, A .3 «3&1
“ 0-,
.9.

.. .fi.

”.er 3‘ ln H .4

u." Q-IH. at): o
L. .. nib.v.obfl\.11
‘11

v!
u

. ‘11:». .v
“Nah: .. L

x A:
szépx .

{S .
5.0%! 1:
Cr 1 IVM“‘+ . ‘ n . . v 'l'l".'.:§
31...- 3!, . .. , “a
{l}.
. . v: ‘
14.... .
. 11..
. ram.
. v . . f :
9."A ‘ ,'
figured? . "can!
55.. 32.2
.flWfflfl.
.pofll:
V ..
:. 1: . sum“...
23.. . ‘3. .-
ctr! ‘I I». try

 

. \ . “lug:-
vle.v'. ..v...ll I II .~l| n'.‘ ‘
3n vv'...»vc'.col.l.vt|Alll.la . u
v ‘ A . . .fnflIuUAFfi

. .I-orlllo.lo. I3 ‘1'. Div. 9

V . . .
III-mule.

.3. .l v~v:

 

qzvcdhvfliJJm‘r. EV:
r.

 

53...“!

. v

II. I .n
. Ix twang
.. .ll......v‘.,l'|... )‘Ln'la u.’|?li2.lt
I‘IVAlll’c-Ilt' '1‘ (I5.IO".I\'~I- K
, , 1.: ‘ I 6| .ul-vvoxv{ vzclqrtin: ., . . ‘
y .. 1‘... .5 . V . . . , . , .
. . , . ‘ ‘ .l o‘qno‘rtivlu‘

 

 

1 a . £535..-. ‘ ‘ : , . p.

Illllll’il llllfillllll’llllllmllll

3 1293 01427 1732

This is to certify that the

dissertation entitled

The Effects of Plant Growth Regulators on
Kentucky bluegrass (Poa pratensis L.) and
Supina bluegrass (Poa supina Schrad.) in

Reduced Light Conditions
presented by

John C. Stier

has been accepted towards fulfillment
of the requirements for

Ph.D. degreein Crop & Soil Sciences

O/fl
/

 

Major pro or

Daté 5,42%»? /9‘9?’

MSU is an Affirmative Anion/Equal Opportuniti- Institution O~12771

 

LIBRARY

Michigan State
University

 

 

 

PLACE IN RETURN BOX
to remove this checkout from your record.
TO AVOID FINE return on or before date due.

 

mns DUE DATE ours I DATE DUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1198 «lemmas-p.14

THE EFFECTS OF PLANT GROWTH REGULATORS ON KENTUCKY
BLUEGRASS (POA PRA TENSIS L.) AND SUPINA BLUEGRASS
(P. SUPINA SCHRAD.) IN REDUCED LIGHT CONDITIONS
By

John C. Stier

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Crop and Soil Sciences

1997

ABSTRACT
THE EFFECTS OF PLANT GROWTH REGULATORS ON KENTUCKY
BLUEGRASS (POA PRA TENSIS L.) AND SUPINA BLUEGRASS (P. SUPINA
SCHRAD.) IN REDUCED LIGHT CONDITIONS
By

John C. Stier

Turfgrass management in reduced light conditions (RLC; < 30% full sunlight) is
difficult because turf growth is affected by lack of sufficient light energy. Turf plants in
RLC are relatively weak and cannot withstand traffic or other damage due to excessive
shoot elongation. reduced tillering, and reduced root growth. In normal light conditions
plant growth regulators which inhibit gibberellic acid (GA) biosynthesis are occasionally
used on turfgrass tO reduce mowing requirements by suppressing shoot growth. The
Objective of the research was to determine the effects of two GA-inhibitors (flurprimidol
and trinexapac-ethyl) on turfgrass in RLC. The primary reason for the research was to
develop a set of management strategies to maintain turfgrass in RLC for athletic events,
e.g. athletic fields in covered stadia, although the results should be applicable to many
turf situations. Three studies were conducted. In the first set of experiments, the effects
of flurprimidol were tested at three nitrogen (N) rates (24, 48, and 96 kg ha'1 month'l ) on
Kentucky bluegrass, with and without traffic, at two levels of RLC (approximately 1-2
and 8 mol photosynthetically active radiation (PAR) day'l). A second study was
undertaken to compare the relative shade tolerance of Supina bluegrass (Poa supina
Schrad.) to Kentucky bluegrass (P. pratensis L.) with different combinations of

trinexapac-ethyl and foliar-applied iron. In the third study the effects of trinexapac-ethyl

on photosynthesis of Kentucky bluegrass and Supina bluegrass in RLC were assessed.
The effects of trinexapac-ethyl on photosynthesis of Supina bluegrass maintained at low
and high N rates (24 and 96 kg ha'1 month") were also evaluated. Both flurprimidol and
trinexapac-ethyl effectively suppressed shoot growth and enhanced turf quality in RLC.
Supina bluegrass was significantly more tolerant of RLC compared to Kentucky
bluegrass although neither grass prospered at 1-2 mol PAR day'l. Supina bluegrass had
greater rates of photosynthesis than Kentucky bluegrass on a turf area basis although this
was related to the higher leaf area index (LAI) of Supina bluegrass. Trinexapac-ethyl did
not affect photosynthetic rates in either Species. Nitrogen rate had little effect on

photosynthesis in RLC but the high N rate did reduce LAI.

Copyright by
JOHN CLINTON STIER
1997

Dedicated to my wife, Valerie Ann Stier

ACKNOWLEDGEMENTS

I would like to extend my deepest appreciation to Dr. John (Trey) N. Rogers, III, for
his guidance, support, and the belief in me he has always held. I will forever consider
myself the most fortunate of graduate students for all the wonderful opportunites Dr.
Rogers has provided. My graduate committee also deserves Special recognition for the
time and efforts they have provided to me: Dr. James Flore, for the training and use of
photosynthesis equipment and his lab space; Dr. Joseph Vargas, for his lab space and
materials for identification of fungal pathogens as well as his insights on interacting with
others; Dr. James Crum, for the special encouragement and wisdoms he shared with me.
I am thankful for the help and friendship of T.J. Lawson, Richard Fogarsi, Thomas
Nikolai, Mark Collins, and John C. Sorochan, as well as the myriad of student workers
and golf course professionals with whom I have interacted, during the long, busy, and
incredibly exciting days when we provided the world with the first indoor turfgrass

athletic field at the Pontiac Silverdome for the 1993 US. Cup and 1994 World Cup.

vi

TABLE OF CONTENTS

LIST OF TABLES ................................................................................................ ix
LIST OF FIGURES .............................................................................................. xvii
CHAPTER 1

INTERACTION OF NITROGEN AND FLURPRIMIDOL ON KENTUCKY
BLUEGRASS (POA PRA TENSIS L.) IN REDUCED LIGHT CONDITIONS... 1

Introduction ............................................................................................... 1
Materials and Methods .............................................................................. 2
Results and Discussion .............................................................................. 8
Experiment I .................................................................................. 8

Turf Quality ....................................................................... ll

Clipping Yields .................................................................. 15

Surface Characteristics ...................................................... 2O

Experiment 11 ................................................................................. 25

Turf Quality ....................................................................... 27

Clipping Yields .................................................................. 33

Surface Characteristics ...................................................... 33

Plant Density ..................................................................... 41

Conclusions ............................................................................................... 41

CHAPTER 2

THE EFFECTS OF TRINEXAPAC-ETHYL AND F OLIAR IRON ON
SUPINA BLUEGRASS (POA S UPINA SCRAD.) AND KENTUCKY

BLUEGRASS (P. PRA T ENSIS L.) ....................................................................... 44
Introduction ............................................................................................... 44
Materials and Methods .............................................................................. 46

Experimental Environment ........................................................... 46

Plot Construction and Maintenance .............................................. 48

Data Collection .............................................................................. 50
Results and Discussion .............................................................................. 52
Turf Color and Quality .................................................................. 52
Experiment I: Turf Not Subjected to Traffic ..................... 52

Experiment 11: Turf Subjected to Traffic ........................... 60

Clipping Yields .............................................................................. 69
Experiment I: Turf Not Subjected to Traffic ..................... 69

VII

Experiment 11: Turf Subjected to Traffic .......................... 76

Turf Shear Resistance .................................................................... 76
Experiment I: Turf Not Subjected to Traffic ..................... 76

Experiment 11: Turf Subjected to Traffic ........................... 82

Plant Density and Biomass ............................................................ 86
Experiment I: Turf Not Subjected to Traffic ..................... 86

Experiment 11: Turf Subjected to Traffic ........................... 91

Chlorophyll Concentration ............................................................ 91
Experiment I: Turf Not Subjected to Traffic ..................... 9]

Experiment II: Turf Subjected to Traffic .......................... 98

Conclusions ............................................................................................... 98

CHAPTER 3

PHOTOSYNTHESIS OF SUPINA BLUEGRASS (POA SUPINA SCHRAD.)
AND KENTUCKY BLUEGRASS (P. PRA T ENSIS L.) IN REDUCED
LIGHT CONDITIONS AS AFFECTED BY NITROGEN AND

TRINEXAPAC-ETHYL ....................................................................................... 1 01
Introduction ............................................................................................... 101
Materials and Methods .............................................................................. 104

Plot Establishment and Testing ..................................................... 104

Experiment 1: Species x PGR Study .................................. 104

Experiment 11: Nitrogen x PGR Study .............................. 107

Gas Exchange Measurements ........................................................ 108

Leaf Area Analysis ........................................................................ 110

Chlorophyll Analysis ..................................................................... l 10

Results ....................................................................................................... lll
Experiment 1: Species x PGR Study .............................................. lll

Experiment 11: Nitrogen x PGR Study ........................................... 111

Discussion .................................................................................................. 129
Conclusion ................................................................................................. l 3 5
APPENDIX ........................................................................................................... 137
LIST OF REFERENCES ...................................................................................... 138

viii

LIST OF TABLES

Table l - Photosynthetically active radiation (PAR) at the Hancock Turfgrass
Research Center, East Lansing ......................................................................................... 9

Table 2 - Mean squares and treatment effects on the quality of Kentucky
bluegrass maintained under ambient light conditions inside the Covered
Stadium Simulator Facility ............................................................................................ 12

Table 3 - Main effects of nitrogen, flurprimidol, and traffic on the quality
of Kentucky bluegrass maintained under ambient light conditions inside
the Covered Stadium Simulator Facility, East Lansing, MI .......................................... 13

Table 4 - Quality rating values for the flurprimidol-by-nitrogen and

nitrogen-by-traffic interactions in Kentucky bluegrass turf maintained in

ambient light conditions in the Covered Stadium Simulator Facility, East

Lansing, MI. .................................................................................................................. 16

Table 5 - Values for quality ratings of nitrogen-by-flurprimidol-by-traffic
interaction of Kentucky bluegrass turf maintained under ambient light
conditions in the Covered Stadium Simulator Facility, 22 Feb. 1994 ............................ 16

Table 6 - Mean squares and significance of treatment effects on clipping yields
of Kentucky bluegrass maintained under ambient light conditions of the Covered
Stadium Simulator Facility, East Lansing, MI. .............................................................. 17

Table 7 - Effect of nitrogen rate, flurprimidol, and traffic on clipping yields of
Kentucky bluegrass maintained under ambient light conditions of the Covered
Stadium Simulator Facility (CSSF), East Lansing, MI. ................................................. 18

Table 8 - Values for the significant nitrogen-by-flurprimidol interaction on
clipping yields of Kentucky bluegrass maintained under ambient light conditions
in the Covered Stadium Simulator Facility (CSSF), 1993-94. ....................................... 21

Table 9 - Values for the significant flurprimidol-by-traffic interactions on clipping
yields of Kentucky bluegrass turf maintained under ambient light conditions of the
Covered Stadium Simulator Facility (CSSF) ................................................................. 22

Table 10 - Mean squares and significance of treatment effects on the shear
resistance of Kentucky bluegrass maintained under ambient light conditions
inside the Covered Stadium Simulator Facility (CSSF) ............................................... 23

Table 11 - Main effects of nitrogen, flurprimidol, and traffic on the shear
resistance of Kentucky bluegrass turf maintained under ambient light conditions
inside the Covered Stadium Simulator Facility (CSSF) ............................................... 24

Table 12 - Mean squares and the significance of treatment effects on the
surface hardness of Kentucky bluegrass turf maintained in ambient light
conditions of the Covered Stadium Simulator Facility (CSSF) .................................... 26

Table 13 - Effects of traffic on Clegg Impact Values of Kentucky bluegrass turf

maintained in reduced light conditions inside the Covered Stadium Simulator
Facility (CSSF) ............................................................................................................. 26

Table 14 - Mean squares for the effects of nitrogen rate, flurprimidol, and traffic on
the quality of Kentucky bluegrass maintained under supplemental light conditions
inside the Covered Stadium Simulator Facility, East Lansing, MI. ............................ 28

Table 15 - Main effects of nitrogen rate and flurprimidol on the quality of Kentucky
bluegrass maintained under supplemental light conditions inside the Covered
Stadium Simulator Facility, East Lansing, MI. ........................................................... 29

Table 16 - Values for the significant interactions of nitrogen rate and flurprimidol
treatment on the quality of Kentucky bluegrass maintained under supplemental

light conditions inside the Covered Stadium Simulator Facility (CSSF), East

Lansing, MI. ................................................................................................................ 31

Table 17 - Quality ratings for the significant nitrogen rate-by-flurprimidol-by-trafiic
interactions on Kentucky bluegrass turf under supplemental light conditions ............. 32

Table 18 - Mean squares and significance of treatment effects on clipping yields of
Kentucky bluegrass maintained under supplemental light conditions of the Covered
Stadium Simulator Facility, East Lansing, MI. ............................................................ 34

Table 19 - Effect of nitrogen rate, flurprimidol, and traffic on clipping yields of
Kentucky bluegrass maintained under supplemental light conditions of the Covered
Stadium Simulator Facility (CSSF), East Lansing, MI. ............................................... 35

Table 20 - Clipping yields for the significant nitrogen-by-flurprimidol interactions
in Kentucky bluegrass turf maintained under supplemental light conditions in the
Covered Stadium Simulator Facility (CSSF) ............................................................... 37

Table 21 - Clipping yields for the significant flurprimidol-by-traffic interactions in
Kentucky bluegrass turf maintained under supplemental light conditions in the
Covered Stadium Simulator Facility (CSSF) .............................................................. 38

Table 22 - Mean squares and significance of treatment effects on the shear resistance
of Kentucky bluegrass maintained under supplemental light conditions inside the
Covered Stadium Simulator Facility (CSSF) .............................................................. 39

Table 23 - Main effects of nitrogen, flurprimidol, and traffic on the shear resistance
of Kentucky bluegrass maintained under supplemental light conditions inside the
Covered Stadium Simulator Facility (CSSF) .............................................................. 39

Table 24 - Mean squares and significance of treatment effects on the surface
hardness of Kentucky bluegrass turf maintained under supplemental light
conditions inside the Covered Stadium Simulator Facility (CSSF) ............................. 40

Table 25 - Clegg Impact Values (gmax) for the flurprimidol-by-traffic interaction

(3 Feb. 1993) and flurprimidol-by-nitrogen interaction (8 Apr. 1994) in Kentucky
bluegrass turf maintained under supplemental light conditions inside the Covered
Stadium Simulator Facility (CSSF) ............................................................................. 40

Table 26 - Plant density, shoot density, and verdure weight of Kentucky bluegrass
maintained under supplemental light in the Covered Stadium Simulator Facility,
10 Dec. 1993 to 23 August 1994 ................................................................................. 42

Table 27 - Photosynthetically active radiation (PAR) at the Hancock Turfgrass
Research Center, East Lansing, MI. ........................................................................... 53

Table 28 - Mean squares and treatment effects on quality ratings of non-trafficked
turfgrass in reduced light conditions, Hancock Turfgrass Research Center, East
Lansing, MI. ............................................................................................................... 54

Table 29 - Mean squares and treatment effects on color ratings of non-trafficked
turfgrass in reduced light conditions, Hancock Turfgrass Research Center, East
Lansing, MI. ............................................................................................................... 55

Table 30 - Effect of species, trinexapac-ethyl, and iron on quality of non-trafficked
turfgrass in reduced light conditions, Hancock Turfgrass Research Center, East
Lansing, MI. ............................................................................................................... 56

Table 31 - Effect of species, trinexapac-ethyl, and iron on color of non-trafficked
turfgrass in reduced light conditions, Hancock Turfgrass Research Center, East
Lansing, MI. ............................................................................................................... 58

xi

Table 32 - Quality rating values from selected dates for the significant species-by-
trinexapac-ethyl interactions on non-trafficked turfgrass in reduced light conditions,
Hancock Turfgrass Research Center, East Lansing, MI. ............................................ 61

Table 33 - Color ratings for the significant species-by-trinexapac-ethyl interaction
on non-trafficked turfgrass in reduced light conditions, Hancock Turfgrass
Research Center, East Lansing, MI. ........................................................................... 62

Table 34 - Mean square and treatment effects on quality of turfgrass subjected to
traffic in reduced light conditions, Hancock Turfgrass Research Center,
East Lansing, MI. ....................................................................................................... 63

Table 35 - Mean square and treatment effects on color of turfgrass subjected to
traffic in reduced light conditions, Hancock Turfgrass Research Center,
East Lansing, MI. ....................................................................................................... 64

Table 36 - Effect of species, trinexapac-ethyl, and iron on quality of turfgrass
subjected to traffic in reduced light conditions, Hancock Turfgrass Research
Center, East Lansing, MI. .......................................................................................... 65

Table 37 - Effect of species, trinexapac-ethyl, and iron on quality of turfgrass
subjected to traffic in reduced light conditions, Hancock Turfgrass Research
Center, East Lansing, MI. .......................................................................................... 67

Table 38 - Quality rating values for the significant species-by-trinexapac-ethyl
interactions on turfgrass subjected to traffic in reduced light conditions ................... 70

Table 39 - Color rating values for the significant species-by-trinexapac-ethyl
interactions on turfgrass subjected to traffic in reduced light conditions ................... 71

Table 40 - Mean squares and significance of treatment effects on clipping yields
of non-trafficked turfgrass in reduced light conditions, Hancock Turfgrass
Research Center, East Lansing, MI. .......................................................................... 72

Table 41 - Effects of species, trinexapac-ethyl, and iron on clipping yields of
non-trafficked turfgrass in reduced light conditions, Hancock Turfgrass Research
Center, East Lansing, MI. ......................................................................................... 73

Table 42 - Values for the significant interactions of trinexapac-ethyl and species on
clipping yields of non-trafficked turfgrass in reduced light conditions, Hancock
Turfgrass Research Center, East Lansing, MI. ......................................................... 75

Table 43 - Mean squares and Significance of treatment effects on clipping yields of
turfgrass subjected to traffic in reduced light conditions, Hancock Turfgrass
Research Center, East Lansing, MI. ......................................................................... 77

xii

Table 44 - Effects of species and trinexapac-ethyl on clipping yields of turfgrass
subjected to traffic in reduced light conditions, Hancock Turfgrass Research
Center, East Lansing, MI. ....................................................................................... 78

Table 45 - Values from significant interactions of trinexapac-ethyl and species
on clipping yields of turfgrass subjected to traffic in reduced light conditions,
Hancock Turfgrass Research Center, East Lansing, MI. ........................................ 80

Table 46 - Mean squares and significance of treatment effects on shear
resistance of non-trafficked turfgrass in reduced light conditions, Hancock
Turfgrass Research Center, East Lansing, MI. ....................................................... 81

Table 47 - Effect of species and trinexapac-ethyl on shear resistance values
(N cm) of non-trafficked turfgrass in reduced light conditions, Hancock
Turfgrass Research Center, East Lansing, MI. ....................................................... 83

Table 48 - Shear resistance values (N am) for the significant species-by-
trinexapac-ethyl interaction on non-trafficked turfgrass in reduced light
conditions, Hancock Turfgrass Research Center, East Lansing, MI. ..................... 84

Table 49 - Mean square and Significance of treatment effects on shear
resistance of turfgrass subjected to traffick in reduced light conditions,
Hancock Turfgrass Research Center, East Lansing, MI. ....................................... 84

Table 50 - Effect of species and trinexapac-ethyl on shear resistance values
(N cm) of turfgrass subjected to traffic in reduced light conditions, Hancock
Turfgrass Research Center, East Lansing, MI. ...................................................... 85

Table 51 - Shear resistance values (N om) for the Significant species-by-
trinexapac-ethyl interactions on turfgrass subjected to traffic in reduced light
conditions, Hancock Turfgrass Research Center, East Lansing, MI. .................... 87

Table 52 - Mean squares and treatment effects on plant density and biomass of
non-trafficked turfgrass in reduced light conditions, Hancock Turfgrass Research
Center, East Lansing, MI. ..................................................................................... 88

Table 53 - Effect of species, trinexapac-ethyl, and iron on plant density and
biomass of non-trafficked turfgrass in reduced light conditions, Hancock
Turfgrass Research Center, East Lansing, MI. ..................................................... 89

Table 54 - Plant density and biomass values for the significant species-by-

trinexapac-ethyl interactions on non-trafficked turfgrass in reduced light
conditions, Hancock Turfgrass Research Center, East Lansing, MI. ................... 90

xiii

Table 55 - Mean squares and treatment effects on plant density and biomass of
turfgrass subjected to traffic in reduced light conditions, Hancock Turfgrass
Research Center, East Lansing, MI. ..................................................................... 92

Table 56 - Effect of species, trinexapac-ethyl, and iron on plant density and
biomass of turfgrass subjected to traffic in reduced light conditions, Hancock
Turfgrass Research Center, East Lansing, MI. .................................................... 93

Table 57 - Plant density and biomass values for the species-by-trinexapac-ethyl
interactions on turfgrass subjected to traffic in reduced light conditions,
Hancock Turfgrass Research Center, East Lansing, MI. ..................................... 94

Table 58 - Mean squares and treatment effects on chlorophyll of non-trafficked
turfgrass in reduced light conditions, Hancock Turfgrass Research Center,
East Lansing, MI. ................................................................................................ 95

Table 59 - Effect of species, trinexapac-ethyl, and iron on chlorophyll of
non-trafficked turfgrass in reduced light conditions, Hancock Turfgrass
Research Center, East Lansing, MI. .................................................................... 96

Table 60 - Mean squares and treatment effects on chlorophyll of turfgrass
subjected to traffic in reduced light conditions, Hancock Turfgrass Research
Center, East Lansing, MI. ................................................................................... 99

Table 61 - Effect of species, trinexapac-ethyl, and iron on chlorophyll content
of turfgrass subjected to traffic in reduced light conditions ................................ 99

Table 62 - Photosynthetically active radiation (PAR) of plots in the Covered
Stadium Simulator Facility (CSSF), Hancock Turfgrass Research Center,
East Lansing, MI. .............................................................................................. 106

Table 63 - Mean squares and treatment effects of species and trinexapac-ethyl

on photosynthetic parameters of turfgrass maintained in reduced light

conditions (approximately 5 mol PAR day'l ), turf surface area basis,

23 November 1996 ............................................................................................ l 12

Table 64 - Photosynthetic differences between Supina bluegrass and
Kentucky bluegrass in reduced light conditions (approximately 5 mol PAR
day'l ), turf surface area basis, 23 November 1996 ........................................... 113

Table 65 - Mean squares and treatment effects of species and trinexapac-ethyl
on photosynthetic parameters of turfgrass maintained in reduced light conditions
(approximately 5 mol PAR day'l), leaf area basis, 23 November 1996 ............ 114

xiv

Table 66 - Photosynthetic differences between Supina bluegrass and Kentucky
bluegrass in reduced light conditions (approximately 5 mol PAR day'l),
leaf area basis, 23 November 1996 ................................................................... 115

Table 67 - Mean squares and significance of treatment effects on leaf area
index (LAI), fresh leaf weight, and chlorophyll concentration of turfgrasses in
reduced light conditions (approximately 5 mol PAR clay'l ), 24 Nov. 1996.... 116

Table 68 - Effects of species and trinexapac-ethyl on foliage and chlorophyll
of turfgrasses in reduced light conditions, approximately 5 mol PAR day",
24 Nov. 1996 ................................................................................................... 117

Table 69 - Mean squares and treatment effects of photosynthetic characteristics
of Supina bluegrass affected by trinexapac-ethyl and nitrogen rate in reduced
light conditions (approximately 5 mol PAR day'l), turf surface area basis ..... 118

Table 70 - Effects of nitrogen and trinexapac-ethyl on photosynthetic
parameters of Supina bluegrass in reduced light conditions (approximately 5
mol PAR day'l), turf surface area basis ............................................................ 121

Table 71 - Interaction of N rate and trinexapac-ethyl on transpiration (E) and
stomatal conductance (gs) of Supina bluegrass maintained in reduced light
conditions of approximately 5 mol PAR day"l ................................................ 123

Table 72 - Mean squares and treatment effects of photosynthetic characteristics
of Supina bluegrass affected by trinexapac-ethyl and nitrogen rate in
reduced light conditions (approximately 5 mol PAR day'l), leaf area basis....124

Table 73 - Effects of nitrogen and trinexapac-ethyl on photosynthetic
parameters of Supina bluegrass in reduced light conditions (approximately
5 mol PAR day'l), leaf area basis ..................................................................... 126

Table 74 - Mean squares and significance of treatment effects on leaf area
index (LAI), fresh leaf weight, and chlorophyll concentration of Supina
bluegrass in reduced light conditions (approximately 5 mol PAR day'l),

17 Nov. 1996 ................................................................................................... 128

Table 75 - Effects of nitrogen rate and trinexapac-ethyl on leaf area index (LAI),
fresh leaf weight, and chlorophyll concentration of Supina bluegrass in
reduced light conditions (approximately 5 mol PAR day'l), 17 Nov. 1996 ..... 130

Table 76 - Mean squares and treatment effects on pink snow mold

(Microdochium nivale) effects on Supina bluegrass in reduced light
conditions (approximately 5 mol PAR day'l), 18 Nov. 1996 .......................... l3]

XV

Table 77 - Effects of nitrogen rate and trinexapac-ethyl on pink snow mold
(Microdochium nivale) damage to Supina bluegrass in reduced light
conditions (approximately 5 mol PAR day'l), 18 Nov. 1996 ........................ 131

Table 78 - Particle size analysis of sand used in sandzpeat mixture
(80:20) ............................................................................................................ 137

Table 79 - Particle size analysis of sand used in Experiment 11: Nitrogen
x PGR study (Chapter 3) ................................................................................ 137

xvi

LIST OF FIGURES

Figure 1 - Photosynthetic photon flux density of sunlight, ambient light inside the
Covered Stadium Simulator Facility (CSSF), and supplemental light inside the CSSF
supplied by 400 W high pressure sodium lamps, 1515 h, 10 Feb. 1994 ......................... 10

xvii

KEY TO SYMBOLS AND ABBREVIATIONS

CER, carbon exchange rate; PGR, plant growth regulator; GA, gibberellic acid; gm“,
peak deceleration; TE, trinexapac-ethyl; PAR, photosynthetically active radiation; PPFD,
photosynthetic photon flux density; Ly, langley; E, transpiration; gs, stomatal
conductance; gm, mesophyll conductance; WUE, water use efficiency; LAI, leaf area
index; N, nitrogen; P, phosphorus; K, potassium; CSSF, Covered Stadium Simulator

Facility.

xviii

Chapter 1
INTERACTION OF NITROGEN AND FLURPRIMIDOL ON KENTUCKY
BLUEGRASS (POA PRA T ENSIS L.) IN REDUCED LIGHT CONDITIONS

INTRODUCTION

Turfgrasses in intense shade have weak tissues, reduced root to shoot ratio, and
reduced tillering resulting in a reduced quality turf which cannot withstand traffic (Beard,
1973; Wilkinson and Beard, 1975). Minimal nitrogen inputs are recommended to
maintain a balance between shoot and root growth and to minimize the growth of
excessively succulent tissue. Traffic is to be minimized or avoided (Dudeck and
Peacock, 1992). Consequently, current recommendations for turf in shade do not allow
for management techniques in which traffic is a factor. Yet golf courses often have areas
subjected to both shade and traffic. In addition, recent interest in the use of turfgrass
systems for covered stadia requires the development of new management techniques for
turf subjected to traffic under intensely shaded conditions (Anonymous, 1995; Kierle,
1995; Rogers, 1994; Tracinski, 1993).

