 B-3 Comparison of theta meter with gras s removed and the gravimetric m ethod of determining volumetri c water content. ............................................................................ 168 B-4 Actual and historical mean air temperatures (C) in experime nt 1 from 23 April to 16 May 2009. ........................................................................................................................169 B-5 Actual and historical mean air temperatur es (C) in experime nt 2 from 9 October to 31 October 2009. .............................................................................................................. 170 B-6 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experim ent 1 from 2 May to 16 May 2009. ..................................................................... 171

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16 B-7 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experim ent 2 from 18 Oct ober to 30 October 2009. ........................................................ 172 B-8 Volumetric water content of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experim ent 1 from 30 April to 12 May 2009. ................................................... 173 B-9 Quality of recently established warm -season putting green cultiva rs on a USGAspecified research green in experi ment 1 from 2 May to 16 May 2009. ......................... 174 B-10 Quality of recently established warm -season putting green cultiva rs on a USGAspecified research green in experiment 2 from 19 Octobe r to 29 October 2009. ............ 175 B-11 Chlorophyll index of recently establis hed warm-season putting green cultivars on a USGA-specified research green as affect ed by nitrogen/potassium ratio (N:K) in experiment 1 from 2 May to 12 May 2009. ..................................................................... 176 B-12 Chlorophyll index of recently establis hed warm-season putting green cultivars on a USGA-specified research green as affect ed by nitrogen/potassium ratio (N:K) in experiment 2 from 19 Oct ober to 25 October 2009. ........................................................ 177 B-13 Normalized difference vegetative index (NDVI) of recently established wa rm-season putting green cultivars on a USGA-specifi ed research green as affected by nitrogen/potassium ratio (N:K) in ex periment 1 from 2 May to 12 May 2009. .............. 178 B-14 Normalized difference vegetative index (NDVI) of recently established wa rm-season putting green cultivars on a USGA-specifi ed research green as affected by nitrogen/potassium ratio (N:K) in experime nt 2 from 19 October to 25 October 2009. 179 C-1 Actual and historical mean air temperatur es (C) in experime nt 1 from 20 September to 30 October 2009. ..........................................................................................................180 C-2 Actual and historical mean air temperatur es (C) in experime nt 2 from 11 November to 12 December 2009. ......................................................................................................181

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17 LIST OF ABBREVIATIONS BMP Best m anagement practices CV Cultivar ET Evapotranspiration ETo Potential evapotranspiration KSAT Saturated hydr aulic conductivity OM Organic matter PCU Polymer-coated urea PF PristineFlora PVC Poly vinyl chloride SD SeaDwarf TD TifDwarf TE TifEagle USGA United States Golf Association VWC Volumetric water content

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18 Abstract of Dissertation Pres ented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy NUTRIENT REQUIREMENTS OF WARM-SEASON PUTTING GREEN CULTIVARS DURING GROW-IN AND THEIR DROUGH T RESISTANCE ONCE ESTABLISHED By John Hudson Rowland May 2010 Chair: John L. Cisar Major: Soil and Water Science Bermudagrasses [ Cynodon dactylon (L.) Pers. x C. transvaalensis Burt Davy] were the primary warm-season species used on golf greens until improved varieties of seashore paspalum ( Paspalum vaginatum Swartz) and zoysiagrass ( Zoysia spp.), with claims of reduced fertilizer and water requirements, became available. Nitrogen is normally applied at 4.9 g N m wk during warm-season putting green establishment to ensure rapid turfgrass cover. Potassium, which reduces turfgrass growth, quality, and tolerance to environm ental stresses when deficient, is often applied at rates equal to or greater th an N in an attempt to increase its benefits. TifDwarf (TD) and TifEagle (TE) bermudagr asses, SeaDwarf (SD) seashore paspalum, and PristineFlora (PF) zoysiagrass [ Zoysia japonica Stued. by Zoysia tenuifolia (L.) Merr.] had varied levels of N, K, and ir rigation applied to compare nutrien t and water use requirements. Cultivars were sprigged at 36.6 m ha on a USGA-specified sand re search green in Sept. 2008 and July 2009. Fertilizer treatm ents included 1.2, 2.4, 3.7, or 4.9 g N m wk and a one-time application of polymer-coa ted urea (PCU) at 39.1 g N m Each N treatment coincided with four N to K fertilization ratios (N:K): 1N:1K, 1N:2K, 1N:3K, or 1N:4K. Within cultivar grow-in

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19 rate was similar for SD,TD, and TE in both ye ars, and PF in year 2 with 2.4, 3.7, or 4.9 g N m wk ; 1.2 g N m wk was similar for SD in year 2. Th ere were no significant effects among N:K. The 2.4 g N m wk rate was generally considered be st for rapid establishment of all cultivars. Although 1.2 g N m wk was usually slower to grow -in, it often provided a more desirable putting surface than 3.7, or 4.9 g N m wk One application of PCU provided sufficient cover for all cultivars in 2009. The US GA green was then fertilized with N at 4.9 g m 30d and K at 1N:1K, 1N:2K, 1N:3K, or 1N:4 K and irrigated at 25, 50 or 100% of potential evapotranspiration (ETo), as determined by the Blaney-Criddle equation. Treatments were initiated in April (experiment 1) and Oct. (e xperiment 2) 2009. All cu ltivars had objectionable wilting at 25% ETo, although PF and SD generally had less in exp. 2. TifDwarf and TE had objectionable wilting at 50% ETo in both exp.s, while PF was objectionable in exp. 2. Wilting did not become objectionable at 100% ETo. There we re no beneficial effects for increasing N:K. SeaDwarf appeared to tolerate deficit irrigation the best. A second water use study, which used identical irrigation treatments and lysimeters to measure evapotranspiration (ET), was conducted with PF, SD, and TD sodded on Hallandale fi ne sand (Siliceous, hyperthermic Lithic Psammaquent). All cultivars had objectionable wilting at 25, 50, and 100% ETo. SeaDwarf had less wilting than PF in both exp., and TD in exp. 2 at 25% ETo. TifDwarf wilted most at 50% ETo in exp. 2. PristineFlora had the highest ET, and SD the lowe st. Irrigation at 100% ETo was insufficient for all cultivars on the native soil. PristineFlora and SD provided high quality putting surfaces and had better drought resistance than TD and TE bermudagrass. SeaDwarf required the least N during establishment.

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20 CHAPTER 1 INTRODUCTION Rationale Ample a mounts of nutrients and water are requ ired to maintain warm-season golf course greens. When deficient, supplemental applications of fertilizer and irrigation become necessary. Best management practices, based on sound rese arch results, should be followed by turfgrass managers to avoid unnecessary applications of nutrients and irrigation, which can pollute and deplete ground and surface waters. Turfgrass Nutrition In addition to providing desirable color and playing conditions, a properly fertilized sward of turfgrass uses water more efficiently (Christians, 1998), reduces weed populations (Lowe et al., 2000; Rajaniemi, 2002), and promotes recovery from foot traffic (McCarty and Miller, 2002), and biotic stresses (Vargas, 1994). The nutrients re quired in the greatest amounts and applied most frequently to tu rfgrass are nitrogen (N), phosphorus (P), and potassium (K). Of these primary nutrients (i.e., macronutrients), N has the largest infl uence on turfgrass color, shoot density and growth (Rodriguez et al., 2001; Snyder et al., 198 4). Warm-season golf course greens require up to 118 g N m yr depending upon the cultivar, am ount of traffic, length of growing season, soil type, and demands of golfers (Cisar and Snyder, 2003; McCarty and Miller, 2002; Sartain et al., 1999). Lightning, rainwate r, and soil organic matte r provide only small amounts of N in comparison to what is requ ired by most warm-season putting green cultivars (Brady and Weil, 1999; Ericks on et al., 2001; FDEP, 2007; Wo lf and Snyder, 2003). To improve putting surfaces, golf course superintende nts apply additional N at regular intervals. Since applications of soluble N >2.4 g N m can increase leaching and runoff potential, smaller, more frequent applications are usually recommended (FDEP 2007; Sartain et al., 1999). If

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21 slow-release N sources are use d, applications up to 15 g N m 90 d can be made without undesired flushes of growth or increased envi ronmental impacts (Sartain et al., 1999). Phosphorus enables plants to store and tr ansfer energy during metabolic processes (Havlin et al., 1999). Since P is not as mobile as N, and occurs naturally in rock, soil and rainwater, soil solution P is often sufficient for warm-season turfgrass growth. Fertilization with P is considered unnecessary, and discouraged unless soil and tissue tests determine there is a deficiency, particularly since excess P can cau se a decline in bermuda grass growth due to reduced tissue N (Sartain et al., 1999), negative environmental eff ects such as algal blooms, and increase populations of noxious aquatic pl ants in surface water bodies (FDEP, 2007). Potassium is often called the health element as it is thought to improve resistance to stresses from drought, disease and temperature extremes (Sartain et al., 1999). Since K is highly soluble and leaches readily in high-sand content gr eens, it is often considered deficient in soil tests. Although research has not shown increased benefits with N/K fertilization ratios higher than 1N:0.5K (Sartain, 1998; Snyde r and Cisar, 2000a), K is often applied at rates equal to or higher than N due to soil test recommendations and a presumed increase in plant health and stress resistance. Though K is not yet tagged as an environmentally damaging nutrient, large applications should be avoided unl ess deficiency is confirmed by ti ssue tests or visual symptoms, such as chlorosis of the older leaves. Fate of Nutrients Applied nutrients that go unused by turfgrass or other plants can rema in in the soil for future use, leach into ground water, or enter surface waters as runoff. Nutrient retention in soils is highly dependent on soil type and organic matter (OM) concentration. Sandy soil generally has very low cation exchange capacity due to it s small surface area and low OM content (Sartain and Snyder, 1999). Soils that include moderate amounts of clay or organic matter can hold

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22 appreciable amounts of nutrients on electrostatic exchange sites until the plant needs them due to larger surface areas. These soils can reduce leaching of nutri ents into groundwater, although runoff into surface waters may increase due to slower infiltration rates. Maintaining a stand of aquatic plants in retention ponds or along lake ba nks in areas prone to runoff reduces pollution of surface waters due to their filteri ng effect (Figure 1; FDEP, 2007). Water Requirements Water is the prim ary requirement for turfgrass function and survival. Turfgrass water levels are normally between 75-85 percent by wei ght, and death occurs wh en water content is less than 60 percent (Cis ar and Miller, 1999). Without adequa te plant moisture, the ability to transport nutrients and water thr oughout the transpiration stream is compromised. As soil water potential decreases below field capacity and nears the permanent wilting point, stomata on turfgrass leaves close in an attempt to protect against dehydration. The l ack of a cooling effect from the release of water vapor through transpiration leads to a reduction of photosynthesis, and increased canopy temperature. If stomata re main closed, plant cell metabolism will be compromised and turfgrass densit y will decline. If drought condi tions persist, turfgrasses can become permanently wilted and die. Water Sources Since water is not always availa ble in sufficient quantities to provide acceptable stands of turf, supplemental irrigation is often used. Pote ntial water sources incl ude ground water, surface water, non-potable, reclaim ed, and effluent wastewater. Ground wa ter, which is the main source for public supply, can be acquired by drilling into aquifers found be tween layers of rock, or the surficial water table (Barnett, 2007). Surface water bodies, such as stormwater runoff detention ponds, lakes, rivers, and canals are most often us ed by golf courses due to the large amounts of water required and ease of pumpi ng. Reclaimed water from treat ment plants has become popular

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23 due to its reduced cost and recent fresh water restrictions. Golf courses are well suited for reclaimed water use, as the dense root syst ems of turfgrasses filt er out nutrients and contaminants, reducing the likeli hood of groundwater contamination. Watering Practices Irrigation applications are based on visual drought symp toms, soil moisture levels, evapotranspiration (ET) rates, predictive models and turfgrass species. When turfgrass is under drought stress, leaves lose turgor, margins roll in ward, and turn blue-green in color (Cisar and Miller, 1999). A commonly accepted practice is to apply irrigation when one-half of the leaves have begun to roll. Another method used to determ ine the onset of drought is the footprint test. After walking across an area of turf, if the foot prints do not spring back within a few minutes, irrigation should be scheduled for the next morning unless rainfall is imminent. Soil moisture levels are evaluated more prec isely with devices that measure electrical resistance and water tension. Theta probes, whic h measure electrical resistance in the soil, are portable, easy to use, and require only a few readings per green to determine if irrigation will be necessary. In most cases, irrigation should not be considered until volumetric water content falls below 20%. When superintendent s encounter hot spots on green s, which often occur on highly sloped sections, a hand syringing of the dry area is preferable to an all-inclusive irrigation. This practice saves water and helps prevent runoff. Te nsiometers measure negative pressure head of soil water with a vacuum gauge to determine mo isture availability, and are often used in conjunction with automatic irrigation systems. When soil moisture reduces to a set tension threshold, irrigation will run until so il moisture becomes sufficient. Using this form of irrigation reduces water use and nitrogen leaching (Snyder et al., 1984). Rain sensors are also used as circuits in automatic irrigation systems, and w ill cancel an upcoming irrigation if rainfall has exceeded a predetermined level.

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24 Predictive models use climatological data and empirical procedures to determine potential ET and net irrigation requirements. McCloud, Thornthwaite, Penman and modified Blaney-Criddle are commonly used ET estimation methods. The McCloud equation was developed to reflect turfgrass water use under Florida conditions and is considered the most accurate model when mean temperatures are higher than 70 F (Augustin, 1983). The Thornthwaite equation, which emphasizes temperature and day length, underestimates ET compared to the McCloud equation. The Penman equation is based upon net radiation, vapor pressure, and wind speed, but also is consid ered to underestimate ET (Augustin, 1983). The modified Blaney-Criddle method is used by most Florida water management districts to allocate water for golf course irrigation. The Blaney-C riddle method is based on mean temperature, percent daylight hours, and clim atic and consumptive use coeffi cients (Blaney and Criddle, 1950). Provided the proper crop coefficient is us ed, and light levels are correct, the model is considered to accurately estimate ET (Augustin, 1983). Adjustments can be made when changes in environmental parameters such as solar radiation, wind, or rain fall dictate. The need for irrigation is increased on sunny days when stomata remain open to increase canopy cooling via water vapor release. Water requirements also increase when wind velocity is high, as the external layer of vapor pressure that protects the leaf from dehydr ation is decreased. If excessive rainfall occurs, irrigation can be delaye d until drought stress becomes evident. Differences in ET between and within turf grass species also influence amount and frequency of irrigation. Warm-seas on turfgrasses generally require less water to maintain plant growth compared to cool-season turfgrasses due to differences in their ca rbon fixation pathways. Cool-season turfgrasses need to keep their stomata open for longer periods of time to capture carbon dioxide, and subsequently lose more wa ter through transpiration. The higher water-use

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25 efficiency rates and lower carbon dioxide co mpensation point of warm-season turfgrasses generally provide higher water-use efficiency (Cisar and Miller, 1999). Differences in morphological characteristics can also influence the ability of turfgrasses to resist drought as horizontal leaf orient ation, slow vertical leaf growth rate, and high shoot and leaf densities can impart lower water-use rates (Cisar and Miller, 1999). Water Quality The mo st salt-tolerant warm-season grasses can tolerate irrigation with seawater for short periods of time, although saline sources are most often mixed with fresh water for prolonged usage (Zinn, 2004). Since fresh water is a limited resource and high in cost, some golf courses have turned to saline and reclaimed water fo r irrigation. Although thes e sources are a viable option, they can have a negative effect on turfgrass quality if not managed properly. Suspended solids and high salinity are of utmost concern on golf course greens, as soil pores can become clogged with solids, causing reduced infiltration a nd an anaerobic environment (Cisar and Miller, 1999). Applications of gypsum can flush sodium off the soil exchange complex and replace it with calcium. The soluble sodium sulfate that is left can then be flushed below the root zone with fresh water (Cisar et al., 1999). High bicarbonate levels in irri gation water can affect plant health even if it is low in sodium and dissolved salts, as calcium and magnesium carbonate precipitate to form lime when soil pH 8 (Cisar et al., 1999). Soils can then become sodium dominant, as calcium and magnesium are no longer exchangeable. Acidif ying materials such as ammonium sulfate can help reduce soil pH when bicarbon ate levels are moderate, but in jections of stronger acids (e.g., sulfuric) into the irrigation system may be need ed under extreme conditions (Sartain and Snyder, 1999).

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26 Figure 1-1. Vegetation on golf course lake banks creates a filter for nutrient runoff.

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27 CHAPTER 2 ESTABLISHMENT OF WARM-SEASON PUTTING GRE EN CULTIVARS AS AFFECTED BY NITROGEN/POTASSIUM FERTILIZATION Introduction Proper fertilization of golf course putting greens during establishment provides rapid turfgrass co ver, high quality putting surfaces, an d limits environmental impact. Of the primary nutrients, N is most important fo r turfgrass culture, and has the grea test influence on color, shoot density and growth (Rodriguez et al., 2001; Snyder et al., 1984). Nitrogen is often applied at higher rates (e.g., 4.9 g N m wk ) during putting green establishment in an attempt to overcome leaching losses from increased irri gation, hydraulic conductivity, reduced cation exchange capacity, turfgrass c over, and root mass (Rodriguez et al., 2001; White, 2003). Slowrelease N sources can provide quality turfgrass with reduced leaching in coarse-textured soils (Brown et al., 1977; Petrovic, 2004; Snyder et al., 1980), and allow larger app lications of N to be applied less frequently without negative agronomic or environmental effects (Sartain et al., 1999). Applying soluble N at a rate greater than 2.4 g m is not recommended due to the potential for decreased ball roll speeds, root growth, increased flushes of top growth, mower scalping, mat development, and potential for leaching and contamination of ground water (FDEP, 2007; Sartai n et al., 1999). Although P does not impart a large influence on turfgrass growth under most conditions, optimum development of young plants during establishment can be limited if soil and tissue levels are insufficient (Havlin et al., 1999; Rodr iguez et al., 2001; Sartain, 1998). To ensure adequate availability, P is often incorporated into the root zone prior to planting, or surface applied as a starter fertilizer (Guertal, 2007; White, 2003). A 1N:0.4P fertilization ratio was considered optimal for establishment of bermuda grass in sandy soil (Rodr iguez et al., 2001).

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28 Potassium, which is beneficial for turfgrass quality and growth (McC arty and Miller, 2002; Snyder and Cisar, 2000), infers increased toleran ce to drought, disease, wear, heat (Turner and Hummel, 1992), and cold (Beard, 19 73) at adequate fertilizati on levels. Although turfgrasses generally utilize half as much K as N (Turge on, 1985), and only marginal increases in tissue K have been observed (Snyder and Cisar, 2000), K is often applied at equal or greater amounts than N in an attempt to increase stress tolerance (Augustin, 1992; Sartain, 1998). Hybrid bermudagrasses [ Cynodon dactylon (L.) Pers. x C. transvaalensis Burt Davy] were first used on golf course putting greens when Tiffine and Tifgreen were released in 1953 and 1956, respectively (Burton, 1991). In 1965, Tifdwarf (TD), a natural mutation of Tifgreen with smaller, shorter, leaves, stems and inte rnodes, was released (B urton, 1991). Due to its ability to provide a high quality putting surf ace at mowing heights below 5 mm, TD was the standard warm-season greens variety for over thirty years, and is still a highly used cultivar (Foy, 2006). Advances in greens maintenance technology, and increased demand for faster green speeds necessitated cultivars that provided a denser, smoother surface and tolerated lower mowing heights (Vermeulen, 1995). TifEagle (T E) bermudagrass, released in 1998, had lower vertical growth characteristics, increased shoot density, finer texture, and could be mown low enough (< 3 mm) to produce a putting surface comparable to creeping bentgrass [ Agrostis stolonifera L. var palustris (Huds.) Farw.], the standard cool -season grass for speed and quality (Busey and Dudeck, 1999; Foy, 1997; Foy, 2006; Ha rtwiger and OBrien, 2006; McCarty et al., 2007). Recently released cult ivars of seashore paspalum ( Paspalum vaginatum Swartz) and zoysiagrass [ Zoysia japonica Stued. by Zoysia tenuifolia (L.) Merr.] also provide high quality putting surfaces, and purportedly require 50% less N and water than bermudagrass (Foy, 2006). SeaDwarf (SD), regarded as the first true dw arf seashore paspalum, was released in 1999, and

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29 can withstand mowing heights below 3 mm. Seas hore paspalum can also be irrigated with seawater containing 34,000 ppm dissolved salts, if necessary (Zinn, 2004). The grass subfamily Chloridoideae, which contains the genera Cynodon and Zoysia are also tolerant to saline irrigation due to their ability to secrete salt th rough leaf glands (Cisar et al., 1999; Marcum, 1999). Zoysia spp. are used in areas where salt stress, limited sunlight, or low temperatures limit the growth of other warm-season grasses (Foy, 2006; Murray and Engelke, 1983). PristineFlora (PF), which is an upright, narrow-leafed, E merald-type zoysiagras s (Scully, 2005), approved for release in 2004 (Scully et al., 2009), provide s a high quality putting surface and tolerates regular mowing at 3 mm. This study was conducted to evaluate the eff ects of varied N and K fertilization rates during grow-in of three warm-season greens grasses spri gged into a USGA-specified sand green. Materials and Methods Experimental Site Two grow-in experime nts were performed at the University of Florida Fort Lauderdale Research and Education Center in Ft. Laude rdale, FL (26' N, 80' W) on a newlyrenovated, 1440 m research gree n, constructed with a United St ates Golf Association(USGA)specified soil mix containing 10 g kg organic matter by weight, from 2008 to 2009 (USGA Green Section Staff, 2004). A pre-plant applica tion of P in the form of triple superphosphate was applied at 4.9 g m in each study. Other nutrients applied prior to sprigging included the sulfate forms of Fe, Mn, and Mg at 4.9, 1.6, and 1.6 g m respectively. The green was sprigged with PF, SD, TD, and TE at 36.6 m ha in Sept. 2008 (Experiment 1) and July 2009 (Experiment 2). The green was initially mo wed at 6.4 mm, with clippings removed, and gradually lowered to 3.6 mm in experiment 1, and 3.8 mm in experiment 2, as the surface

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30 became smoother. Irrigation was applied as needed to maintain healthy turfgrass. Pesticides were applied on a curative basis, and included chlorothalonil and bifenthrin for algae, brown patch, leaf spot, green aphid, and sod webworm control. We eds were removed by hand on a regular basis due to differing herbicide tolerances among cultivars. Experimental Design and Statistical Analysis Cultivar, N, and K treatment factors were arra ng ed in a split-plot, completely randomized design with three replications. Main plots (cultivar and N) we re 4 m by 4 m and sub-plots (K ratio) were 2 m by 2 m. SAS (version 9.2) PROC MIXED and the Tukey-Kramer multiplecomparison procedure were used to determine si gnificant (P<0.05) treatment effects (Littell et al., 2006; SAS, 2004). The SAS macro PDMIX 800 was used to convert mean separation output to letter groupi ngs (Saxton, 1998). Fertilizer Treatments Nitrogen (5.3 % ammoniacal, 5.7% polymer coated urea (PCU), and 1% water insoluble N from activated sludge), from Harrells 124-12, was applied at 1.2, 2.4, 3.7, and 4.9 g N m wk Another N treatment was a one-time a pplication of PCU (42-0-0) at 39.1 g N m Potassium, in the form of KCl, was applied as N/K fertilization ratios (1N:1K, 1N:2K, 1N:3K, and 1N:4K) with the weekly N treatments. A one-time application of polymer-coated KCl at 39.1, 78.2, 117.3, and 156.4 g K m was applie d at the same time as PCU. Measurements Turfgrass cover was visually rated weekly on a percent basis. Relative chlorophyll content was determ ined weekly by averaging thr ee readings from a hand-held reflectance meter (model CM 1000, Spectrum Technologies, Plainfield, IL). Thatch depth and root length were determined by direct physical measurement at the end of each experiment. Thatch and root

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31 weights were determined at the end of each e xperiment from 10 cm diam. and 20 cm deep cup cutter cores separated into 0 and 10 cm deep sections. Thatch was separated from the 0 to 10 cm deep section, oven-dried (60C), weighed, ashed in a 550C muffle furnace, and reweighed to determine ash-free weight (Snyder and Cisar, 2000). Roots were separated from soil with a 2 mm diam. sieve and garden hose, oven-dried (60C), weighed, ashed in a 550C muffle furnace, and re-weighed to determine ash-free weight (Snyder and Cisar, 2000). Surface compressibility was determined by averagi ng two readings per sub-plot from a weightbased thatch displacement instru ment (Volk, 1972). Ball roll sp eed was obtained by averaging the distance of two golf balls rolled in two oppos ite directions using a 19-cm modified USGA stimpmeter (Gaussoin et al., 1995). Visual estim ates of mower scalping were rated on a 1-10 scale (10 = complete loss of leaf blades). Tw o weeks after a 1 cm d eep verticutting (0.6 cm spacing between blades) was perfor med, turfgrass quality and recove ry were visually rated from 1-10 (10 = highest/most). Algae was rated visually from 1-10 (10 = most). Results and Discussion Turfgrass Cover In experime nt 1, SD, TD, and TE took 13 weeks to obtain 90% cover, while PF required 27 weeks when fertilized with 2.4, 3.7, or 4.9 g N m wk Cover was reduced for SD, TD, and TE with 1.2 g N m wk and PCU (Figures 2-1, 2-2, 23; Table 2-1). The 1.2 g N m wk treatment took 1, 2, and 4 weeks longer to obtain 90% cover for SD, TD, and TE, respectively. There were no significant differe nces in cover among N/K fertilizat ion ratios (Figure 2-4). In experiment 2, only PF and TE fertilized with PCU and 1.2 g N m wk had <90% cover at nine weeks (Figures 2-5, 2-6, 2-7; Table 2-2). Ther e were no significant differences in cover among N/K fertilization ratios (Figure 2-8). As in expe riment 1, SD, TD, and TE had similar cover with

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32 2.4, 3.7, and 4.9 g N m wk Unlike the first study, PF had similar cover, at some N rates, to TD and TE, and 1.2 g N m wk was similar to the higher weekly N rates for SD. Because experiment 1 was initiated in cooler autumn te mperatures it took several more weeks to achieve 90% cover than experiment 2, which was initiated at the peak of summer. Hence, as each cultivar had similar cove r with 2.4, 3.7, and 4.9 g N m wk in both experiments, the higher rates were considered excessi ve and increased potential for nutrient leaching, runoff, and subsequent contamination of nearby water bodies. Chlorophyll In experime nt 1, SD, TD, and TE had less ch lorophyll when fertilized with 1.2 g N m wk compared to the higher weekly N rates (Fig ure 2-9; Table 2-3). In experiment 2, all cultivars had less chlorophyll wh en fertilized with 1.2 g N m wk compared to the higher weekly N rates (Figure 2-10, Table 2-4). Though 1N:1K was higher (P=0.042) than 1N:3K in 2008 there were no within cultiv ar significant differences in chlorophyll among N/K ratios in either experiment (Tables 2-3, 2-4). The chlorophyll index seemed to be an effective indicator of N status in relation to turfgra ss cover, particularly in expe riment 1 (Figure 2-3). This relationship suggests that reflecta nce meters can be used during grow-in to optimize growth and reduce N usage. This is supported by prev ious studies that found correlations between reflectance meters and turfgrass clipping yield, leaf hue, darkness and density (Mangiafico and Guillard, 2005; Trenholm et al., 1999). Thatch Development In experime nt 1, SD had a shallower thatch depth when fertilized with PCU compared to 4.9 g N m wk (Figure 2-11; Table 2-5). PristineFlora, and PCU had the shallowest thatch

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33 depths among cultivars, and N treatments, re spectively. There were no within cultivar differences among N treatments in experiment 2 (Figure 2-12; Table 2-6), though PF had the shallowest thatch among cultivars, and PCU had less thatch than 1.2 and 2.4 g N m wk There were no significant differe nces for thatch depth among N/ K ratios in either experiment (Tables 2-5, 2-6). Since thatch accumulation is attributed to accelerat ed vegetative growth (Beard, 1973), the slower-growing PCU N treatment likely caused the reduction in thatch depth in experiment 1. The lack of pronounced differe nces in thatch depth among N rates was not entirely unexpected, as previous results have been mixed. Carrow et al. (1987), and Smith (1979) found no differences in thatch depth, wh ereas Baldwin (2009), Duble (2000), Snyder and Cisar (2000), Unruh et al. (2007), and White et al. (2004) reported greater thatch depths with increased N fertilization rates. Root Development In experime nt 1, SD fertilized at 4.9 g N m wk had reduced root development compared to 1.2, 2.4, and 3.7 g N m wk (Figure 2-13; Table 2-7). PristineFlora had the shallowest root system among cultivars. In experiment 2, there were no within cultivar differences among N treatments, though PF had the shallowest roots among cultivars (Figure 214; Table 2-8). There were no significant differe nces in root length among N/K ratios in either experiment (Tables 2-7, 2-8). Excessive N fertilization reportedly incr eases aboveground tissue growth and causes a reduction in root growth (Beard, 1973; Christians, 1998). Although the highest weekly N rate decreased root length in SD in this study, Unruh et al. (2007) reported both increased and decreased root weights duri ng grow-in of seashore paspalum putting green cultivars fertilized at 4.9 g N m 14 d

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34 Surface Compressibility and Ball Roll In both experiments, all cultivar s fertilized with 3.7 and 4.9 g N m wk generally had increased surface compressibility compared to 1.2 g N m wk and PCU (Figures 2-15, 2-16; Tables 2-9, 2-10), although PF was unaffected by N rate in experiment 1. There were no significant differences in surface compressibility among N/K ratios in either experiment (Tables 2-9, 2-10). The increases in surf ace compressibility at higher week ly N rates were likely due to accelerated aboveground growth, as Volk ( 1972) reported significant regressions of compressibility (P<0.01) on rate of gr ass growth and thatch accumulation. There were no within cultivar differences in ba ll roll length due to N in either experiment (Figures 2-17, 2-18; Tables 2-11, 2-12), and TD and TE had longer ball roll than PF and SD. In experiment 2, PCU and 1.2 g N m wk provided longer ball roll than 2.4 and 3.7 g N m wk There were no significant differenc es in ball roll among N/K ratios in either experiment (Tables 2-11, 2-12). Different management practices, such as lower mowi ng height, N rate, and custom topdressing programs seem to be required for PF and SD to obtain ball roll lengths similar to TD and TE. Mower Scalping Scalping of TD and TE were higher at 2.4, 3.7, and 4.9 g N m wk compared to 1.2 g N m wk and PCU in both experime nts, and experi ment 2, respectively (Figures 2-19, 2-20; Tables 2-13, 2-14); TE had mo st scalping with 4.9 g N m wk in experiment 1. There were no significant differences in mower scalping among N/K ratios in eith er experiment (Tables 2-13, 214). PristineFlora and SD seemed to easily tole rate the mowing heights used in this study, as they exhibited very little scalping regardless of N treatment. Lower N rates were very beneficial for TD since it is not considered an ultradwarf, and seemed to scalp more readily at the mowing

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35 heights used in these experiments. The increased height of cut in experi ment 2 was due in large part to the tendency of TD to become scalped. Quality and Recovery In experi ment 1, SD quality was higher two weeks after verticutting when fertilized with PCU or 1.2 g N m wk compared to 3.7 and 4.9 g N m wk (Figure 2-21; Table 2-15). PristineFlora had higher quality than: TD rega rdless of N treatment, SD at 2.4, 3.7 and 4.9 g N m wk and TE at 2.4 and 4.9 g N m wk In experiment 2, SD quality was higher when fertilized with PCU compared to 2.4, 3.7, and 4.9 g N m wk (Figure 2-22; Table 2-16). All N treatments for PF had higher quality than TD, and SD fertilized at 3.7 and 4.9 g N m wk ; PF had higher quality than TE at 1.2 and 4.9 g N m wk There were no significant differences in quality among N/K ratios in either experiment (Tables 2-15, 2-16). After verticutting, PF was relatively unscathed due to its minimal thatch development and upright growth habit, while TD, and SD likely had reduced quality due to grow th habit, and thatch density, respectively. In experiment 1, SD fertilized with PCU and 1.2 g N m wk had recovered more than 3.7 and 4.9 g N m wk two weeks after verticutting (Figur e 2-23; Table 2-17) PristineFlora had recovered more than TD. In experiment 2, TD fertilized with PCU had recovered more than 3.7 g N m wk (Figure 2-24; Table 2-18). SeaDwarf a nd TD exhibited less recovery than PF. There were no significant differenc es in recovery among N/K ratios in either experiment (Tables 2-17, 2-18). Since PF sustained minimal damage af ter verticutting, it was generally the fastest to recover. Conversely, since SD and TD were severely damaged from verticutting, more time was required for recovery.

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36 Algae In experime nt 1, PF had reduced algae when fertilized with PCU (Figure 2-25; Table 219). In experiment 2, PF and TD had reduced al gae when fertilized with PCU compared to 4.9 g N m wk (Figure 2-26; Table 2-20). In both expe riments algae was generally higher in PF, particularly when fer tilized with 4.9 g N m wk There were no signifi cant differences in algae among N/K ratios in either experiment (Tables 2-19, 2-20).

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37 Figure 2-1. Trends of weekly means for turfgr ass cover during grow-in of a USGA-specified research green in experiment 1 from 2 October 2008 16 April 2009.

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38 Figure 2-2. Trends of weekly means for turfgras s cover as affected by N fertilization during grow-in of a USGA-specified research gr een in experiment 1 from 2 October 2008 16 April 2009.

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39 Figure 2-3. Effect of grass*N itrogen (N) on turfgrass cover of a USGA-specified research green in experiment 1 at week 13 on 1 January 2009. Mean estimates with same letter are not statistically different at 0.05 significance level based on the Tukey-Kramer method. PCU=39.1 g N m Table 2-1. Anova table for turfgrass cover of a USGA-specified research green in experiment 1 at week 13 on 1 January 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 671.4 <0.0001 2.8 Nitrogen (N) 4 194.3 <0.0001 3.4 Potassium (K) 3 0.3 0.8507 2.8 Grass*N 12 7.3 <0.0001 8.7 Grass*K 9 0.3 0.9855 7.6 N*K 12 0.3 0.9807 8.7 gh fg hi i a a c de a a bc d a a ab d ef

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40 Figure 2-4. Trends of weekly means for turfgrass cover, as aff ected by N/K fertilization ratio during grow-in of a USGA-specified research green in experiment 1 from 2 October 2008 16 April 2009.

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41 Figure 2-5. Trends of weekly means for turfgr ass cover during grow-in of a USGA-specified research green in experiment 2 from 30 July 4 November, 2009.

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42 Figure 2-6. Trends of weekly means for turfgras s cover as affected by N fertilization during grow-in of a USGA-specified research gr een in experiment 2 from 30 July 4 November, 2009.

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43 Figure 2-7. Effect of grass*N on turfgrass cove rage of a USGA-specified research green in experiment 2 at week 9 on 23 September 2009. Mean estimates with same letter are not statistically different at 0.05 significance level based on the Tukey-Kramer method. PCU=39.1 g N m Table 2-2. Anova table for turfgrass cover of a USGA-specified research green in experiment 2 at week 9 on 23 September 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 58.6 <0.0001 1.9 Nitrogen (N) 4 66.1 <0.0001 2.2 Potassium (K) 3 1.3 0.2694 1.9 Grass*N 12 4.3 <0.0001 5.9 Grass*K 9 0.3 0.9787 5.1 N*K 12 0.4 0.9726 5.9 b-e c-f d-g fg h d-g abc a a ab a-d c-g c-f a efg gh

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44 Figure 2-8. Trends of weekly means for turfgras s cover as affected by N/K fertilization ratio during grow-in of a USGA-specified research green in experiment 2 from 30 July 4 November, 2009.