Plant growth regulators (PGRS) which are gibberellic acid biosynthesis-inhibitors
(GA-inhibitors) have been used successfully to decrease vertical growth (i.e., clipping
yields) (Dernoeden, 1984; Diesburg and Christians, 1989; Johnson, 1988) by inhibiting

cell elongation (Kaufmann, 1986a). Side effects of GA-inhibitors include darker green

2

color and increased turf density due to enhanced tillering, often following a transient
phytotoxic response resulting in tip die back (Demoeden, 1984; Watschke, 1981). In
shade, excessive turfgrass shoot elongation leads to weak, traffic-intolerant turf (Beard,
1973). Preliminary research has proven the potential of GA-inhibitors to control shoot
elongation and provide a higher quality turf compared to untreated turf in reduced light
conditions although phytotoxicity can occur (Rogers et al., 1996; Rogers and Stier, 1993).
In normal light situations multiple applications of GA-inhibitors increase the level of
suppression but also increase the potential for phytotoxicity, especially when turf is
grown under a stress condition (Demoeden, 1984; Johnson, 1988; Vitolo et al., 1990).
Nitrogen fertilization in concert with PGR application has been reported to successfully
minimize or overcome the Short-term deleterious effects of PGRS in normal light
situations (Devitt and Morris, 1988). The effects of nitrogen rate on PGR-treated turf in
reduced light conditions are unknown.

The primary obj ective of this research was to determine the appropriate rate of
nitrogen to apply to flurprimidol-treated Kentucky bluegrass turf in reduced light
conditions. Secondary objectives included determining the amount of light required to
maintain turf in an enclosed environment, the effects of traffic, and turf response to

flurprimidol in reduced light conditions.

MATERIALS AND METHODS

The research was conducted inside the Covered Stadium Simulator Facility (CSSF) at

the Hancock Turfgrass Research Center between Dec. 1992 and April 1994. The CSSF

3

was constructed to simulate the conditions inside the Pontiac Silverdome, a covered
stadium (Stier et al., 1993). The CSSF was a 600 m2 air-supported structure constructed
of Sheerfill II®, a fiberglass fabric (Chemical Fabrics Corporation, Buffalo, NY) which
transmitted approximately 11 i 2% sunlight. Temperature and relative humidity were
recorded daily with a sling psychrometer. Furnaces on the endwalls of the facility were
used to maintain the temperature typically at 16.8 i 0.9 sd °C. Actual temperatures
occasionally ranged from 3 to 23 ° C due to the poor insulating characteristics of the
fiberglass fabric, the inability of the furnaces to compensate for excessively low outdoor
temperatures (e.g., -10 C), and lack of an active cooling mechanism. Relative humidity
(RH) averaged 44.8 i 6.2 Sd % with a range of 24-70% RH.

Portable plots were established in wood boxes (1.2 x 1.2 x 0.15m depth) filled with a
sandzpeat mix (80:20 v/v) (Table 78, Appendix). The pH was 7.3 with initial P and K
levels of 63 kg ha'1 and 30 kg ha", respectively. Holes were drilled in the bottoms of the
boxes for drainage. The sandzpeat mixture was compacted using hand-held tampers.
Starter fertilizer (13-25-12) was applied to the soil which supplied 7.6 g N m'z, 6.4 g P m'
2, and 5.8 g K me. On 30 Sept. 1992 the plots were sodded with a washed Kentucky
bluegrass blend (20% each of ‘Trenton’, ‘Midnight’, ‘Aspen’, ‘Rugby’, and ‘Kelly’). The
plots were moved into the CSSF for testing on 7 Dec. 1992 through 10 April 1993. The
experiments were repeated 3 second year (season). In 1993, plots were sodded 10 Sept.
using a washed Kentucky bluegrass blend (20% each of ‘Trenton’, ‘Midnight’, ‘Aspen’,
‘Glade’, and ‘Parade’). These plots were moved into the CSSF on 10 Dec. 1993 and

maintained until 8 April or 23 August 1994 depending on the experiment. In both years

4

plots were mowed once to twice weekly at 3.8 cm during establishment and irrigated as
necessary to prevent moisture stress. Urea (2.4 g N m'z) was applied to aid establishment
at three weeks after sodding in 1992 and at two and five weeks after sodding in 1993.
Two experiments were conducted to assess the effects of nitrogen rate in PGR-treated
turf. Experiment I was conducted in the ambient light conditions of the CSSF .
Experiment 11 was conducted in the CSSF under supplemental lighting. Supplemental
light was supplied by 430 W high pressure sodium (HPS) lamps suspended 2.7 m above
the turf surface. An automatic timer controlled the lamps to provide a 12 hr photoperiod
(0700 to 1900 hr). Reflective (metallic) mylar sheets were suspended in parallel along
the two long sides of the rectangular plot area to separate the lighted plots from the
unlighted plots and to reflect light from the lamps for increased uniformity of irradiance.
Radiation data outside the CSSF were collected with a LI-PY14226 pyranometer and
integrated daily. Radiometric units (Ly day") were converted to quantum units using the
following equation based on conversion units from Thimijan and Heins (1983):
Equation 1: ((Ly day”/1.05)*3600*24)/ 106 = mol PAR day'l.
Radiation data for plots in ambient light conditions of the C SSF were estimated based on
the percent transmission of photosynthetically active radiation (PAR) through the fabric,
measured at the turf surface. Radiation data inside the CSSF from Dec. 1992 through
April 1993 were determined at the turf surface weekly within one hour of the solar zenith
using a hand-held photometer (Greenlee Inc., Rockford, IL). Occasionally a portable
spectroradiometer (Li-Cor, Lincoln, NE) was used from Dec. 1992 to April 1993 to

determine only photosynthetically active radiation (PAR), 400-700 nm. Starting

5
Dec. 1 993 radiation data inside the CSSF were collected weekly using only the

spectroradiometer.

For plots in supplemental light conditions in 1992-1993, photometeric units (lux) were
converted to quantum units (umol rn'2 s") by multiplying against a conversion factor
(0.2215) derived from data collected concurrently with the photometer and the
spectroradiometer. Starting Dec. 1993 radiation data inside the CSSF were collected
weekly using only the spectroradiometer. Based on measurements collected when
ambient PAR inside the CSSF was low (e.g., 10 umol m'2 5'1 during rainstorms, pre-
dawn, or evening), the HPS lamps supplied approximately 173 i 22 umol PAR m"2 s".
The metallic mylar curtains on both sides of the plot area blocked much of the light
transmitted into the CSSF. Measurements at different times of the day under a range of
sunlight conditions (sunny, cloudy) Showed approximately 10% of the sunlight
transmitted into the CSSF impinged on the plots under supplemental light in the morning
and late afternoon; at midday approximately 80% of the light transmitted into the CSSF
fell on the plots under supplemental light. Because ambient light levels peaked at
midday, it was estimated that approximately 50% of the daily ambient PAR inside the
C SSF contributed to the total daily PPF D of plots under supplemental light. The total
daily photosynthetic photon flux density (PPFD) of plots in supplemental light conditions
was estimated as follows using the average PPFD (umol m'2 s") from all plots:

Equation 2: (((173 umol m’2 s’1 PAR*60 sec min’l)*60 min h‘l)*12 h)/1 x 106 =
mol PAR day" from HPS lamps + 0.5 mol PAR day'I ambient light =

mol PAR day", supplemental light plots

The experiments were arranged as randomized complete block, Split plot designs with
three replications. Treatments were arranged in a 3 x 2 x 2 factorial with nitrogen rate
and flurprimidol as main plots. Simulated soccer traffic was applied as a sub-plot
treatment split over the main plots. Nitrogen rates were 24, 48, and 96 kg ha'1 per
treatment date. Urea nitrogen was applied with a drop spreader on the same dates as
flurprimidol. Flurprimidol was applied at the label rate of 1.12 kg ha'1 in 1168 L H20 ha"
I using a COz-powered backpack sprayer; control plots received no flurprimidol.
Nitrogen and flurprimidol were applied on the following dates: 16 Dec., 21 Jan., and 26
Feb. (supplemental light study only) 1992-93, and 17 Dec., 4 F eb., and 21 Mar. 1993-94.
The turf was irrigated with approximately 1.25 cm water immediately following
fertilization and flurprimidol applications. Additional irrigation was supplied as
necessary to prevent visible drought stress symptoms (blue-green turf color, footprinting,
wilting). Plots in ambient light conditions received approximately 1.25 cm water at 14-
21 day intervals, while plots in supplemental light conditions received approximately
1.25 cm at seven to 10 day intervals. Traffic was applied to one-half of each plot by
having a person (approximately 75-115 kg) walk 50 passes while wearing molded soccer
cleats on each of the following dates: 29 Dec., 14 Jan., 21 Jan., 29 Jan., 6 Feb., 20 Feb.,
10 Mar., and 24 Mar. (supplemental lighted study only on latter two dates) 1992-93, and
6 Jan., 11 Jan., 25 Jan., 1 Feb., 10 Feb., 22 Feb., 2 Mar., 17 Mar., 24 Mar., and 31 Mar.
1993-94. Traffic was applied immediately after mowing and prior to irrigation.

Fungicides were applied at the onset of disease symptoms. On 9 Jan. 1993 and 14 Jan.

7
1994 chlorothalonil (tetrachloroisophthalonitrile; 16.5 kg ha") was applied to control

leafspot and melting out diseases caused by Drechslera/Bipolaris spp.

Plots were mowed once to twice weekly as needed to prevent removal of more than
one-third of the leaf tissue. Clippings were collected, oven-dried at 60 °C for 48 h, and
weighed. Turf quality was rated visually at five to 14 day intervals; ratings were
conducted more frequently at the beginning of each year to assess rapid changes in turf
quality and became less frequent as turf quality fluctuated less abruptly. Visual turf
quality was based on a one to nine scale, with one representing completely necrotic turf
or bare soil and nine representing dense, uniform turf with good color. A value of five
was considered the minimum value for acceptable turf. Turf and rooting strength were
evaluated periodically using an Eijkelkamp Shear vane apparatus (Eijkelkamp, Giesbeek,
The Netherlands) (Rogers and Waddington, 1990). The amount of force (torque)
required to tear the turf was collected in two locations from each plot on every
measurement date. Treatment effects on the turf surface hardness were periodically
evaluated using a Clegg Impact Soil Tester (CIT) (Lafayette Instrument Co., Lafayette,
IN). The CIT provided surface hardness values by measuring maximum deceleration of
a 2.25 kg hammer when dropped from a 0.46 m height (Rogers and Waddington, 1990).
Impact values were collected from three locations in each plot on each measurement date.
On 23 August 1994, one core (10 cm diam) was collected for plant biomass estimates
from each plot which had received supplemental light. Plant density was evaluated by
counting the number of live plants in each core. Verdure was removed from each core,

and all living tissue was oven-dried at 60° C for 48 h then weighed. The number of

8

Shoots per plant was determined by averaging the number of shoots from five plants
selected at random from each plot.

Data were analyzed using MSTAT analysis of variance procedures for a 3-by-2
factorial experiment in a randomized complete block, split-plot design with three
replications. The three nitrogen rates and two flurprimidol levels were split into

trafficked and non-trafficked turf.

RESULTS AND DISCUSSION
Experiment I

Turf quality, growth, and other attributes declined over time. To document the trends
data are presented for individual dates throughout the course of the experiment. Data are
presented for each year due to different results between years. Although some of the
differences could have been due to different cultivars in the second year, the differences
were probably due to a longer and more favorable establishment period during the
autumn 1993. Average daily PAR values of ambient light in the CSSF increased steadily
from December through April from, ranging from approximately 1 mol PAR day'1 in
December to approximately 3 mol PAR day'l in April, but the turf did not respond (Table
1). Light quality transmitted through the fiberglass fabric of the CSSF mirrored the light

quality of sunlight but light quantity was reduced approximately 90% (Figure 1).

9

Table l. Photosynthetically active radiation (PAR) at the Hancock Turfgrass Research Center, East
Lansing, MI.

 

 

 

 

 

 

 

 

 

 

 

 

 

Location Dec. 1992 Jan. 1993 Feb. 1993 Mar. 1993
Outside mol PAR day'1 I
average 7.5 12.6 23.2 21.1
stnd deviation 3.9 5.4 3.1 12.2
CSSF,
ambient light 1
average 0.8 1.4 2.5 2.3
stnd deviation 0.4 0.6 0.3 1.3
CSSF,
Supplemental light §
average 7.9 8.2 8.7 8.6
stnd deviation 1.2 1.2 1.1 1.6
Dec. 1993 Jan. 1994 Feb. 1994 Mar. 1994 Apr. 1994
Outside mol PAR clay'l
average 9.5 10.8 19.3 24.3 31.7
stnd deviation 4.9 5.0 7.0 9.9 14.5
CSSF,
ambient light
average 1.0 1.2 2.1 2.7 3.5
stnd deviation 0.5 0.6 0.8 1.1 1.6
CSSF,
Supplemental light
average 8.0 8.1 8.5 8.8 9.2
stnd deviation 1.2 1.2 1.4 1.5 1.8

 

T PAR was collected with a pyranomter (Li-Cor, model PY 14226, Lincoln NE) and integrated daily.
Radiation units (Ly clay'I ) were converted to quantum units (mol PAR day'I ) based on the conversion
methods in Thimijan and Heins (1983).

1 CSSF = Covered Stadium Simulator Facility. Ambient PAR inside the CSSF was estimated by
measuring the percent PAR transmitted into the CSSF at turf levels with a photometer (Greenlee Inc.,
Rockford IL) or a portable spectroradiometer (Li-Cor, Lincoln NE).

§ Supplemental lighting was supplied by 400 W high pressure sodium lamps. Because reflective mylar
curtains on two sides of the plots blocked an estimated 50% of the ambient light from plots which
received supplemental light, 50% of the total daily PAR was added to the total daily PAR supplied by the
lamps (5.4 mol m"2 day'l ) to estimate the total daily PAR received by turf under the supplemental light.

.32 .8“. A: .5 32 .859 $2qu 2385 :9; 3 8v 3 8:33 “Ammo 9: gas 29. 3285233 new .Aummov
Esau. 56.355 5286 8.98 m5 mass 29. Essen .2923. Co :28 x3 86%. 285588;“. A 9%:

AES Smco_o>m>>
coo omm oom

co».

 

10

 

I
I ‘ll

 

 

oo+woo.o

roamooh

oo+moo. r

oo+womé

oo+wood

, oo+womN

oo+moo.m

oo+mom.m

oo+moo.v

oo+mom.v

 

oo+woo.m

 

A

A
A

A 3 we .25 was 29. 323238 ammo ......
A E «.5 .85 8: 29. A8553 .ammo l
A 3. We .85 OS: 2923 i i I

(1'5 z_UJ mind) Ausuap xnu uoioud ogreutu/lsoioud

1111mm

Significant treatment effects on Kentucky bluegrass quality are shown in Table 2. In
1992-93 there were no interactions between treatments. In 1993-94 occasional
interactions occurred between nitrogen-by-flurprimidol and nitrogen-by-traffic; a three-
way interaction occurred on 22 Feb. 1994. In both 1992-93 and 1993-94 the turf
recovered from winter dormancy once placed inside the CSSF, but did not survive well.
Quality declined to unacceptable values (< 5.0) within 49 days after installation in the
CSSF in 1993 and within 82 days in 1994 regardless of treatment. The turf became
nearly completely necrotic within 72 days in 1993 although better quality was sustained
for the entire trial (105 days) in 1994.

Traffic rapidly decreased turf quality and affected turf quality more often than
nitrogen or flurprimidol (Table 2). Nitrogen rate did not affect turf quality in 1992-93; in
1993-94, the high rate (96 kg ha'l month'l) reduced turf quality within 74 days after
installation in the CSSF (Table 3). High nitrogen rates are known to result in succulent
tissues which render turf more susceptible to traffic and disease injury (Beard, 1973).
High nitrogen rates have also been associated with decreased shoot density and root to
shoot ratio in Shaded conditions (Burton et al., 1959; Eriksen and Whitney, 1981;
Schmidt and Blaser, 1967); flurprimidol did not alter this response at this level of light.
Flurprimidol increased turf quality on two dates only after the second application in both
seasons. Traffic began to decrease turf quality after one application (50 passes) in 1992
and after four applications (200 passes) in 1994. In 1993, the flurprimidol-by-traffic

interaction on 3 Feb. showed flurprimidol increased turf quality in a non-trafficked

12

.33 .5: 0 Es: 393m 8: 33 058,—. H

.82 AonEoooD am :E: 35% A0: 33 QEEH +

.AAozsame .232 AAAAAAARAEAA AAAAA Ea 3AA 2AA AA. AAASeAchm t...

 

 

 

 

 

2.: 8A: 8.2 on: 2.: ANNA NE 3:. 3.... A3 SAN as. .>O
$2 $2 MANNAA 22 £3 8% 8A; 085 as; -- -- NA SEA
$3 82 33A :2 SN 33 N86 Need 83 -- -- N e x A x z
3.2 $2 «$5 83 ES 32A 83 AAAAAAAA Sod -- -- A e x .A
ANA: NSAA .22 :83. .82 82 8A .AA 83 EAAAA -- -- N e x z
:NSAN toga tam: .38.: :SmNN :A A AN 33 MANAAAA SAAAA -- -- A A At 2&5
SNN ANS. SAN SSA was A AA.N 83 N3 SEA EAAA ASAA AAA SEA
AAANN SAAN 89A .. ANNN .VNsN MAN? SNAA $3 N86 NAVAAAA :3 N A x z
22: E9: AAAAA :SSA :AAXAHN .AEAAA EA 3A; 32A 83A :3 A AAA Beaten:
SANA AN: .38.: :39: :mANNN «8.». SN 32 NMAAA AAAAAA 33 N 9c 5352
$2 MAAAAA SN 82 RA .AA 33 .NAAAAA. .83 2: :35 33 N :oAASAAAAsA
HA2 N a: AAA a1: AA a: N 8A NN ABA AAA .ASA N .52 AN .52 NA .52 m 8o N
$-82
3.3 A3: 3.2 A AN SN 2; a? AA; 86 SN. .>O
33 BAN 33 NNAAA mm; a; 3A; -- -- NA SEA
83 3A; 83 N3 or; 955 8A; -- -- N e x A x z
E .AA LEA 83 RNA BSA 82 AA AAA -- -- A A. x A
82A RNA :3 82 «NE ANoAA A; A .AA -- -- N e x z
:3 A :AANAAAAM :AAXAHN :33 2533 $2 4%... -- -- A .A A: 2&3
3.3 SAN 89o EAAA ABNAA 68 ES 32A SSA AAA SEA
83A N42 2: 2.2 NNA .AA 83 ANNAA 085 EA; N ,.A x z
2.3 :AAAAAAAV SN .62 ES :2 AAWNAA 83A 83A A AAA AoAUAEAAezAhA
83 N86 :2 RNA 33 83A 2N.AA 33 NA .AA N :6 5322
was 8A; 83 8A; a; Res 33 as: SAAA N AAoAASAAAAABA
8A NA SBA N as «N .5. ON .5 2 .5: N So 8 Rd N 8AA AAA AAV 85%
8-82

 

.AE .wfimcaq Ammm 550mm 83—38%
8235 3330 05 £55 22553 Em: 253:8 ABE: 35852: $8333 EosAcovA .6 5:56 2: co Beebe 22585 28 83:3 :32 .N 038.

l3

 

:mN 30:0. :o.m N.N.m Wm 811. _.m On .6 -- -- 5:3

 

 

 

 

 

 

NA. NA. N A. N A. AN N N N.N N.N A8 -- -- SEAN;
$2.85
N.N NA. NA. :3. N.N .NN N.N N.N N.N N.N N.N NA.A
N.N N.N A.N N.N N.N AA. N.N ANN N.N N.N N.N 88
A :2 N8 6259::
N: N: A: We 9o N: N: N: N: N: N: G98 Om;
N.N N.N N.N N.N N.N NA. N.N N.N N.N N.N N.N 8
NA. AA. 3. NA. N.N N.N N.N N.N A8 A8 N.N NA.
N.N N.N AA. NA. N.N NA. NA. N.N N.N o8 N.N A.N
E #2 NAA A8N952
.82 NN .82 NA .82 AA .82 N NA.A NN .8.A AAA NANA N .5 A.N .8. NA .5: N .25 NN 28.58:
t. 8.82

Ego.— **©.~ **V.M 3.8.? Nag—w v6 *Noh .. 2. 5T5
N.N N.N AN N.N N.N N.N N.N -- -- 52:3
855
NA ..o.N NA. .N.N N.N N.N N.N N.N N.N NA.A
NA N.N NA. N.N ANN N.N N.N N.N AN 88
A52 3:025:93:
N: N: N: N: N: N: N: N: N: 398 Om;
NA A..N NA. N.N ANN N.N N.N o8 N.N No
NA N.N AAA. N.N ANN N.N N.N N.N N.N NA.
NA N.N NA. N.N N.N N.N N.N N.N N.N AN
2 72A N8 8822
NARA NA .8; N .52 NN .5: NN .5: NA .5 N .80 oN .89 NN .89 NA 28.58:

AANNNNNA

 

A .AsA 8523 83 £38 bAAAoNN .9225 5288
38500 2.: 022: 283950 Em: EuEEAN .AonEA BESEANE NmmAquA—n xxoacox .5 .6296 of so 0595 has .AoEE_.AE=c .cowobE no muooto 52.4 .m 038,—.

l4

4&2 .82 vm ES .82 2 .82 N :82 mm :80 o. :80 _ :52. mm :52. _ _ :52. o 8:25 mm? 0580‘ 3

32 .52 5. Es 30,2 2. .82 .80 2 so 35 8 33% 85 582:2 n,

.32 .80 2 :o ammo 2: 822: 8>oE Ea 623:0 8:23.38 .82 .38m 2 828m 883 303 t
.82 .82 0 Ba :5: on :5: 8 £3 2 .82 .80 am 33% £3 2&5 8

688.95 883 $03 35:8 £865: .8 b6 2:3 2: :o 8:28 mm? 628292.; F

.32 .5: M: Ba 32 .80 3 co 8.: 8 8:98 83 cowoéz a

:32 .80 N. co ammo 2: oEmE .838 Ea 623:0 85:98.8 .92 48m on 8288 8.53 205 w
0:: stats: 68% 58% fmvuo can :8 2323 8% u_ .2QO 2— a co 8839a 83 23:0 .2
2.8228982 .232 9:885 Ed can 36 85 a “52.:ch 3......