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45 Figure 2-9. Effect of grass*N on chlorophyll index of a USGA-s pecified research green in experiment 1 at week 17 on 29 January 2009. Means with same letter are not statistically different at th e 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N m Table 2-3. Anova table for chlorophyll index of a USGA-specified research green in experiment 1 at week 17 on 29 January 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 334.7 <0.0001 12.7 Nitrogen (N) 4 262.9 <0.0001 15.1 Potassium (K) 3 2.8 0.0416 12.7 Grass*N 12 21.9 <0.0001 39.3 Grass*K 9 0.5 0.8913 34.0 N*K 12 1.0 0.4409 39.3 f f f a ab b c d f cd d e f cd d e f

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46 Figure 2-10. Effect of grass*N on chlorophyll in dex of a USGA-specified research green in experiment 2 at week 6 on 3 September 2009. Means with same letter are not statistically different at th e 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N m Table 2-4. Anova table for chlorophyll index of a USGA-specified research green in experiment 2 at week 6 on 3 September 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 81.9 <0.0001 13.2 Nitrogen (N) 4 82.9 <0.0001 15.6 Potassium (K) 3 0.8 0.5199 13.2 Grass*N 12 6.0 <0.0001 40.8 Grass*K 9 1.1 0.3825 35.3 N*K 12 0.5 0.9243 40.8 a a a a abc abc ab cde def ghi bcd de f-i de d-g d-g d-h e-h hi i

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47 Figure 2-11. Effect of grass*N on thatch depth of a USGA-specified research green at the end of experiment 1. Means with same letter are not statistically different at the 0.05 probability level based on the T ukey-Kramer method. PCU=39.1 g N m Table 2-5. Anova table for thatch depth of a USGA-specified research green at the end of experiment 1. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 24.0 <0.0001 0.13 Nitrogen (N) 4 9.5 <0.0001 0.15 Potassium (K) 3 0.1 0.9488 0.13 Grass*N 12 1.7 0.0607 0.40 Grass*K 9 0.4 0.9291 0.34 N*K 12 1.0 0.4505 0.40 a ab abc a-d a-d a-e a-e a-e a-f a-f b-f c-f def def ef def f

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48 Figure 2-12. Effect of grass*N on thatch depth of a USGA-specified research green at the end of experiment 2. Means with same letter are not statistically different at the 0.05 probability level based on the T ukey-Kramer method. PCU=39.1 g N m Table 2-6. Anova table for thatch depth of a USGA-specified research green at the end of experiment 2. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 13.3 <0.0001 0.13 Nitrogen (N) 4 4.0 0.0044 0.15 Potassium (K) 3 0.5 0.6602 0.13 Grass*N 12 1.0 0.4089 0.40 Grass*K 9 0.6 0.7899 0.34 N*K 12 0.9 0.5283 0.40 a a ab abc abc a-d a-d a-d a-d a-d a-d a-d a-d a-d a-d a-d bcd cd d

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49 Figure 2-13. Effect of grass*N on root length of a USGA-specified research green at the end of experiment 1. Means with same letter are not statistically different at the 0.05 probability level based on the T ukey-Kramer method. PCU=39.1 g N m Table 2-7. Anova table for root length of a USGA-specified research green at the end of experiment 1. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 264.2 <0.0001 0.84 Nitrogen (N) 4 1.2 0.3074 1.00 Potassium (K) 3 0.3 0.8266 0.84 Grass*N 12 2.6 0.0038 2.61 Grass*K 9 0.2 0.9908 2.25 N*K 12 0.8 0.6075 2.61 a a a a a ab c a a a a ab b c

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50 Figure 2-14. Effect of grass*N on root length of a USGA-specified research green at the end of experiment 2. Means with same letter are not statistically different at the 0.05 probability level based on the T ukey-Kramer method. PCU=39.1 g N m Table 2-8. Anova table for root length of a USGA-specified research green at the end of experiment 2. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 26.8 <0.0001 1.44 Nitrogen (N) 4 1.2 0.2933 1.72 Potassium (K) 3 2.0 0.1209 1.42 Grass*N 12 1.5 0.1173 4.48 Grass*K 9 1.3 0.2286 3.84 N*K 12 0.5 0.8872 4.45 a a a a a a ab ab ab abc abc abc abc abc abc abc bc c c

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51 Figure 2-15. Effect of grass*N on surface compressibi lity, as measured with a Volkmeter, of a USGA-specified research green in expe riment 1 at week 15 on 13 January 2009. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N m Table 2-9. Anova table for surface compressibili ty of a USGA-specified research green in experiment 1 at week 15 on 13 January 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 278.8 <0.0001 0.19 Nitrogen (N) 4 201.4 <0.0001 0.22 Potassium (K) 3 0.2 0.9290 0.19 Grass*N 12 19.7 <0.0001 0.58 Grass*K 9 1.1 0.3875 0.50 N*K 12 0.6 0.8542 0.58 fgh gh gh hi a a ab b gh cd de d ef i bc cd fg i

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52 Figure 2-16. Effect of grass*N on surface compressi bility, as measured with a Volkmeter, of a USGA-specified research green in expe riment 2 at week 10 on 3 October 2009. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N m Table 2-10. Anova table for surface compressibili ty of a USGA-specified research green in experiment 2 at week 10 on 3 October 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 48.0 <0.0001 0.21 Nitrogen (N) 4 67.0 <0.0001 0.26 Potassium (K) 3 1.9 0.1282 0.21 Grass*N 12 1.8 0.0561 0.67 Grass*K 9 1.0 0.4589 0.58 N*K 12 1.4 0.1743 0.66 cde a a ab ab abc a-d a-d b-e cde def def d-g e-h e-i f-i f-i ghi i hi

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53 Figure 2-17. Effect of grass*N on ball roll dist ance of a USGA-specified research green in experiment 1 at week 24 on 20 March 2009. Means with same letter are not statistically different at th e 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N m Table 2-11. Anova table for ball ro ll distance of a USGA-specified research green in experiment 1 at week 24 on 20 March 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 49.0 <0.0001 2.36 Nitrogen (N) 4 1.1 0.3714 2.80 Potassium (K) 3 1.6 0.1907 2.36 Grass*N 12 1.1 0.3514 7.31 Grass*K 9 1.4 0.1934 6.32 N*K 12 0.5 0.8913 7.31 a ab abc a-e a-d a-e a-f ag a-f a-g b-g c-g d-g ef g fg g

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54 Figure 2-18. Effect of grass*N on ball roll distan ce of a USGA-specified research green in experiment 2 at week 11 on 9 October 2009. Means with same letter are not statistically different at th e 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N m Table 2-12. Anova table for ball ro ll distance of a USGA-specified research green in experiment 2 at week 11 on 9 October 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 154.1 <0.0001 1.70 Nitrogen (N) 4 6.1 0.0001 2.02 Potassium (K) 3 0.6 0.6141 1.70 Grass*N 12 2.8 0.0015 5.27 Grass*K 9 0.8 0.6210 4.56 N*K 12 0.9 0.5584 5.27 a fg g g g a-d de def cde efg a a a ab a-d a-d abc b-e

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55 Figure 2-19. Effect of grass*N on mower scalpi ng of a USGA-specified research green in experiment 1 at week 20 on 19 February 2009. Scalping ratings: 1-10 (1 = none, and 10 = complete loss of leaf blades). Means with same letter are not statistically different at the 0.05 probability level ba sed on the Tukey-Kramer method. PCU=39.1 g N m Table 2-13. Anova table for mowe r scalping of a USGA-specified research green in experiment 1 at week 20 on 19 February 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 86.8 <0.0001 0.38 Nitrogen (N) 4 24.8 <0.0001 0.46 Potassium (K) 3 0.8 0.4944 0.38 Grass*N 12 14.1 <0.0001 1.19 Grass*K 9 1.6 0.1179 1.03 N*K 12 0.9 0.5854 1.19 d d d d d bc ab a c d d d d d

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56 Figure 2-20. Effect of grass*N on mower scalping of a USGA-specified research green in experiment 2 at week 10 on 1 October 2009. Scalping ratings: 1-10 (1 = none, and 10 = complete loss of leaf blades). Means with same letter are not statistically different at the 0.05 probability level based on th e Tukey-Kramer method. PCU=39.1 g N m Table 2-14. Anova table for mowe r scalping of a USGA-specified research green in experiment 2 at week 10 on 1 October 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 211.5 <0.0001 0.44 Nitrogen (N) 4 44.4 <0.0001 0.53 Potassium (K) 3 0.7 0.5673 0.44 Grass*N 12 16.3 <0.0001 1.38 Grass*K 9 0.9 0.5072 1.19 N*K 12 0.3 0.9865 1.38 a ab abc b c b c c def de d def ef ef f ef

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57 Figure 2-21. Effect of grass*N on quality of a USGA-specified research green two weeks after verticutting at the end of experiment 1. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with same le tter are not statistical ly different at the 0.05 probability level based on the Tu key-Kramer method. PCU=39.1 g N m Table 2-15. Anova table for quality of a USGA -specified research green at the end of experiment 1. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 85.1 <0.0001 0.20 Nitrogen (N) 4 9.4 <0.0001 0.24 Potassium (K) 3 0.9 0.4260 0.20 Grass*N 12 10.4 <0.0001 0.62 Grass*K 9 0.6 0.7628 0.54 N*K 12 0.6 0.8331 0.62 a ab ab b -f gh h c-g d-g efg fgh ab abc b -e a-d b-f

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58 Figure 2-22. Effect of grass*N on quality of a USGA-specified research green two weeks after verticutting at the end of experiment 2. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with same le tter are not statistical ly different at the 0.05 probability level based on the Tu key-Kramer method. PCU=39.1 g N m Table 2-16. Anova table for quality of a USGA -specified research green at the end of experiment 2. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 321.7 <0.0001 0.16 Nitrogen (N) 4 16.2 <0.0001 0.19 Potassium (K) 3 0.1 0.9563 0.16 Grass*N 12 6.4 <0.0001 0.50 Grass*K 9 0.1 0.9999 0.43 N*K 12 0.1 1.0000 0.50 a ab abc a-d bcd cde cde cde de ef fg fgh fgh gh gh h

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59 Figure 2-23. Effect of grass*N on recovery of a USGA-specified research green two weeks after verticutting at the end of experiment 1. Recovery ratings 1-10 (10 = completely recovered). Means with same letter are not statistically di fferent at the 0.05 probability level based on the T ukey-Kramer method. PCU=39.1 g N m Table 2-17. Anova table for rec overy of a USGA-specified re search green at the end of experiment 1. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 92.3 <0.0001 0.48 Nitrogen (N) 4 6.8 <0.0001 0.57 Potassium (K) 3 0.4 0.7819 0.48 Grass*N 12 3.9 <0.0001 1.49 Grass*K 9 0.7 0.7202 1.29 N*K 12 0.4 0.9396 1.49 a ab ab bcd c-f def c-f c-f ef ef f bc ab bc bcd b -e

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60 Figure 2-24. Effect of grass*N on recovery of a USGA-specified research green two weeks after verticutting at the end of experiment 2. Recovery ratings 1-10 (10 = completely recovered). Means with same letter are not statistically di fferent at the 0.05 probability level based on the T ukey-Kramer method. PCU=39.1 g N m Table 2-18. Anova table for rec overy of a USGA-specified re search green at the end of experiment 2. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 116.2 <0.0001 0.47 Nitrogen (N) 4 7.4 <0.0001 0.56 Potassium (K) 3 0.6 0.5822 0.47 Grass*N 12 1.4 <0.0001 1.45 Grass*K 9 0.2 0.9975 1.25 N*K 12 0.2 0.9993 1.45 a ab abc abc a-d b-e c-f def ef efg efg fg fg fg fg g

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61 Figure 2-25. Effect of grass*N for algae on a USGAspecified research green in experiment 1 at week 7 on 24 November 2008. Means with same letter are not statisti cally different at the 0.05 probability level based on the Tukey-Kramer met hod. PCU=39.1 g N m Table 2-19. Anova table for alg ae on a USGA-specified research gr een in experiment 1 at week 7 on 24 November 2008. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 73.9 <0.0001 4.86 Nitrogen (N) 4 16.6 <0.0001 5.77 Potassium (K) 3 0.4 0.7711 4.86 Grass*N 12 5.4 <0.0001 15.07 Grass*K 9 0.4 0.9562 13.02 N*K 12 0.2 0.9958 15.07 cd a a a ab b c cd cd cd cd cd cd cd cd d d d d

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62 Figure 2-26. Effect of grass*N for algae on a USGAspecified research green in experiment 2 at week 4 on 22 August 2009. Means with same lette r are not statistically different at the 0.05 probability level based on the Tu key-Kramer method. PCU=39.1 g N m Table 2-20. Anova table for alg ae on a USGA-specified research gr een in experiment 2 at week 4 on 22 August 2009. Effect Degrees of freedom F value Probability > F Least significant difference Grass 3 30.6 <0.0001 6.99 Nitrogen (N) 4 10.1 <0.0001 8.30 Potassium (K) 3 2.3 0.0792 6.99 Grass*N 12 2.4 0.0069 21.67 Grass*K 9 0.2 0.9860 18.72 N*K 12 0.5 0.8853 21.67 a ab abc bcd bcd bc bc bcd b-e b-e cde cde b-e de de e

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63 CHAPTER 3 DROUGHT RESISTANCE OF NEWLY-ES TABLISHED WARM-SEASON PUTTING GREE N CULTIVARS AS AFFECTED BY NITROGEN/POTASSIUM FERTILIZATION Introduction Water is req uired by turfgrass for chemical a nd biochemical processes, nutrient transport, physical support, temperature regulation, and growth (Tanino and Baldwin, 1996; Haman and Izuno, 2009). The use of fresh water for irrigation has been limited due to competition and a shrinking supply of water sources (Aronson et al., 1987; Barnett, 2007; Brown, 2008; Glennon, 2002; Huang, 2004; Kim and Beard, 1988). Irrigation applications are based on visual drought symptoms, soil moisture levels, evapotranspira tion (ET) rates, pred ictive ET models, and turfgrass species (Cisar and Mill er, 1999). Visual signs of drought in turfgrass include slowed tissue production, leaf wilting, and firing (Huang, 2004). Soil moisture is determined by gravimetric methods and moisture sensing devi ces. Predictive ET m odels use historical climatological data, ET rates of common turfgrasses, and empirical procedures to determine potential ET (ETo), and net irrigation requi rements (Augustin, 1983; Cisar and Miller, 1999). The Blaney-Criddle ET calculation method, implem ented by three of Floridas five water management districts, is based on mean temperat ure, percent daylight hours, and uses climatic and consumptive use coefficients (Augustin, 198 3). The Florida Automated Weather Network uses the Penman equation to determine ET from a vegetated surface (Jon es et al., 1984). Longterm climatological data is often used in conjunction with ETo to determ ine the total amount of irrigation to be applied over a given period. Differences in morphological characteristics can also influence the abilit y of turfgrasses to resist drought as horizontal leaf orientation, slow vertical leaf growth rate, and high shoot and leaf densities can impart lower water-use rates (Cisar and Miller, 1999).

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64 Tifdwarf (TD) bermudagrass was the st andard warm-season greens variety for over thirty years (Foy, 1997) until advances in greens maintenance technology, and increased demand for faster green speeds eventually necessitated th e development of cultivars that could tolerate lower mowing heights (Vermeulen, 1995). TifEagl e (TE) bermudagrass, released in 1998, had lower vertical growth characterist ics, increased shoot density, fi ner texture, and could be mown low enough to provide putting speeds comparable to creeping bentgrass [Agrostis stolonifera L. var palustris (Huds.) Farw.], the standard cool season grass for putting speed and quality (Busey and Dudeck, 1999; Foy, 1997; Foy, 2006; Hartwiger and OBrien, 2006; Mc Carty et al., 2007). With dwindling fresh water supplies, cultivars that require less water and tolerate irrigation with alternative sources are becoming necessary. Improved seashore paspalum and zoysiagrass cultivars can provide high quality putting surfaces, tole rate saline irrigation (Marcum, 1999), and are thought to require less water than bermuda grasses (Foy, 2006). SeaDwarf (SD) seashore paspalum, regarded as the first true dwarf seas hore paspalum, was released in 1999 and is used locally on several golf courses. PristineFlora (PF), an uprig ht, narrow-leafed, Emerald-type zoysiagrass was approved for release in 2004 an d can tolerate 3 mm mowing heights (Scully, 2005; Scully et al., 2009). When K is available in adequate levels, turf grass quality is improve d (Snyder and Cisar, 2000), and increased tolerance to drought, diseas e, wear, heat (Turner and Hummel, 1992), and cold (Beard, 1973) is inferred. Fertilization w ith K ratios above 1N/0.5K does not necessarily increase tissue K, turf quality (Snyder a nd Cisar, 2000a; Trenholm et al., 1998), or drought resistance, as turfgrasses generally utilize only half as much K as N (Turgeon, 1985). Regardless, turfgrass managers ha ve been applying ever-increasing rates of K in relation to N in

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65 an attempt to increase stress tolerances (Augustin, 1992; Sartain, 1998; Snyder and Cisar, 2000a). This study was conducted to evaluate drought resistance for cultiv ars of three main warm-season turfgrass species used on golf course putting greens under deficit irrigation, and the effect of varied N/K fe rtilization ratios. Materials and Methods Experimental Site Research was performe d at the University of Floridas Fort Lauderdale Research and Education Center in Ft. Lauderd ale, FL (26' N, 80' W) after renovation of the Otto Schmiesser research green in Sept. 2008 and Ju ly 2009. PristineFlora, SD, TD, and TE were established from sprigs in 4 m by 4 m sub-pl ots on United States Golf Association (USGA)specified sand containing 1% organic matter by weight (Table 1; USGA Green Section Staff, 2004). The green contained 30 separately valv ed 4 m by 8 m irrigati on zones (main plots) equipped with Toro 570 series stationary 10 cm pop-up sprinklers. Irriga tion was distributed at 0.56 mm min with 91, 89, and 89% uniformity for gr ass, irrigation, and K treatments, respectively. Deficit irrigation experiments were initiated in April (Experiment 1) and Oct. 2009 (Experiment 2). The green wa s fertilized with 4.9 g N m 30d from Harrells 12-4-12 greens Polyon mixture, and mowed at 3.6 mm with clippings removed. Potassium, as KCl, was applied in four N/K ratios (1N:1K, 1N:2K, 1N:3K, and 1N:4K) were applied to 2 m by 2 m sub, sub-plots. Irrigation was applie d at 200% ETo for two days pr ior to the initiation of each experiment to ensure all plots were thoroughly watered; subseque nt irrigation was applied daily at 25, 50, or 100% ETo, calculated monthly with the modified Bl aney-Criddle equation (Blaney and Criddle, 1950), and 50 years of climatological data from th e Ft. Lauderdale, FL weather

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66 station. Irrigation was increased to 200% ETo daily after wilting became severe or a significant rainfall occurred for the duration of each experime nt. Water used for irrigation had a pH of 7.3, moderate carbonate, hardness, salts and total di ssolved solids. In Experiment 1, mean air temperature at 60 cm height was 25.6 C, and mean soil temperature at 10 cm depth was 27.6 C. Average ETo, as estimated with the Penman method, was 4.6 mm d whereas the modified Blaney-Criddle equation estimated ETo at 5.2 mm d over the same period. In Experiment 2, mean air temperature at 60 cm height was 26.4 C, and mean soil temperature at 10 cm depth was 28.9 C. Average ETo, as estimated with the Penman me thod, was 3.1 mm d, whereas the modified Blaney-Criddle equation estimated ETo at 4.2 mm d over the same period. Chlorothalonil, trifloxystrobin, a nd bifenthrin were applied as needed for disease and insect control. Measurements Bulk density and pore sp ace within the root zone were determined in the lab by American Society for Testing and Materials (ASTM) method F 1815-06 on relatively undisturbed 5.1 cm diam. by 9.4 cm deep soil cores with verdure and thatch removed (ASTM, 2006). Saturated hydraulic conductivity (Ksat) was determined on a constant hydraulic head permeameter, with samples collected over 0.5 h (ASTM, 2006). Init ially, Ksat was evalua ted with thatch and verdure intact, as well as removed. Because physi cal removal of thatch a nd verdure with a knife affected Ksat measurements (P<0.00 1), soil cores with thatch and ver dure left intact were used to report effects. Rowland et al (2009) observed a similar reducti on of Ksat in an ultradwarf bermudagrass research green. Visual estimates of leaf w ilting were rated daily at approximately 1400 h, on a percent basis (10% = objectionable, and 100% = complete wi lting). Turfgrass qual ity was visually rated

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67 daily at approximately 1400 h, on a 1-10 scale (1 = dead, 6 = minimally acceptable, and 10 = best). Volumetric water content (VWC) was de termined daily at approximately 1500 h, by one 6 cm deep theta reading from each 2 m by 2 m sub, sub-plot with a Soil Moisture Meter (model TH2O, Dynamax, Houston, TX), calibrated for mine ral soil (Figure A-1, A-2, A-3). Relative chlorophyll content was determined daily at a pproximately 1400 h using a hand-held reflectance meter (model CM 1000, Spectrum Technologies, Plainfield, IL) with a near infrared/red reflectance ratio of 700 nm /840 nm. Each meter value was an average of three random readings taken from each sub, sub-plot. The GreenSeeker Hand Held optical sensor unit (model 505, NTech Industries, Inc., Ukiah, CA) with a near infrared/red reflectan ce ratio of 660 nm /770 nm was used daily at approximately 1400 h to m easure normalized difference vegetative index (NDVI), which has been used to estimate stress injury in warm-season and cool-season turfgrass species (Dacosta and Huang, 2006; Jiang and Ca rrow, 2005; Merewitz et al., 2010; Trenholm et al., 1999). Canopy resistance was determined by measuring shoot density (shoots cm ), leaf density (leaves shoot ), leaf width (lowest/oldest green leaf), and leaf orient ation (1 = horizontal, and 10 = vertical) from 20 cm cores (Kim and Beard, 1988). Thatch and root depths were determined prior to the initiation of irriga tion treatments from 10 cm diam. by 20 cm deep soil cores; each was measured at three points. The thatch was then separated from the remaining soil core with a 20 cm long, serrated knife, oven-dr ied (60C), and ashed in a 550 C muffle furnace to determine ash-free thatch weight (Snyder and Cisar, 2000a). A 2 mm diam. sieve was then used to strain excess soil from roots in the remaining soil core. Roots were then oven-dried (60C), and ashed in a 550C muffle furnace to determine ash-free root weight (Snyder and Cisar, 2000a).

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68 Statistical Analysis A split, split-plot, rando mized complete block design with five replications was used to estimate irrigation level, cultivar, and N/K ratio e ffects (Littell et al., 2006). Each irrigation zone (whole-plot experimental units) contained two different cultivars (split-plot experimental units). Each cultivar contained four N/K ratios (split, split-plot experimental units). SAS PROC MIXED using the Tukey-Kramer multiple-comparison procedure was used to determine significant (P<0.05) treatment differences (SAS, 2004). Results and Discussion Turfgrass Wilting In experime nt 1, wilting became evident on day 8 and was generally the same among cultivars under 25% ETo until irrigation was incr eased to 200% ETo on day 14 due to severe drought stress (Figure 3-1). Wilting for TD and TE increased for three days after irrigation was increased, and SD and PF generally had less wilt ing, as they recovered more quickly. Plots receiving 50% ETo had similar wilting from days 12, then TD and TE had more wilting than PF and SD until recovered (Figure 3-2). TifDwa rf and TE exhibited severe wilting under 50% ETo, but began to recover soon after 16 mm of rainfall on day 18. Some wilting was observed in TD and TE under 100% ETo, but it wa s not significantly higher th an PF and SD, which did not exhibit wilting. Wilting was slower to occur, and recovery began sooner for TD and TE under 50 and 100, compared to 25% ETo. In experiment 2, wilting became evident on day 9 when TD and TE had more wilting than PF and SD under 25% ETo (Figure 3-4). Wilting for TD and TE remained generally higher than PF and SD for the remainder of the experiment. Wilting was also observed on day 9 in plots irrigated at 50 % ETo, and followed a trend similar to 25% ETo, although SD did not wilt as much as PF, and TE r ecovered more than TD after 17 mm or rain fell on day 12 (Figure 3-5). Although not severe, wilting was observe d in all cultivars under 100%

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69 ETo, and likely would have continued to decline had rainfall not occurr ed (Figure 3-6). The abnormally high temperatures and wind speeds duri ng experiment 2 appeared to increase drought stress for PF and SD irrigated at 50 and 100% ETo, as only minimal wilting occurred under normal conditions in experiment 1. There were no statistical differences in wilting among N/K ratios in either experiment. U nder average climatic conditions, 50% ETo seemed to be sufficient for SD, whereas TD and TE appeared to require higher irrigation rates, as they exhibited severe wilting in both experiments; PF was intermediate in its drought resistance and may normally tolerate 50% ETo. For prolonged periods of water stress, TD and TE would likely require irrigation in excess of 100% ETo, whereas PF and SD would be expected to perform well at 50% ETo. Soil Moisture In experime nt 1, SD had higher VWC than TD on three rating days under 25% ETo (Figure 3-7). Volumetric water content fell belo w 12% for PF, TD, and TE after 11 days of 25% ETo irrigation. After four days of irrigati on at 200% ETo on days 14, and 16 mm of rainfall on day 18, VWC was above 20% for all cultivars. Under 50% ETo, SD had highest VWC among cultivars several times and was regularly above 18% (Figur e 3-8). Only PF fell below 12% VWC at 50% ETo. Under 100% ETo, VWC fo r SD was sometimes higher, and generally within 20%, than the other cultivars which usually ranged from 17% (Figure 3-9). In experiment 2, VWC fell to approximately 12% fo r PF, TD, and TE, whereas SD remained above 14% after 11 days at 25% ETo (Figure 3-10). Ti fEagle was the only cultivar to fall below 12% VWC after 11 days under 50% ETo, while SD rema ined above 15%, and PF and TD were below 14% (Figure 3-11). PristineFlora, TD, and TE had VWC at or below 16%, and SD declined below 17% after 11 days under 100% ETo (Figure 3-12) There were no statistical differences in VWC among N/K ratios in either experiment. A lthough there were often st atistical differences

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70 in VWC among cultivars in experiment 1, mostly with SD being higher, they were minimal in experiment 2. All cultivars except SD had reduced VWC under 25 and 50% ETo in both experiments. Volumetric water content remained relatively steady for all cultivars at 100% ETo in experiment 1, though it declined in experime nt 2. The unusually hot and windy conditions encountered in experiment 2 seemed to increase mois ture stress for all cultivars. Turfgrass Quality In experime nt 1, PF had higher quality than TD and TE on several rating days under 25% ETo (Figure 3-13). After irriga tion was increased to 200% ETo due to excessive wilting, PF generally had the highest quality. PristineFlora had higher qualit y than TD on all rating dates, and TE several times under 50% ETo; SD had highe r quality than TD on most dates (Figure 314). PristineFlora generally had higher qual ity than TD and TE under 100% ETo, as did SD on several rating days (Fig ure 3-15). In experiment 2, PF and SD had higher quality than TD and TE under 25% ETo (Figure 3-16). SeaDwarf conti nued to have higher quality than TD and TE, while PF had higher quality on several rating date s after a 17 mm rainfall on day 12. Under 50% ETo, SD had higher quality than TD and TE, while PF was higher than TD (Figure 3-17). After rainfall occurred, SD had the highest quality on several rating dates. PristineFlora and SD had higher quality than TD and TE under 100% ETo just prior to rainfall, and generally maintained their superiority throughout the experiment, as th ey did not experience noticeable reductions in quality (Figure 3-18). There were no statistical differences in quality among N/K ratios in either experiment. All cultivars exhibited redu ced quality and objectionable wilting in both experiments when irrigated at 25% ETo (Fi gures 3-1, 3-4, 3-13, 316). TifDwarf and TE declined in quality under 50% ETo in both expe riments, while PF and SD were relatively unaffected in experiment 1. Irrigating at 50% ET o appeared to be insufficient for TD and TE,

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71 and marginal for PF and SD, while 100% ETo appeared to be marginal for TD and TE, and sufficient for PF and SD to maintain high quality for extended periods. Chlorophyll Levels In experime nt 1, TE generally had higher chlorophyll than PF and TD under 25% ETo, and after irrigation was increased (Figure 319). Although TE and SD regularly had higher levels than PF and TD, chlorophyll appeared to be unaffected at 50 and 100% ETo (Figures 3-20, 3-21). In experiment 2, although SD was generall y the highest, all cultivars exhibited reduced chlorophyll, regardless of irrigation level (Figures 3-22, 3-23, 324). There were no statistical differences in chlorophyll index among N/K ratios in either experiment. Although severe wilting was observed under 25 and 50% ETo in both experi ments, the only within cultivar difference observed was on day 14 in experiment 1, when SD at 25% ETo had a lower chlorophyll index than SD at 100% ETo. The d ecline in chlorophyll index at al l irrigation levels observed in experiment 2 was likely due to abnormally high temperatures and wind speeds that increased moisture stress. Normalized Difference Vegetative Index In experime nt 1, SD and TE generally ha d higher NDVI readings, which were an indicator of reduced drought stress, than PF under all irrigation levels (F igures 3-25, 3-26, 3-27). Only 25% ETo seemed to cause a decline in NDVI, as all cultivars appeared to rise slightly after irrigation was increased. In experiment 2, NDVI a ppeared to decrease at every irrigation level (Figures 3-28, 3-29, 3-30). SeaDwarf always had the highest NDVI, regardless of irrigation level. TifEagle had higher NDVI than PF under 50%, and both PF and TD under 100% ETo. There were no statistical differe nces in NDVI among N/K ratios in either experiment. Although there were clearer distincti ons among cultivars for NDVI compared to chlorophyll index, no cultivar x irrigation interactions were observed in e xperiment 1. In experiment 2, TE and SD at

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72 25% ETo had lower NDVI than 100% ETo on day 10 and 11, respectively. As with the chlorophyll meter, the noticeable decline in NDVI in experiment 2 may have been due to above average temperatures and wind speeds. Alt hough NDVI is more commonly used to analyze plant stress, it was not entirely su rprising that the reflectance me ter and optical sensor produced relatively similar results, as the wavelength ba nds used in each are somewhat close. Drought Resistance Characteristics Canopy. There were inherent differences for canopy characteristic s, as leaf orientation, shoot density, and leaf de nsity differed among cultivars (Table 3-2). Although TE had greater shoot density than PF and SD, more leaves pe r shoot than PF, and a more desirable leaf orientation than PF and SD, it did not have superior drought resistance. Morphological characteristics associated with PF, such as a mo re upright leaf orienta tion and lower number of leaves shoot would be expected to reduce drought resistance (K im and Beard, 1988), however it was among the most drought resistant cultivars studied. Thatch and roots. PristineFlora had the shallowest thatch depth and root lengths among cultivars in both experiments (Table 3-3). The sh allower thatch depths a nd root lengths for PF may have allowed water to evaporate more read ily from the root zone (Sass and Horgan, 2006), and hastened the onset of moisture stress due to an inability to reach water deeper in the soil profile when moisture is limited n ear the surface, respectively.

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73 Table 3-1. Physical properti es of USGA-specified soil. Bulk density Organic Matter Saturated hydraulic conductivity Total porosity Macroporosity Microporosity g cm g kg cm h % 1.69 10.0 14.0 36.8 10.6 26.2 Table 3-2. Canopy characteristics of warm-season putting green cultivars. Cultivar Shoot density Leaves Leaf Width Leaf Orientation cm shoot mm 1-10 PristineFlora 14b 3.7b 1.1b 4.5a SeaDwarf 13bc 4.4a 1.6a 3.8b TifDwarf 12c 4.2a 1.1b 3.7b TifEagle 16a 4.5a 1.1b 3.2c LSD 1.4 0.4 0.11 0.49 Leaf width measured at lowest green leaf. Leaf orient ation: 1-10 (1 = horizontal and 10 = vertical). Means with different letters are statistically different at the 0.05 probability level based on the Tukey-Kramer method. Table 3-3. Thatch depth and root le ngth of warm-season putting green cultivars. Cultivar Thatch depth Root length cm Experiment 1 Experiment 2 Experiment 1 Experiment 2 PristineFlora 0.65c 0.61b 7.52c 11.16c SeaDwarf 1.05a 0.86a 14.08b 15.52a TifDwarf 0.91b 0.85a 15.60a 15.44a TifEagle 0.97ab 0.90a 14.94a 13.98b LSD 0.13 0.13 0.84 1.44 Means with different letters are statistically different at the 0.05 probability level based on the Tukey-Kramer method.

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74 0 5 10 15 20 25 30 35 40 8910111213141516171819202122 DayWilting (%) SD PF TE TD Figure 3-1. Wilting ratings: % (0 = none, 10 = objecti onable, and 100 = completely wilted) of recently established warm-season putti ng green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 1 from 2 May 16 May 2009. Means with different letters are statistica lly different at the 0.05 probability level based on the Tukey-Kramer method. SD=S eaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates start of daily irrigation at 200% ETo. b a a a ab ab b b b b b a a a b a a b a a a a ab b

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75 0 5 10 15 20 25 30 35 111213141516171819202122 DayWilting (%) SD PF TE TD Figure 3-2. Wilting ratings: % (0 = none, 10 = objecti onable, and 100 = completely wilted) of recently established warm-season putti ng green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 1 from 5 May 16 May 2009. Means with different letters are statistica lly different at the 0.05 probability level based on the Tukey-Kramer method. SD=S eaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and st art of daily irrigation at 200% ETo. aa a a a a a a a b b b c b b b b b

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76 0 1 2 3 4 5 6 7 8 111213141516171819202122 DayWilting (%) SD PF TE TD Figure 3-3. Wilting ratings: % (0 = none, 10 = objecti onable, and 100 = completely wilted) of recently established warm-season putti ng green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 1 from 5 May 16 May 2009. Means with different lette rs are statistically different at the 0.05 probability level based on the Tukey-Kramer me thod. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo.

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77 0 5 10 15 20 25 30 35 40 45 891011121314151617181920 DayWilting (%) SD PF TE TD Figure 3-4. Wilting ratings: % (0 = none, 10 = objecti onable, and 100 = completely wilted) of recently established warm-season putti ng green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 2 from 18 October 30 October 2009. Means with different letters are statistically different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. a b b a b c bc a b c c a a b b a a b b a a b b c c a a b b a b b a a b a b b

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78 0 5 10 15 20 25 30 35 89101112131415161718 DayWilting (%) SD PF TE TD Figure 3-5. Wilting ratings: % (0 = none, 10 = objecti onable, and 100 = completely wilted) of recently established warm-season putti ng green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 2 from 18 October 28 October 2009. Means with different letters are statistically different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. a ab ab b a a b b a a a b a a b b a b b b a ab b b a b b b

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79 0 2 4 6 8 10 12 14 89101112131415161718 DayWilting (%) SD PF TE TD Figure 3-6. Wilting ratings: % (0 = none, 10 = objecti onable, and 100 = completely wilted) of recently established warm-season putti ng green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 2 from 18 October 28 October 2009. Means with different letters are statistically different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily ir rigation at 200% ETo.

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80 10 12 14 16 18 20 22 24 6789101112131415161718 DayVolumetric water content (%) SD PF TE TD Figure 3-7. Soil moisture of a USGA-specified research green under 25% ETo irrigation in experiment 1 from 30 April 12 May 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrow ( ) indicates start of daily irrigation at 200% ETo. a a a b ab ab ab b ab b b a ab

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81 10 12 14 16 18 20 22 24 6789101112131415161718 DayVolumetric water content (%) SD PF TE TD Figure 3-8. Soil moisture of a USGA -specified research green under 50% ETo irrigation in experiment 1 from 30 April 12 May 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. a a a a a a a a a a a ab ab ab ab ab b b b b b b b b a ab b b ab b b b b b b ab b b b ab b b b c c b ab

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82 16 17 18 19 20 21 22 23 24 6789101112131415161718 DayVolumetric water content (%) SD PF TE TD Figure 3-9. Soil moisture of a USGA-specified rese arch green under 100% ETo irrigation in experiment 1 from 30 April 12 May 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. ab a a a a a ab b ab b b ab b b ab a b b a b b b a b b b

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83 10 12 14 16 18 20 91 01 11 21 31 4 DayVolumetric water content (%) SD PF TE TD Figure 3-10. Soil moisture of a USGA-specified rese arch green under 25% ETo irrigation in experiment 2 from 19 October 24 Oc tober 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo.

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84 10 12 14 16 18 20 91 01 11 21 31 4 DayVolumetric Water Content (%) SD PF TE TD Figure 3-11. Soil moisture of a USGA-specified re search green under 50% ETo irrigation in experiment 2 from 19 October 24 Oc tober 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. a ab ab b

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85 15 16 17 18 19 20 21 91011121314 DayVolumetric Water Content (%) SD PF TE TD Figure 3-12. Soil moisture of a USGA-specified re search green under 100% ETo irrigation in experiment 2 from 19 October 24 Oc tober 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo.

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86 7 7.5 8 8.5 9 9.5 8910111213141516171819202122 DayQuality (1-10) SD PF TE TD Figure 3-13. Quality of recently established warm-season putting green cultivars on a USGAspecified research green unde r 25% ETo irrigation in experiment 1 from 2 May 16 May 2009. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with different letters are statistically different at the 0.05 probability level based on the Tukey-Kramer method. SD=S eaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates start of daily irrigation at 200% ETo. a b a ab bc c a ab b a ab b b a bc a b c a b b c a b bc c ab bc c a b b b b ab a ab c a

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87 7 7.5 8 8.5 9 8910111213141516171819202122 DayQuality (1-10) SD PF TE TD Figure 3-14. Quality of recently established warm-season putting green cultivars on a USGAspecified research green unde r 50% ETo irrigation in experiment 1 from 2 May 16 May 2009. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with different letters are statistically different at the 0.05 probability level based on the Tukey-Kramer method. SD=S eaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and st art of daily irrigation at 200% ETo. a a a b a a a b a a a a a a a a a a a a a a a ab ab ab ab a a a ab a a b a b ab b ab b ab b bc c bc c bc c b b b b b b bc c a a b

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88 7 7.5 8 8.5 9 8910111213141516171819202122 DayQuality (1-10) SD PF TE TD Figure 3-15. Quality of recently established warm-season putting green cultivars on a USGAspecified research green unde r 100% ETo irrigation in experiment 1 from 2 May 16 May 2009. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with different letters are statistically different at the 0.05 probability level based on the Tukey-Kramer method. SD=S eaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and st art of daily irrigation at 200% ETo. a b b a a b b a a ab b a b a a ab b a ab b b a ab ab b a ab b b a ab b b a ab bc c a ab bc c a b c c a ab bc c a a b b a ab b b

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89 6 6.5 7 7.5 8 8.5 910111213141516171819 DayQuality (1-10) SD PF TE TD Figure 3-16. Quality of recently established warm-season putting green cultivars on a USGAspecified research green under 25% ETo irrigation in experi ment 2 from 19 October 29 October 2009. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with different letters are statis tically different at the 0.05 probability level based on the TukeyKramer method. SD=SeaDwarf; PF=PristineF lora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain even t and start of daily irrigation at 200% ETo. b b a a a a a a a a a a a a b b a b b ab c ab bc c ab bc c b c c a b b b b a b b

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90 6.5 7 7.5 8 8.5 910111213141516171819 DayQuality (1-10) SD PF TE TD Figure 3-17. Quality of recently established warm-season putting green cultivars on a USGAspecified research green unde r 50% ETo irrigation in expe riment 2 from 19 October 29 October 2009. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with different letters are st atistically different at the 0.05 probability level based on the Tukey-Kramer me thod. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. a ab b c a a a a a a a b ab bc c b b a a b b cd b b b b bc d ab bc c b a a

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91 6.5 7 7.5 8 8.5 910111213141516171819 DayQuality (1-10) SD PF TE TD Figure 3-18. Quality of recently established warm-season putting green cultivars on a USGAspecified research green unde r 100% ETo irrigation in expe riment 2 from 19 October 29 October 2009. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with different letters are statistically di fferent at the 0.05 probability level based on the Tukey-Kramer me thod. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. a a a b a a a a ab c ab b b b b b b a ab bc c a b a ab bc c a b b a ab b b

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92 275 300 325 350 375 89101112131415161718 DayChlorophyll index SD PF TE TD Figure 3-19. Chlorophyll index of recently establ ished warm-season putting green cultivars on a USGA-specified research green under 25% irrigation in experiment 1 from 2 May 12 May 2009. Means with different letter s are statistically different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates start of daily irrigation at 200% ETo. ab a a a ab a a a a a a a bc c ab b b ab b b b b ab b b ab b b ab b b ab b b ab b b b b b

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93 250 275 300 325 350 375 400 89101112131415161718 DayChlorophyll index SD PF TE TD Figure 3-20. Chlorophyll index of recently establ ished warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 1 from 2 May 12 May 2009. Means with different lett ers are statistically different at the 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. b a a b b a a b a a b b a ab bc c a a b b a a b b a a b a a b b a a b b a a b b b b a a