3.280 m 22¢

15
situation but did not affect turf quality in a trafficked situation (Table 3). Flurprimidol-

by-nitrogen and nitrogen-by-traffic interactions occurred in the second season (Table 4).
In the flurprimidol-by-nitrogen interaction, flurprimidol increased turf quality at the low
and medium nitrogen rates but did not affect quality at the high nitrogen rate because the
high nitrogen rate decreased turf quality regardless of flurprimidol application. In the
nitrogen-by-traffic interaction, traffic decreased turf quality at the medium and high
nitrogen rates, but did not significantly affect turf quality at the low nitrogen rate. For the
three-way interaction on turf quality, traffic did not affect quality at low or medium
nitrogen rates when treated with flurprimidol, but did significantly reduce turf quality at

the medium and high nitrogen rates in the absence of flurprimidol (Table 5).

Weekly clipping yields were affected by flurprimidol and traffic in 1992-93 and by all
three treatment groups individually in 1993-94 (Table 6). Data presented are intended to
describe trends of main effects and interactions therefore interactions occurring only once
were not discussed. Flurprimidol and traffic significantly reduced clipping yields
beginning immediately after their first application (Table 7). The second application of
flurprimidol inhibited vertical growth nearly completely, causing clipping yields to be at
or near zero for the duration of the studies. Zero vertical growth is undesirable if it
prevents turf recovery following damage. In this study flurprimidol did not appear to
prevent recovery any more than untreated turf because the low light level was the limiting

factor for growth. In 1994, high nitrogen rates resulted in decreased yields compared to

16

00200008: 8 8300 28m 85 8:08 83 008 8.58 080000 85 83 800 F

.82 .80 v 88 82 .80 8 8:08 83 32509:: a

.82 .80 2 08 .80 _ .8. 8 .8. : .8. o 8:08 83 808; H
.003 000200 .8080 .088 080 Mo 008 20m 8800:: 080 n_ .288 a; 8 00 88088 .83 9800 +

 

 

 

 

 

.3 6250.030 8 22 z 8838.. 2 S S. .2 8.
to 2.080 8838.0 8 Z S 2 2.
an on S 2. 8
28.2 02 N: 25 2.. 88 E :8 80 882:2
a ALE 8: 3220.020
808: 500 2.02 8923

 

.082 .80 mm .0580 88355 5288 8830 85 5

2006000 Ew: 000508 800: 080800800 002 888820 30203. 00 0008805 05.80-3202E_0E:c->0-0ow00_0 “08202.0 85 000 $580 .0225 .m 8380.

.002 .82 N 008 .080 mm :80 o. :80 _ :02. mm :02. 0 _ :02 o 8:008 83 00008; F
00202000: 8 080 203 85 8:08 .83 008 858 080000 85 83 800 a

.82 .80 v 28 82 .80 8 8:08 83 6250020 0

.002 20:00 .8000 .080 0.80 No 008 20m 080000 080 H_ .288 0-. 8 00 88:88 83 5:800 +

 

 

 

 

:0 so 8.0 00.8 03
N._ m.m 0; 9m 02 QM 00
Nam N.m _.v m.m me 00 wv
w.m 0.0 m6 0.0 0.0 ”mm cm
003 000003 003 000003 003 000003 A 0-80 wv: come: Z
F 2.08:
.82 _ _ .82 m .80 mm

 

0008085 00.80.00.088”?

2 0.0
Wm Wm 0m Wm
wh mg». m0 ed
0.0 w.m 00 ed

50.2 000
8
2.
8

 

N: cod 2.. 006

 

H A :2 20 6250.02...

 

.82 m .80 mm
0008820
08020202005009:— 0

2 :2 we: 808:2

 

. .002 ._2 @0508.— 080 .558 0 008—0005 80:80 8830 05 0_ 3020000
Ew: 085:8 E 80800800 .tB $88803 5.0303— E 200882 0580-3080000 0.8 0om0£0$0202EtB=¢ 0080238 05 000 $580 0:800 .v 2000.

5020000000 .0096. 2:80.000 .00 008 00.0 000 8 000020002 1....

 

7
l

 

 

 

 

00.00 0000 8.00 00.00 8.2 00.00 00.00 00.00 0.0. 00 00.00 00.00 .0 .>0
000 .0 000 .0 000.0 000.0 0.00 000.0 0.00.0 000.0 80.0 000.0 -- 000.0
08.0 .800 000.0 80.0 000.0 000.0 000.0 000.0 02 .0 000 .0 -- 00 .0 0 0 0 z
2.00.0.0 2.0000 :0000 2.0000 2.0000 000.0 ...000.0 000.0 000.0 2.0000 -- 0 0 0 0
2.0.0 .800 000.0 80.0 80.0 000.0 000.0 000.0 00.0 .0 :00 -- 0 0 0 z
:080 2.0000 ...000.0 3000.0 2.0000 000.0 3.0000 000.0 20.0 :0000. -- 0 0000 0000.0
000.0 2.00 000 .0 000.0 000.0 80.0 000.0 0.000 0000 000.0 000.0 00 .000
2.0000 .0000 ...00.0.0 .000... 000.0 .0000 000.0 000.0 00 0.0 000.0 0.000 0 0 0 z
2.02.0.0 2.00000 3.00.000 2.20.00 2.00000 :08: 2.00000 :0000 2.2.0.02 3.00000 .0008 0 00 002500020
:0000 .0000 2.800 .0000. 0000 .0000 000.0 000.0 00 0.0 08.0 .0000 0 020 50022
000.0 00.00 02.0 000.0 000.0 000.0 0.00.0 0.00.0 000.0 000.0 0000 0 02820000
I002 00 .82 00 402 0 .000 00 .000 00 .000 00 .80 00 .80 0.0 .80 00 .80 0 0 .80 0.
82
-- -- -- 2 .3. 2 .00 00.0: 00.00 00.00 00.00 00.: 00.00 .0 .>0
-- -- -- 000.0 .000 08.0 000.0 000.0 000.0 000.0 -- 00 .000
-- -- -- 000.0 20.0 000.0 000.0 000.0 08.0 000.0 -- 0 0 0 0 0 z
-- -- -- 2.0000 2.0000 1.0000 2.0000 $00.00 10000 3.80.0 -- 0 0 0 0
-- -- -- 000.0 20.0 000.0 000.0 20.0 000.0 000.0 -- 0 0 0 z
-- -- -- .....000.0 2.0000 :0000 2.0.00.0 3.0000 2.080. 2.0000. -- 0 HE 0000.0
-- -- -- 000.0 000.0 000.0 000.0 000 .0 000.0 0.00 00 0 .0 00 800.0
-- -- -- 000.0 000.0 000.0 000.0 20.0 000.0 000.0 00 0 .0 0 0 0 z
-- -- -- 3.0000. 2.0000 3.0000 3.0000 2.000... :2 0.0 ....000.00 3.00.00 0 00 0020200500
-- -- -- 20.0 000.0 000.0 000.0 08.0 00 0 .0 08.0 000.0 0 020 50022
-- -- 0-- 000.0 000.0 20.0 20.0 000.0 000.0 000.0 000 .0 0 02820000
.000 2 .000 0 .000 0 .80 00 .80 00 .80 00 .80 0 .000 00 00 8500
002 002

 

.02 $000084 08.0 5:080 00800008 05:80m
000300 00 000000000 Em: 000508 0000: 000800800 0008.020 00000003. .00 00.2.0 wEQEB 00 0000000 000E820 .00 0280000020 008 008000 0.82 .0 0.080.

18

.32 .80 o_ 28 No.2 .89 N. :o mmmu 2: 95 ESE 28 5:33 05 5 023:0 conmzpfimo 22.» 82m 9.
.modum «a EmoEcwfi Ho: n 2 503838“ .205— bzfimnoa .od 98 mod 05 8 EnocEwi I. x,

 

 

 

 

 

 

 

 

 

 

 

 

two.— _.:._N._ «*o; 42%.— ..Swd 0.6 3;; —._ a; 1%.— HH 5;»
S S S 3 2 3 2 I N.N E” :55?
2%;

..io.o ..:..o.o .156 1.06 «1.0 3.56 **m.o .I.w.o 3.06 3.5.0 .1. N- .—
3 mm 2 mm 3 2 2 I 3 mm cod
A .2 my: sagas:

no 3 no 2 8 2. 8 m: m: 2 G98 am;
we 3 2 2 S no 3 a. 3 N.N co
3 E I 3 2 9o 2 2 f 3 3
3 ed M: Z S we 2 3 M: E g
.32 on .52 2 .52 N .pfi mm .8; 2 8m 2 .52. cm .52 «N .52 M: .52 : i :2 my: Swazi

:3

25¢ :3 id :3 :3 :3 :2 F 5:,

no to E .3 S 3 3 E

0&5

:3 :3 :o.o :o.o :3 :3 :2 mm:

3 no to no no 2 cm cod

A 72 9: 62:69::

m: m: m: m: m: m: m: 30.8 qu

to we do do to 9o 3 3
no 3 No No 2 S M2 M3

to mo 3 No we 3 3 E
.8; 2 fig a 8m _ .5: am .5 mm .52 2 .52 0 HA :2 9: smegz

82 25:58:.

3:. no my 22»

 

:2 $533 “mam .Qmmov 550mm “92:85 EEvSm vegoo 2:
E 32:28 Em: EoEEn Sue: BESEmE mmfiwuan 303:3. :8 $33 @393 :0 Sta: can ._oEEtE=c .88 coon: mo Seam .N. 2an

19

.voo. .EE vm can :32 2 :52 m rnon— mm :30”— 2 room _ :53 mm 52 Z :5: o 3:an £3 2.:th H
.5on: 3 >8 2:3 05 no 32%? 33 BEEEQSE t.
.32 .32 a 23 :3 v .82 .89 t 33% 33 $23 cowogz a

.82 .8”. 0 2a £2 am £2 K .5. E :82 8Q on 33% 33 2&5 F
.5on: 8 >3 2:8 2: co Bing £3 BEEtEBm m

.82 .5: 2 can mag .89 3 :o «2: mm “Va—Qua £3 5352 H

35:08 h 2an

20

medium and low nitrogen rates. The adverse response to high nitrogen has been reported
previously for bermudagrass and forage grasses in reduced light conditions (Burton et al.,
1959; Eriksen & Whitney 1981). More importantly, nitrogen and flurprimidol interacted
on clipping yields in the second season. Nitrogen did not affect clipping yields when
flurprimidol was applied (which resulted in zero yield for all nitrogen rates) while
clipping yields were decreased proprotionally to increased nitrogen rates in the absence of
flurprimidol (Table 8). This is in contrast to Devitt and Morris (1988) who reported high
nitrogen rates reduced the effects of GA-inhibitors, although Johnson (1988) found higher
nitrogen rates (25 vs. 50 kg ha'l) did not decrease the effectiveness of flurprimidol on
bermudagrass in full sun. Traffic and flurprimidol also interacted in both seasons with

flurprimidol decreasing clipping yields more than traffic (Table 9).

We;

Shear resistance of turf was most affected by traffic and only minimally affected by
nitrogen or flurprimidol. No interactions occurred (Table 10). Traffic consistently
decreased shear resistance values. High nitrogen rates decreased shear resistance
compared to low nitrogen rates (Table l 1). Low shear resistance values due to traffic and
high nitrogen rates were probably due to reduced turf cover and possibly reduced root
structure although rooting was not measured. Flurprimidol had little effect, causing an
increase on one date in 1994. Shear resistance declined over time regardless of treatment

due to lack of sufficient light energy to sustain growth, particularly rooting.

2]

40233833 mm 32% 2:8 05 :0 8:: mm 3:an $3 coonZ a
.33 .32 a 3% .83 v .82 So 2 .3 33% 83 A :2 E 2.: 3233.23 H
.32 .80 A: :o mmmu 05 SE 35E 3:3 32 5:33 macaw 023:0 327.2988 803 30E +

 

 

 

 

 

 

 

Z A: to A: 2 A38 am;
A; 3 AS A: A; 3 9o 3 A; A: 8
AS 3 AS 2 A; Z A; S A; S a.
A; 3 A; S. A; f. A; 3 A; f «N
A N.3 no 3 3»
2 .3 8.0 m: 8.3 m: 8.3 E ._ 8.0 e ._ 83 3A .2 was 5on2
H A 72 was 33:83:
.32 cm .32 E .52 N .83 mm .83 A:
332

 

+ :2 333%; 38 .Ammmov 3:333 3%33m 323m 328 as 5
22:38 Em: 255:8 83:: 32:85.2: ta $3:ng 303:3— ..o 83% mango :0 530885 _oEE:&=c-E-:owobE 38533 05 38 82m> .w 2an

22

.82 .32 E 3% .32 2 :32 m .33 8 :83 A: .32 _ ..%A 8 .32 : .32 o 33% 83 0:3: I
.82 .32 z 3% .83 v .82 8a 2 33% 83 A .2 2. 2.: 333.23 3
.82 .83 o 3% .32 8 ..%A a ..%A 3 .82 .95 8 33% was 2.32 a
.82 SA 2 3% 82 So 2 33% was A :2 2. 2.: 32:22.2 3..

.MGG— .000 A: van N00_ .009 h :0 n—mmU 05 CHE U0>OE USN amok 502 m0 :Eazw mats—u fiozmzsmamo 9.03 mac—m +

 

 

 

 

 

 

 

 

no no No No No No 2 A38 23
A; A: AS 3 A; Z A; 3. 3 2 No 3 9o 2 t. 5?
A; S. A; 3 AS 3 AS 3 3 3 2 Z no A? 3233
2._ 8A: 2._ 8A: 2._ of: 2._ 3o 2._ 88 2 ._ A38 2._ 88 3.3.:
«A :2 w: 3238::
32 2 .%2 2 .32 N .83 mm .83 2 3.: CM .52 :
82
we do do do we do No A8233
A3 3 A; S o.o A; A; A; A3 to 2: no no A: a .33
S 2 A; 2: A3 3 2: 9o 3 2 E: 3 3o 3. :55?
2._ 88 2._ 88 2._ 8A. 2._ 88 2._ 88 2._ 8.0 2._ 3o 2.33

 

 

be”. 0. bum w

”A .2 9: 32332::

 

 

 

bum _ .53. am .5: mm .52. m_ .52 o

 

mag

 

A we no 2 23>

12 .wEmqu “mam .Emmov 326mm— SBEEE E:_3Sm 32050 23 5
22223280 Ew: 255:8 83:: 32:32.32: 33 mmfiwozz 32:33. :0 333A wcaazo no 2532225 oEab-zn-_03_E:E:: Emoc_:w_m 23 .8 mos—,3 .o 033%

23

Table 10. Mean squares and significance of treatment effects on the shear resistance of Kentucky
bluegrass maintained under ambient light conditions inside the Covered Stadium Simulator Facility
(CSSF), East Lansing, MI.

 

Shear resistance (N-m)

 

 

 

 

1992-93 1993-94
Source of variation (if 22 Dec. 11 Jan. 3 Feb. 28 Dec. 8 Apr.
Replication 2 22.028 2.507 9.299 9.528 1.021
N rate (N) 2 5.778 21.049" 5.132 0.778 37.646*
Flurprimidol (F) 1 23.361 0.563 10.028 0.028 30250"
N x F 2 0.444 5.063 1.799 8.778 3.771
Error 10 8.828 4.724 3.624 4.828 5.738
Traffic (T)T 1 ----- 25840" 40.1 1 1 ----- 20250"
N x T 2 ----- 4.215 4.090 ----- 2.146
F x T 1 ----- 2.007 4.000 ----- 0.250
N x F x T 2 ----- 7.340 0.896 ----- 0.187
Error 12 ----- 3.993 1.681 ----- 2.507
CV, % 0.00 10.74 8.38 0.00 15.97

 

"‘ Significant at the 0.05 probability level.
‘1 Traffic applications were not started until 29 Dec. 1992 and 6 Jan. 1994.

24

Table 11. Main effects of nitrogen, flurprimidol, and traffic on the shear resistance of Kentucky bluegrass
turf maintained under ambient light conditions inside the Covered Stadium Simulator Facility (CSSF), East
Lansing, M1.

 

Shear resistance (N-m)

 

 

 

 

 

 

1992-93 1993-94
Treatment 22 Dec. 1 1 Jan. 3 Feb. 28 Dec. 8 Apr.
Nitrogen (kg ha'l ) ‘1
24 20.9 20.1 16.2 22.6 11.7
48 19.9 18.2 15.0 22.8 10.0
96 21.2 17.5 15.2 22.5 8.1
LSD (0.05) ns 2.0 ns ns 3.1
Flurprimidol (kg ha’1 )
none 19.9 18.7 15.0 22.5 9.0
1.12 i 21.5 18.5 16.0 22.6 108*
Traffic
without ---- 19.4 16.5 22.5 10.7
with § ---- 17.7* 14.4" 22.5 9.2“

 

"', ** Significant at the 0.05 and 0.01 probability levels, respectively.

T Nitrogen was applied as urea on 16 Dec. 1992, 18 Jan., 17 Dec. 1993, 4 Feb., and 21 Mar. 1994.

I F lurprimidol was applied on the same days as nitrogen.

§Traffic was applied 29 Dec. 1992, 14 Jan., 21 Jan., 29 Jan., and 6 Feb. 1993, and 6 Jan., 11 Jan., 25 Jan.,
1 Feb., 10 Feb., 22 Feb., 2 Mar., 17 Mar., and 24 Mar. 1994.

25

Treatment effects on surface hardness were not consistent between years (Table 12).
Relative differences in gmax values between years were probably due to the use of
different accelerometers in the CIT equipment following a repair in 1993. In the first
season (1992-93) traffic treatments appeared to reduce surface hardness, while in the
second season traffic treatments increased surface hardness (Table 13). Generally traffic
will increase surface hardness by compaction and reduction of thatch and turf cover
(Rogers and Waddington, 1990). Surface hardness is also affected by soil moisture with
higher soil moisture providing lower gmax values (Rogers and Waddington, 1992),
however, soil moisture was not determined in this study. In Feb. 1993 most turf in
trafficked areas was dead although a thick (approximately 1.5 cm) mat layer remained
which may have retained sufficient moisture to cause a decrease in gmax. Compaction in
the mat layer by the traffic may also have caused decreased water infiltration. Non-
trafficked areas may have had lower soil moisture values due to water uptake by the turf
and increased infiltration rates. In Feb. and Apr. 1994 turf cover was higher than in 1993

and soil moisture values may have been more equivalent between trafficked and non-

trafficked turf.

Experiment 11
Supplemental lighting supplied approximately 8.4 i 1.4 mol PAR day'l (Table 1).
The HPS lamps emitted a significant portion of their light in the yellow, orange, and red
wavelengths (Figure 1). Ambient light in the CSSF was minimal and contributed little to

the PAR on plots under supplemental light.

26

Table 12. Mean squares and the significance of treatment effects on the surface hardness of Kentucky
bluegrass turf maintained in ambient light conditions of the Covered Stadium Simulator Facility (CSSF),
East Lansing, MI.

 

 

 

 

1993 1994
Source of variation df 3 Feb. 3 Feb. 8 Apr.
Replication 2 99.750 398.401 * 240.465
N rate (N) 2 1226.750 33.347 106.747
F lurprimidol (F) 1 205.444 31.923 30.988
NxF 2 196.861 143.191 37.814
Error 10 78.783 93.879 130.947
Traffic (T) 1 3211.111" 753.503" 1497.690"
N x T 2 206.194 57.341 116.328
F x T 1 225.000 9.714 124.695
N x F x T 2 37.750 6.930 45.859
Error 12 157.333 18.056 50.820
CV, % 9.09 6.23 9.48

 

*, ** Significant at the 0.05 and 0.01 probability levels, respectively.

Table 13. Effects of traffic on Clegg Impact Values of Kentucky bluegrass turf maintained in reduced light
conditions inside the Covered Stadium Simulator Facilty (CSSF), East Lansing, M1.f

 

 

 

 

 

 

 

 

 

 

 

gmax
Ambient light Supplemental light 3‘,
1993 1994 1993 1994
Treatment Feb. 3 3 Feb. 8 Apr. 3 Feb. 3 Feb. 8 Apr.
Nitrogen (kg ha'l ) §
24 141.3 66.5 72.2 156.0 74.4 83.5
48 134.8 69.8 75.4 146.6 69.2 79.0
96 134.8 68.2 78.1 147.2 71.0 79.2
LSD (0.05) ns ns ns ns ns ns
Flurprimidol (kg ha" )
0.00 139.8 67.2 74.3 144.3 72.6 82.9
1.12 1] 134.1 69.1 76.2 155.6 70.5 78.2
Traffic
without 147.4 63.6 68.8 154.9 66.4 73.8
with # 128.6" 72.8" 81.7" 145.0 76.7" 87.3"

 

*, " Significant at the 0.05 and (YOI probability levels, respectively; ns = not significant at p=0.0§

T Plots were established outside during autumn of each year and moved into the CSSF on 7 Dec. 1992 and
on 10 Dec. 1993.

I Supplemental light was supplied from 400 W high pressure sodium lamps.

§ Nitrogen was applied as urea on 16 Dec. 1992, 18 Jan., 26 Feb., 21 Dec. 1993, and 4 Feb., 21 Mar. 1994.

11 F lurprimidol was applied on the same dates as nitrogen fertilizer.

# Traffic was applied on 29 Dec. 1992, 14 Jan., 21 Jan., 29 Jan., 6 Feb., 20 Feb., 10 Mar., 24 Mar. 1993,
and 6 Jan., 11 Jan., 25 Jan., 1 Feb., 10 Feb., 22 Feb., 2 Mar., 17 Mar., 24 Mar., and 31 Mar. 1994.

27

Turf quality remained relatively stable under the supplemental light conditions. Traffic
had more of an effect on the turf in the first year than in the second year for probably two
reasons: 1) shorter period of establishment in the first year, and 2) a heavier person
(approximately 115 kg) applied the traffic the first year while a lighter person
(approximately 75 kg) applied the traffic the second year. The turf responded
significantly to flurprimidol applications in most cases although surface characteristics

(shear resistance, surface hardness) were not greatly affected.

luquualjty

Nitrogen rate and flurprimidol generated main effects on turf quality throughout the
study in both seasons (Table 14). Turf quality increased in proportion to nitrogen rate
(Table 15). Flurprimidol significantly enhanced turf quality in both seasons.
Interactions between nitrogen and flurprimidol in both seasons showed higher nitrogen
rates particularly enhanced turf quality when treated with flurprimidol (Table 16). Traffic
decreased turf quality in season one but had little effect in season two. A three-way
interaction occurred on turf quality 91 days after installation in the C SSF in both seasons:
Traffic decreased turf quality of flurprimidol-treated turf only at the low nitrogen rate;
otherwise traffic had no effect. Flurprimidol was responsible for most of the three-way

interaction as it enhanced the effects of nitrogen at each successive nitrogen rate (Table

17).

28

.888_ .888 8 E88 88:88 888 883 8888.8 8

888_ .888 88 :88: 88:38 888 883 88888.8 8

8.8888882 .232 88888888 88.8 888 88.8 28 .8 8888288 .. ._..