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94 250 275 300 325 350 375 89101112131415161718 DayChlorophyll index SD PF TE TD Figure 3-21. Chlorophyll index of recently establ ished warm-season putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 1 from 2 May 12 May 2009. Means with different lett ers are statistically different at the 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. a a b b a ab bc c a a b b a ab bc c a a b b a a b b a b b a a b b a a b b a a b b a a b b

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95 175 200 225 250 275 91 01 11 21 31 41 5 DayChlorophyll index SD PF TE TD Figure 3-22. Chlorophyll index of recently establ ished warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 2 from 19 October 25 October 2009. Means with differe nt letters are stat istically different at the 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. b ab ab a a b b b a b b b a b b a ab b b a b b b a ab b b

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96 175 200 225 250 275 300 91 01 11 21 31 41 5 DayChlorophyll Index SD PF TE TD Figure 3-23. Chlorophyll index of recently establ ished warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 2 from 19 October 25 October 2009. Means with differe nt letters are stat istically different at the 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. a ab b b a b b b b b b a b b b a a ab bc c a a ab b b ab b b

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97 175 200 225 250 275 300 91 01 11 21 31 41 5 DayChlorophyll index SD PF TE TD Figure 3-24. Chlorophyll index of recently establ ished warm-season putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 2 from 19 October 25 October 2009. Means with differe nt letters are stat istically different at the 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and start of daily irrigation at 200% ETo. a a b b a b bc c a b bc c a b b b a b b a a b b b

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98 0.77 0.79 0.81 0.83 0.85 0.87 89101112131415161718 DayNDVI SD PF TE TD Figure 3-25. Normalized difference vegetativ e index (NDVI) of recently established warmseason putting green cultivar s on a USGA-specified research green under 25% ETo irrigation in experiment 1 from 2 May 12 May 2009. Means with different letters are statistically different at the 0.05 pr obability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow () indicates start of daily irrigation at 200% ETo. a ab bc c a ab ab b a ab bc c a ab bc c a a ab b a ab bc c a a ab b a ab bc c a a ab b a ab bc c a ab bc c

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99 0.74 0.76 0.78 0.8 0.82 0.84 0.86 0.88 89101112131415161718 DayNDVI SD PF TE TD Figure 3-26. Normalized difference vegetativ e index (NDVI) of recently established warmseason putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 1 from 2 May 12 May 2009. Means with different letters are statistically different at th e 0.05 probability level based on the TukeyKramer method. SD=SeaDwarf; PF=Prist ineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and star t of daily irrigation at 200% ETo. a a b c a a b c a ab b c a ab bc c a ab bc c a ab bc c a ab bc c a a b b a ab bc c a ab bc c a ab b c

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100 0.74 0.76 0.78 0.8 0.82 0.84 0.86 0.88 89101112131415161718 DayNDVI SD PF TE TD Figure 3-27. Normalized difference vegetativ e index (NDVI) of recently established warmseason putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 1 from 2 May 12 May 2009. Means with different letters are statistically different at th e 0.05 probability level based on the TukeyKramer method. SD=SeaDwarf; PF=Prist ineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and star t of daily irrigation at 200% ETo. a ab b c a a a b a ab b c a ab b c a ab b c a ab b c a ab b c a ab b c a ab b c a a b b a a b b

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101 0.69 0.71 0.73 0.75 0.77 0.79 0.81 0.83 0.85 91 01 11 21 31 41 5 DayNDVI SD PF TE TD Figure 3-28. Normalized difference vegetativ e index (NDVI) of recently established warmseason putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 2 from 19 October 25 October 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and st art of daily irrigation at 200% ETo. b b a c b b a b a b b a b b a b b b a b b b a b b b

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102 0.69 0.71 0.73 0.75 0.77 0.79 0.81 0.83 0.85 91 01 11 21 31 41 5 DayNDVI SD PF TE TD Figure 3-29. Normalized difference vegetativ e index (NDVI) of recently established warmseason putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 2 from 19 October 25 October 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and st art of daily irrigation at 200% ETo. b b c a b b c c a a b b c c b b b a b b a c c b a a b b b

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103 0.69 0.71 0.73 0.75 0.77 0.79 0.81 0.83 0.85 91 01 11 21 31 41 5 DayNDVI SD PF TE TD Figure 3-30. Normalized difference vegetativ e index (NDVI) of recently established warmseason putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 2 from 19 October 25 October 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrow ( ) indicates a rain event and st art of daily irrigation at 200% ETo. b a c c a b c c c c b a a b b c c a b c c a b b c b b a c

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104 CHAPTER 4 DROUGHT RESISTANCE OF WARM-SEASON PUTTING GREEN CULTIVARS SODDED ON SANDY NATIVE SOIL Introductio n The need for drought-resistant turfgrasse s on golf course putting greens has greatly increased as fresh water irriga tion has become more restrict ed due to recen t regulations, population demands, and shrinking supplies (Barnett, 2007; Brown, 2008; Glennon, 2002; Huang, 2004). Physiological characteristics, su ch as reduced evapotranspirational water use (Huang, 2004), increased rooting depth and density (Carrow, 1996; White et al. 1993), and canopy resistance (Kim and Beard, 1988) help turfgra sses avoid and tolera te drought stress. Irrigation quantity is often based upon soil moisture levels turfgrass species, climatological conditions, and predictive eva potranspiration models (Cis ar and Miller, 1999). Mini-lysimeters have been used successfully to measure water consumption of cool and warm-season turfgrasses, which can differ among species and cultivar (Aronson et al., 1987; Huang et al., 1997; Kim and B eard, 1988; Kim et al., 1988). Gr asses with higher rates of evapotranspiration (ET) are usually less able to tolerate prolonge d periods of drought stress due to the rapid depletion of soil water. Root depth becomes important when surface moisture is reduced and available water is only found deeper in the soil profile. Because roots can only obtain water that is in close proxi mity, root density is also importa nt, particularly near the soil surface, where shallow lateral roots can obtain wa ter from light rains and irrigation. Improved canopy resistance has been inferred with increased leaf and shoot densities and horizontal leaf orientation (Kim and Beard, 1988). For example, a sparse stand of turfgrass with an upright growth habit may have higher soil temperatures and ET compared to a dense stand with a prostrate growth habit, although increased leaf area would likely have increas ed transpiration.

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105 Predictive ET models use historical climatol ogical data, ET rates of common turfgrasses, and empirical procedures to determine potential ET (ETo), and net irrigation requirements. The adjusted Blaney-Criddle ET cal culation method, implemented by th ree of Floridas five water management districts, is based upon mean air te mperature, percent daylight hours, and uses climatic and consumptive use coefficients (Augus tin, 1983). Water use is often restricted to a certain percentage of ETo during periods of drought. Under 2008 phase III drought restrictions, irrigation allotments for golf courses in the South Florida Water Management District were reduced by nearly 50% (Reitman, 2008). In Ge orgia, where drought conditions were more severe, golf course superintendents were for ced to water greens with 10% of the amount normally used (Reitman, 2008). Establishment of United States Golf Associ ation (USGA)-specified putting greens from sprigs is a costly and time-consuming process. The high hydrauli c conductivity and low nutrient-holding capacity of the r oot zone also requires large input s of fertilizer and water for optimal turfgrass growth (Rodriguez et al., 2001; White, 2003). A less-expensive alternative is to construct greens on native sand-based soils that contain sufficient organic matter, and minimal silt and clay. Sodding provides immediate covera ge, and requires fewer fertilizer and water inputs to establish compared to sprigging. With dwindling fresh water supp lies, grasses that require less water and tolerate irrigation with alternative, reduced quality sources have become popular (Foy, 2006; OBrien and Hartwiger, 2007). Seashore paspalum and zoys iagrass are recognized for their tolerance to saline irrigation (Marcum, 1999), and may require less water than bermudagrasses, which have been used almost exclusively on warm-season putting greens until recently (Foy, 2006; Hartwiger and OBrien, 2006). Although claims of superior drought tolerance for the newer

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106 releases of seashore paspalum and zoysiagrass ar e advertised, little research has been conducted to prove these claims, particularly when these cu ltivars are maintained at putting green heights. For these reasons, this study was conducted to evaluate and compare drought resistance characteristics of sodded warm-season putting gr een cultivars established on a native sand and irrigated at varied levels of ETo. Materials and Methods Experimental Site This study was performed at the University of Floridas Fort La uderdale Research and Education Ce nter in Ft. Lauderd ale, FL (26' N, 80' W) on native Hallandale fine sand (Siliceous, hyperthermic Lithic Psammaquent), under a fully-aut omated rainout shelter. Experiments 1 and 2 were initiated in September and November 2009, respectively. PristineFlora (PF) zoysiagrass, TifDwarf (TD) bermudagrass, and SeaDwarf (SD) seashore paspalum, obtained as sod (5 cm deep) from a USGA-specified sand research green, were installed in 1 m plots with 0.2 m wide grassed borders in mid-July, 2009. Irrigation was applied at 200% ETo for two days prior to the initiation of each experiment to ensure that all plots were thoroughly watered. Irrigation wa s then applied every three da ys at approximately 0900 h at either 25, 50, or 100% of the modified Blaney -Criddle equation (Blaney and Criddle, 1950). Irrigation was increased to 200% ETo, applied every three days, when drought stress became severe. After three 200% cycles, irrigation was applied daily at 200% ETo to help maintain soil moisture and facilitate recovery. Climatological data from the Ft. Lauderdale, FL weather station, located 100 m from the experimental site was used in ETo calculations. Both 25 and 100% ETo plots were replicated four times, while 50% ETo plots were replicated three times due to space constraints that existed under the rainout sh elter. Water used for irrigation had a pH of 7.2, moderate carbonate, hardness, sa lts and total dissolved solids. Mean air temperature at 60

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107 cm was 28.0 C, and mean soil temperature at 10 cm was 29.3 C during experiment 1. Average ETo, as estimated with the Penman method, was 3.6 mm d whereas the modified BlaneyCriddle equation estimated ETo at 5.4 mm d in experiment 1. Mean air temperature at 60 cm was 22.3 C, and mean soil temperature at 10 cm was 23.8 C during experiment 2. Average ET, as estimated with the Penman method, was 1.8 mm d whereas the modified Blaney-Criddle equation estimated ET at 2.5 mm d in experiment 2. The area was fertilized with 3.7 g N m from Harrells 12-4-12 greens Polyon mixture two days prior to the initiation of each experiment, and mowed daily at 4.4 mm with clippings removed. Pesticides applied the week prior to the initiation of each study included trifloxystr obin and bifenthrin fo r disease and insect control, re spectively. Measurements Visual estim ates of leaf wilting were rated daily on a 1-10 scale (2 = objectionable, and 10 = completely wilted). Theta readings were taken for volumetric water content (VWC) at a depth of 6 cm with a Soil Mois ture Meter (model TH2O, Dyna max, Houston, TX) calibrated for mineral soil (Figure A-1, A-2, A-3). A calibrated Toro Turf Guard wireless soil monitoring system with TG2 dual level sensors (The Toro Company, Bloomington, MN) was used to measure moisture content on a volumetric basis. Sensors were set at 2.5 and 14.0 cm soil depths, prior to sodding, and readings were taken daily at 1600 h. Evapotranspiration was determined daily at approximately 1600 h using 10 cm wide by 20 cm deep poly vinyl chloride (PVC) Minilysimeters, which received irrigation as needed to maintain turfgrass quality. Mini-lysimeters were initially driven into the center of each sodded plot with a 20 cm tamper, and removed to attach PVC inset end caps to the bottom. When determining ET, mini-lysimeters were removed by lifting the PVC cylinder out of th e plot with pliers, weighed, a nd re-set gently with a 20 cm

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108 tamper. Turfgrass quality was rated daily on a 1-10 scale (1 = dead, 6 = minimally acceptable, and 10 = best). Relative chlorophyll content wa s determined daily, at approximately 1500 h, with a hand-held reflectance meter (model CM 1000, Spectrum Technologies, Plainfield, IL); each meter value was an average of four readings The GreenSeeker Hand Held optical sensor unit (model 505, NTech Industries, Inc., Ukiah, CA ) was used daily at approximately 1500 h to measure NDVI, which has been used to estimate stress injury in warm-season and cool-season turfgrass species (Dacosta and Huang, 2006; Jiang and Carrow, 2005; Me rewitz et al., 2010; Trenholm et al., 1999). Statistical Analysis A split-pl ot, randomized complete block design was used to increase treatment effect precision and reduce spatial variab ility (Littell et al., 2006). Irrigation levels were assigned to whole plot experimental units, and putting green cultivars were assigned to split-plot experimental units. SAS PROC MIXED and the Tukey-Kramer multiple-comparison procedure were used to determine significan t (P<0.05) treatment differences (SAS, 2004). Results and Discussion Turfgrass Wilting In experime nt 1, wilting became evident on da y 6, and was objectionable for all cultivars by day 10 under 25% ETo (Figure 4-1). PristineFlora exhibited the most wilting on two rating dates, and had more than TD, and SD one, and four other times, respectively; SD had least wilting on day 17. Wilting continued to increase for all cultivars, even after irrigation was increased to 200% ETo and applied every three days on day 9. Recovery did not begin until irrigation was applied daily at 200% ETo. Alt hough SD exhibited a trend of less wilting, all cultivars generally recovered at the same pace, and took 27 days for wilting to become unobjectionable after irrigation was increased. Wilting became evident on day 9, and was

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109 objectionable for all cultivars on day 13 under 50% ETo (Figure 4-2). Although SD had less wilting than TD and PF on days 20, and 34, respectiv ely, all cultivars had similar wilting which became unobjectionable 23 days after irrigati on was increased. Wilting for all cultivars under 100% ETo became evident on day 12 and obj ectionable on day 17 (Figure 4-3). All cultivars had similar wilting, which became unobjectionable 17 days after irrigation was increased. In experiment 2, wilting became evident on day 4, and was objectionable for all cultivars by day 10 under 25% ETo (Figure 4-4). TifDwarf exhibited most wilting on two rating dates, and had more than SD four other time s; SD had less wilting than PF seven times. SeaDwarf was first to recover, as it had unobjec tionable wilting 7 days after irrigation was increased. PristineFlora and TD took 8 days longer to recover. Wilting became evident on day 4, and was objectionable for all cultivars by day 5 under 50% ETo (Figure 4-5). TifDwarf had most wilting on eight rating dates and more than SD two other times. SeaDwarf was first to maintain unobjectionable wilting, starting 6 days after irrigation was increased, while PF and TD recovered 10 and 17 days after increased irrigation, respectively. Wilting was evident for all cultivars on day 5, and objectionable on day 6 for PF and TD under 100% ETo; SD only had objectionable wilting on day 20 (Figure 4-6). Wilting was objectionable for PF and TD on 16, and 18 rating days, and took 12, and 13 days to recover after irrigation was increased, respectively. Soil Moisture In experime nt 1, although there were no stat istical differences among cultivars, VWC fell below 10% for PF and TD, and 13% for SD under 25% ETo before irrigation was increased on day 9 (Figure 4-7). Volumetric water content co ntinued to decrease, as PF and TD fell below 8%, until after the second irrigation at 200% ETo. A noticeable increase in VWC did not occur until irrigation was applied daily at 200% ETo. There were no statistical differences in VWC

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110 among cultivars at 50% ETo (Figure 4-8). The VWC for PF and TD fell below 12%, and SD was below 13% before irrigation was increased on day 12. Volume tric water content continued to fall, as PF and TD were below 8% until afte r the second irrigation at 200% ETo. There were no statistical differences in VWC among cultivars under 100% ETo (Figure 4-9). Under 100% ETo, TD fell to 15%, while SD, and PF were belo w 14 and 12% VWC, respectively. A notable increase in VWC did not occur un til irrigation was applied daily. In experiment 2, there were no statistical differences among cultivars prior to increasing irrigation, and VWC fell below 11% for PF and TD, and 14% for SD, under 25% ETo (Figur e 4-10). After irrigation was increased on day 9, SD had the highest VWC on three rating date s and was higher than PF and TD three, and two other times, respectively. Volumetric water content did not rise above 14% for PF and TD until irrigation was applied daily at 200% ETo, while SD maintained VWC in excess of 16% after the first irriga tion with 200% ETo. Though there were no significant differences among cultivars under 50% ETo, TD had VWC below 12%, while PF and SD fell below 15 and 14%, respectively (Figure 4-11). Af ter the first irrigation at 200% ETo, PF and SD rose above 16% and generally remained there for the remainder of the experiment, while TD took 14 additional days to reach 16% VWC. There were no stat istical differences in VWC among cultivars under 100% ETo and all remained above 15% VWC (Figur e 4-12). After the fi rst irrigation at 200% ETo, only PF had VWC below 17%. Volumetric water content declined for all cultivars under all irrigation treatments in both experiments, si gnifying that none were apt to be sufficient for extended periods. This was corr oborated by the objectiona ble wilting that occurred. Volumetric water content was not allowed to drop as low in experiment 2 due to the severity of wilting observed in experiment 1, and moisture levels ap peared to increase fast er after irrigation was increased. For example, under 25% ETo, VWC con tinued to decline until the second irrigation

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111 at 200% ETo in experiment 1, while VWC seemed to stabilize after only one irrigation with 200% ETO in experiment 2. This may have been to be due to a hysteretic effect that increased suction during desorption, causing a delay in rewetting until it had decreased sufficiently (Hillel, 1998). Evapotranspiration In experime nt 1, after 28 sampling days, SD had the lowest ET on two occasions, and was lower than TD and PF, 2 and 8 more times, respectively (Figure 4-13). Daily ET ranged from 1.5 to 4.2 mm d and averaged 2.8, 2.9, and 3.1 mm d for SD, TD, and PF, respectively, over the course of the experiment. In experi ment 2, after 24 sampling days, PF and TD each had the lowest ET once, and TD was lower than PF one other time (Figure 4-14). Daily ET ranged from 0.7 to 3.3 mm d and all cultivars averaged 1.9 mm d over the course of the experiment. When ETo was measured daily with the Blaney-C riddle and Penman methods the averages were 4.5 and 3.3 mm d in experiment 1, and 2.6 and 1.8 mm d in experiment 2, respectively (Figures 4-15, 4-16). While the Penman me thod provided a good estimation of ET the BlaneyCriddle method tended to overestimate ET. SeaDwa rf appeared to have better ET when moisture stress was the greatest, although this advantage seemed to be negated in cooler, lower ETo conditions. Turfgrass Quality In experime nt 1, turfgrass quality declined below acceptable levels for all cultivars under 25% ETo (Figure 4-17). TifDwarf had the high est, while PF had the lowest quality prior to increasing irrigation. TifDwarf and SD had highe r quality than PF on 3 and 7 rating days prior to daily irrigation at 200% ETo, after which all cultivars exhibited similar quality as they recovered. Turfgrass quality declined below acc eptable levels for all cultivars under 50% ETo (Figure 4-18). All cultivars had similar qual ity prior to increasi ng irrigation on day 12.

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112 Afterwards, the only difference among cultivars was on day 14 when SD had higher quality than PF. Turfgrass quality, which was similar among cultivars, declined below acceptable levels under 100% ETo (Figure 4-19). In experiment 2, turfgrass quality declined below acceptable levels for PF and TD under 25% ETo (Figure 4-20 ). SeaDwarf had the highest quality on two rating days, and higher quality than TD four other times prior to increasing irrigation. During recovery, SD and PF had higher quality than TD eight and four times, respectively. Although all cultivars exhibited a decline in quality, only TD was unacceptable under 50% ETo (Figure 4-21). SeaDwarf and PF had higher quality than TD on 10 and 5 rating days, respectively, after irrigation was increased. Although irrigation was increased before quality became unacceptable, TD had lower quality than SD under 100% ETo (Figure 4-22). SeaDwarf and PF had higher quality than TD on 11 and 6 rating days, respectiv ely, after irrigation was increased. Generally, quality did not increase consistently until irrigation was applied daily at 200% ETo. This was likely due to the rapid decline in VWC that o ccurred when irrigation was applied every three days, as field capacity was usually reached within 7 hours of irrigation. Chlorophyll Levels In experime nt 1, all cultivars exhibited a decline in chlorophyll index under 25% ETo, and TD was higher than SD and PF on one and five rating days, respectively (Figure 4-23). There was little difference among cultivars after irrigation was applied daily. Although all cultivars declined, there were no differenc es in chlorophyll among cultivars under 50% ETo (Figure 4-24). A consistent decline was not observed, and all cultivars had similar chlorophyll under 100% ETo (Figure 4-25). In experiment 2, TD and SD had higher chlorophyll than PF on one rating day under 25% ETo (Figure 4-26). Only SD was higher than PF after irrigation was increased. SeaDwarf and PF had higher chlorophyll than TD on seve ral rating dates when irrigation was applied daily. Chlorophyll was similar among cultivars under 50% ETo, and

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113 remained so until irrigation was applied daily (F igure 4-27). Subsequently, PF and SD were mostly higher than TD. Chlorophyll was si milar among cultivars and did not consistently decrease under 100% ETo (Figure 4-28). After irrigation was increase d, TD was often lower than PF and SD. Within cultivar differences were only observed in experiment 1, when PF under 50 and 100% ETo had higher chlorophyll than 25% ETo on five a nd six rating days, respectively. Also, TD at 100% ETo was hi gher than 25 and 50% ETo three and two times, respectively. The reason for within cultivar differences in experiment 1 was likely due to the severe wilting that occurred. Normalized Difference Vegetative Index In experime nt 1, all cultivars exhibited a decline in NDVI, although TD was higher than PF on four rating dates under 25% ETo (Figure 4-29). Cultivars rec overed similarly, although SD had highest NDVI on the final two rating date s. All cultivars had similar NDVI, though they exhibited a decline under 50% ETo (Figure 430). Cultivars remained similar as NDVI increased until the last two days, when SD had higher NDVI than TD. Although all cultivars seemed to have increased NDVI after irriga tion was increased to 200% ETo daily, a steady decline was not observed under 100% ETo, and all cu ltivars were similar until the last two days of the experiment when SD was highest (Figur e 4-31). In experiment 2, TE and PF exhibited a noticeable reduction, and SD generally had th e highest NDVI under 25% ETo (Figure 4-32). Although TD began to recover afte r irrigation was increased, it exhi bited a decline that caused it to regularly have lower NDVI than PF and SD. TifDwarf had lower NDVI than PF and SD on two and seven rating dates, respectively, under 50% ETo (Figure 433). After all cultivars began to recover, NDVI became reduced for TD and it was lower than PF and SD six and 13 times, respectively. The NDVI remained relatively st able for all cultivar s under 100% ETo, though SD was often the highest (Figure 4-34). After irri gation was increased, a noticeable decrease in

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114 NDVI was observed for TD and it remained lower than PF and SD. Within cultivar differences were mostly observed in experiment 1, as th e 50 and 100% ETo treatments for PF had higher chlorophyll than 25% ETo on four and seven rating dates, respectively. Only one within cultivar difference was observed in experiment 2 when on day 14, 100% ETo was higher than 25% ETo for PF. The reason for the abundance of within cultivar differences in experiment 1 was likely due to the severe wilting that occurred. Table 4-1. Physical properties of Hallandale fine sand. Bulk density Organic Matter Saturated hydraulic conductivity Total pore space Macropore space Micropore space g cm g kg cm h % % % 1.35 29.0 13.1 45.5 6.0 39.5

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115 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 57911131517192123252729313335373941 DayWilting (1-10) SD PF TD Figure 4-1. Wilting ratings: % (1 = none, 2 = objectionable, and 10 = completely wilted) of sodded warm-season putting green cultivars und er 25% ETo irrigation in experiment 1 from 25 September to 31 October 2009. Means with different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. b a b a b b a a b b b a ab a ab b b a a a ab b

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116 1.0 2.0 3.0 4.0 5.0 6.0 7.0 681012141618202224262830323436384042 DayWilting (1-10) SD PF TD Figure 4-2. Wilting ratings: % (1 = none, 2 = objectionable, and 10 = completely wilted) of sodded warm-season putting green cultivars und er 50% ETo irrigation in experiment 1 from 26 September to 1 November 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. b ab a a ab b

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117 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 11131517192123252729313335373941 DayWilting (1-10) SD PF TD Figure 4-3. Wilting ratings: % (1 = none, 2 = objectionable, and 10 = completely wilted) of sodded warm-season putting green cultivars und er 100% ETo irrigation in experiment 1 from 31 September to 31 October 2009. Means with different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively.

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118 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 357911131517192123252729 DayWilting (1-10) SD PF TD Figure 4-4. Wilting ratings: % (1 = none, 2 = objectionable, and 10 = completely wilted) of sodded warm-season putting green cultivars und er 25% ETo irrigation in experiment 2 from 14 November to 10 December 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a b b a b b a ab b a ab b a a b a ab b b b a ab a ab b a ab b a ab b a ab b

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119 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 3579111315171921232527 DayWilting (1-10) SD PF TD Figure 4-5. Wilting ratings: % (1 = none, 2 = objectionable, and 10 = completely wilted) of sodded warm-season putting green cultivars und er 50% ETo irrigation in experiment 2 from 14 November to 9 December 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. b a a b b b a b b a b b a b b a a b b b ab a ab a b a b b

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120 1.0 1.5 2.0 2.5 3.0 3.5 4.0 357911131517192123252729 DayWilting (1-10) SD PF TD Figure 4-6. Wilting ratings: % (1 = none, 2 = objectionable, and 10 = completely wilted) of sodded warm-season putting green cultivars und er 100% ETo irrigation in experiment 2 from 14 November to 10 December 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a b ab

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121 5.0 7.0 9.0 11.0 13.0 15.0 17.0 19.0 21.0 23.0 25.0 13579111315171921232527293133353739 DayVolumetric water content (%) SD PF TD Figure 4-7. Soil moisture for sodded warm -season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively.

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122 7.0 9.0 11.0 13.0 15.0 17.0 19.0 21.0 23.0 25.0 13579111315171921232527293133353739 DayVolumetric water content (%) SD PF TD Figure 4-8. Soil moisture for sodded warm -season putting green cultivars under 50% ETo irrigation in experiment 1 from 20 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively.

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123 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 13579111315171921232527293133353739 DayVolumetric water content (%) SD PF TD Figure 4-9. Soil moisture for sodded warm -season putting green cultivars under 100% ETo irrigation in experiment 1 from 20 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively.

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124 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 1357911131517192123252729 DayVolumetric water content (%) SD PF TD Figure 4-10. Soil moisture for sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 12 N ovember to 10 December 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively. a ab b a ab b a b b a ab b a ab b a ab b b ab a a b b a b

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125 10.0 12.0 14.0 16.0 18.0 20.0 22.0 1357911131517192123252729 DayVolumetric water content (%) SD PF TD Figure 4-11. Soil moisture for sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 2 from 12 N ovember to 10 December 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively.

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126 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 23.0 1357911131517192123252729 DayVolumetric water content (%) SD PF TD Figure 4-12. Soil moisture for sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 2 from 12 N ovember to 10 December 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively.

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127 1.5 2 2.5 3 3.5 4 4.5 912141618202225272933353739 DayEvapotranspiration (mm) SD PF TD Figure 4-13. Evapotranspiration of sodded warm-season putting green cultivars in experiment 1 from 29 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TD=TifDwarf. a ab b a a b c a b a b b b a ab a b b b b a a b a b b a b a a ab b

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128 0.5 1 1.5 2 2.5 3 3.5 13591113151720232527 DayEvapotranspiration (mm) SD PF TD Figure 4-14. Evapotranspiration of sodded warm-season putting green cultivars in experiment 2 from 12 November to 9 December 2009. Means with different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TD=TifDwarf. ab a a b a b a b

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129 1 2 3 4 5 912141618202225272933353739 DayEvapotranspiration (mm) SeaDwarf PristineFlora TifDwarf Blaney-Criddle Penman Figure 4-15. Comparison of eva potranspiration (ET) calculation me thods in experiment 1 from 29 September to 30 October 2009. Actual ET of grasses was determined with lysimeters and compared to the Blan ey-Criddle and Penman methods.

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130 0.5 1 1.5 2 2.5 3 3.5 13591113151720232527 DayEvapotranspiration (mm) SeaDwarf PristineFlora TifDwarf Blaney-Criddle Penman Figure 4-16. Comparison of eva potranspiration (ET) calculation me thods in experiment 2 from 12 November to 9 December 2009. Actual ET of grasses was determined with lysimeters and compared to the Blan ey-Criddle and Penman methods.

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131 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 1357911131517192123252729313335373941 DayQuality (1-10) SD PF TD Figure 4-17. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best) of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 September to 31 October 2009. Means with different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a ab b a ab b c a b b a a a ab b a a b b ab a a ab b b ab a a ab b

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132 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 1357911131517192123252729313335373941 DayQuality (1-10) SD PF TD Figure 4-18. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best) of sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 1 from 20 September to 31 October 2009. Means with different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a ab b

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133 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 1357911131517192123252729313335373941 DayQuality (1-10) SD PF TD Figure 4-19. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best) of sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 1 from 20 September to 31 October 2009. Means with different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively.

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134 5.5 6.0 6.5 7.0 7.5 8.0 8.5 1357911131517192123252729 DayQuality (1-10) SD PF TD Figure 4-20. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best) of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 12 November to 10 December 2009. Means w ith different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a ab b a ab b a a b a ab b a b b a b b a ab b b ab a a ab b ab a b a ab b b a a a a b a a b b a a

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135 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 1357911131517192123252729 DayQuality (1-10) SD PF TD Figure 4-21. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best) of sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 2 from 12 November to 10 December 2009. Means w ith different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. b ab a b a a a b a a b b a a a b b ab a ab a b a ab b ab a b b a ab a ab b b a a a a b b a a a ab b

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136 6.0 6.5 7.0 7.5 8.0 8.5 9.0 1357911131517192123252729 DayQuality (1-10) SD PF TD Figure 4-22. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best) of sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 2 from 12 November to 10 December 2009. Means w ith different letters are statistically different at the 0.05 probability leve l based on the Tukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=T ifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. b ab a a b b ab ab b a a ab b a ab a a b b ab a a b a a b b a a a a b b a a

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137 120 140 160 180 200 220 240 260 13579111315171921232527293133353739 DayChlorophyll index SD PF TD Figure 4-23. Chlorophyll index of sodded warm -season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively. a ab b a ab b a ab b b ab a a ab b b a ab a b b a ab a ab b

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138 120 140 160 180 200 220 240 260 13579111315171921232527293133353739 DayChlorophyll index SD PF TD Figure 4-24. Chlorophyll index of sodded wa rm-season putting green cultivars under 50% ETo irrigation in experiment 1 from 20 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively.

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139 150 160 170 180 190 200 210 220 230 240 250 13579111315171921232527293133353739 DayChlorophyll index SD PF TD Figure 4-25. Chlorophyll index of sodded wa rm-season putting green cultivars under 100% ETo irrigation in experiment 1 from 20 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively.

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140 175 200 225 250 275 300 1357911131517192123252729 DayChlorophyll index SD PF TD Figure 4-26. Chlorophyll index of sodded wa rm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 12 N ovember to 10 December 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively. b ab a b ab a a ab b a ab b b a aba ab b b ab a b a a a a b a a a ab b b

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141 175 200 225 250 275 300 1357911131517192123252729 DayChlorophyll index SD PF TD Figure 4-27. Chlorophyll index of sodded wa rm-season putting green cultivars under 50% ETo irrigation in experiment 2 from 12 N ovember to 10 December 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigation at 200% ETo, respectively. a a b b ab a b a a a a b b a a a a a a b b

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142 175 200 225 250 275 300 1357911131517192123252729 DayChlorophyll index SD PF TD Figure 4-28. Chlorophyll index of sodded wa rm-season putting green cultivars under 100% ETo irrigation in experiment 2 from 12 N ovember to 10 December 2009. Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method. SD=SeaDwarf ; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200 % ETo every three days and start of daily irrigati on at 200% ETo, respectively. a ab b a ab b ab a b b a a a a b a a b b a a a a b b b a a

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143 0.450 0.500 0.550 0.600 0.650 0.700 0.750 0.800 13579111315171921232527293133353739 DayNDVI SD PF TD Figure 4-29. Normalized difference vegeta tive index (NDVI) of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. b ab a b ab a a ab b b a ab a a b b a ab b b b b a a

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144 0.500 0.550 0.600 0.650 0.700 0.750 0.800 13579111315171921232527293133353739 DayNDVI SD PF TD Figure 4-30. Normalized difference vegeta tive index (NDVI) of sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 1 from 20 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a ab b b ab a

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145 0.550 0.600 0.650 0.700 0.750 13579111315171921232527293133353739 DayNDVI SD PF TD Figure 4-31. Normalized difference vegeta tive index (NDVI) of sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 1 from 20 September to 30 October 2009. Means with different letters are statistically different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a b a b

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146 0.65 0.7 0.75 0.8 0.85 1357911131517192123252729 DayNDVI SD PF TD Figure 4-32. Normalized difference vegeta tive index (NDVI) of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 12 November to 10 December 2009. Means with diffe rent letters are statisti cally different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a ab b a b b a b b a b b b b a a b b a b b a b b b b a a b b a ab b a ab b a ab b a ab b a b b a b b a b b a ab b ab a b b a b a a a a a a a a ab b b b b b b b b a a a ab a a a

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147 0.65 0.7 0.75 0.8 0.85 1357911131517192123252729 DayNDVI SD PF TD Figure 4-33. Normalized difference vegeta tive index (NDVI) of sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 2 from 12 November to 10 December 2009. Means with diffe rent letters are statisti cally different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a ab b b ab a b a a a b b a ab a b a ab a ab b b ab a b a ab ab a b b a ab b ab a b b b b b b b b ab a a a ab a a a a a a a a a a a

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148 0.65 0.7 0.75 0.8 0.85 1357911131517192123252729 DayNDVI SD PF TD Figure 4-34. Normalized difference vegeta tive index (NDVI) of sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 2 from 12 November to 10 December 2009. Means with diffe rent letters are statisti cally different at the 0.05 probability level based on the T ukey-Kramer method. SD=SeaDwarf; PF=PristineFlora; TE=TifEagle; TD=TifDwarf. Arrows ( and ) indicate irrigation at 200% ETo every three days and start of daily irrigation at 200% ETo, respectively. a ab b a b b b b a a b b a ab b b b a a ab b b ab a a b b a b b a ab b ab a a ab b b ab a a a b b a ab a b a a a b a a b b a a a a a a a a a a a a a a a a b b b b b b b

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149 CHAPTER 5 CONCLUSIONS Concerns of non-point source pollution and dw indling fresh wa ter supplies are forcing turfgrass managers to adopt best management practices (BMP) and consider the use of putting green cultivars that require fewer nutrient and fresh water inputs. To accommodate these concerns turfgrass breeders have developed cultivars of seashore paspalum and zoysiagrass that are purported to require only half the N and water compared to the more commonly used bermudagrasses. The purpose of this disserta tion was to compare the nutrient and water use characteristics of selected bermudagrass, s eashore paspalum and zoysiagrass putting green cultivars. Results indicated that the commonly accepted practice of applying 4.9 g N m wk during grow-in of warm-season grasses may be excessive, as growth with 2.4 g N m week was similar to the higher weekly rates within a ll cultivars. Even less N is required for rapid establishment of SeaDwa rf (SD), as 1.2 g N m wk was similar to all higher weekly N rates in warmer temperatures. Furthe rmore, applying N at 1.2 g m wk to the cultivars studied provided cover similar to the highe r weekly rates in as little as a week, and provided superior stands of turf, as thatch development, surface compressibility, and mower scalping were reduced. Increasing N/K fertilization ratios above 1N:1 K did not decrease grow-in time or improve turfgrass quality for the cultiv ars studied. Although informati on on newer putting green cultivars is limited, the lack of differences among N:K ratios was not completely un expected, as previous research conducted on bermudagrass cv. Tifgreen showed no increase in color, disease resistance, growth, quality, or rooting with N/K ratios above 1N:0.5K (Peacock et al., 1997; Snyder and Cisar, 2000a). Establishing warm-seas on cultivars during the fall and winter seasons

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150 in subtropical climates can slow the rate of tu rfgrass coverage dramatically, particularly for zoysiagrass, and should be avoided, as the ability to utilize nutrients is reduced, and the potential for nutrient leaching is increased (Snyder and Cisar, 2000b; Snyder and Cisar 2008). Most warm-season putting green cultivars released after 1996 are considered ultradwarves, and tend to develop th atch quickly. Thatch acts as a cushion that protects turfgrass from traffic, but can cause a reduction in putting green quality due to increased surface compressibility and mower scalping if allowed to become excessive (McC arty and Miller, 2002). Cultural practices used to contro l thatch can reduce putting surface quality, and interrupt play for several weeks until recovered (Landreth et al., 2 007). Cultivars that can tolerate current mowing heights without developing excessive thatch can save time, labor and the expense of putting green down-time. Although PristineFlora (PF) was so mewhat slower to establish, particularly in the winter, it provided a high quality stand of turf that develo ped minimal thatch, tolerated mowing heights of 2.8 mm, and did not seem to require the same cultural inputs as the other cultivars. If time rest raints demand faster establishment, higher sprigging rates (i.e., 54.9 73.2 m ha ), or sod could be used to reduce grow-in time. With increased water restric tions, the development of drought resistant turfgrasses has become imperative. Turfgrass researchers have focused their attention on the mechanisms of drought tolerance, and are using inter-specifi c breeding and biotech methods to enhance desirable characteristics. Grasses that have lo w evapotranspiration (ET) rates and do not exhibit excessive leaf firing or wilting under moderate drought stress, are desirable for golf greens since a high quality putting surface is of utmost concern. In the phase III water restrictions enacted in 2008, golf courses were allowed to use 50% of the adjusted Blaney-Criddle ET estimation me thod (ETo). This amount of irrigation would

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151 normally be sufficient for PF and SD grown on Un ited States Golf Association (USGA) greens, as objectionable wilting of thes e cultivars only occurred duri ng above normal temperatures and wind speeds. The bermudagrasses studied required in excess of 50% ETo, as severe wilting was observed. Irrigation requirements are increased on sandy native soils that do not have a choker layer similar to that used in USGA-specified greens due to an inability to delay drainage of water through the root zone. All of the cultivars studied exhibited objectionable wilting when irrigated at 100% ETo on native soil. SeaDwarf appeared to be the most drought resistant cultivar studied, as at times it exhibited lowest ET ra tes, wilting, highest chlorophyll, normalized difference vegetative index, soil mo isture, turfgrass quality, and faster recovery from drought stress. Although most golf course superi ntendents apply K in relation to N at N/K ratios ranging from 1N:1KN-2K, some use ratios in excess of 1N:10K. These ultr a high N/K ratios are thought to help maintain turfgrass quality wh en N and irrigation are reduced to promote increased green speeds. Results indicated incr easing N:K ratios above 1N:1K does not improve, and may have a negative impact on drought resistance in the cultivars studied, as wilting was marginally increased (P<0.10) on two rating da tes for 1N:4K compared to 1N:1K. Also, Trenholm et al. (1998) reported decreased qua lity in FloraDwarf bermudagrass as K was increased from 0.6 to 4.9 g m mo Furthermore, although K is not considered to be a nutrient of impairment, the use of N/K ratios higher than 1N:1K should be avoided as the potential for leaching and runoff, as well as reductions of soil Ca and Mg are increased. The nutrient and water use studies shown in this dissertation contribute to the understanding of the effects of nutrients and wa ter on putting green cultivars. Ultimately, this

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152 information could be used to develop BMP for fe rtilization and irrigati on to help reduce the environmental impacts of golf courses.