 

 

 

 

 

88.8 88.8 88.. 88.8 88.8 88.8 88.8 888 88.8 88.8 8_ .8 88 .>o
888.8 888.8 888.8 888.8 _88.8 888.8 888.8 38.8 888.8 - - 8_ 88:8
888.8 888.8 .8888 888.8 888.8 _88.8 888.8 88.8 888.8 - - 8 .8 x 8 x 2
888.8 888 888.8 _ :8 .8888 888.8 888.8 888.8 888.8 - - _ .8 x 8
_88.8 888.8 .8888 888.8 888.8 888.8 888.8 88.8 888.8 - - 8 8 x 2
888.8 888 888.8 .8888 888.8 888.8 888.8 888.8 888.8 - - _ 8.. E 8.88888
88.8 888.8 888.8 888.8 888 8.8.8 888.8 888.8 :88 88 .8 .88 8_ 88:8
888.8 8882 .882 .8888 :8: .8 :888 t; _ 2. 888._ 888.8 :888._ 888.8 8 8 x 2
£888.88 £88.88 .8888 2._ _ .88 3888.88 :88 _ .:. 2.8888 :_ _ _.8 .388 .888 888.8 _ 888 8288.28
.88; 3:88.88 :8888 :8888 :8888 2.8888 :8 _ 3: :88. .8 ......88.8 888.8 3.88 8 828 es 2
88.8 888.8 .8888 888.8 888.8 8: .8 888.8 888.8 : _.8 188.8 88.8 8 88888888
.82 88 a: 8_ a: : a: 8 888 88 888 8_ 888 8 888 88 888 8_ 888 8 888 88
88-882
88.: 88.8 88.8 88.: 88.8_ 88.8 88... 88.8 88.8 8_.8 8.8 .8 .>o
888.8 888.8 8 _ _.8 888.8 888.8 888.8 888.8 888.8 888.8 888.8 - 8_ 88:8
82 .8 888.8 8888.8 888.. 888.8 888.8 888.8 888.8 82.8 888.8 - 8 8 8 8 x 2
8:8 _:.8 888.8 888.8 _ :8 8:8 8:8 _:.8 888.8 888.8 - _ 8 x 8
: _.8 888.8 838 8.8.8 888 888.8 88.8 888.8 888.8 888.8 - 8 8 x z
.8888 :8 _ _.: 2888.8 3,888.2 .8888 1888.8 888.8 888.8 :88: 2.888.. - _ 8 E 88888
888.8 882 888.8 888.8 888.8 888.8 88.8 :88 88 8.8 888.8 88.8 8_ 88:8
_88._ _88._ .8888 2.8.88.8 .888 2.8.88 83.8 888 888.8 888.8 888.8 8 8 x 2
3,888.88 ....888.88 £8.88; 2.88.: 1.88.88 1.88.88 2.888.: 3.8888. 888.8 888.8 8888.8 _ 888 828558
88.8 28.8 .888 .888 .8888 1.888 88.. 888.8 2888.8 .8888 88.8 8 28 888 z
82 ._ 888.8 888.8 8888 28.8 .888 _ :8 .828 888.. 888.8 8888 8 88888888
a< 8. a: .8 a: 8 888 8_ 888 8 888 88 888 88 888 8_ 888 8 888 88 8m 88 88 8888
88-888_

 

dz $5853 888m 5:688— 892385 EEvSm @2300 86 8285 8:286:06

Em: 55883858 828:: “82:58:88: 888E822 zxoacox 80 5:25 2: :o 8588 88:8 4025:8838 .888 cowobE .80 8888.88 85 88 88.8188 :82 .3 038,—.

29

 

 

8_ . _
88.8
A .88 888 62888.28

A888 8.84
88
88
88

A 78: was 5on Z

 

88 A23
8223

2.828

882
88.8

 

 

8:ng 5.8. fined 8:..o.w 3L.” tame. 8.8—.8. {*NF 3.5.0 0.0 _.0
v.m _.m Q? Qv M0 _.m Wm m0 o0 m0 _.0
Yo m: v.0 Yo Yo We Yo 5.0 wd m: m:
0.0 m8 N.N. _.8. 8.0 0.0 MK. m6 OS 0.0 N0
0.0 m0 0.0 w.0 AS m0 m0 5.0 V0 #0 N0
N0 N6 Nam v.0 N0 50 N6 _.0 v.0 N0 w.m
58—2 mm .582 n; .32 Z .852 m .00“— NN .00.» o- .00..» m .58.. vm .58.. N_ .58.. m .000 mm
.1. vanmoo—

1&0 838.0 536 8.2.0.? **m.m 8:806 V0 5.0 8&0 *N.0 1.
Wm m0 M0 o0 m0 m0 m0 @0 AS 0.0 l
**N.0 .350 8.1.8. 8:56 81.0.8. 1.0.8. 1.5 $8.8. OS v.0 *m.w
QM _.m o.m 048 0.? ”in 06 m0 o0 v.0 w.m
m: m: 0.o wd 5o md 28 m: md m.o m:
Qm 0.0 0.0 6.0 m0 m0 w.0 OK. 88.8. m0 8mm
o6 0.0 o0 o.m Nam o0 v.0 M0 OK. w.0 w.m
m6 N6 Wm 0.? 06 _.0 N0 81.0 #0 o0 M0
na< A: .832 _N .32 w bum : .Don— M £3. mm d9. ON d2. 2 .53. w .80 0m .89 w—

 

8 88-888A

A .88 88 32888928

A888 A888
88
88
88

8 A .88 888 8888882

 

8588828.

 

8.82 .8523 888 .8888 8.8388 3883888 858888
882260 85 828A: 8:286:98 Em: 3858838838 8888:: 358588: 888E853 .0635! me 88:83: 85 :o 32855.5: can 88. coon: .«o 88.8.80 :82 .2 038,—.

30

.30. .882 cm .858 .882 S .882 m :88 mm 388 A: :88 A :5: mm .888 Z .88.. 0 3:858 88>» 858:. mm

.32 .80 A: 8285 co>oE 88:8 Agnew A: 8828080 5:83 2: E 828:6 8885:9888 283 8828— t.

482 .882 vm 88:8 .882 A: :38 om :08..— 0 :52 om :5: _m .88.. E :30. .80 mm 3:858 883 858:. 88
8:008:83 88820.58 A23 88:85.88 5 A 78: m8. 2.: 6288893: 5:5 .8835 295 828 F

85,885 8.83 828 2 8:8 :8 78; m8. em 8o .8» .vm 88 888: 88 882—8538 883 somoEZ m

Noo— doQ A. 8285 32:: 88:8 Agnew om “8838080 c8338 85 E 82850 8858:5888 8883 8828 H

.8952 5:608 88888288 :mE 3 cow .3 8888:8988 883 A 1388 ~28 7:: Ya boafiioammv mEEm: 3582855 .8
583888888 .833. 3:88.305 56 88:8 mod 85 88 EmoEcmfi 3......

 

8.8 8.8 8.8 .88 8.8 8.8 8.8 8.8 8.8 -- -- 88 883
8.8 8.8 8.8 8.8 8.8 8.8 8.8 8.8 8.8 -- -- 8885:,
88828

A8883 8_ 2888

31

8:283:38 hofiztom 5:5 cocoa—8.38 E 83:38 883 A 78: wx Q .C BEECEEHA a
2822.: x33 x5 8 58 H8 88: m8 nozamsm 883 coonZ H
.888. 8:68 2383 LE: 3 oov 5:5 3:995 883 A 38¢ m<m .08 v.» A_oH8E_xohaa8v wEEw: 5560395 +

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8.8 88 88 no 3 8.8 no A38 03
8.8 E 8.8 3 8.8 2 Q 3 N8 3 E 8.8 S 8.8 88
2. 2 N8 3 3 mm 2 3 3 8.8 3 3 2 N8 88
3 8.8 8.8 2 8.8 3 E ”A 8.8 mm mm 8.8 8.8 3 E
80> 02 80> 02 an; 02 mo> 02 88> oZ 80> 02 R; 02 A 78: wxv coonZ
32.5.86
.32 t .82 : .32 m 8.8 mm .88 S .808 m .5: 8
$2
2 I 3 8.8 A38 93
88 ed 2 3 M: 3 E on 8
3 88 8.8 we 3 mm 8.8 m8 3
8.8 3 3 S 3 mm B 8.8 88
mm; 02 mm; 02 mo> 02 88> 02 A 78: wvc 5on Z
32888::
.32 8 88 t .88 m .5: 88
82

 

:2 .8523 838 .0588 9:5 sasém 52898 82260 2: 02% 22:28 58:

3582.53 #6:: 3588588 mmfiwosz b.0383— mo 5:83 2: so E2588“ _oEEt&:c 8:8 888 5on: .3 32885:: 2.805%? 85 88 838> .2 038%

32

38:90.“ :owobE FEB cocoa—3.88 E @3758 v.83 A 78: 3 m_ . 3 BEES—2m n
28>..an v.83 5m 9 S8 88 88: 88 3:33 883 some: Z F
$2 .82 88 Ba :82 t :82 N .98 mm ,8“. S .88 _ .5. mm .5. : .82 8 823% ms: at“: a

.82 .82 3 Ba :22 2 .38 cm :68 8 :5: am :5 a :5: E 83. .80 an 823% we» 0&8; H
8928— 8:68 2335 :wE 3 cow Eo¢ 8:33 m8? A 7A8“. 5E .08 8.x 388899253 macaw: 358235 +

 

 

 

 

 

 

 

 

 

ed 06 AoEEtfizc .8 888. Z 88389
Ad No 8585 5253
A38 om;
Sm 3 ca 3 8.8 3 m8 m8 3
S we 3 we 3 8.8 2 3 88
S 3 3 3 8.8 S. 3 3 cm
808 82 oz 82 808 oz 808 «on. CZ 368 808 oz FA .2 my: 22 58052

02.85 058:. oz 355 2&8: oz

32 8282 : 82 8282 8

 

22 85.0.53 mam .588 9:88 .9235 52898 8238 2: 022:
8:05:38 2w: BESS—mag $25 LtB mmflwozi 303:3— 5 88288.25 859513-32EcfiscinéowobfiE80£=w_m 2t 88 «.9588 hum—8:0 .: 038.

33
Cl. . . I!

Treatments indicated significant main effects and two-way interactions between
nitrogen and flurprimidol and between flurprimidol and traffic on clipping yields in both
seasons (Table 18). Clipping yields were proportional to nitrogen rates while
flurprimidol and traffic both significantly decreased clipping yields (Table 19). The
nitrogen-by-flurprimidol interactions showed flurprimidol negated the effects of nitrogen
on clipping yields while increasing nitrogen rates significantly increased clipping yields
in the absence of flurprimidol (Table 20). The flurprimidol-by-traffic interaction showed
traffic did not reduce clipping yields when flurprimidol was applied because flurprimidol

acutely reduced clipping yields compared to traffic (Table 21).

rf c h ra ri i s

Treatments affected turf shear strength in both seasons (Table 22). No interactions
occurred. Traffic and higher nitrogen rates decreased turf shear strength. Unlike the
results in experiment one, the lower shear resistance values were probably due to reduced
rooting and increased turf succulence as turf cover was not significantly diminished by
either treatment. Flurprimidol did not affect shear strength in season one but caused a
slight decline in season two (Table 23).

Treatment effects on surface hardness (CIT values) were inconsistent between
seasons. In season one only the flurprimidol-by-traffic interaction was significant, while
in season two the nitrogen-by-flurprimidol interaction was significant plus flurprimidol

and traffic main effects (Table 24). In season one, traffic apparently decreased surface

.bo>tuoam2 .232 £3308 36 can mod 2: 3 E8555 1. ._._

 

34

 

 

 

 

8.2 3.3. N? 86 8.2 8.NN 2.: S: 3.2 32 .x. .>u
23 3x2 83 $3 2 3 ”2._ 8:. 5:3 83 -- N_ 55
N25 83 955 $3 0N; ”who 33 em; 3N5 -- N H x n. x z
:NNN.: 33% 82. :ctN 83. $3 $3 omNd :23 -- _ H x h.
~de BAN 83 NNNd Sod 3N4 :3 $3 2.3 -- N .N x z
:8N.N_ emNd cmNd :2; 8g 83. 83 £5 :ENé -- _ E 2&5
on? at». $2 $2 3.3 if 53 SN; NoNN 8N.” 2 55
R; SoN .Nm: saga :83” :EN real: 2.53.2 2.808 :3 N a x 2
:SNES :ENamN :NRNow :83: read” :ESS :33: :3. _ mm :covfiv :83 _ N _ Q 625:35
mmmNN :52 .NN .NRN :NoNé :83 2.02.? 338.2 :SQNN :3th .23; N g 83:2
$3 $3 ENN RS. .58.. :33 ES .33 :3 N88 N Susie”.
.32 cm a: 2 .8; NN .8; 2 NE a sum N .5: «N .52 M: .5... : .5 v :c 858
$2
5.2 .2: 2.3 8.x 3% 21% BNN 32 E: S. _ m .x. .>o
2N5 £3 0N: 89o “SN; 32 3.3 $3 25. -- N_ sew
No; SE 8:. £55 and N23 33 2N5 NNNd -- N P x a x 2
E: Rod 5.: m: ._ :32: :23 :33 Loos $3. -- _ F x a
No; «SN E: 32 3:8 NNNd mNNd SE 23 -- N e x z
«86 :82: 23.8.2 £82 :62: :33 :83 :NENN LE: -- _ E 2&5
Row 3; VNN? 5.3 N. 3 «NE 32. 22 a Z: NNN.N_ 2 .25
$3 2% 83 ”New mm: 82 was aNS in? in: N a x z
:SNNN :cS. _ 2 .EOSN $8.3 :5: :NQS :SN.$_ :8. .Bm :SoSNN :QNNSQ _ E 3258::
85 8&2 «$3 33 mm? a: :83 :SNNi .NmNNS :38 N 9c 32:2
None 302 $3». 3.: .83 N93 :3 5N waN. 3: N cofieaom
.32 NN 5.: N_ .8; 2 non m sea _ .52 NN .52 NN as. 2 .5... a .95 oN :c 850m
82 No2

 

$5 no 8 22>

 

dz .wEmSS “mam 5:63 BEEEE 823% 3350
go mcoEccoo Em: EEQEQEQE Bug: 35859: 32ng xxozacox go 3.2% wcimzo :o acute Eocbmob no oogoEcwfi 28 33:3 :32 .m- 2an

35

 

 

 

 

 

 

 

 

 

 

:3 N.N 3. :Ne oN 3 N.N 3 :fi -- ma 5:,
>6 2: we 3: N.N _.m _.m od 50 : 5223
058,—.
.356 ..:..?._ Sued *iwd 3.0.6 *im; 3.5.0 *1... *imN 3.0.? N_.—
0.: 0.0 v6 m.» Em Nd 9m w.» 06 o.~_ 25:
A :2 9: 35:92...

2. S 2 no 9o N._ no 3 Z N.N 28.8 mm;
vs 9m fim _.m Em ed QM .6 m.» 2: co
v.0 o6 Nm _.m N.N Q? _.m 0.? We 9o 3
he Om w.m m.m mg 9». o; m.m m6 w.m vm
HA :2 wé 88 cowobmz
.32 om .32 2 ho”— mm bum m _ he; a bum N 9: vm .S: M: .22 _ _ .5: v 2.258;

t. $2

m.— ..:..N.N .15.? :0; {0.0 1.0.— **?.N 3.5.? ..:..?.o I. n 55»
2 9m ob fim o.m hm v6. w.m 0: -- 505:5
2.:th
“Rod fro; *NN *?._ 1.96 *1.— **w.o **O.N *NN **wh?.N N—A
o.m ad 3. 0m QN NM 3: M: 3: mmodm use:
f :2 EV 326:9:

m: m: m: m: m: 3 9o o._ ox.“ we $6.8 mm:—
o._ w.m ad 9m N.N v.m m.m m6 0.2 n2 oo
o._ _.m wé N.N 2 N.N ad 5? 2: 0.: w?
5o M: m.m _.m ed o2 vN Qm 06 v6 vm
Q was my: 88 5on2
.32 N.N .32 m_ be; 3 ben— w be”. _ .5: am .5... mm .5: 2 .5: o .ooQ am 2258....

82 H N3
35 no 3 22>

 

22 .383 mam .Emmuv $.35 533:5 822% 8530

05 .3 252250 Ew: Econ—3&3 Etc: BESENE mmeg—n ancox 20 £22» @393 :o oEmb EB .EEEESc .28 cowobE mo 68mm .2 2an

36

4&0— ..aZ vm was in: E .522 N .bom mm rank 2 room _ 3:: mm 25—. I :54 c @239“ mm? 059:. mm

32 .52 a Barnum v ”82 8o 2 .5 we: a 33% 33 5on2 H

.32 .89 S no ammo 05 95 ESE Ba Mai 2528 wESn 0233 3.7.2983 29$ 32m i

.32 .52 g Ea £22 2 :3 cm :6; c :5 am :52 a £2 E ”82 So am 33% 83 2&5 k
.989» Eon E cowobE 3 Sun 08% 2t :0 8:an 33 3255.55 F

.82 new on n5 £2 M: :82 .89 2 S 85 a 33% 33 32:2 a

.moo. .80 N. :o mmmu 05 85 322: was mom: 5:33 9:26 023:0 352%qu 803 30E H

.383 E268 2885 :wE 3 09. 3 vozaasm m2» Em: gauche—nag +

.mcdua 8 685%; 8: u m: 503633.. .232 bzfimnoa 56 can mod 05 “a Exogcwfi 3.. ....

3,253 a 03$

37

._oEEt&=c 3 8:8 2:3 2: :0 «.2: mm BEE.“ mm? 5on2 u
.voi .82 _m can snow v .32 .80 _m 98 spam cm :5: w. .mofi .80 3 :o v2.3a 32; 7m: wx NZV BEthS—m F
.82 .80 o_ co mmmu 05 95 ESE new 39 =EB=m waist 023:0 352983 203 $05 m
.32 .80 b :o mmmu 2: BE v26:— 28 mag 5:33 wESv 0233 35383 295 32m H
.382 8:68 2335 :wE 3 cow Soc wow—a9; £3 wEEw: 3580396 JP

 

 

 

 

 

o; wd ad _.N 2 m._ a; m.m v.0 $98 qu
o6 NA: o._ m.@ ad we 04 9: ad 06 o; 0.2 v.m Wm— o.m :Vm Wm ohm co
od m6. 9. vd ad m.m _.m 0.5 m._ wé vN v.» YM md 54 02 ON m._m we
od 06 m6 m6 md 9m 5o «6 9o NM : m.m o; 06 o.m Q: a; QC vm
mo» 0: 3% o: 8» 0: an» o: 8» o: 8% c: me» o: 8» o: 8% o: i 7m: wxv
cowo£z
F sagas“.
.afimm bum m _ bum F bon— N .23 um damm— .=2 _ _ .52. a .80 mm
32: 82 H No2

 

A we no 3 22>

 

 

:2 .323 Em .Qmmuv ESE 833:5 522% 8.260 2a a 82:28
Em: ESEEoEasm Eva: BESEmE t3 3.8ng 3085M E 228835 _oEEt&:c-3-:owobE 38$ch 05 8w 8.2» wEanzo .om 2an

8
3

32 .32 a .9; v Ba .82 So a .8» cm :5. 2 .92 8o 2 33% we: :2 3 2.: 32529:: a
.82 .32 a Ba :52 2 an: N :2 mm :2 2 :3 _ :5 mm :3 : .5. c 23 82 .5: am 2a .5. a £2 E .SE So 8 33% 33 2&5 F

.33 .8D 3 co ammo 95 95 ESE can moi 5:83 mats—u 023:0 vozmsnfimo 0.53 805 a

.N00— .000 5 co RWMU on“ 0H5 U0>OE tam N00— Sagan warn—U Ohmmuzo UQSmZDSmO 0.53 mac—mm N

.852 5:68 838R .33 3 oov 5:5 32%.; mm? Em: EEQEoEQ=m +

 

 

 

 

 

 

 

 

 

ad .3 wd N; wd 9o o._ 335 Om:

5o 5o 5o wd Om 9m ed M: ad m._ 5o 9. o.— md N:
2: fig M: 0.x 3w 2: od o6 v.m oé _.v Em m6 Nd cod
mo> oZ mo> oZ mo> oZ R; 02 mo> oZ mo> oz mo> oZ n A 7m: mxv
32.5.85

F 0E“;
.32 om bon— m. .22 Z bum _ .52. om .52 mm .5: 2
3&2 H 82

 

A we no 3 22>

 

22 $5284 “mam .Emmuv bmzomm 88.58% 823% @2260 05
E 32:28 Em: DSEEoEQa 825 358.58 t3 mmflwoan 302:3. E 228885 oEmb-3-_oEEtE:c 38535 05 “8 $5» 3:520 .70. £an

39

Table 22. Mean squares and significance of treatment effects on the shear resistance of Kentucky

bluegrass maintained under supplemental light conditions inside the Covered Stadium Simulator Facility,
East Lansing, MI.

 

Shear resistance (N -m)

 

 

 

 

1992-93 1993-94

Source df 22 Dec. 11 Jan. 3 Feb. 20 May 28 Dec. 8 Apr.
Replication 2 50.361 * * 10.896 10.882 5.027 23 .083 5.090
N rate (N) 2 0.528 6.813 12.340 127.823M 5.250 281.757M
Flurprimidol (F) 1 1.000 16.000 16.000 15.867 8.028 20.250"
N x F 2 19.083 10.146 3.271 3.151 0.861 6.896
Error 10 5.828 6.929 8.315 3.643 9.083 3.599
Traffic (TN 1 ------ 12.250 4.000 125.814" ------ 20250"
N x T 2 ------ 2.021 4.146 2.014 ------ 10.021
F x T 1 ------ 0.694 0.111 1.914 ------ 2.778
N x F x T 2 ------ 1.882 1.549 0.034 ------ 0.632
Error 12 ------ 4.604 7.271 2.537 ------ 3.764
CV, % 0.00 9.61 12.87 12.82 0.00 10.95

 

*, ** Significant at the 0.05 and 0.01 probability levels, respectively.
T Traffic was not started until 29 Dec. 1992 the first year and 6 Jan. 1994 the second year.

Table 23. Effects of nitrogen, flurprimidol, and traffic on the shear resistance of Kentucky bluegrass
maintained under supplemental light conditions inside the Covered Stadium Simulator Facility (CSSF),
East Lansing, MI.“

 

Shear resistance (N -m)

 

 

 

 

 

 

1992-93 1993-94
Treatment 22 Dec. 1 1 Jan. 3 Feb. 20 May 28 Dec. 8 Apr.
Nitrogen (kg ha'1 ) I
24 21.8 23.1 22.0 16.1 23.7 22.2
48 21.5 22.2 20.0 11.5 24.7 18.4
96 21.9 21.6 20.8 9.7 24.9 12.6
LSD (0.05) ns ns ns 1.7 ns 2.4
Flurprimidol (kg ha'l )
none 21.9 21.7 20.8 11.8 24.9 18.5
1.12§ 21.6 23.0 21.6 13.1 23.9 170*
Traffic
without -—-- 22.9 21.3 14.3 ---- 18.5
with 11 ---- 21.8 20.6 10.6 -—-- 17.0“

 

* Significant at the 0.05 probability level; ns=not significant at p=0.05.

1' Supplemental light (approximately 8.4 mol day'l ) was supplied by 400 W high pressure sodium lamps.

I Nitrogen was applied as urea on 16 Dec. 1992, 18 Jan., 17 Dec. 1993, 4 Feb., and 21 Mar. 1994.

§ Flurprimidol was applied on the same days as nitrogen.

11 Traffic was applied 29 Dec. 1992, 14 Jan., 21 Jan., 29 Jan., and 6 Feb. 1993, and 6 Jan., 11 Jan., 25 Jan.,
1 Feb., 10 Feb., 22 Feb., 2 Mar., 17 Mar., and 24 Mar. 1994.

40

Table 24. Mean squares and significance of treatment effects on the surface hardness of Kentucky
bluegrass turf maintained under supplemental light conditions in the Covered Stadium Simulator
Facility, East Lansing, MI.

 

 

 

 

1993 1993-94
Source (if 3 Feb. 3 Feb. 8 Apr.
Replication 2 2762.861“ * 85.343 146.551*
N rate (N) 2 331.361 84.010 77.048
Flurprimidol (F) 1 1156.000 37.414 198810“
N x F 2 245.583 109.471 214.666"
Error 10 316.228 35.931 23.308
Traffic (T) 1 880.111 945.563" 1653.778”
N x T 2 525.194 2.843 0.564
F x T 1 2177.778" 0.122 17.921
N x F x T 2 739.528 9.880 41.792
Error 12 195.889 19.469 30.086
CV, % 9.33 6.17 6.81

 

*, ** Significant at the 0.05 and 0.01 probability levels, respectively.