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153 APPENDIX A CHAPTER 2 DATA 15 17 19 21 23 25 27 123456789101112131415161718192021222324252627 WeekMean Air Temperature (C) Actual Historical Figure A-1. Actual and historical mean air temperatures (C) in experiment 1 from 20 October 2008 16 April 2009.

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154 23 24 25 26 27 28 29 30 123456789101112131415 WeekMean Air Temperature (C) Actual Historical Figure A-2. Actual and hist orical mean air temperatures (C) in experiment 2 from 23 July to 4 November 2009.

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155 Table A-1. Effect of potassium on turfgrass cover. Cover Factor 2008 2009 % Nitrogen (N) / Potassium (K) ratio 1N:1K 71.8 a 94.7 a 1N:2K 72.2 a 94.5 a 1N:3K 72.8 a 93.3 a 1N:4K 72.4 a 94.2 a LSD 0.05 2.8 1.9 Grass*K PristineFlora*1N:1K 43.3 d 89.7 bc PristineFlora*1N:2K 42.7 d 89.0 bc PristineFlora*1N:3K 44.0 d 86.7 c PristineFlora*1N:4K 43.3 d 88.7 c SeaDwarf*1N:1K 82.7 abc 98.0 a SeaDwarf*1N:2K 83.7 abc 98.0 a SeaDwarf*1N:3K 83.3 abc 97.3 a SeaDwarf*1N:4K 83.7 abc 97.3 a TifDwarf*1N:1K 85.0 ab 95.7 a TifDwarf*1N:2K 84.7 ab 96.0 a TifDwarf*1N:3K 85.3 a 95.3 a TifDwarf*1N:4K 83.7 abc 95.3 a TifEagle*1N:1K 76.3 c 95.3 a TifEagle*1N:2K 77.7 bc 95.0 a TifEagle*1N:3K 78.3 abc 94.0 ab TifEagle*1N:4K 79.0 abc 95.3 a LSD 0.05 8.7 5.1 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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156 Table A-2. Effect of potassium on chlorophyll index. Chlorophyll index Factor 2008 2009 Nitrogen (N) / Potassium (K) ratio 1N:1K 206.0 a 276.4 a 1N:2K 200.2 ab 274.9 a 1N:3K 192.2 b 269.2 a 1N:4K 196.9 ab 273.8 a LSD 0.05 12.7 13.2 Grass*K PristineFlora*1N:1K 116.8 c 238.2 cd PristineFlora*1N:2K 112.2 c 217.9 d PristineFlora*1N:3K 109.9 c 221.6 d PristineFlora*1N:4K 109.9 c 226.4 d SeaDwarf*1N:1K 268.9 a 295.6 ab SeaDwarf*1N:2K 264.6 a 309.5 a SeaDwarf*1N:3K 261.7 a 295.6 ab SeaDwarf*1N:4K 262.0 a 297.2 ab TifDwarf*1N:1K 226.7 b 289.7 ab TifDwarf*1N:2K 209.5 b 289.5 ab TifDwarf*1N:3K 201.2 b 286.9 ab TifDwarf*1N:4K 209.6 b 279.7 ab TifEagle*1N:1K 211.4 b 282.3 ab TifEagle*1N:2K 214.4 b 282.6 ab TifEagle*1N:3K 196.1 b 272.6 bc TifEagle*1N:4K 206.0 b 291.7 ab LSD 0.05 34.0 35.3 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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157 Table A-3. Effect of potassium on thatch depth. Thatch depth Factor 2008 2009 cm Nitrogen (N) / Potassium (K) ratio 1N:1K 0.89 a 0.80 a 1N:2K 0.91 a 0.81 a 1N:3K 0.89 a 0.77 a 1N:4K 0.88 a 0.83 a LSD 0.05 0.13 0.13 Grass*K PristineFlora*1N:1K 0.67 bc 0.64 ab PristineFlora*1N:2K 0.67 bc 0.70 ab PristineFlora*1N:3K 0.67 bc 0.49 b PristineFlora*1N:4K 0.59 c 0.62 ab SeaDwarf*1N:1K 1.02 a 0.84 a SeaDwarf*1N:2K 1.09 a 0.86 a SeaDwarf*1N:3K 0.99 ab 0.89 a SeaDwarf*1N:4K 1.08 a 0.91 a TifDwarf*1N:1K 0.88 abc 0.82 ab TifDwarf*1N:2K 0.89 abc 0.83 ab TifDwarf*1N:3K 0.91 abc 0.87 a TifDwarf*1N:4K 0.95 ab 0.87 a TifEagle*1N:1K 1.01 ab 0.90 a TifEagle*1N:2K 0.98 ab 0.85 a TifEagle*1N:3K 0.98 ab 0.91 a TifEagle*1N:4K 0.90 abc 0.93 a LSD 0.05 0.34 0.34 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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158 Table A-4. Effect of potassium on root length. Root length Factor 2008 2009 cm Nitrogen (N) / Potassium (K) ratio 1N:1K 13.2 a 13.9 a 1N:2K 13.0 a 14.8 a 1N:3K 12.9 a 13.4 a 1N:4K 13.0 a 13.9 a LSD 0.05 0.84 1.42 Grass*K PristineFlora*1N:1K 7.9 b 11.1 de PristineFlora*1N:2K 7.6 b 11.2 cde PristineFlora*1N:3K 7.2 b 9.7 e PristineFlora*1N:4K 7.4 b 12.6 b-e SeaDwarf*1N:1K 14.0 a 16.0 ab SeaDwarf*1N:2K 14.1 a 15.8 ab SeaDwarf*1N:3K 14.2 a 14.8 a-d SeaDwarf*1N:4K 14.1 a 15.4 ab TifDwarf*1N:1K 16.0 a 15.3 ab TifDwarf*1N:2K 15.5 a 16.6 a TifDwarf*1N:3K 15.4 a 15.0 abc TifDwarf*1N:4K 15.4 a 14.9 a-d TifEagle*1N:1K 15.0 a 13.3 a-e TifEagle*1N:2K 14.7 a 15.4 ab TifEagle*1N:3K 15.0 a 14.3 a-d TifEagle*1N:4K 15.1 a 12.9 a-e LSD 0.05 2.25 3.84 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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159 Table A-5. Effect of potassi um on surface compressibility. Compressibility Factor 2008 2009 mm Nitrogen (N) / Potassium (K) ratio 1N:1K 3.39 a 3.99 a 1N:2K 3.38 a 4.04 a 1N:3K 3.34 a 3.85 a 1N:4K 3.37 a 3.95 a LSD 0.05 0.19 0.22 Grass*K PristineFlora*1N:1K 2.53 c 4.35 ab PristineFlora*1N:2K 2.37 c 4.45 a PristineFlora*1N:3K 2.42 c 4.20 abc PristineFlora*1N:4K 2.35 c 4.43 a SeaDwarf*1N:1K 4.43 a 4.43 a SeaDwarf*1N:2K 4.60 a 4.37 ab SeaDwarf*1N:3K 4.32 a 4.05 a-d SeaDwarf*1N:4K 4.63 a 4.12 abc TifDwarf*1N:1K 3.23 b 3.48 de TifDwarf*1N:2K 3.20 b 3.70 cde TifDwarf*1N:3K 3.28 b 3.45 e TifDwarf*1N:4K 3.10 b 3.47 e TifEagle*1N:1K 3.35 b 3.68 cde TifEagle*1N:2K 3.35 b 3.63 cde TifEagle*1N:3K 3.35 b 3.68 cde TifEagle*1N:4K 3.40 b 3.80 b-e LSD 0.05 0.50 0.58 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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160 Table A-6. Effect of potassium on ball roll. Ball roll Factor 2008 2009 cm Nitrogen (N) / Potassium (K) ratio 1N:1K 58.0 a 53.9 a 1N:2K 59.5 a 53.6 a 1N:3K 59.2 a 54.2 a 1N:4K 58.0 a 53.3 a LSD 0.05 2.36 1.70 Grass*K PristineFlora*1N:1K 52.5 de 46.5 d PristineFlora*1N:2K 52.0 e 46.0 d PristineFlora*1N:3K 54.7 cde 46.0 d PristineFlora*1N:4K 53.0 de 45.7 d SeaDwarf*1N:1K 55.2 cde 52.8 bc SeaDwarf*1N:2K 61.0 abc 52.8 bc SeaDwarf*1N:3K 56.9 b-e 52.8 bc SeaDwarf*1N:4K 57.9 b-e 52.3 c TifDwarf*1N:1K 61.0 abc 58.1 a TifDwarf*1N:2K 60.5 abc 58.8 a TifDwarf*1N:3K 60.5 abc 58.6 a TifDwarf*1N:4K 58.8 a-d 59.3 a TifEagle*1N:1K 63.2 ab 58.1 a TifEagle*1N:2K 64.6 a 56.9 ab TifEagle*1N:3K 64.9 a 59.3 a TifEagle*1N:4K 62.5 ab 55.9 abc LSD 0.05 6.32 4.56 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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161 Table A-7. Converted modified st impmeter ball roll distances. Ball Roll Factor 2008 2009 cm Grass PristineFlora 222.8 d 193.3 c SeaDwarf 242.3 c 221.0 b TifDwarf 252.7 b 246.4 a TifEagle 267.7 a 241.6 a Nitrogen 1.2 244.8 a 231.1 a 2.4 247.3 a 221.6 b 3.7 244.2 a 220.0 b 4.9 244.2 a 223.5 ab 39.1 251.5 a 231.5 a Potassium 1N:1K 243.3 a 226.1 a 1N:2K 249.9 a 225.0 a 1N:3K 248.7 a 227.3 a 1N:4K 243.6 a 223.8 a Cultivar*Nitrogen PristineFlora*1.2 215.9 g 198.1 fg PristineFlora*2.4 224.8 fg 188.0 g PristineFlora*3.7 228.6 efg 196.8 fg PristineFlora*4.9 215.9 g 193.0 g PristineFlora*39.1 228.6 efg 190.5 g SeaDwarf*1.2 248.9 a-f 222.2 cde SeaDwarf*2.4 240.0 c-g 221.0 de SeaDwarf*3.7 234.9 d-g 218.4 def SeaDwarf*4.9 241.3 b-g 209.6 efg SeaDwarf*39.1 246.4 a-g 233.7 a-d TifDwarf*1.2 242.6 a-g 248.9 a TifDwarf*2.4 251.5 a-f 243.8 abc TifDwarf*3.7 256.5 a-e 240.0 a-d TifDwarf*4.9 252.7 a-f 243.8 abc TifDwarf*39.1 260.4 a-d 255.3 a TifEagle*1.2 271.8 ab 255.3 a TifEagle*2.4 273.0 a 233.7 a-d TifEagle*3.7 256.5 a-e 224.8 b-e TifEagle*4.9 266.7 abc 247.6 a TifEagle*39.1 270.5 abc 246.4 ab Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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162 Table A-8. Effect of pot assium on mower scalping. Scalping Factor 2008 2009 1-10 Nitrogen (N) / Potassium (K) ratio 1N:1K 1.8 a 3.0 a 1N:2K 1.8 a 2.8 a 1N:3K 1.7 a 2.8 a 1N:4K 1.9 a 3.0 a LSD 0.05 0.38 0.44 Grass*K PristineFlora*1N:1K 1.0 d 1.3 c PristineFlora*1N:2K 1.0 d 1.4 c PristineFlora*1N:3K 1.0 d 1.3 c PristineFlora*1N:4K 1.0 d 1.4 c SeaDwarf*1N:1K 1.2 cd 1.4 c SeaDwarf*1N:2K 1.2 d 1.4 c SeaDwarf*1N:3K 1.2 cd 1.4 c SeaDwarf*1N:4K 1.2 d 1.4 c TifDwarf*1N:1K 3.5 a 4.9 a TifDwarf*1N:2K 2.8 ab 4.3 ab TifDwarf*1N:3K 2.9 ab 5.0 a TifDwarf*1N:4K 3.5 a 4.7 ab TifEagle*1N:1K 1.5 cd 4.4 ab TifEagle*1N:2K 2.2 bc 4.0 ab TifEagle*1N:3K 1.6 cd 3.6 b TifEagle*1N:4K 1.9 bcd 4.3 ab LSD 0.05 1.03 1.19 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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163 Table A-9. Effect of pot assium on turfgrass quality. Quality Factor 2008 2009 1-10 Nitrogen (N) / Potassium (K) ratio 1N:1K 7.34 a 6.92 a 1N:2K 7.27 a 6.94 a 1N:3K 7.30 a 6.92 a 1N:4K 7.22 a 6.92 a LSD 0.05 0.20 0.16 Grass*K PristineFlora*1N:1K 7.93 a 7.77 ab PristineFlora*1N:2K 7.93 a 7.80 a PristineFlora*1N:3K 7.93 a 7.77 ab PristineFlora*1N:4K 7.93 a 7.80 a SeaDwarf*1N:1K 7.17 bcd 6.60 c SeaDwarf*1N:2K 7.00 bcd 6.57 c SeaDwarf*1N:3K 7.00 bcd 6.60 c SeaDwarf*1N:4K 6.77 d 6.57 c TifDwarf*1N:1K 6.83 cd 5.97 d TifDwarf*1N:2K 6.70 d 6.00 d TifDwarf*1N:3K 6.80 cd 5.97 d TifDwarf*1N:4K 6.83 cd 6.00 d TifEagle*1N:1K 7.43 ab 7.33 b TifEagle*1N:2K 7.43 ab 7.37 ab TifEagle*1N:3K 7.43 ab 7.33 b TifEagle*1N:4K 7.33 bc 7.37 ab LSD 0.05 0.54 0.43 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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164 Table A-10. Effect of pota ssium on turfgrass recovery. Recovery Factor 2008 2009 1-10 Nitrogen (N) / Potassium (K) ratio 1N:1K 8.39 a 7.56 a 1N:2K 8.28 a 7.42 a 1N:3K 8.22 a 7.33 a 1N:4K 8.23 a 7.52 a LSD 0.05 0.48 0.47 Grass*K PristineFlora*1N:1K 9.87 a 9.20 a PristineFlora*1N:2K 9.87 a 9.10 ab PristineFlora*1N:3K 9.87 a 9.10 ab PristineFlora*1N:4K 9.87 a 9.20 a SeaDwarf*1N:1K 8.53 b 6.63 c SeaDwarf*1N:2K 8.20 bc 6.40 c SeaDwarf*1N:3K 8.13 bc 6.13 c SeaDwarf*1N:4K 7.67 bcd 6.50 c TifDwarf*1N:1K 6.80 d 6.37 c TifDwarf*1N:2K 6.80 d 6.23 c TifDwarf*1N:3K 6.53 d 6.07 c TifDwarf*1N:4K 7.00 cd 6.40 c TifEagle*1N:1K 8.37 b 8.00 ab TifEagle*1N:2K 8.27 bc 7.93 b TifEagle*1N:3K 8.33 b 8.00 ab TifEagle*1N:4K 8.40 b 8.00 ab LSD 0.05 1.29 1.25 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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165 Table A-11. Effect of potassium on algal cover. Algae Factor 2008 2009 % Nitrogen (N) / Potassium (K) ratio 1N:1K 8.9 a 31.8 a 1N:2K 10.0 a 28.8 ab 1N:3K 10.8 a 29.1 ab 1N:4K 10.5 a 24.8 b LSD 0.05 4.86 6.99 Grass*K PristineFlora*1N:1K 23.0 a 45.0 a PristineFlora*1N:2K 27.0 a 43.0 a PristineFlora*1N:3K 28.0 a 42.0 a PristineFlora*1N:4K 30.0 a 39.0 ab SeaDwarf*1N:1K 2.7 b 27.0 a-d SeaDwarf*1N:2K 2.0 b 19.3 cd SeaDwarf*1N:3K 2.7 b 20.3 bcd SeaDwarf*1N:4K 2.3 b 18.7 cd TifDwarf*1N:1K 6.0 b 19.7 cd TifDwarf*1N:2K 5.3 b 20.7 bcd TifDwarf*1N:3K 7.0 b 22.0 bcd TifDwarf*1N:4K 5.7 b 15.0 d TifEagle*1N:1K 4.0 b 35.3 abc TifEagle*1N:2K 5.7 b 32.3 a-d TifEagle*1N:3K 5.3 b 32.0 a-d TifEagle*1N:4K 4.0 b 26.3 a-d LSD 0.05 13.02 18.72 Means with different letters are statistically di fferent at the 0.05 probabi lity level based on the Tukey-Kramer method.

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166 APPENDIX B CHAPTER 3 DATA y = 0.9696x 3.1662 R2 = 0.8581 0 5 10 15 20 25 0 5 10 15 20 25 30Theta Meter with Grass (%)Theta Meter in Soil (%) Soil Linear ( Soil) Figure B-1. Comparison of theta meter with grass in place, and removed fo r direct reading of volumetric water content.

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167 y = 0.9812x 2.993 R2 = 0.7657 0 5 10 15 20 25 0 5 10 15 20 25 30Theta Meter VWC (%)Gravimetric VWC (%) VWC Linear (VWC) Figure B-2. Comparison of theta meter with gr ass in place and the gravimetric method of determining volumetric water content.

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168 y = 1.039x 0.0931 R2 = 0.9405 0 5 10 15 20 25 0 5 10 15 20 25Theta Meter VWC (%)Gravimetric VWC (%) VWC Linear (VWC) Figure B-3. Comparison of theta meter with grass removed and the gravimetric method of determining volumetric water content.

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169 23.0 24.0 25.0 26.0 27.0 28.0 1234567891011121314151617181920212223 DayMean Air Temperature (C) Actual Historical Figure B-4. Actual and hi storical mean air temperatures (C) in experiment 1 from 23 April to 16 May 2009.

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170 17 19 21 23 25 27 29 31 12345678910111213141516171819202122 DayMean Air Temperature (C) Actual Historical Figure B-5. Actual and hi storical mean air temperatures (C) in experiment 2 from 9 October to 31 October 2009.

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171 0 2 4 6 8 10 12 14 16 8910111213141516171819202122 DayWilting (%) 1:1 1:2 1:3 1:4 Figure B-6. Wilting ratings: % (0 = none, 10 = objecti onable, and 100 = completely wilted) of recently established warm-season putti ng green cultivars on a USGA-specified research green as affected by nitrogen/potas sium ratio (N:K) in experiment 1 from 2 May to 16 May 2009. Means with different le tters are statistically different at the 0.05 probability level based on the Tukey-Kramer method.