Table 25. Clegg Impact Values (gum) for the flurprimidol-by-traffic interaction (3 Feb. 1993) and
flurprimidol-by-nitrogen interaction (8 Apr. 1994) in Kentucky bluegrass turf maintained under
supplemental light conditions in the Covered Stadium Simulator Facilty, East Lansing, MI.*

 

 

 

 

 

 

 

 

 

g max
3 Feb. 1993 8 Apr. 1994
flurprimidol (kg ha" )1; flurprimidol (kg ha'T )§
Trafficfl 0.00 1.12 Nitrogen (kg ha" )# 0.00 1.12
g —— g ————--

without 157.0 152.8 24 83.2 83.8
with 131.6 158.4 48 86.3 71.8

96 79.3 79.0
LSD (0.05) 14.4 6.2

 

T Supplemental light (approximately 8.4 mol day'I ) was supplied by 400 W high pressure sodium lamps.
I Flurprimidol was applied 16 Dec. 1992 and 18 Jan. 1993

§ F lurprimidol was applied 21 Dec. 1992 and 4 Feb. 1993.

1] Traffic was applied 29 Dec. 1992, 14 Jan., 21 Jan., and 29 Jan. 1993

# Nitrogen was applied on the same dates as flurprimidol.

41
hardness in the absence of flurprimidol; traffic did not affect surface hardness of turf

treated with flurprimidol (Table 25). Untreated turf was flaccid and traffic caused a
prostrate growth (grain), forming a cushion on the surface which absorbed the impact of
the CIT hammer. Turf treated with flurprimidol remained rigid and had an upright
growth which resulted in similar amounts of foliage removal during mowing, thus
providing similar cushioning, regardless of traffic. The flurprimidol-by-nitrogen
interaction was more difficult to decipher. CIT values were inconsistent among

treatments and did not indicate an orderly or meaningful response (Table 25).

BlanLdensjtx

By August 1994 all turf was maintaining fair to excellent quality and had completely
recovered from traffic. Plant biomass data showed flurprimidol significantly affected turf
growth five months after the final treatment had been applied. While the number of
plants per unit area was less in plots treated with flurprimidol compared to control plots,
the number of shoots per plant was nearly double, and verdure mass was approximately
25% greater (Table 26).

CONCLUSIONS

Kentucky bluegrass turf in the early stages of winter dormancy recovered sufficiently
within two weeks at approximately 1 mol PAR rn'2 day'1 and temporarily provided
acceptable quality. However, this level of light was insufficient to maintain acceptable
Kentucky bluegrass turf for periods of longer than eight weeks. At 1-—3 mol m'2 day '1

PAR the best nitrogen rates were a low or medium rate (24 and 48 kg ha'1 month'l).

42

Table 26. Plant density, shoot density, and verdure weight of Kentucky bluegrass maintained under
supplemental light in the Covered Stadium Simulator Facility, 10 Dec. 1993 to 23 August 1994.’

 

 

 

 

No. of

Treatment No. of plants m’2 I shoots plant'l § Verdure (g m‘2 )1]
Nitrogen rate (kg ha'l ) #
24 8885 2.8 60.8
48 8144 3.2 60.7
96 7095 3.5 49.1

LSD (0.05) ns ns ns
F lurprimidol rate (kg ha'1 ) Ti
0.00 9474 2.2 49.7
1.12 6609 ** 4.0 “ 64.1

 

*,** Significant at the 0.05 and 0.01 probability levels, respectively.
1‘ Supplemental light, approximately 8.4 mol PAR day", was supplied from 400 W high pressure sodium
lamps.
1 Plants were counted from a 10 cm diam core extracted from each plot.
§ Five randomly selected plants from each plot were used for analysis.
1] Verdure was collected from a 10 cm diam core extracted from each plot and included all living above
ground
plant tissue.
# Nitrogen was applied as urea on 21 Dec. 1993, 4 Feb. 1994, 21 March 1994.
11' Flurprimidol was applied on the same dates as nitrogen fertilizer.

43
Traffic and high nitrogen rates (e. g., 96 kg ha") hastened demise of the turf, while

flurprimidol extended the period of acceptable quality for a short period (e. g., two
weeks). Two or more full rate applications of flurprimidol at four to six weeks halted the
turf vertical growth rate which may have reduced the potential for recovery from damage
(Stier et al., 1994), although lack of sufficient light would probably have been the
limiting factor for recovery.

Kentucky bluegrass turf recovered from winter dormancy within two weeks when
placed in supplemental light conditions. Reduced light of approximately 8.4 mol PAR m'
2 day'I was sufficient to maintain high quality turf indefinitely, even in trafficked
conditions. The medium nitrogen rate (48 kg ha'1 mol) was considered optimal as it
provided the most desirable combination of quality, yield, hardness, and shear resistance.
Flurprimidol significantally improved turf quality throughout the study and was
paramount for maintaining high turf quality. Timing of flurprimidol applications and
rates need to be further assessed as turf vertical growth was nearly totally halted
following the second application. Flurprimidol rates and application intervals should be
determined that allow a steady suppression of growth without inhibiting turf recovery
from traffic and other damages. Diesburg and Christians (1989) reported the combination
of growth phase and season affected turf response to PGRS. Since the environment of
indoor stadia is moderated, long-term or permanent use of turf in covered stadia or other
reduced light conditions may require unique rates and application intervals due to the lack

of seasonal changes.

Chapter 2
THE EFFECTS OF TRINEXAPAC-ETHYL AND FOLIAR IRON

ON SUPINA BLUEGRASS (POA S UPINA SCHRAD.)
AND KENTUCKY BLUEGRASS (P. PRA T ENSIS L.)

INTRODUCTION

Commonly used cool-season turfgrasses are thought to have evolved near the margins
of forests in Eurasia where light would not have been limited (Beard, 1973).
Consequently, most commonly used cool-season turfgrass species have relatively poor
shade tolerance with the exception of the fine fescues (e.g., F estuca rubra L., F. rubra
var. commutata Gaud.). As a turf, fine fescues perform best in conditions of well-drained
soil and low fertility but have poor traffic tolerance due in part to a slow recuperative rate
(Beard, 1973). Kentucky bluegrass (Poa pratensis L.) is the most commonly used cool-
season turfgrass but its growth can be severely limited in the shade due to insufficient
light and enhanced disease susceptibility (Beard, 1973; Vargas and Beard, 1981). Rough
bluegrass (Poa trivialis L.) has better shade tolerance than Kentucky bluegrass but lacks
traffic tolerance. A relatively shade and traffic tolerant cool-season turfgrass species is
desirable for golf courses, lawns, and athletic fields.

Supina bluegrass (P. supina Schrad.) has been cultivated as a cool-season turfgrass in
Germany for over 20 years (Bemer, 1984). Supina bluegrass is a stoloniferous turfgrass

capable of forming a dense turf at low mowing heights suitable for lawns, athletic fields.

44

45

and golf course fairways, tees, and putting greens (Berner, 1980; Nonn, 1994; Pietsch,
1989). The stolons are significantly more robust and have shorter intemodes compared to
rough bluegrass (personal observation). Supina bluegrass is found naturally in high
traffic areas (e. g., human and cattle paths) and in moist, shaded areas in woods near the
Alps (Bemer, 1984; Pietsch, 1989). Supina bluegrass is well adapted to cold weather and
is common even in the sub-alpine regions of the Alps (Bemer, 1984; Kéck and Walch,
1977; Skirde, 1971). In Germany, Supina bluegrass often encroaches and fills in high
wear areas on sports fields (Kéck and Walch, 1977); subsequent testing documented the
high wear tolerance which is at least partly due to a rapid recuperative rate (Bemer, 1980;
Berner 1984). In addition, Supina bluegrass has been observed to have a high level of
shade tolerance on golf courses, lawns, and in controlled tests in Germany although the
actual data have not been reported (Pietsch, 1989). The ability to persist in moist, shaded,
high traffic environments makes Supina bluegrass a suitable candidate for use as a turf for
shaded golf course or athletic field situations (e.g., partially or wholly covered stadia).
Drawbacks to the production and use of Supina bluegrass are its poor seed yield (hence,
high cost), poor drought tolerance, undefined management schemes, and light green leaf
color (Berner, 1980; Leinauer et al., 1991). The development of management schemes
requires controlled investigation. While seed yield and drought tolerance are
characteristics not easily altered, leaf color is an adjustable parameter which could
increase the acceptablity of Supina bluegrass if a darker color can be easily obtained.
Plant growth regulators (PGRS) and foliar applications of iron have been used

successfully to enhance (darken) turf foliage in normal field conditions (Brueninger et al.,

46
1983; Freeborg, 1983; Glinski et al., 1992; Yust et al., 1984). F oliar applications of iron

have also been useful to negate the transient phytotoxicity which can result from a PGR
(Carrow & Johnson, 1990). Recent reports indicate PGRS can also significantly enhance
turf color and quality in reduced light conditions (RLC) (< 30% full sunlight) (Rogers et
al., 1996; Stier et al., 1994) although the effects of iron are relatively unknown. Although
moderate RLC result in increased chlorophyll content, extreme RLC reduce chlorophyll
content resulting in a lighter green color (Beard, 1973). In our research we have found
chlorophyll levels in Kentucky bluegrass decline at less than approximately 10 mol
photosynthetically active radiation (PAR) day'l, equivalent to approximately 20% full
summer sunlight (unpublished data).

The objectives of this research were to: 1) Compare the shade tolerance of Supina
bluegrass and Kentucky bluegrass under a defined light regime, and 2) Determine the
effects of multiple applications of trinexapac-ethyl (below label rates) and foliar
applications of iron on the growth and quality of Supina bluegrass and Kentucky

bluegrass in RLC.

MATERIALS AND METHODS
Experimental environment
The research was conducted inside the Covered Stadium Simulator Facility (CSSF) at
the Hancock Turfgrass Research Center from Dec. 1994 through May 1996. Constructed
initially in 1992 with a fiberglass fabric (Sheerfill IV, Chemical Fabrics Corporation,

Buffalo, NY) which transmitted 11 :t 2% sunlight, the fabric was replaced in late October

47
1994. The new fiberglass fabric, Sheerfill IV®, transmitted approximately 10.5 i 1.4%

solar radiation from Nov. 1994 through April 1995. After being bleached by the sun in
the spring and summer of 1995, the fabric transmitted approximately 15.5 i 3.0 % solar
radiation from Dec. 1995 through May 1996. Quality of the light transmitted through the
Sheerfill IV® was equivalent to that transmitted by Sheerfill II® (Figure 1, Chapter 1).
Temperature and relative humidity were recorded daily with a sling psychrometer.
Temperature was maintained typically at 16.6 C using furnaces. Actual temperatures
ranged from 12.2 to 24.4 C due to the inability of the furnaces to compensate for
extremely low outdoor temperatures (e. g., -10 C) and due to the lack of an active cooling
system as outdoor air temperatures rose during the spring. Relative humidity averaged
45.6 i 12.5 % with a range of 28-63%.

Daily totals of photosynthetically active radiation (PAR) in the CSSF were determined
based on the percent of PAR transmitted through the fabric onto the turf surface inside
the CSSF. To determine percentage of light transmission, data were collected weekly
from each plot inside the CSSF within one hour of the solar zenith using a Li-Cor 1800
portable spectroradiometer (Li-Cor, Lincoln, NE). Two to four measurements were
collected outside the CSSF with the spectroradiometer immediately before and
immediately after collecting data inside the CSSF. Daily solar radiation data outside the
CSSF were collected with a Li-Cor PY 14226 pyranometer (Li-Cor, Lincoln, NE) located
approximately 15 m away from the CSSF. Pyranometer data were integrated hourly and

daily through a Maxi weather station (Rain Bird Sales. Inc., Glendora, CA). Radiometric

48

units from the pyranometer were converted to quantum units using the following equation
which was based on conversion units from Thimijan and Heins (1983):

Equation 1: ((Ly day'l/l .05)*3600*24)/106 = mol PAR day".
The average percentage of light transmitted into the CSSF was used to determine the

daily PAR inside the C SSF based on the data recorded outside with the pyranometer.

t i n m in n

Portable plots were established in wood boxes (1.2 x 1.2 x 0.15m depth) filled with a
sandzpeat mix (80:20 v/v) (Table 78, Appendix). The pH was 7.3 with initial P and K
levels of 85 and 90 kg ha", respectively, in 1994. In 1995, the pH was 7.7 with initial P
and K levels of 131 and 85 kg ha", respectively. Sixteen holes (0.6 cm diam) were
drilled in the bottoms of each box to provide drainage. The sandzpeat mixture was
compacted using hand-held tampers. Starter fertilizer (13-25-12 in 1994) was added to
the sandzpeat mixture surface prior to sodding to supply 66 kg P ha'1 and 58 kg K ha'I in
1994. The plots were sodded 28 September 1994 and 28 August 1995. Additional
fertilizer was applied twice in 1994 (24, 20, and 18.5 kg N, P, K ha'l, respectively, on 29
Sept. and 36, 30, and 28 kg N, P, K ha", respectively, 13 Oct.) and once in 1995 (24, 20,
and 18.5 kg N, P, K ha", respectively, on 29 Sept.) prior to moving the plots into the
CSSF. Supina bluegrass ‘Supranova’ and Kentucky bluegrass ‘Victa’l’Abbey’ (50:50
v/v) were used both years. In 1994 the Supina bluegrass sod had been raised in a woody
yard waste compost media while in 1995 washed Supina bluegrass sod grown in a sandy

loam soil was used for establishment (sod raised in the woody compost was not

49

available). In both 1994 and 1995 washed Kentucky bluegrass sod grown in an organic
soil was used for establishment. Plots were mowed once to twice weekly depending on
height of cut and growth rate. During establishment (approximately three weeks) plots
were mowed with a rotary mower set at 5 cm height. The height was gradually lowered
to 3 cm; a reel mower was used once a 3 cm cutting height was achieved. Plots were
irrigated as necessary to prevent visible drought stress (bluish-green color, footprinting,
wilting). Trinexapac-ethyl (0.19 kg ha], approximately two-thirds the full label rate for
Kentucky bluegrass) was applied to six plots each of Supina bluegrass and Kentucky
bluegrass on 3 Oct. 1994 and 9 Oct. 1995. A COz-powered backpack sprayer with 8002
flat fan nozzles was used to apply the trinexapac-ethyl in 896 L H20 ha". Plots were
moved into the CSSF for testing from 12 Dec. 1994 through 12 April 1995 and from 8
Dec. 1995 through 11 June 1996.

The plots were arranged in the CSSF in a completely randomized design with three
replications per treatment. Two experiments were designed to determined treatment
effects in both non-trafficked (Experiment I) and trafficked (Experiment 11) conditions.
Traffic was applied by having a person (approximately 70-75 kg) jog 50 passes each
week. Traffic was applied 28 Dec. 1994 through 16 Mar. 1995 (total of 144 passes) and
26 Jan. 1995 through 26 Apr. 1996 (total of 168 passes). Additional trinexapac-ethyl
(0.08 kg ha", approximately one-quarter the full label rate for Kentucky bluegrass,
diluted in 896 L H20 ha") was applied on 21 Dec. 1994, 20 Jan., 18 Feb., and 16 Mar.
1995 for the first year’s testing and on 31 Jan., 15 Mar., and 26 Apr. 1996 for the second

year’s testing. Iron (1.14 kg ha'1 as FeSO4-7HZO) was applied to foliage using F erromec

 

 

50
AC (PBI Gordon Corp., Kansas City, M0) on the following dates: 10 Jan., 14 F eb., and

17 Mar. 1995; 28 Feb. and 13 May 1996.

Plots were fertilized monthly with 24, 2, and 20 kg ha'l N, P, and K, respectively (1 8-
3-18). Approximately 1.25 cm water was applied immediately following fertilizer
application. Additional irrigation was applied as necessary to prevent drought stress
(approximately 1.25 cm at seven to 14 day intervals). Industrial fans were occasionally
used for 24—72 h periods to dry the turf surface following irrigation to discourage fungal
pathogen activity. Iprodione (3-(3,5-Dichlorophenyl)-N-(l-methylethyl)-2,4-dioxo-l-
imidazolidinecarboximide) was applied to all plots on 23 Dec. 1994 (3 kg ha'l), 6 Mar. (6
kg ha") and 14 Apr. (6 kg ha'l), 1995 to control Microdochium patch (Microdochium

nivale), primarily on the Supina bluegrass.

Data eellectien

A reel mower was used to maintain turf height at 3 cm. The turf was mowed once to
twice weekly to prevent removal of more than one-third of the leaf tissue. Mowing was
always performed immediately preceding data collection or fertilizer, trinexapac-ethyl, or
traffic application. Clippings were generally collected for clipping yield determination
except occasionally when time limits precluded clipping collection. Clippings were
collected from a 41 x 117 cm strip through the center of each trafficked and non-
trafficked plot. Clippings were dried in a forced-air oven at 60 C for 48 h then weighed.

Turf color and quality were evaluated visually on a one to nine scale. A one rating
represented 100% necrotic turf/bare soil, while a nine rating represented dark green or

ideal turf, respectively. A value of five was considered the minimum acceptable unit.

51

Turf rooting and strength were evaluated periodically using an Eijkelkamp shear vane
apparatus (Eijkelkamp, Giesbeek, The Netherlands). The torque required to tear the turf
with the shear vane was recorded as an average of two measurements per plot (Rogers
and Waddington, 1990). On 24 March 1995 and 30 May 1996, plant densities were
determined by counting the number of plants in eight random squares (32.7 cm2 each) of
a 0.4 m quadrat(Skog1ey and Sawyer, 1992). Leaf samples from 10 randomly selected
plants were collected from each non-trafficked plot for chlorophyll analysis on 4 Apr.
1995 and 29 May 1996 (trafficked plots were not sampled because adequate plant
material was often not available). A 10 mm segment from the youngest fully expanded
leaf of each plant was excised starting 5 mm above the leaf collar. The leaf portion next
to the shoot (< 5 mm distant) was avoided due to possible physiological differences
compared to the more mature leaf region (Skinner and Nelson, 1995). Chlorophyll was
extracted in three ml MN-dimethlyformamide (DMF) incubated in the dark at 4 C for 48
h (Moran and Porath, 1980). A double-beam spectrophotometer was used to determine
absorbances and the extinction coefficients described by Inskeep and Bloom (1985) were
used to calculate levels of chlorophyll a, b, and total chlorophyll. On 12 Apr. 1995 and
31 May 1996 samples of ten randomly selected plants were collected from each plot for
biomass assessments. Average leaf number shoot’l, average shoot number plant", and
average oven-dry weight plant'I were determined for each sample.

Data were analyzed using MSTAT analysis of variance procedures. Data were

analyzed as a 2x2x2 factorial in a completely randomized design with three replications.

52
RESULTS AND DISCUSSION

Temperature inside the CSSF averaged 16.6 C i 1.5 C with a range of 12-24 C.
Relative humidity averaged 46% i 12% with a range of 28-63%. Photosynthetically
active radiation inside the CSSF ranged from approximately 1 mol PAR day'1 during
December 1994 to approximately 5 mol PAR day'1 in May 1996 (Table 27). The Supina
bluegrass responded to the increased PAR in the spring more than did Kentucky
bluegrass. In general, quality of the Supina bluegrass in 1995-96 was superior to that in
1994-95, probably largely due to the higher light transmittance of the Sheerfill IV fabric

due to bleaching by the sun during the summer of 1995.

Infisnlnnandnualitx
Ex r’me I: Tur n 4b '6 ' d1 tra zc

Turf color and quality was affected by both species and trinexapac-ethyl as soon as
observations began once inside the CSSF (Tables 28 and 29). The turf was dormant
when it was brought into the CSSF and recovered quickly the first year (1994) but slowly
the second year (1995). In 1995 the weather had become quite cold in early November
without an appropriate transition (“hardening-oft”) period between growing and non-
growing conditions which probably caused the delay in recovery inside the C SSF. The
extra N application in autumn 1994 may also have contributed to faster green-up of turf
inside the CSSF. Turf treated with trinexapac-ethyl was particularly slow to recover

inside the CSSF during the second year (Tables 30 and 31). Once recovered from

53

Table 27. Photosynthetically active radiation (PAR) at the Hancock Turfgrass Research Center, East

 

 

 

 

 

 

 

 

 

Lansing, MI.
Location Dec. 1994 Jan. 1995 Feb. 1995 Mar. 1995 Apr. 1995
mol PAR day'l I

average 8.4 9.4 19.2 24.8 26.9

stnd deviation 3.9 6.5 6.6 10.4 12.8

CSSF 1,

Ambient light

average 0.9 1.0 2.0 2.6 2.8

stnd deviation 0.4 0.7 0.7 1.1 1.4

Dec. 1995 Jan. 1996 Feb. 1996 Mar. 1996 Apr. 1996 May 1996
mol PAR day'I

average 9.5 10.6 14.6 27.8 29.0 34.1
stnd deviation 4.4 4.7 7.6 10.2 14.6 14.5
CSSF,
Ambient light

average 1.5 1.6 2.3 4.3 4.5 5.3
stnd deviation 0.7 0.7 1.2 1.6 2.3 2.2

 

1' PAR was collected with a pyranomter (Li-Cor, model PY 14226, Lincoln NE) and integrated daily.
Radiation units (Ly day'l ) were converted to quantum units (mol PAR m'2 day'I ) based on the
conversion methods in Thimijan and Heins (1983).

i CSSF = Covered Stadium Simulator Facility. Ambient PAR inside the CSSF was estimated by measuring
the percent PAR transmitted into the CSSF at turf level with a photometer (Greenlee Inc., Rockford IL)
or a portable spectroradiometer (Li-Cor, model L1-1800, Lincoln NE).

S4

53:00am»: 8:32 bzfimnoa Ed 28 mod 8 “50$:me 3......

 

 

 

 

 

whom we: 92 an: 8.2 8.2 88 ~02 as 3.2 .8 .>u
83 23 E; 23 83 83 2 S 82 o: .o m _ no 2 88m
:85 ~23 S no «85 33 o. no 83 23 ~35 82 _ a x me x m
22 8g 23 82 42; 29c 23 23 $3 89o _ on x m:
23 $3. 23 23 22 23 .22 god 9.3. mg: _ 8 x m
3.2. 83 S 2 3.3 22 $2.. :82 22. $3 $3 _ 8.: 8:
:88: 288.2 zoom: 3.38.: 23.” :82” 29c :23 2.228 :32 _ m: x m
niochN— aquoW— 3.0— mfi- .Ibcnmwm 88005N~ 3.505% 3.50m.— aOOhM fumvodm .iNvoN— _ AP: Ecuotomamxofikr
:2me 182.2: .252: 188% :38: .82 :83 3.3 $3 82 _ av 888%
2.2 : 8: mm 82 2 .a< 8 .82 mm .82 w .8... 2 8. 2.. .8. m 88o om :8 888., 8 88cm
82-32
3.2 2.2 _N.: a: 8.8 88 mm: .x. .>o
9.2 8.2 82. $3 82 mm: $8.2 2 88m
SS 83 22 23 83 ~23 god _ 8 x m: x m
582 .256 83 2.3 3.3 $3 23 _ o". x my
god £2 23 .33 82 .83 3.3 _ 8.2 x m
.33 $3 god sad 2 no :85 38.0 _ EV 8:
god :3? 4.8.8.3 252.2 :22 8.888 83 _ me x m
855.3. 288.3 $48.8 855.8 853.2 :32 32 _ at 158.8885:
348.8 :83 8g o _ 9o :82 1%..» 3.8: _ av 888%
.a< o .82 t .88 4m .8... a .5: 8 .84 o 8n om .8 888., .8 888
82-82

 

.22 858.85

“mam .8350 5883* mmfiwtzh x085: £536.80 Em: 3262 E 383:: coxowtmbéo: mo amaze bzmsc co muoobo E2588 can 883cm :32 .wm 038.

55

553833.. .232 255.302. 5.0 EB nod 55 EmoEcwfi in...