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172 0 5 10 15 20 25 891011121314151617181920 DayWilting (%) 1:1 1:2 1:3 1:4 Figure B-7. Wilting ratings: % (0 = none, 10 = objecti onable, and 100 = completely wilted) of recently established warm-season putti ng green cultivars on a USGA-specified research green as affected by nitrogen/potas sium ratio (N:K) in experiment 2 from 18 October to 30 October 2009. Means with differe nt letters are statistically different at the 0.05 probability level based on the Tukey-Kramer method.

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173 14.0 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 23.0 6789101112131415161718 DayVolumetric water content (%) 1:1 1:2 1:3 1:4 Figure B-8. Volumetric water content of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 1 from 30 April to 12 May 2009. Means with di fferent letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method.

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174 7.7 7.8 7.9 8.0 8.1 8.2 8.3 8.4 8.5 8910111213141516171819202122 DayQuality (1-10) 1:1 1:2 1:3 1:4 Figure B-9. Quality of recently established warm-season putting green cultivars on a USGAspecified research green in experime nt 1 from 2 May to 16 May 2009. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method.

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175 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8.0 8.1 8.2 910111213141516171819 DayQuality (1-10) 1:1 1:2 1:3 1:4 Figure B-10. Quality of recently established warm-season putting green cultivars on a USGAspecified research green in experiment 2 from 19 Octobe r to 29 October 2009. Quality ratings: 1-10 (1 = dead, 6 = mini mum acceptable, and 10 = best). Means with different letters are statistically different at the 0.05 probabili ty level based on the Tukey-Kramer method.

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176 300 305 310 315 320 325 330 335 340 89101112131415161718 DayChlorophyll index 1:1 1:2 1:3 1:4 Figure B-11. Chlorophyll index of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 1 from 2 May to 12 May 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method.

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177 200 210 220 230 240 250 260 91 01 11 21 31 41 5 DayChlorophyll index 1:1 1:2 1:3 1:4 Figure B-12. Chlorophyll index of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 2 from 19 October to 25 October 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method.

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178 0.805 0.810 0.815 0.820 0.825 0.830 0.835 0.840 89101112131415161718 DayNDVI 1:1 1:2 1:3 1:4 Figure B-13. Normalized difference vegetativ e index (NDVI) of recently established warmseason putting green cultivars on a USGA-specified resear ch green as affected by nitrogen/potassium ratio (N:K) in expe riment 1 from 2 May to 12 May 2009. Means with different letters are statistically different at th e 0.05 probability level based on the Tukey-Kramer method.

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179 0.720 0.730 0.740 0.750 0.760 0.770 0.780 0.790 9101112131415 DayNDVI 1:1 1:2 1:3 1:4 Figure B-14. Normalized difference vegetativ e index (NDVI) of recently established warmseason putting green cultivars on a USGA-specified resear ch green as affected by nitrogen/potassium ratio (N:K) in experi ment 2 from 19 October to 25 October 2009. Means with different letters are statistica lly different at the 0.05 probability level based on the Tukey-Kramer method.

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180 APPENDIX C CHAPTER 4 DATA 17 19 21 23 25 27 29 31 1357911131517192123252729313335373941 DayMean Air Temperature (C) Actual Historical Figure C-1. Actual and historic al mean air temperatures (C) in experiment 1 from 20 September to 30 October 2009.

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181 15 17 19 21 23 25 27 1234567891011121314151617181920212223242526272829303132 DayMean Air Temperature (C) Actual Historical Figure C-2. Actual and hi storical mean air temperatures (C) in experiment 2 from 11 November to 12 December 2009.

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182 LIST OF REFERENCES Aronson, L.J., A.J. Gold, R.J. Hull, and J.L. Cisar. 1987. Evapotranspiration of coolseason turfgrasses in the humid northeast. Agron. J. 79:901. Augustin, B.J. 1983. W ater requirements of Flor ida turfgrasses. IFAS Publication BUL200. Augustin, B.J. 1992. Surviving drought Grounds Maintenance. 27(5):65,94. Baldwin, C.M., H. Liu, L.B. McCarty, H. Luo, and J.E. Toler. 2009. Nitrogen and plant growth regulator influence on Champion be rmudagrass putting green unde r reduced sunlight. Agron. J. 101:75. Barnett, C. 2007. Mirage: Florida and the vanish ing water of the Eastern U.S. The University of Michigan Press, Ann Arbor, MI. Beard, J.B. 1973. Turfgrass: Science and culture Prentice-Hall, Inc. Englewood Cliffs, NJ. Blaney, H.F., and W.D. Criddle. 1950. Determin ing water requirements in irrigated areas from climatological data. U.S.D. A. Soil Conservation Service Tech. Pub. 96. Brady N.C., and R.R. Weil. 1999. The Nature and Properties of Soils. Prentice Hall, Upper Saddle River, NJ. Bremer, D.J. 2003. Evaluation of microlysimeter s used in turfgrass evapotranspiration studies using the dual-probe heat-pulse technique. Agron. J. 95:1625. Brown, L.R. 2008. Plan B 3.0: Mobilizing to save civilization. W.W. Norton & Company, New York, NY. Brown, K.W., R.L. Duble, and J.C. Thomas. 1977. Influence of management and season on fate of N applied to golf greens. Agron. J. 69:667. Burton, G.W. 1991. A history of turf research at Tifton. USGA Green Section Record 29(3):1214. Busey, P., and A.E. Dudeck. 1999. Bermudagrass varieties. P. 97-99. In Unruh, J.B., and M.L. Elliott (ed.) Best management practices for Florida golf courses. 2nd ed. SP-141. University of Florida, Institute of Food and Agricultural Sciences. Carrow, R.N., B.J. Johnson, and R.E. Burns. 1987. Thatch and quality of Tifway bermudagrass turf in relation to ferti lity and cultivation. Agron. J. 79:524. Carrow, R.N. 1996. Drought avoidance of divers e tall fescue cultivars. Crop Sci. 36:371 377.

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183 Christians, N.E. 1998. Fundamentals of turf grass management. Ann Arbor Press, Chelsea, MI. Cisar, J.L., A.E. Dudeck, and G.L. Miller 1999. Irrigation water quality. p. 37 In J.B. Unruh and M.C. Elliott (ed.) Best management practices for Florida golf courses. 2nd ed. SP-141. University of Flor ida, Gainesville, Florida. Cisar, J.L., and G.L. Miller. 1999. Irriga tion water quantity and Effluent wastewater use on turf. p. 25, 47, respectively. In J.B. Unruh and M.C. Elliott (ed.) Best management practices for Florida golf courses. 2nd ed. SP-141. University of Florida, Gainesville, Florida. Cisar, J.L., and G.H. Snyder. 2003. Evaluati on of ultradwarf bermudagrass cultural management practices. TPI Turf News Jan./Feb. 2003. DaCosta, M., and B. Huang. 2006. Minimum water requirements for creeping, colonial, and velvet bentgrasses unde r fairway conditions. Crop Sci. 46:81. Duble, R.L. 2000. Nitrogen isnt always the be st prescription. Golf Course Mgt. 68:65. Duncan, R.R., and R.N. Carrow. 2005. Managing seashore paspalum greens. Golf Course Mgt. 73(2):114. Erickson, J.E., J.L. Cisar, J.C. Volin, and G.H. Snyder. 2001. Comparing nitrogen runoff and leaching between newly established St. Augustingrass turf and an alte rnative residential landscape. FDEP. 2007. Best management practices for th e enhancement of environmental quality on Florida golf courses. Depa rtment of Environmental Protection. Foy, J.H. 1997. The hybrid bermudagrass scene. USGA Green Section Record 35(6):1 4. Foy, J.H. 2006. Selecting the right grass. USGA Green Section Record. 44(6):1. Gaussoin, R., J. Nus, and L. Leuthold. 1995. A modi fied stimpmeter for sma ll-plot turfgrass research. HortScience 30(3):547-548. Glennon, R. 2002. Water follies: Groundwater pump ing and the fate of Americas fresh waters. Island Press, Washington, DC. Guertal, E.A. 2007. Phosphorus leaching from sand-based putting greens. USGA Turfgrass Environ. Res. Online 6:1. Haman, D.Z., and F.T. Izuno. 2009. Soil plant water relationships. http://edis.ifas.ufl.edu/ae021

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184 Hartwiger, C., and P. OBrien. 2006. The ultradwa rf invasion. USGA Green Section: Greens Articles. http://www.usga.org/turf/regional _updates/regional_reports /southeast/11-20-2006.html Havlin, J.L., J.D. Beaton, S.L. Tisdale, and W .L. Nelson. 1999. Soil fertility and fertilizers. Prentice Hall, Upper Saddle River, NJ. Hillel, D., 1998. Environmental soil physics. Academic Press. San Diego, CA. Huang, B. 2004. Recent advances in drought and heat stress physiology of turfgrass A recent review. Acta Hort. 661:185. Huang, B., R.R. Duncan, and R.N. Carrow. 1997. Drought-resistance mechanisms of seven warm-season turfgrasses under surface soil drying: I. Shoot response. Crop Sci. 37:1858 1863. Jiang, Y., and R.N. Carrow. 2005. Assessment of canopy narrow-band spectral reflectance and turfgrass performance under drought stress. Hort. Sci. 40:242. Jones, J.W., L.H. Allen, S.F. Shih, J.S. R ogers, L.C. Hammond, A.G. Smajstrala, and J.D. Martsolf. Estimated and Measured Evapotranspiration for Florida Climate crops and soils. IFAS technical Bulletin 840, 1984. Kim, K.S., and J.B. Beard. 1988. Comparative turfgrass evapotranspi ration rates and associated plant morphologi cal characteristic s. Crop Sci. 28:328. Kim, K.S., J.B. Beard, and S.I. Sifers. 1988. Drought resistance comparisons among major warm-season turfgrasses. USGA Green Section Record 26(5):12. Landreth, J., D. Karcher, and M. Richardson. 2007. Cultivating to manage organic matter in sand-based putting greens. USGA Turf grass and Environmental Research Online 6(19):1. TGIF Record Number: 128563. Littell, R.C., G.A. Miliken, W.W. Stroup, R.D. Wolfinger, and O. Schabenberger. 2006. SAS for mixed models, 2nd Ed. Cary, NC: SAS Institute Inc. Lowe, D.B., T. Whitwell, L.B. McCarty, and W.C. Bridges. 2000. Mowing and nitrogen influence green kyllinga ( Kyllinga brevifolia ) infestation in Tifw ay bermudagrass ( Cynodon dactylon x C. transvaalensis ) turf. Weed Technol. 14:471. Mangiafico, S.S., and K. Guillard. 2005. Tu rfgrass reflectance measurements, chlorophyll, and soil n itrate desorbed from anion exch ange membranes. Crop Sci. 45:259. Marcum, K.B. 1999. Salinity tolerance mechan isms of grasses in the subfamily Chloridoideae. Crop Sci. 39:1153.

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185 McCarty, L.B., M.F. Gregg, and J.E. Toler. 2007. Th atch and mat management in an established creeping bentgrass go lf green. Agron. J. 99:1530-1537. McCarty, L.B., and G.L. Miller. 2002. Managing bermudagrass turf. Ann Arbor Press, Chelsea, MI. Merewitz, E., W. Meyer, S. Bonos, and B. Huang. 2010. Drought stress respons es and recovery of Texas x Kentucky hybrids and Kentucky bluegrass genotypes in temperate climate conditions. Agron. J. 102:258. Murray, J.J., and M.C. Engelke. 1983. Explorati on for zoysiagrass in eastern Asia. USGA Green Section Record 21(3): 8. OBrien, P. and C. Hartwiger. 2007. Paspal um: Big advances are making golf more fun. USGA Green Section: Greens Articles. http://lucks.golfserve rs.net/uploads/USGA.pdf Peacock, C.H., A.H. Bruneau, and J.M. Dipa ola. 1997. Response of the cynodon cultivar Tifgreen to potassium fertiliza tion. Intl. Turfgrass Soc. Res. J. 8:1308. Petrovic, A.M. 2004. Nitrogen sou rce and timing impact on nitrate leaching from turf. Acta Hort. 661:427. Rajaniemi, T.K. 2002. Why does fertilizati on reduce plant divers ity? J. Ecol. 90:316. Reitman, J. 2008. Drought will affect preparatio ns for TurfNet Media Network. http://www.turfnet.com/view_news.php?obj_id=79 Rodriguez, I.R., G.L. Miller, and L.B. McCarty. 2001. Berm udagrass establishment on high sand-content soils using vari ous N-P-K ratios. Hort. Sci. 37(1):208. Rowland, J.H., J.L. Cisar, G.H. Snyder, J.B. Sa rtain, and A.L. Wright. 2009. USGA ultradwarf bermudagrass putting green properties as affected by cultural practices. Agron. J. 101:1565 1572. Sartain, J.B. 1998. Fertilize bermudagrass green s smartly and safely. Grounds Maintenance. 33(9):25,28,32,36. Sartain, J.B. 2002. Tifway bermudagrass response to potassium fertilization. Crop Sci. 42:507 512. Sartain, J.B., G.L. Miller, G.H. Snyder, J.L. Ci sar, and J.B. Unruh. 1999. Fertilization programs, and plant nutrition. p. 65. In J.B. Unruh and M.C. Elliott (ed.) Best management practices for Florida golf courses. 2nd ed. SP. University of Florida, Gainesville, Florida.

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186 Sartain, J.B., and G.H. Snyder. 1999. Soil chem ical properties. p. 55. In J.B. Unruh and M.C. Elliott (ed.) Best management practices for Florida golf courses. 2nd ed. SP 141. University of Flor ida, Gainesville, Florida. SAS Institute. 2004. SAS/STAT users guide. Version 9.2. SAS Institute, Cary, NC. Sass, J.F., and Horgan, B.P. 2006. Irrigation sc heduling on sand-based creeping bentgrass: Evaluating evapotranspiration estimation, capacitance sensors, and defic it irrigation in the upper Midwest. Online. Applied Tu rfgrass Science doi:10.1094/ATS-2006-0330-01-RS. http://www.plantmanagementnetwork.org/pub/ats/re search/2006/schedule/ Saxton, A.M. 1998. A macro for converting m ean se paration output to lette r groupings in Proc Mixed. p. 1243. In Proc. 23rd SAS Users Group Int. SAS Institute, Cary, NC. http://animalscience.ag.utk.edu/FacultyStaff/Saxton/pdmix800.sas Scully, B.T. 2005. Varieties bred for a purpose. Turfgrass trends Nove mber 1, 2005. http://www.turfgrasstrends.com/turfgrasst rends/content/printC ontentPopup.jsp?i d=193850 Scully, B.T., R.T. Nagata, R.H. Cherry, L.E. Trenholm, and J.B. Unruh. 2009. Registration of 'Pristine' zoysiagrass. Journal of Plant Registrations. 3(1):65. Smith, G.S. 1979. Nitrogen and aerif ication influence on putting green thatch and soil. Agron. J. 71:680. Snyder, G.H., B.J. Augustin and J.M. Davi dson. 1984. Moisture sensor-controlled irrigation for reducing N leaching in bermudagrass turf. Agron. J. 76:964 969. Snyder, G.H., E.O. Burt, and J.M. Davids on. 1980. Nitrogen leaching in bermudagrass turf: 2. Effect of nitrogen sources a nd rates. Proc. Int. Turfgrass Res. Conf. 4:313. Snyder, G.H., and J.L. Cisar. 2000a. Nitr ogen/potassium fertilization ratios for bermudagrass turf. Crop. Sci. 40:1719. Snyder, G.H., and J.L. Cisar. 2000b. Monitori ng vadose-zone soil water for reducing nitrogen leaching on golf courses. Chapt. 14, p. 243 In J.M. Clark and M.P. Kenna (eds.), Fate and Management of Turfgrass Chemicals. American Chemical Society Symposium Series 743. Oxford University Press, NY, NY. Snyder, G.H., and J.L. Cisar. 2008. Biosolid inclusion in sand root zone media for establishment of cv. Tifdwarf bermudagrass. Proc. IInd IC on Tu rfgrass Acta Hort. 783, ISHS p. 463. Tanino, K.K., and B.Baldwin.1996. Physiology of drought in stressed plants. http://gardenline.usask.ca/misc/xeris.html

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187 Trenholm, L.E., R.N. Carrow, and R.R. Duncan. 1999. Relationship of multispectral radiometry data to qualitative data in turfgrass research. Crop Sci. 39:763. Trenholm, L.E., A.E. Dudeck, J.B. Sartain, and J.L. Cisar. 1997. Cynodon responses to nitrogen, potassium, and day-length during vegetative establishment. Intl. Turfgrass Soc. Res. J. 8:541. Turgeon, A.J. 1985. Turfgrass management. Re ston Publishing Company, Inc. Reston, VA. Turner, T.R., and N.W. Humm el. 1992. Nutritional requirem ents and fertilization. p. 408 410. In D.V. Waddington et al. (ed.) Turfgrass. Agron. Monogr. 32. ASA., Madison, WI. Unruh, J.B., B.J. Brecke, and D.E. Partridge. 200 7. Seashore paspalum performance to potable water. USGA Turfgrass and Environmenta l Research Online 6(23):1. TGIF Record Number: 130531. USGA Greens Section Staff. 2004. USGA reco mmendations for a method of putting green construction. USGA Wo rld Wide Web Site 2004, p. [1]. http://www.usga.org/coursecare /articles/construction/greens/USGA-Recommendations-ForA-Metho d-Of-Putting-Green-Construction(2)/ Vargas, J.M. 1994. Management of turfgrass diseases. CRC Press, Boca Raton, FL. Vermeulen, P. 1995. S.P.E.E.D. Consider whats right for your course. USGA Green Section Record 43(3):18-19. Volk, G.M. 1972. Compressibility of turf as a measure of grass growth and thatch development on bermudagrass greens. Agron. J. 64:503. White, C.B. 2003. The birth of a putting gr een. USGA Green Section Record. 41(6):1. White, R.H., A.H. Bruneau, and T.J. Cowett. 1993. Drought tolerance of diverse tall fescue cultivars. P. 607. In R.N. Carrow et al. (ed.) Int. Turf. Soc. Res. J. Palm Beach, FL. 1824 July 1993. Intertec. Publ. Corp. Overland Park, KS. White, R.H., T.C. Hale, D.R. Chalmers, M. H. Hall, J.C. Thomas, and W.G. Menn. 2004. Cultural management of selected unltadw arf bermudagrass cultivars. Online. Crop Mgt. doi:10.1094/CM-2004-0514-01-RS. http://www.plantmanagementnetwork.or g/pub/cm/research/2004/ultradwarf/ Wolf, B., and G.H. Snyder. 2003. Su stainable soils: The place of organic matter in sustaining soils and their productivity. Food Products Press, Binghamton, NY. Zinn, S. 2004. Suggestions for the care of seashore paspalum. Ft. Pierce, FL: Environmental Turf Inc.

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188 BIOGRAPHICAL SKETCH John Rowland was born in Neptune City, New Jersey in 1966. He attended Woodrow W ilson elementary school in Neptune City, NJ and high school in Neptune, NJ. After taking some turfgrass management courses at Rutgers University, he obtained a bachelor degree in turfgrass science at the University of Florida s Fort Lauderdale Research and Education Center (FLREC). He then worked seve ral years as a turfgrass manageme nt consultant and golf course superintendent before returning to FLREC for hi s master and doctorate in soil and water science with a focus on turfgrass.