 

 

 

 

 

 

555 555 N55 55.... 55 mm... 55.: 3 5 55.5 55.5. 55.: .3 .>o
5.5 .355 555 5555 255 .25 5555 5555 855 53.5 5555 5. 5cm
255 .5555 355 55.5 255 355 555.. 5555 255 5.5.5 5555 . 5... 5. mp x m
255 :525 355 555.. 5555 .355 555.. 35.. 255 255 55.5 . 55 x m:
255 :5555 555.5 555.. 255 355 .555 35.. .555 255 55.5 . 5,. x 5
5.5.5 .5555 55.5 555.. 255 :53 5555 5555 5555 555.. 5555 . .55 8..
.5555 .55.... .5552 .555 5555 5555 5555 555.5 :255. 2555.55 555:5. . E x m
3.565%” {Lb—d 1.0692 EKCQNM 1.35m; _ *uoood {LENN— _.:._Nvo.m 1.6— m.w nuochdm *Lb—dN _ Apt 350
.8355...
.5555: 3,555.55. :3552 555.5. .5533 555.5 2355.: :353 5.5.5 .555 .5555 . a. 8.52.5
25. : 82 55 82 2 .5... 5m .82 55 .82 5 .55”. 5N .555 2 .8. 5m .8. 5 .85 55 .5 8.8.8.,
m0 oohzom

552-555.
35 55.5 5.5 .55. 2.5 8.5 5.5.5 .3 .>o
3.55 53 .5 53 5 5555 5. .5 5. .5 5 . .5 5. 5cm
.355 355 5555 5. 55 555.5 355 .555 . 5... 8 me x m
.355 355 55.5 5555 5555 355 5555 . on. x E
355 255 355 255 :23 355 .555 . on. x m
355 55N5 :355 55.5... 355 355 5 _ 55 . 8,... 52.
5.55 :55: :55? 3.25.: :555. :35. :55... . m: x m
:3555 :3555 :3555 :3555 355.55 335.3 :2 5.5 . at .255
$8555....
:355 :35: .5555. .355 .525 :353 :2 5. . m . a. 8.52.5
5< 5 .82 t .55“. .5 .55.. 5 .8. 5m .8. 5 .85. 55 .5 8.8.8.,
we ooh—flow

555.352
.=2 $5553

55.5m— ...850 £88.53. amewtah 5.08:5: 5:256:05 Em: “58:3. 2 55.2th 85.555.55.05. mo $222 8.8 co acute 2.25525 can 8.5.55 :52). .om 035...

56

 

 

 

 

 

 

 

 

 

1.x.m fad ..:..N.v 5.13m 5:500 3.0.0 3.5.0 *N.m ..:..w.m Sand F3»
Om Wm Wm ad a... 3m v.0 od 0.5 N... o:
350-055.5585....
tum.— ..So. 1.0.— *_..©.N 5.5—WV *mfi ..:..N.0 M6 06 w.m games—D xxoacovm
a... fin ow ...m 5.0 0.5 .6 ob m... N». 5583:... 5595
3.89m
2:: . . 25.2 am .55.). m. .55. cm 55.2 om 5.5.2 m be”. 0. 25.. cm .22 m don. cm 55.552...
052-32
5... 55 S. .5 5.5 5.5 5.5 55.2
we o.V w... od .5 5.5 v.0 o:
:2.
Ioé 1.6 2.2m 3o... .19.: .... We H55...
~.m Wm Em .6 5... md 55 o:
350-055.5205....
1m.m ..:..m.m 2v .6 1.3m .6 m.m mmfiwosfi 3.03:3.
5.5 m... .3. ed m6 m... 5.0 5589:... 5596
3.0on
53¢. 5 55$. b. be“. vm 5.5,. o .55.. em .55.. o don. cm 2.253....
30.4.3.

 

.2 55.28. 58“,.

52:50 5.583. 555.35... 5.0855... .25.: :8. w. 8.. o. E 522w .3 o 2 5.5.5: o b. 5.... :o .52 :5 . 38-585205: 5285.5 .0 Set”. .3 0.5.5...
2.. F_...5 .5 . . .55.... m... .5.

57

 

 

 

 

 

 

 

 

 

 

3&6. 3.5M 3._N.v 3.....0 3..M.0 3.0.0 3.0.0 *N.w 3&6 3am.N Fmox
Om Om Wm 5N a... in 5.... Q0 o.m m... o:
350-52.55.05. .1
3m. 3o. 1.0.. 3.9m 3%..V ...m.m 1N0 m.m ow w.m m5.5.9:... 5.53:3.
5.5 N.m 9m 5m 5.0 0.0 .8 od 3. NM. m$.32... 55.9%
3.5on
2:... .. >52 mm 253. m . .5... cm .52 am .52 m .35... o. 55. cm .:5.. m .250 om E25529
037mg.
.3. 3 S. .5 5.5 3 5.5 5.8.
.35 o... w... 9m .0 5.0 5.0 o:
:8.
3.6.0 3....0 3&0 3.5.0 3.5... .8 0.0 ”wok
NM ma ...m :5 a... m... ad 2.
355-52.55.55...
:2 :3 5.5 .5 1.55 .5 Wm 35.55:... 5.53:3.
3 m... 5... 5.5 5.5 3 5.5 58.52.... 2.95
3.5on
....< 0 .52 n. be... 5N be“. a .:5.. cm .55. 0 .80 cm E2555...
33-53.
.2 .5523 .25.”.

52:50 5.583. 35.2.3.5 5.5.52.3. .25....558 Em: .5836. E 85.th 555.555..-.8: .0 32.515 .8 :8. .555 ..>...o-o5m5xo..... .862; .3 Beam. .3 0.95...

58

 

 

 

 

 

 

 

 

 

.306 3..N.v 5.2.8.". 3&6 53.0 3._w.0 3.0.0 5.5.0 ...w.0 3..N.m 3..o.N Fmoz
5N 9m .3 ad 5.5 ”m 9m ow 5m .0 w.m o:
355.552.5585...
3'0.— ..30. 3.0.— ...N.m ..:..04V ..&.0 3.5.0 335.0 3&0 3.,N.m 35¢...” mmm..wo=_n Axuacov—
5.5 5.5 55 5... 5.5 5.5 5... a... 55 .5 5.5 95.5253 2.955
3.5on
55... .. >52 om 52 m. ....< 0m .52 am .52 m .95... mm be”. «5. :2 0m :2 m .550 om 5:55.55...
052-30.
55 55 55 a... 55 3 N5 58.
m6 ow o.m m... Nam 9m .0 o:
:o..
3&0 3..w.0 3.0.0 3.5.0 330 3._M.0 3.0.0 Hmox
N... Wm 56 Wm N.5 5.5 56 0:
355-52.55.55...
3.5.0 3.0% 3.6.0 50.0 Law 3.3530 33.... mmm..wo:_n %x03:ov—
..m m... 5.5 5.5 0.5 5.5 ow 5.55.9.5... 5.59%
8.5on
.5... 0 .52 5. be... 5.5. 5.5.... a :5. 0m :5. 0 .550 on 52555...
32-500.

 

..2 $5551. .55.. 52:50 5.5553.

555.55.... .1 5.58:2. 5:256:05 555.555.5éo: .2555 2.0.5.255 Em: .5825. E +5.8 5.55.3.5 :c 55.. .55 .1556555555 55.52.... .5 555,...m. ..m 5.95...

59

.58. 5.2 m. .55 .55. 55 .5 .055... a 52.5% as. .52. 55. 3.: =2. 5..

.5550 £555
75.. wx mod. 03. ....< 0m ...52 m. .55. .m A 75.. 9. o. .8 35. .550 a ”5552.55.55 :. 950% 5.5 55.5. ”5555.5 w:.30=0.. 5... :0 05:35 553 355-02.55.55... F
.3... .52 t .25 .55. E .55.. .5. co .055. 55 52.5% 33. 75.. 55. 3... =8. 5

A850 5055
75.. M5. mod. 85. .52 0. .55. w. ..:5. cm A 75.. w5. 2.8 555. .550 m ”5552.55.55. :. 550% 5.5 55.5. 5555.5 w:.30..0.. 2.. :0 02.5.5.5 553 355-55.55.55... H
5.5. :55.w 5.5.555: .55 0.50.0552: 5.50.020 550.: n 5:0 5.555 55: 05 5:0 5 :0 2:53.? 055. 553 .200 ..r
2.53.5535. .m_5>5. 5.5590... .o.o 0:5 no.0 .5 5:50....cw.m 3......

 

 

NM 1&6 Om m... m.m 2....0 ...N.0 m0 Wm N...V ..m 555»
N.N. m.m m.m w.m Nm o0 Wm N0 m.m 5.5 5N 0:
:0..

35.500. .m 535...

60
dormancy, Supina bluegrass turf quality was superior to that of Kentucky bluegrass

(Table 30). Turf density, uniformity, and overall appearance contributed to the quality
ratings. Kentucky bluegrass turf density declined over time and the turf died in 1996 due
in part to powdery mildew (Erysiphe gramim's). No powdery mildew was observed on
Supina bluegrass although Microdochium patch (Microdochium nivale) occasionally
occurred. The Microdochium patch was controlled by using fans to dry the turf and with
fungicide. Supina bluegrass had a lighter green color than Kentucky bluegrass except
towards the end of the second year when the Kentucky bluegrass became necrotic (Table
31). Iron had negligible effect on either color or quality of turf in either year except for
minor, transient (< 4 wks) increases in turf color which, while statistically significant,
were not as dramatic as those caused by trinexapac-ethyl.

Interactions between species and trinexapac-ethyl occurred frequently (Tables 32 and
33). Supina bluegrass was more sensitive to trinexapac-ethyl than Kentucky bluegrass.
Trinexapac-ethyl usually increased the turf quality and enhanced the color of Supina
bluegrass compared to Kentucky bluegrass except at the beginning of the second year

when trinexapac-ethyl delayed recovery from winter dormancy.

xr'mnI: r 'cd r 6
Treatment effects on the quality and color of turf subjected to traffic were similar to
those of untrafficked turf although actual values differed (Tables 34 and 35). Traffic
treatments resulted in unacceptable turf quality and color (rating values < 5) two to three
weeks after traffic applications began in 1994-1995 and three to five weeks after traffic

applications began in 1996 (Tables 36 and 37). Traffic killed most of the turf within

6l

.2...U .23 7.... 5. 5......
000. ...0< 0m :52 m. ..:5~ .m A ..5.. wv. 0. .8 000. .00 0 ”5555.05.50 5 :30..5 5.5 55.5. ”55.50 w530..0.. 5... :0 05.005 55>» 30.50.505.85... 0
.255 .08 1... 5. 5......
000. .52 0. :05“. w. ..:5~ cm A .-5.. wv. 0. .8 000. .00 m ”5555.05.50 5 :30..5 5.5 55.5. ”55.50 w530..00 5... :0 052005 553 355-550.50.55... H
0.... 5.05.0585 .0. 5:.5> 50:55.: 5... 55>. m at... 5.0.5:: .55:50n0 .005 5.500.... 0550 300.”. ”5.505 55: 0. 5:0 5 :0 3.535..» 05.5. 553 5.500 +

 

 

 

 

 

 

 

 

 

5... 5... 5... 5.. 5... o... 0.. .50.... 05.
o. 5.. .... I S 5.. 5.5 o... .5 5.5 5.5 5.5 5.5 .... 55252.... 0.25.3.
0.0 m.m 0.0 0.m 5.0 v.m n... 5.5 0... 0.m ..m w.0 N.N m... 555.w5:... 5500m
55.. 0: 55.. 0: 55.. 0: 55.. 0: 55.. 0: 55.. 0: 55» 0: 55.550m
0 3555505055..
5:... . . 552 0.5. 55$. m . .0< 0m .52 w :5. 0m 050 om
00-000.

0.0 0.0 0.0 .20 0.0 .008 Om.
0.0 0.... 0.0 m...N M0 M3. 0.0 5.0 N0 ..0 555.w5..... 5.03:3.
m0 5.0 5.0 QM w.0 m.m o... 0.0 o... 0.0 555.w5..... 5500m
55.. 0: 55.. 0: 55% 0: 55.. 0: 55.. 0: 55.550m

H 3550505055..

.52 0. 050 cm 050 0 :5. 0m :5. 0
000.

 

.=>. 055:5. .55m .5550 50.55550 5.55.8.0...
5.5055... 5:050:05 Ew: 055305. 5 555.50.... 050.50.50-50 :0 5.5.85.8... 1.0555055554355.5505 5550555 5... .0. .55=.5> w5.5. 5.25:0 .8 5.05.5

62

..5.50 0055
.-5.. 00. no.8 000. ..0< 0m :52 m. :05. .m A 75.. wv. 0. .8 000. .00 0 ”5555.05.50 5 :3005 5.5 55.5. 55.50 0532.0. 5... :0 05:005 553 0.0.5-0505x55.... a
..5.50 0055
_.5.. m. 00.8 000. 05$. 0. .05.. w. ..:5. cm A ..5.. w. 0..8 v00. .00 m ”5555.05.50 5 :3005 5.5 55.5. 55.50 w530:0. 5... :0 052005 55..» 3550505085.... H
0.... :55.w 0..50n55: wt... 0..0.05:\..:. 0.8.0.00 .0000. n 5:0 ”5.505 55: 0. 5:0 5 :0 .._5..5.> 05.5. 553 .200 ..

 

 

v... N... m... .20 0.0 0.0 30.8 Om;
0.. 0.. 5.. 0.. 5.. 5.. 05 5.5 5... 5... 5.5 o... m05.55:... 0.20.50.
N0 .5... 0.0 M... .... .0 0.0 m... 0.. 0.0 m. Nam 555.w5...0 5500m
55. 0: 55. 0: 55. 0: 55. 0: 55. 0: 55. 0: 55.050m

 

 

m ......5-0505..5:...

 

 

 

5.5. : .52 55 .52 5. .5. 55 .5. 5 .80 55
552-555.
.0... 5... 5... .0... E. .0... .50.... 05.
5.. .5 m... 5... 5.5 3 5.0 5... 5.5 5.5 5.. N. mm5.52.... 0.2.5.3.
5.5 .5 5.5 5.5 0.5 55 5.5 55 5.5 o... 5.5 .0 35.55:... 5.....05
55. 0: 55. 0: 55. 0: 55. 0: 55. 0: 55. 0: 55.050m

 

H 3550505085..

 

 

.52 0. .05.. vm .050 0 :5. 0m :5. 0 .05.... om

 

000 . -000.

 

.2 055:5». .55m. ..5.:5U 00.5555”. 555.35...
0.08:5... 5:050:00 .00.. 050005. 5 555.00.... 050.0...05..-:0: :0 :0..05.5.:. _.0.5-0505X55..-..0-55.0505 .:50....:w.5 5... .0. .55...5> 0.5.5. .200 .mm 5.05 0.

63

502338; .m_o>o_ £3305 Ed can mod 3 EmoEcwE in.

 

 

 

 

 

 

3.2 on? 2.8 3.: $8 3.2 a: .x. .>o
Rod $3 $3 $3 $2 38.. $3 2 Sum
23. 83 «85 .33 «85 3mm .58... _ on x E x m
23 8g 82. 2.38.0 v23 oz; «85 _ on x we
82 «33 23 £85 23 82 Sod _ a x m
8.8 33 33 tag; v33 23” v33 _ EV 8:
:Swfl :vgé :20: 2:03 .8: 82 83 _ m: x m
2.3%.: 3.3%.: 258.2 :Ea .85 .32. .82 _ at 350-8%55;
:2qu .38.: .552 :33 .33 23 .33 _ Q 36on
as: : 32 an 32 .2 .a< em .32 am .32 x 3m 2 “a 8:3? “o 858
c9:
.23 2.? 8.x 8.: 3.2 ”S: .x. .>u
$66 was 83 23 S; SS 2 Sum
$9 $3 ~23 Sac N23 22 _ on x me x m
$3 $3 N23 22. $3 83 _ on x 3
$3 ~35 N2; 23. $3 $3 _ on x m
fine Sod ~36 Sod $3 $3 _ Ev 8:
82 £8 :85 _.._.,oE.m :finfi :E .w _ E x m
LEN Read :82 .33 :Svmm :3? _ at aeoéamxoafi
$3 a: .o 82. *o _ 2 32 $3 _ av 360%
.a< o .52 : bum vm bum a .5: 8 .52 e 96 =2§§ ‘8 8.8m
82
d2 .3qu

“mam c850 nouaomom 38MB; x828: .mcoEucoo Em: 3262 5 Stab 9 @2833 $8th («0 bzmsc so 38%» 258305 98 89:5 :32 em 28¢

64

220380.800 .m_0>0_ bzfimnoa Ed 98 mod 05 8 Emu—£35 .1. ._..

 

 

 

 

8.8 8.8 8. _ m :8 8.8 8.: 8.2 8.: .8 .>0
8.8 8-.~ 83 82. :~.o 83 Ed 82 2 3:0
88.8 ~82 8:8 88.8 88.8 83 83 82 _ 8 x m: x m
88.8 ~82 88.8 88.8 88.8 85.8 .8_ .8 82 _ 0.. x E
88.8 8; 8:8 82 88.8 8~.o ~88 8~._ _ 8 x m
88.8 8. .8 88.8 83 .83 23 83 88.8 _ EV 8:

:83 :83.” .888 .82. .83 82 ~82 88.8 _ m: x m
:83 288.8 :88; :83 .83 82. :83. .888 _ at 350-8855;
:83: :~8.8 .88.: :83 82 2 no 88.: 88.8 _ be .288
as: : 82 8 82 2 a... 8~ .32 8 .32 w .88 w~ .88 a 8 888? 8 85cm

88_

8.8 ~_ .8 :8 82~ 8.8 8.8 .8. .>0

~82 83 83 8:8 82 .8 83 2 Sum

8~._ 88.8 88.8 .22 ~88 88.8 _ on x mp x m

8~._ 88.8 88.8 88.8 .82 88.8 _ 8 x my

88.8 2 8.8 88.8 38.8 :83 8:8 _ 8 x m

88.8 88.8 88.8 88.8 ~28 8:8 _ 9.: 8:

8~._ 8~._ 88.8 :8_.8 :E~._ :8~._ _ mp x m

8~._ 8~._ 88.8 :82. :82: :8~.~_ _ at 150-8865;

88.8 88.8 88.8 .23 .82. :8~.~_ _ av 860%

.a< 8 .52 2 .8... 8 .88 8 .52 8~ .3 8 8 88:9. 8 85%

 

moa—

 

.§ .8583
“mam £0300 £03083— mmfiwtsh 0.000ch 8.83650 Em: @0268 E 058“ 8 “0080.33, 88th mo .28 co $00»? 28580.: 98 08:3 502 .mm 033.

65

.bo>:oo%2 .232 £3805 5.0 can mod 3 Emoc_:w_m 2,...

 

 

 

 

 

23m 32 23~ .22 :2 ~22 33. 2. ,>u
m~3 3:3 ~o~3 ~23 $~3 33 3-3 2 .85
3:3 8~3 223 .33 33 2.3 .82 _ on x m: x m
23 83 83 :33 33 3:3 223 _ a x we
82 223 S 3 :33 3:3 83 3:3 _ on x m
83 223 223 :~3._ 223 3:3 223 _ Ev 8:
2.23.2 123.2 ten: :53 .8: 8:. 8~3 _ me x m
.23.: 3.33.2 2.33.2 2.33 .8: .33 .83 _ at 250.832:
353.2 333.2 :o_o.m~ :33 .32 3:3 .33 _ 8V 86on
2:: : 3: 3~ 3: 2 .22 o~ .32 o~ .32 w .32 2 3 SEE? 3o 833
82

2.8 2.? ~33 8. _ ~ 3.2 -.o_ .2. ,>0

33 $3 83 33 $3 $8 2 55

£3 $3 ~23 83 ~23 E3 _ on. x mp x m

~23 $3 ~23 23 $3 323 _ on x we

~23 ~23 ~23 23 ~22 ~23 _ a x m

E3 ~23 ~23 o. 3 E 3 $3 _ Ev 8:

82 £3 .33 2.323 :32: :3; _ m: x m

.33 .~3.~ :82 .3m.~ $8.2 :33 2 at 25908205:

$3 $3 83 2:3 33 $3 _ Q 3625

.a< o .52 E .82 v~ .82 a .52 o~ .5: e :V :25? L6 858

32

 

:2 .383

“mam .8280 28331 mmfiwtsh x828: .mcoEncoo Em: 3262 E etc: 9 @8833 $8th .8 9:26 so acute 28.585 98 03:3 :82 .3 2an

66

.82 $2 2 Ba fin mm S .80“. 8 33% 8: .2 9. 2.: :8. 3.

A83 :08
7m: 3 wodv 32 .a< cm £22 m. :53. _m A 7m: wx m: .8 33 .80 o ”womoficofim E 5505. 2m 83. ”most w530=8 05 :o @239“ was» Enuoémawxocth F
.32 .52 : 23 :3 E .8. 2 .5 0.02". 8 33% 8i :2 9. 3.: .8: a

A83 some
72 wx no.8 mag .32 2 room M: 38.. cm A vs: w: 2 .8 32 .80 m ”885:28 5 :32? 03 menu 58% 9.36:8 05 co com—nan 83 35063305.? H
E 038385 8m 02:; 82558 05 mm? m mtg gobs: .omcouno £8 "tapas“ 3% $2: u_ ”2QO 2:: 8 use a 5 >525; U88 mm? .0530 +
igfiame .225. £3305 :3 Ba 86 a “game? 2....

 

 

N.N N.N N.N :3 M: S. E E;
3 E 3 .2 2 3. ed 2.
:o:

3.283 3 29¢

67

 

 

 

 

 

 

 

 

 

3.5m Elam 3.5% _.:.._.N “.0.— ..m 1&6 {*wd 79A
o.m v; m._ N. N; o6 oh Em 0:
350-8355;
“3o.— _....o._ 1.0.. .._..o._ m._ 5v .36 $6 mmfiwoap xxoacox
3 3 3 mm M: 3 3 9m 323:3 2&5
86on
25.. 2 >22 mm >22 m _ .E< em .32 om .32 w bum mm be“. S 25:58;
33
2 E 2 3 mm 3 as»
o._ n; N.N o.m m6 9m 0:
so:
a; w._ *N.m ..:..v.m “.300 3.300 Mme»
mg mg m._ m.m Nd a; 0:
350-8355;
m._ m._ YN EM. Ed the 3&ng 303:3—
o; 2 _.m m.m we o6 $.3ng «Emzm
$6on
.E< c .82 S bum vm be“. a .22 cm .53. o EQEEEH
moo—

 

.=2 .9553 5mm

£850 5883* mmfiwfish x828: .mcoEucoo Em: 3262 E oEwb 9 380.33 mmetB .3 .875 so so: can .Efioémmmonb .88on .3 80km Sm Bomb

68

.82 $2 2 Ba .6“ mm 8 ,0QO a 33% m2: .2 E 3.: 8: n

.328 some
72 wx modv cog .a< cm :82 2 :5: _m A 72 wx 2.8 32 .80 0 ”385553 E :32? 8a v.88 $.23 w:_3o__8 of so 32%? 83 35983on; F
.32 .32 2 Ba :2 3 :52 2 so .0QO a 33% a: 72 3 3.: so: a

.326 :23
Ta; wx woe 39 .52 m: rnom w. :5: om A 72 wx a. .8 vmfl .80 m ”885:0th E :32: Rm 822 $83 wage—.8 2: co Big 33 350-8355; H
EB 52w fimvnoE: $3 03885th 058020 o\ooo_ u 28 ”2QO 2:: 2 28 a co xzmsmg $38 was 8:5 +
.bo>uuoam2 .m_o>o_ 323395 56 can mod 8 Emu—.tcwfi t...»

 

 

m.m _.m wN 9m .5; ad ad v.0 two»
m.m ON ”N v... m._ m6 v6 9o o:
:o:

3.253 2 2E

69

eight to nine weeks in both years. Supina bluegrass showed signs of recovery, however,
within three weeks after traffic treatments were ended; Kentucky bluegrass did not
recover. Trinexapac-ethyl treatments resulted in superior recovery of Supina bluegrass
compared to untreated turf (Tables 38 and 39) while Kentucky bluegrass was unaffected.

As with non-trafficked turf, iron had little or no effect.

1' in i
x r'ment I: Tur n u ' d Ira z
Clipping yields of Kentucky bluegrass were significantly different compared to Supina
bluegrass yields throughout the study (Table 40). Kentucky bluegrass clipping yields
were greater than those of Supina bluegrass for the first two to three months inside the
CSSF after which they were either no different (1995) or significantly less as the
Kentucky bluegrass died (1996) (Table 41). In this study clipping yield data was only
partly indicative of the turf’ 5 response to RLC; Supina bluegrass has a creeping growth
habit which can be expected to result in less clipping yield compared to Kentucky
bluegrass in even normal sunlight (Bemer, 1980). Trinexapac-ethyl treatments
significantly reduced clippings of both species on most dates. As with the effect on color
and quality, Supina bluegrass was more sensitive to trinexapac-ethyl than Kentucky
bluegrass in terms of clipping yield reduction (Table 42).
Lack of PGR efficacy after the first application and the rapid growth flushes following
growth suppression commonly documented in non-RLC were not observed (Cooper et
al., 1985; Shearing and Batch, 1982). The potential decline in turf color and quality

observed due to the potential for retention of senescent foliage/suppression of new growth

7O

.ABmv some

72 wx no.8 oaa_ ..a< cm :32 m. :5: _m A 7m: wx 2.8 maa_ .80 a “$855.8 5 :39? 2a moat $83 wEBo:£ 05 co 8:35 83 350-8355; m

.328 some

7m: wx no.8 maa_ .82 2 snow 2 :52. cm A 7m: wx a_ .8 vaa. .80 m ”885:0qu E :39? 2a 8:: ”82% w530=£ 05 :o 3:95 83 350-3355; H
£8 22388 “8 o:_m> E2558 05 mm; m ”f2 ESE: .omcouna .28 23%.: Eat face—u— mofiom 05: 9 one a co >=m=£> 8:2 33 £330 .r

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

_._ ad ad md 0.0 $98 Dwa—
o._ N._ o._ o._ N... m._ _ _ o._ m._ m._ 8.2ng 325:3—
: Z 3. 2 S «M 3 2 nm E 889:3 2&5
mo» 0: mo» o: mo» 0: mo» 0: 8» o: 363m
m 350-333,?“
2:: : 52 am a: 2 .a< em .32 am
caa_
ad ad wd Amodv Om;
a.N _.m _.m 9v a.m w.m $.2ng 5.03:3—
w.m m._ ad 9m 3. oh $8323 «Eqsm
me» 0: mo» 0: me» o: 860nm
H 350-8355:
ho..— a .53. cm .5: o
maa_

 

A2 .wfimfifi “mam .6800 5.808% 383.5%
x085: £53628 Em: 3262 E oEmb 9 380.33 mmfiwta so 3258an Ecsémamonb$9m28am EmoE=w_m 05 com mwcufi >530 .mm 033.

71

A33 :08

7a: m: no.8 eaa_ .a< cm :32 2 £2 3“ A 72: w: a. .8 maa_ .80 a “88558“: E 5.6% 2a 822 $83 wEBo=£ 05 so 3:9? 83 Thfioomaaxofic. a

.38: :08

_.m: w: no.8 maa_ .82 2 ran: a: $8.. om A 7a: m: a: .8 Va: .60 m 68055qu 5 =265. 2m 8:2 3.3% wage—:8 05 co Bias mm? 350-8%55; H

“ta :0on faunas: f3 0:88:th cacao—:0 caco— n 25 6.an 2:: 9 28 m :o 2:253 :88 83 .830 +

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Nd N.N _._ 5o 9o A38 amu—
o._ 3 3 3 I 3 2 3 n. S snags Sussex
3 ca E M: E 3 mm 3 2 2 means; «59%
me» o: 8% o: 8% o: 8% 0: me» o: 86on
w Sandmamxofih
2:: : :2 am a: 2 .a< 8 .32 am
oaa_
wd Yo Yo A38 Om:
9m 9m m6 we ”.0 ma mmflwosn 5.03:3.
N.m m: _.o m.m w.m a.m 38ng «Easm
8% o: 8% o: 8» 0: 3:00am
“ 350633055
do“: a .5... om 9:. o
maa_

 

:2 $5284 “mam c850 5383:
$835... :08ch £536.80 Em: 3262 E eta: 9 380.33 323:: no 22883:: _x:uo-umaaxo=_b-3-mo_8am 280.:st 05 co: +328 .530 . a m 033.

203838.. .m_u>o_ 9:92.05 36 can mod 05 um Emoficwfi I...

 

 

72

 

 

 

3.9.. ”3.3 32:. $8 2.2 $3 :3 3.2 8.3 .3 .>u
323 83 83 3.3 ”8.... N32. 32.: 3% 333 2 Sum
.83 $2 3:... 33.2 E: 23 25.2 .33... 82 _ m”. x B x m
:3 33 85. ~32 33 33.3 :33 an... 333 _ m: x m:
38.3 :55 33.3 3.2 83.3 32.3 Sim 338 33.3 _ mm x m
RS. 83 35.2 .83.? 32: 22: S52 .3332 33 _ 9n: 8:
.39.: .332 .2 2m .33? .338 38.8 33st 333:. 32.3 _ B x m
.38.: .33.: . 633 News 3.238 .3322: 3:38 39.9. 33.3 _ me
.383 33.8 33.2 23 3322 £89. 823 .3332 3.8;: _ av 328%
£2 2 32 w 32 m .a< 3N .a< 2 .a< _ .32 3. .32 E .32 a
33.2
2.2 2.9. 2.3. 3 .mm 2.: ER 33 3.3 a}: £5. 33: .x. .>o
33 3.3.... 83 ~83 SS 22 was 2:3 53 E: 2: 2 Sum
32 god was 83 mm: 3: .N 83 2: .o RS 39m 2?. _ m: x me x m
33 _ .m 2:” 2.2 38; a: .o 33.3 93.3 23 £3 39 a: _ m: x E
33 83.3 a; 83.3 «8.3 32.3 «8.3 38.3 $2 $3 333 _ mm x m
23 333. $3 ”2.3 83.3 38.3 83.3 ~23 33.3 33 23.3 _ an: 8:
2o... 83 83.3 $3 83 3.3 .38.... 83 .33... 83.3 ”SN _ me x m
33.3 3.2 .3 .133 .33.? :82... .3313 :5: .333: .382 333.: .32.»: _ mp
33 82 .E .3 .332: .38.: .182 it. a .332 .333 .33. _ N .3: .33 _ av 328%
.32 mm .52 2 .32 w .32 _ .3". mm .8... 2 .83 w .8... ~ .5. mm .5: E .5: 2 :3 853m
3.2

 

.=2 $533 “mam £8.80 £933.01
mmfiwtsh x828: .mcoEcaoo Em: c0262 5 $2th woonmbéoc .0 £22» winazu :o acute Eon—“mob .8 3.805%; 98 33:3 582 .9. 2an

73

 

 

 

 

 

 

 

 

 

 

 

3L.— ..uvg *N.m wfi Lam *w.v Law 5W: QM mo»
Wm w.m Nm Nd v.2 od ”.2 93 ad on
350635on;
:wd fin..— m.m ma .3»: "Imam NE 1&2 fim mmflwoap goacov~
wN 9m _.m N.» We m.m Nd Z: 9m $8323 «596
36on
«-8 w

$2 2 £2 w 522 m .a< an a< 2 .a< _ .32 3. .32 m. .32 w 2258:

32
ow 3 N.N E 3 N.N 3. 3 mm 3. E Va
3‘ Nam o.~ 0.. N.N N.N o.m vd NM fin We o:
no:
QM *ON EL.— ..imd 1.6.— _.:._N.~ .I.N._ ER.— ..:..m.N *m.N **m.v .50»
Nm Tm _.m w.m Em m.m wN NM NV Qm v.0 0:
350-8355;
_.m m6 0N m.N N.m *...o.m **o.m _.:..N.m 3&6 **N.v “aged games—n \0:93:02
3 3 3 3 2 Z I E 3 ma 3 magmas «59%
E m 363m
.82 mm .32 2 .82 m .32 _ bum mm how 2 how w bum _ .92. mm .53. M2 .5: 2 Enchant.

moa—

 

..=z $5284 “mam c850
ganged mmfiwtsh x8283 £53650 Em: 3262 E 38th uoonabéo: («a £22» wzaazo no so: new .Rfioémamxofib .882? .3 Sootm .3. £an

74

.82 52 2 as non mm .5 6QO a 33%. a: 72 9. 3.: .5: _r

A23 :08
Tu: wx no.8 com. .E< cm :52 2 :22. _m A 7m: wx 2 .8 32 .80 a ”835:0th E 550% 8a 3:2 ”8:3 wEBoze 2: so Bin? 83 ifioémqnxoafi. a
.32 .32 2 2a :9; z .5. 2 8 Smog 8 33% 83 A .2 wx 3.: S: H

A88 some
7m: 3 8.8 32 .52 2 spam M: :5: om A 72 wx E .8 32 .80 m ”$855.3 5 53% 8a 822 38% wEBozfl 2: :0 Rings 33 SSoéQOfiEfi. +
52883. .232 £3305 :3 Ba 36 a Escewa t...

 

M: 2 .3 as 3 5 .5 to: 3 7%
M: N.N nm E E 3 n: S: 3 2.
.8:

23:58 3» 03m...

75

A83 some

7m; 9. 3.8 09$ .E< em 9.82 2 £5. 5 A was wx 2 .8 .32 .80 o ”momoficoaa E :32? 2a 3%... $83 336:8 2: co coins was 350-8355; H

A83 :28

7mg wx no.8 mag .32 E rnom M: :52. om A was wv. 2 .8 go— .80 m ”$855.8,“ 5 Esonm 2m v.88 $.83 w53o=8 05 co com—mam £3 350-835:th +

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ad 5o v4 ad m.m m.m ad ”6 6o 3: .1. Na 5.2 ”.2 NE NE mmfiwozz 308:3.
m._ 3. v; 9v _.m 2. Em 2: M: E: N.N ow 9v odm ms ad. mmfiwosz «Easm
0
we c
me» 0: mo» 0: 8» o: 8% o: 8» 0: me» c: me» 0: 3» o: 83on
«SSuémqaxofih
32 2 $2 x Q: m .a< om .a< 2 .a< _ .52 «N .52 E
009
3 3 mo 5. 3 3. _.~ 3 M: 2. mm 3 E 3 mm 3 383:3 Agassi
ed 9N ed a; o6 To. Nd Wm 5o m._ o._ Wm o._ N.N NM— w.~ mwfiwozfi «Easm
~-E m
me» c: we» on mm» o: 3% c: me» 0: me» o: 8% o: 8» o: 860%
Lzfioémamxofih
.32 w .32 _ bum mm bum 2 bum w bon— _ .52 mm .5: M:

 

32

 

dz .wfimamq “mam £850 :ohwomom mmSth.
x0855 £83628 Em: 8262 E $8th noonmbéoc .8 $33 quEB so 86on can Efioégmxofib no 328885 Emoficwv. how 32m> .9 03m...

76

resulting from long-term PGR applications was also not observed (Watschke, 1976;
Kaufmann, 1986b). Apparently the successive low rate (0.08 kg ha") applications of
trinexapac-ethyl suppressed growth only to the point where carbohydrates may have been
shifted to enhance tillering without causing growth cessation (Hanson and Branham,
1987). For practical use it may be important to be able to monitor the level of active PGR
in the turf if PGRS are to be used on a continuous basis to maintain turf in RLC.
Immunological techniques may prove to be the most expedient method for determining

the amount of active ingredient in the plant.

Ex "rim nt [1: ur '11!) 'e ' ’ tra I

Treatment effects on the clipping yields of trafficked turf were similar to non-
trafficked turf (Table 43) but actual yields were much lower than those from non-
trafficked turf (Table 44). Trinexapac-ethyl continued to affect Supina bluegrass more
significantly compared to Kentucky bluegrass (Table 45). In 1995 yields of Supina
bluegrass were zero after Feb. 1 although turf yields in 1996 indicated continued growth
throughout the trial. Since total inhibition of growth will slow or eliminate turf recovery

it is important to match timing and rates of application of PGRS to maintain acceptable

turf cover.
W
E r' ' t ' r l

Turf species and trinexapac-ethyl consistently affected turf shear resistance while

other treatment effects were rare and inconsistent (Table 46). Shear resistance declined

77

50380nt .m_o>o_ 325305 _o.o EB mod 2: E EmoEcwE 3.. ....

 

 

 

 

 

on; 3.3 2.: 3.2. :d. 8.9. 8.8 a. _ m 3.: x .>o
a: .o 32. $3 :3 3: ._ $3 N3; :3 a _ S 2 Sum
83 3.3 :3 $2“ 32 La: 5.8 $2.3 o: ._ _ m... x mp x m
32. 83 S: $3 33 we; _ _ S a _ .o Red _ m: x m:
83. 83 a: 83 ES 255 2.3 2 S 33 _ mm x m
~86 2 3 2 m... 83; 33 83 23 E _ .: 2 do _ ab .5:
:83 83 38.2 SN.» :33 S 3. ~22: 33 o: .o _ me x m
:33 83. an: 83 :Ene :89: :33? age 2.3 _ mp
.33 :os .: cm: 33 92.2 80. _ N $3. :330 83 _ @ macaw
3: t a: a a: m .a< am .22 2 .23. _ a: «N a: 2 .32 m
0%

EN. 032 $23 8.2: 2.3 6.2. 3.8 mm: 3.2 NS». Sam .x. .>0
8? mm; :3 83 83V 53 £3 32 82 8: £3 2 Sum
89o $2 .355 23 83 RS. 33 23 :50 2: .o :30: _ m: x E x m
23 m2: 08¢ 83. mm; 89 v8.0 33 :56 E: 22 _ m: x E.
3; ._ cam .53 £8 £2. 82 23 83 89¢ 22. £3 _ m: x m
as; 3.2 Sod Sod 83. 83 03¢ 83 83 $2. $8; _ 33 .5:
onto :2 .136 .22 :33. £356 .33 :§._ :5; wood :2: _ me x m
:3 Sad :83 :ofle :83 :3 no :82 :82 :53 :20: :Equ _ me
$3 $3 82 .22 :33 .8? :NSo :c8.§ :03: £38 :mflafl _ av 860%

.52 mm .52 2 .52 w .32 _ .fia mm a: 2 .fia m sea _ .5: mm .5: M: .52 2 :c 853
82

 

:2 $2355 “mam .3300 5.880%

mmflwta. x828: £52280 Em: 30sz 5 uEmb 9 c8833 38th mo mac—2» wcaazo :o 303% 82585 mo ougoc_:w_m 38 83:3. :82 .3 03m...

78

 

 

 

 

 

 

 

 

 

 

 

 

.390 {ad 0; ”M _.:._w._ f..m.N 3.9% w.v m._ am?»
m._ w; QM Em m.m .6 ad Ev _.m o:
35063305;
.2 :3 3 mm mm 3 E to E 383:3 5.323.
m2 QN o.m N6 52 vd 3‘ _.m Nu— mmfiwosfi 2:96
E w museum
32 2 b3 u bwE m a< am .5. 2 .a< _ .52 E. .32 2 .52 w 2258:
32
2 ad Yo Yo wd ed 5o m._ o.m wd fie H3»
5o Yo Yo Yo 5o wd 9o m2 o.m 5m 9m 0:
so:
We v.0 .3." _ .o trod ..:..N.o *.._N.o frmd .I,w.o firm.— **O.N .256 .2. m2»
2 ad 5o Mg m._ N; ad 2 "mm m.m ms 0:
35868305;
m..— o._ 9o :06 11 *2 3.. _ ._ :NN film Ioé 33.x 383:3 .9835!
2 no 3 mo 3 S 3 do no I 2 $3.33 2&3
N.E w 363m
.32 mm .82 2 .32 m .32 _ bon— NN how 2 bum m be; _ .52 mm .5: M: 5:. 2 Hanged.
32

 

._2 $5234 “mam .5250
53832 mmfiwtsh x085: .mcoEncou Em: 8262 E oEmb 8 380.33 38th go .633 wcaazo co 350-3355: can 860% .3 38.2.5 .3 033

79

.82 32 2 Ba .8“. mm :0 6QO 8 33% a: :2 mx 3.: no: _r

A23 some
72 wx M33 03— .E< cm £22 m. :5: _m A 7a: wx S .8 32 .80 o ”momoficobwa E 5505 2a mesh 68% wEBo:£ 2: so 32%? mm? Efioéamaxofifi a
.82 .52 t 23 so; 2 :52 2 8 6%“. 8 33% as A :2 w; 2.: :2. H

A88 some
72 wx wodv 39 .32 2 rnom M: :5: cm A 7m: wx 2.8 go. .80 m ”885:0th E 5505. 2a 82$ 38% wage—.8 05 co 3:qu mmB ifiobamxocth +
52:89.2 .232 £3305 :3 as 8d a Eocewa :9.

 

 

ad 2 3 3 E ”A E E M: F 3»
3 3 _.~ 3 X .3 mm 3 E 2.
:8.

3:53 3 22¢

80

A33 none
72 wx no.8 82 ..a< on :82 m.— ..5: 1m A 72 wx o. .8 32 .80 o “momoficoaa E 5597. 2a 8E ”menu 9.50:8 2: co 3:an 83 350-3355; H

Aofiu some
72 wx no.8 3E .32 3 room M: :5: cm A 7s... wx 2.8 $2 .80 m ”8855.22. 5 56% 2m 8:: $23 wEBo—é 2: co v3.3a 33 150-8355; +

 

 

 

 

v.0 ad ozm 8 ad 3 m: m: Amodv Om:

We Yo wd We a; 04 Q». 9N N.m m.m QM 9v 9m 2. :. Qm 389:3 5.08:3.

2 3 3 3 3 we 5 3 no 3 2 cm «A no 3 5 383:3 2&3
#8 w

no» 0: mo» 0: me» 0: me» o: 8» o: 8% 0: we» on me» o: mfluoam

 

 

H 35983555

 

 

 

 

 

 

$2 2 32 w 32 m .a< om .a< a .a< _ .52 a .32 N.
coa—
2 2. no 3 no to 9o 3 A38 mm;
_.o m._ od m._ vd Wm Yo Om 5o 0.. o; w.m Nam 3V Qm 0A: 3.3ng 533:3—
o.o md ed to ad No od _.o od _.o o.o md md 5o 9m 5v mmfiwoan Siam
E w
NO
8» 0: mo» 0: 3» 0: mm» 0: me» o: 8» o: 8% 0: 8» o: 86on

 

 

* Efioémamxofih

 

 

 

.32 w .32 _ do“. mm bon— m. .nom w bum _ .23. mm .5: 2 E2535.

 

moo—

 

.=2 .wfimcmq “mam c850 5883* $8th x085:
.mcoEnzoo Em: 3268 E stab 2 380.33 323:: mo 33% wEaE—u so 860% new 350-0333?“ .3 328885 EmoEcwv. Eat mo=_m> .mv 2an

81

Table 46. Mean square and significance of treatment effects on shear resistance of non-trafficked turfgrass
in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

 

 

 

 

1994-1995
Source of variation df 20 Dec. 20 Jan. 22 Feb. 31 Mar.
Species (S) 1 369.094" 2.344 546.260" 240.667"
Trinexapac-ethyl (TE) 1 0.010 94.010" * 0.260 20167“
S x TE 1 3.760 10.010 1.760 3.375
Iron (Fe) 1 3.760 15.844 3.760 2.042
S x Fe 1 0.010 17.510 0.260 2.667
TE x Fe 1 0.010 36.260 1.260 32.667"
S x TE x Fe 1 7.594“ 0.094 0.010 15042"
Error 16 1.042 17.760 2.271 3.219
CV, 0/o 5.57 25.77 10.17 14.08

1996

Source of variation (if 17 Jan. 12 Mar. 31 May
Species (S) l 121.500M 48.167* 28.711”
Trinexapac-ethyl (TE) 1 l .500 18.375 5.753"‘
S x TE 1 7.042 15.042 6773*
Iron (Fe) 1 4.167 5.042 0.023
S x Fe 1 2.042 30.375 0.315
TE x Fe 1 7.042 16.667 0.003
S x TE x Fe 1 0.667 32.667 0.065
Error 16 2.281 8.000 0.815
CV, % 7.29 16.80 10.31

 

*, ** Significant at the 0.05 and 0.01 probability levels, respectively.

82

over time in both years regardless of treatment (Table 47). The decline in shear
resistance indicated a lack of sufficient turf growth and rooting probably due to
insufficient light energy to sustain turf permanently. In the first year Kentucky bluegrass
had higher shear resistance than Supina bluegrass probably due to the presence of
rhizomes in Kentucky bluegrass which added stability to the turf (McNitt, 1994).

Shear resistance values of Kentucky bluegrass were significantly lower than those of
Supina bluegrass in 1996, perhaps due to increased root growth of Supina bluegrass
during the longer establishment period in autumn of 1995 compared to autumn 1994.
However the practical significance of such a difference in shear resistance may not be
important as values were still relatively close. In addition, a desirable value for shear
resistance using the Eij kelkamp shear vane has not been established despite previous
attempts (Liesecke and Schmidt, 1978) . Shear resistance values are generally important
for their ability to indicate relative turf strength and rooting differences. In 1996 the
shear resistance of Supina bluegrass was significantly increased by trinexapac-ethyl while
Kentucky bluegrass shear resistance was unchanged (Table 48). Trinexapac-ethyl
enhanced Supina bluegrass growth and development more than Kentucky bluegrass,
which resulted in more biomass aboveground which enhanced the shear resistance of the

Supina bluegrass.

E r' ' r ' t r
Treatment effects on turf shear resistance were similar to those on non-trafficked turf
(Table 49). Shear values declined over time due to loss of turf density and actual values

were lower than for non-trafficked turf (Table 50). Supina bluegrass continued to be

83

Table 47. Effect of species, trinexapac-ethyl, and iron on shear resistance values (N'm) of non-trafficked
turfgrass in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1994-1995
Treatment 20 Dec. 20 Jan. 22 Feb. 31 Mar.
Species N m
Supina bluegrass 14.2 16.0 10.0 9.0
Kentucky bluegrass 22.4” 16.7 19.6M 15.3M
Trinexapac-ethyl
no 18.3 14.4 14.7 11.2
yesl' 18.3 18.3" 14.9 130*
Iron
no 18.7 15.5 15.2 12.4
yes: 17.9 17.2 14.4 11.8
1996
Treatment 17 Jan. 12 Mar. 31 May
Species N m
Supina bluegrass 23.0 18.2 9.9
Kentucky bluegrass 18.5” 15.4“ 7.7M
Trinexapac-ethyl
no 20.5 16.0 8.3
yes§ 21.0 17.7* 92*
Iron
no 20.3 16.4 8.7
yes1l 21.1 17.3 8.8

 

*, ** Significant at the 0.05 and 0.01 probability levels, respectively.

TTrinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 3 Oct. 1994
(o. 19 kg ha" ), 20 Jan., 18 Feb., 16 Mar. 1995 (0.08 kg ha" each date).

1' Iron (1.14 kg ha'l ) was applied as FeSO4 on 10 Jan., 14 Feb., 17 Mar 1995.

§ Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 9 Oct. 1995
(0.19 kg ha'l ), 31 Jan., 15 Mar., 26 Apr. 1996 (0.08 kg ha'l each date).

1| Iron (1.14 kg ha'l ) was applied as FeSO4 on 28 Feb. and 13 May 1996.

84

Table 48. Shear resistance values (N-m) for the significant species-by-trinexapac-ethyl interaction on non-
trafficked turfgrass in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

31 May 1996

 

 

 

trinecapac-ethylt

 

 

 

Species no yes
N m

Supina bluegrass 8.8 10.9

Kentucky bluegrass 7.7 7.6

LSD (0.05)

1.1

 

l“ Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 9 Oct. 1995
(0.19 kg ha" ), 31 Jan., 15 Mar., 26 Apr. 1996 (0.08 kg ha" each date).

Table 49. Mean square and significance of treatment effects on shear resistance of turfgrass subjected to
traffic in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

 

 

 

 

1994-1995

Source of variation df 20 Jan. 22 Feb. 31 Mar.
Species (S) 1 8.167 546.260M 152.510"
Trinexapac-ethyl (TE) 1 60.167 10.010 15.844* *
S x TE 1 12.042 1.260 8760*
Iron (Fe) 1 4.167 8.760 10010“
S x Fe 1 18.375 6.510 4.594
TE x Fe 1 22.042 1.760 0.844
S x TE x Fe 1 1.500 0.260 25.010"
Error 16 15.010 3.083 1.948
CV, % 25.62 13.57 15.47

1996
Source of variation (if 12 Mar. 31 May
Species (S) 1 45.375* 19.260"
Trinexapac-ethyl (TE) 1 5.042 16.667"
S x TE 1 2.667 24.000"
Iron (Fe) 1 5.042 2.344
S x Fe 1 6.000 0.094
TE x Fe 1 6.000 0.667
S x TE x Fe 1 15.042 0.167
Error 16 6.667 1.255
CV, % 18.33 15.86

 

*, ** Significant at the 0.05 and 0.01 probability levels, respectively.

85

Table 50. Effect of species, trinexapac-ethyl, and iron on shear resistance values (N -m) of turfgrass
subjected to trafficT in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1994-1995
Treatment 20 Jan. 22 Feb. 31 Mar.
Species N m
Supina bluegrass 14.5 8.2 6.5
Kentucky bluegrass 15.7 17.7“ 11.5”
Trinexapac-ethyl
no 13.5 12.3 8.2
yesi 16.7* 13.6 9.8"
Iron
no 14.7 12.3 9.7
yes§ 15.5 13.5 8.4*
1996
Treatment 12 Mar. 31 May
Species N m -----------------
Supina bluegrass 15.5 8.0
Kentucky bluegrass 12.7 6.2"
Trinexapac-ethyl
no 13.6 6.2
yesfl 14.5 7.9”
lron
no 13.6 7.4
yes# 14.5 6.8

 

*,** Significant at the 0.05 and 0.01 probability levels, respectively.

T Traffic was applied by persons who jogged on the turf 50 passess each week while wearing molded
soccer cleats on the following dates: 28 Dec. 1994 through 16 Mar. 1995 and 26 Jan. through 26 Apr.
1996.

I Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 3 Oct. 1994
(0.19 kg ha'1 ), 20 Jan., 18 Feb., 16 Mar. 1995 (0.03 kg ha" each date).

§ Iron (1.14 kg ha'I ) was applied as FeSO4 on 10 Jan., 14 Feb., 17 Mar 1995.

11 Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 9 Oct. 1995

(o. 19 kg ha" ), 31 Jan., 15 Mar., 26 Apr. 1996 (0.08 kg ha‘1 each date).

# Iron (1.14 kg ha'l ) was applied as FeSO4 on 28 Feb. and 13 May 1996.

86

more sensitive to trinexapac-ethyl applications in both 1995 and 1996 compared to

Kentucky bluegrass (Table 51).

Blantdensjtyjnihiomass
Ex r' n ' T r ' 1

Species, trinexapac-ethyl, and species-by-trinexapac-ethyl interactions existed for
specific plant weight, plant density, tiller, and leaf counts (Table 52). The turf density of
Supina bluegrass was much greater than Kentucky bluegrass and positively influenced
quality ratings. Supina bluegrass had more tillers and leaves per plant plus a higher
specific plant weight (Table 53). Plant density (number plants per unit area) was either
the same or greater than Kentucky bluegrass.

Trinexapac-ethyl increased turf density by increasing the plant density, number of
tillers and leaves per plant, and specific plant weight. Apparently trinexapac-ethyl was
effective at repartitioning carbohydrates in the plant to produce axillary tillers and more
leaves per plant similar to the effects of paclobutrazol and fiurprimidol (Hanson and
Branham, 1987). Turf left untreated, particularly Kentucky bluegrass, exhibited a
spindlier, more upright growth habit and may have exhausted carbohydrate reserves by
cell and shoot elongation without benefitting from an increased leaf area index (LAI)
resulting from the trinexapac-ethyl application. As with color, quality, and clipping
yields, Supina bluegrass was more sensitive to trinexapac-ethyl than Kentucky bluegrass

and exhibited a strong positive response while Kentucky bluegrass was largely unaffected

(Table 54).

87

Table 51. Shear resistance values (N -m) for the significant species-by-trinexapac-ethyl interactions on
turfgrass subjected to traffic’( in reduced light conditions, Hancock Turfgrass Research Center, East
Lansing, MI.

 

 

 

 

 

 

 

 

 

31 March 1995 31 May 1996
trinexapac-ethyl'
Species no yes: no yes§
N m
Supina bluegrass 5.1 7.9 6.1 9.8
Kentucky bluegrass 1 1.3 1 1.8 6.3 6.0
LSD (0.05) 1.6 1.0

 

1' Traffic was applied by persons who jogged on the turf 50 passess each week while wearing molded
soccer cleats on the following dates: 28 Dec. 1994 through 16 Mar. 1995 and 26 Jan. through 26 Apr.
1996.

I Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 3 Oct. 1994
(0.19 kg ha'l ), 20 Jan., 18 Feb., 16 Mar. 1995 (0.08 kg ha‘1 each date).

§ Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 9 Oct. 1995
(0.19 kg ha'I ), 31 Jan., 15 Mar., 26 Apr. 1996 (0.08 kg ha'1 each date).

88

Table 52. Mean squares and treatment effects on plant density and biomass of non-trafficked turfgrass in
reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

12 April 1995

 

 

 

 

Plant density Specific plant
Source of variation df (No. plants m'z) Tillers plant'l Leaves plant’I weight (mg)
Species (S) 1 1695697630 15.360” 180950" 94.169“
Trinexapac-ethyl (TE) 1 13834140784" 2.667* 34.800" 143.277"
S x TE 1 749137.231 3.227* 33.844“ 48.053"
Iron (Fe) 1 4924.957 0.202 3.300 1.242
S x Fe 1 60.805 0.135 1.170 0.814
TE x Fe 1 102207.627 0.375 13.650 14.291
S x TE x Fe 1 572082.701 0.482 3.920 2.857
Error 16 610266.41 1 0.400 4.872 7.807
CV, % 13.71 33.27 30.82 29.72

31 May 1996

Plant density Specific plant
Source of variation df (No. plants m'z) Tillers plant'l Leaves plant'l weight (mg)
Species (S) 1 20665817941“ 10.402M 388.815" 2061.277“
Trinexapac-ethyl (TE) 1 832314.080" 0.807” 12.042" 10.010
S x TE 1 1208798011“ 0.807" 1.500 2.306
Iron (Fe) 1 26813.528 0.240 2.282 58.033
S x Fe 1 32164.085 0.240 8.167 191.648
TE x Fe 1 1520.039 0.082 1.500 198.490
S x TE x Fe 1 547.217 0.082 0.015 220.584
Error 16 28759.193 0.087 2.187 66.212
CV, % 15.79 17.84 20.17 33.78

 

*,** Significant at the 0.05 and 0.01 probability levels, respectively.

89

Table 53. Effect of species, trinexapac-ethyl, and iron on plant density and biomass of non-trafficked
turfgrass in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

12 April 1995

 

 

 

 

 

 

 

 

 

 

Plant density Specific plant
Treatment (No. plnts m") Tillers plant" Leaves plant" weight (mg)
Species
Supina bluegrass 5430.8 2.7 9.9 1 1.4
Kentucky bluegrass 5962.4 1.1" 4.4* 7.4"
Trinexapac-ethyl
no 4937.4 1.6 6.0 7.0
yesl‘ 6455.8" 2.2* 8.4" 11.9"
lron
no 5710.9 1.8 6.8 9.2
yes: 5682.2 2.0 7.5 9.6

31 May 1996

Plant density Specific plant
Treatment (No. plnts m") Tillers plant" Leaves plant" weight (mg)
Species
Supina bluegrass 1990. 2.3 1 1.4 33.4
Kentucky bluegrass 134" 1.0" 3.3" 14.8"
Trinexapac-ethyl
no 875 1.5 6.6 23.4
yes§ 1248'” 1.8" 8.0“ 24.8
lron
no 1028 1.6 7.0 22.5
yesfil 1095 1.8 7.6 25.6

 

*, ** Significant at the 0.05 and 0.01 probability levels, respectively.
TTrinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 3 Oct. 1994
(0.19 kg ha" ), 20 Jan., 18 Feb., 16 Mar. 1995 (0.08 kg ha" each date).

1 Iron (1.14 kg ha'1 ) was applied as FeSO, on 10 Jan., 14 Feb., 17 Mar 1995.
§ Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 9 Oct. 1995
(0.19 kg ha" ), 31 Jan., 15 Mar., 26 Apr. 1996 (0.08 kg ha" each date).
11 Iron (1.14 kg ha" ) was applied as FeSO4 on 28 Feb. and 13 May 1996.

90

Table 54. Plant density and biomass values for the significant species-by-trinexapac-ethyl interactions on
non-trafficked turfgrass in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, Ml.

 

12 April 1995

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Plant density Specific plant
(no. plants m'2 ) Tillers plant" Leaves plant" weight (mg)
trinexapac-ethylf
Species no yes no yes no yes no yes
Supina
bluegrass 49370 6366 2.0 3.4 7.5 12.3 7.5 15.2
Kentucky
bluegrass 5379 6544 1.1 1.1 4.4 4.4 6.4 8.4
LSD (0.05) ns 0.8 2.7 3.4
31 May 1996
Plant density Specific plant
(no. plants m'2 ) Tillers plant" Leaves plant" weight (mg)
trinexapac-ethylz
Species no yes no yes no yes no yes
Supina
bluegrass 1579 2400 2.0 2.7 10.4 12.3 33.0 33.7
Kentucky
bluegrass 172 96 1.0 1.0 2.8 3.8 13.9 15.8
LSD (0.05) 208 0.4 ns ns

 

1' Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 3 Oct. 1994
(o. 19 kg ha" ), 20 Jan., 18 Feb., 16 Mar. 1995 (0.08 kg ha" each date).
I Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 9 Oct. 1995
(0.19 kg ha" ), 31 Jan., 15 Mar., 26 Apr. 1996 (0.08 kg ha" each date).

91
Trinexapac-ethyl had less effect on the biomass of turf subjected to traffic compared to
non-trafficked turf (Table 55). Supina bluegrass continued to exhibit a higher plant
density, more tillers and leaves per plant, and higher specific plant weight compared to
Kentucky bluegrass (Table 56). In addition, both species exhibited a higher specific plant
weight compared to untrafficked turf apparently due to less competition for light and
perhaps water and nutrients. Unlike non-trafficked turf, trinexapac-ethyl had little effect

on response to traffic between species (Table 57).

Chlamhxflflmemraticn
xr'mn'Tlrn u' t

Species and trinexapac-ethyl significantly affected chlorophyll a and b levels and total
chlorophyll (Table 58). The greater levels of chlorophyll a, b, and total chlorophyll in
Kentucky bluegrass compared to Supina bluegrass were consistent with the darker green
color of Kentucky bluegrass but were not effective in providing superior shade tolerance
(Table 59). Trinexapac-ethyl also enhanced chlorophyll concentration (leaf area basis) in
both turf species probably due to decreased cell enlargement. Trinexapac-ethyl cannot be
expected to affect chlorophyll synthesis directly since its known modes of action have
been described as blocking gibberellic acid (GA) biosynthesis only at the end of the
pathway, primarily by preventing 3-13 hydroxylation of the biologically inactive GAZO to
the biologically active GA, (Rademacher, 1991). Since carotenoids and GA, have a

common precursor, geranylgemalypyrophosphate (GGPP), it is possible GA inhibition

92

Table 55. Mean squares and treatment effects on plant density and biomass of turfgrass subjected to traffic
in reduced light conditions, Hancock Turfgrass Resarch Center, East Lansing, MI.

 

12 April 1995

 

 

 

 

Plant density Specific plant
Source of variation df (No. plnts m") Tillers plant" Leaves plant" weight (mg)
Species (S) 1 1368037471 15.844" 301.750" 193.007"
Trinexapac-ethyl (TE) 1 51 13419.885 * 0.260 9.004 9.805
S x TE 1 107254.135 0.304 3.450 1.540
Iron (Fe) 1 8755.448 0.000 0.120 4.200
S x Fe 1 190673.985 0.020 2.100 1.101
TE x Fe 1 1 17712.025 0.004 0.454 1.224
S x TE x Fe 1 78798.975 0.000 2.220 1.325
Error 16 689430.079 0.293 4.807 8.944
CV, % 39.94 26.78 25.16 21.78

31 May 1996

Plant density Specific plant
Source of variation df (No. plnts m") Tillers plant" Leaves plant" weight (mg)
Species (S) 1 5545355292" 6.934" 320.470“ 2058.869“
Trinexapac-ethyl (TE) 1 818147.252M 0.350 6.720 110.039
S x TE 1 934886.447" 0.510 4.420 98.537
Iron (Fe) 1 41101.925 0.070 1.450 5.482
S x Fe 1 107254.140 0.020 0.400 31.763
TE x Fe 1 35021.756 0.034 0.634 0.196
S x TE x Fe 1 0.000 0.004 0.034 224.298
Error 16 94729.003 0.125 2.390 125.984
CV, % 50.62 22.59 22.95 39.29

 

‘2" Significant at the 0.05 and 0.01 probability levels, respectively.

93

Table 56. Effect of species, trinexapac-ethyl, and iron on plant density and biomass of turfgrass subjected
to trafficl in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

12 April 1995

 

 

 

 

 

 

 

 

 

 

Plant density Specific plant
Treatment (No. plnts m") Tillers plant" Leaves plant" weight (mg)
Species
Supina bluegrass 1840 2.8 12.3 16.6
Kentucky bluegrass 2317 1.2“ 5.2” 10.9”
Trinexapac-ethyl
no 1617 1.9 8.1 13.1
yes§; 2540* 2.1 9.3 14.4
lron
no 2098 2.0 8.8 14.1
yes§ 2060 2.0 8.6 13.3

31 May 1996

Plant density Specific plant
Treatment (No. plnts m") Tillers plant" Leaves plant" weight (mg)
Species
Supina bluegrass 1089 2.1 10.4 37.8
Kentucky bluegrass 127* * 1.0M 3.1" 19.3"
Trinexapac-ethyl
no 423 1.4 6.2 26.4
yesfil 793" 1.7 7.3 30.7
lron
no 649 1.5 6.5 28.1
yes# 567 1.6 7.0 29.0

 

*, ** Significant at the 0.05 and 0.01 probability levels, respectively.
‘1 Traffic was applied by persons who jogged on the turf 50 passes each week while wearing molded soccer
cleats on the following dates: 28 Dec. 1994 through 16 Mar. 1995 and 26 Jan. through 26 Apr. 1996.
TTrinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 3 Oct. 1994
(0.19 kg ha" ), 20 Jan., 18 Feb., 16 Mar. 1995 (0.08 kg ha" each date).
I Iron (1.14 kg ha" ) was applied as FeSO4 on 10 Jan., 14 Feb., 17 Mar 1995.
§ Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 9 Oct. 1995
(0.19 kg ha" ), 31 Jan., 15 Mar., 26 Apr. 1996 (0.08 kg ha" each date).
11 Iron (1.14 kg ha" ) was applied as FeSO4 on 28 Feb. and 13 May 1996.

94

Table 57. Plant density and biomass values for the species-by-trinexapac-ethyl interactions on turfgrass
subjected to traffic* in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

12 April 1995

 

Plant density Specific plant
(no. plants m'2 ) Tillers plant" Leaves plant" weight (mg)

 

 

trinexapac-ethylI

 

 

 

 

Species no yes no yes no yes no yes
Supina
bluegrass 1445 2234 2.6 3.0 11.3 13.2 16.2 17.0
Kentucky
bluegrass 1789 2846 1.2 1.2 4.9 5.4 10.0 1 1.8
LSD (0.05) ns ns ns ns
31 May 1996
Plant density Specific plant
(no. plants m'2 ) Tillers plant" Leaves plant" weight (mg)

 

 

 

 

trinexapac-ethyl§

 

 

 

Species no yes no yes no yes no yes
Supina

bluegrass 707 1471 1.8 2.4 9.4 1 1.4 33.7 42.0
Kentucky

bluegrass 140 1 14 1.0 1.0 3.0 3.2 19.2 19.4
LSD (0.05) 377 ns ns ns

 

‘1 Traffic was applied by persons who jogged on the turf 50 passes each week while wearing molded soccer
cleats on the following dates: 28 Dec. 1994 through 16 Mar. 1995 and 26 Jan. through 26 Apr. 1996.

I Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 3 Oct. 1994
(o. 19 kg ha" ), 20 Jan., 18 Feb., 16 Mar. 1995 (0.08 kg ha" each date).

§ Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 9 Oct. 1995
(0.19 kg ha" ), 31 Jan., 15 Mar., 26 Apr. 1996 (0.08 kg ha" each date).

95

Table 58. Mean squares and treatment effects on chlorophyll of non-trafficked turfgrass in reduced light
conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

4 April 1995

 

 

 

 

Total Chlorophyll

Source of variation df Chlorophyll a Chlorophyll b chlorophyll asb

Species (S) 1 238.644" 30.173" 435.968" 0.029
Trinexapac-ethyl (TE) 1 314.071" 47.124" 601.301" 0.163*
S x TE 1 1.815 0.008 2.227 0.000
Iron (Fe) 1 5.587 0.980 10.921 0.000
S x Fe 1 4.267 0.022 5.125 0.035
TE x Fe 1 1 1.289 1.701 21.263 0.001
S x TE x Fe 1 19.802 1.071 30.759 0.009
Error 16 13.265 2.285 26.225 0.027
CV, % 15.21 19.45 16.16 5.25

29 May 1996
Total Chlorophyll

Source of variation df Chlorophyll a Chlorophyll b chlorophyll asb

Species (S) 1 32.109 2.734 55.937“ 0.029
Trinexapac-ethyl (TE) 1 121.590” 10.935M 200.797 *" 0.020
S x TE 1 8.592 0.680 15.360 0.029
Iron (Fe) 1 19.91 1 2.257 33.844 0.032
S x Fe 1 13.681 1.344 22.042 0.000
TE x Fe 1 0.341 0.070 1.033 0.022
S x TE x Fe 1 0.928 0.109 1.288 0.034
Error 16 4.710 0.470 7.887 0.043
CV, % 10.03 9.78 9.79 6.70

 

*,** Significant at the 0.05 and 0.01 probability levels, respectively.

96

Table 59. Effect of species, trinexapac—ethyl, and iron on chlorophyll content of non-trafficked turfgrass in

reduced light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4 April 1995
Total Chlorophyll
Treatment Chlorophyll a Chlorophyll b chlorophyll axb
11g cm'2 leaf tissue
Species
Supina bluegrass 20.8 6.7 27.4 3.1
Kentucky bluegrass 27.1" 8.9" 36.0" 3.1
Trinexapac-ethyl
no 20.3 6.4 26.7 3.2
yesl 27.6” 9.2" 36.7" 30*
Iron
no 24.4 8.0 32.4 3.1
yes§: 23.5 7.6 31.0 3.1
29 May 1996
Total Chlorophyll
Treatment Chlorophyll a Chlorophyll b chlorophyll asb
pg cm'2 leaf tissue
Species
Supina bluegrass 20.5 6.7 27.1 3.1
Kentucky bluegrass 228* 7.3 30.2" 3.1
Trinexapac-ethyl
no 19.4 6.3 25.8 3.1
yes§ 23.9" 7.7** 31.6M 3.1
Iron
no 20.7 6.7 27.5 3.1
yes1l 22.5 7.3* 29.9 3.1

 

‘, " Significant at the 0.05 and 0.01 probability levels, respectively.
TTrinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 3 Oct. 1994
(0.19 kg ha" ), 20 Jan., 18 Feb., 16 Mar. 1995 (0.08 kg ha'1 each date).

1 Iron (1.14 kg ha'l ) was applied as FeSO4 on 10 Jan., 14 Feb., 17 Mar 1995.
§ Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 9 Oct. 1995
(0.19 kg ha" ), 31 Jan., 15 Mar., 26 Apr. 1996 (0.08 kg ha" each date).
11 Iron (1.14 kg ha" ) was applied as FeSO4 on 28 Feb. and 13 May 1996.

97

could cause a feedback mechanism to shunt additional GGPP to carotenoid production.
Current evidence does not support the existence of such a feedback mechanism as
typically non-active gibberellins(GA1 precursors) continue to accumulate in the presence
of a (GA) biosynthetic inhibitor (Rademacher, 1991).

Iron application caused only minor, temporary darker green turf color. Chlorophyll
levels were relatively unaffected within two weeks following an application of iron. This
result suggests the plants were already at their maximum capacity for using iron for
chlorophyll production or else energy levels within the turfgrass plants were too low to
utilize the iron. Auxiliary studies showed that while foliar applications of iron failed to
enhance turf color or chlorophyll levels in Kentucky bluegrass, iron levels in plant tissues
were increased threefold following an application of iron sulfate at the same rate used in
the current study (unpublished data). Another possible explanation for the inconsistency
between color enhancement and lack of effect on chlorophyll content is that the leaves
used for chlorophyll analysis might have been partially unexpanded at the time of the iron
application thus the effect would have been seen particularly on older leaves.

Chlorophyll asb ratios were relatively unaffected by any treatment. Chlorophyll asb
ratios were approximately 3:1 which is equivalent to the ratio of approximately 3:1
observed for sun plants (Nobel, 1991). This indicates Supina bluegrass is not a “shade”
plant per se but apparently has mechanisms for shade tolerance which are lacking in

Kentucky bluegrass.

98

E r'm ' r

Treatment effects on chlorophyll quality and quantity were similar between trafficked
and untrafficked turf in 1995 (Table 60). As expected, data from 1995 indicated traffic
did not affect chlorophyll content (Table 61). Data were not collected in 1996 due to
insufficient plant material (the youngest fully matured leaves were consistently too short

from mowing to use in analysis).
CONCLUSIONS

Supina bluegrass was more tolerant of RLC than Kentucky bluegrass. The light
conditions tested were too low to sustain Supina bluegrass permanently in a trafficked
conditions and were marginal for non-trafficked conditions. The enhanced growth of
Supina bluegrass due to increasing light levels and photoperiod in the spring indicated the
actual light requirement to sustain Supina bluegrass under traffic was greater than the test
conditions generally provided.

Iron had negligible effect on any characteristic of either turfgrass species. Trinexapac-
ethyl treatments provided superior enhancement of color and quality compared to iron. In
addition, iron did not provide the enhanced biomass associated with trinexapac-ethyl
treatments.

Supina bluegrass was consistently more responsive to trinexapac-ethyl than
Kentucky bluegrass. Trinexapac-ethyl may have helped to increase the turf quality in
RLC by shifting carbohydrate partitioning away from primary shoots to stimulate

tillering with a subsequent increase in the LAI in addition to promoting a more prostrate

99

Table 60. Mean squares and treatment effects on chlorophyll of turfgrass subjected to traffic in reduced
light conditions, Hancock Turfgrass Research Center, East Lansing, MI.

 

4 April 1995

 

 

Total Chlorophyll

Source of variation df Chlorophyll a Chlorophyll b chlorophyll a:b

Species (S) 1 104.125M 14.774" 278.734" 0.077"
Trinexapac-ethyl (TE) 1 179.252* * 23. 108* * 328486" * 0.027
S x TE 1 0.017 0.134 4.708 0.010
Iron (Fe) 1 5.636 0.485 12.600 0.007
S x Fe 1 0.956 0.002 5.180 0.020
TE x Fe 1 24.990 3.190 52.896* 0.000
S x TE x Fe 1 13.395 3.046 4.797 0.056
Error 16 7.701 1.048 11.416 0.013
CV, % 10.98 12.94 10.18 3.54

 

*,** Significant at the 0.05 and 0.01 probability levels, respectively.

Table 61. Effect of species, trinexapac-ethyl, and iron on chlorophyll content of turfgrass subjected to
traffic in reduced light conditions, Hancock Turfgrass Research Center, East Lansing, M1.T

 

4 April 1995

 

 

 

 

 

 

 

Total Chlorophyll

Treatment Chlorophyll a Chlorophyll b chlorophyll asb

pg cm'2 leaf tissue
Species
Supina bluegrass 23.2 7.1 29.8 3.3
Kentucky bluegrass 27.4* * 8.7* * 36.6* * 3 .2*
Trinexapac-ethyl
no 22.5 6.9 29.5 3.3
yes: 28.0" 8.9M 36.7” 3.2
Iron
no 24.8 7.8 32.5 3.2
yes§ 25.8 8.1 33.9 3.2

 

*, ** Significant at the 0.05 and 0.01 probability levels, respectively.

T Traffic was applied by persons who jogged on the turf 50 passes each week while waring molded soccer
cleats from 28 Dec. 1994 through 16 May 1995.

I Trinexapac-ethyl was applied on the following dates; rates are shown in parentheses: 3 Oct. 1994
(0.19 kg ha" ), 20 Jan., 18 Feb., 16 Mar. 1995 (0.08 kg ha" each date).

§1ron (1.14 kg ha" )was applied as FeSO4 on 10 Jan., 14 Feb., 17 Mar 1995.

100

and compact growth. These attributes could be expected to enhance net
photoassimilation on a turf area basis, creating a favorable cycle as more carbohydrates
can be produced to regenerate tissues damaged by traffic or disease.

Supina bluegrass was superior to Kentucky bluegrass in RLC due in part to an
apparent resistance to powdery mildew. Supina bluegrass was more susceptible to pink
snow mold in RLC compared to Kentucky bluegrass. This problem was partly controlled
by providing wind movement over the turf with portable fans although occasional

fungicide applications were still necessary to prevent noticeable disease damage.

Chapter 3
PHOTOSYNTHESIS OF SUPINA BLUEGRASS (POA SUPINA SCHRAD.) AND

KENTUCKY BLUEGRASS (P. PRA T ENSIS L.) IN REDUCED LIGHT
CONDITIONS AS AFFECTED BY NITROGEN AND TRINEXAPAC-ETHYL

INTRODUCTION

Turfgrass performance in reduced light conditions (RLC; < 30% sunlight) is often
poor due to insufficient light for photosynthesis and normal turf growth. Turfgrass
species and cultivars may vary widely in their tolerance to RLC although all may exhibit
reduced tillering, reduced rooting, and an upright spindly growth (Beard, 1973). Supina
bluegrass (Poa supina Schrad.), a stoloniferous grass native to the sub-alpine regions of
Europe, has been developed in Germany as a turfgrass with purportedly good to excellent
shade and traffic tolerance (Bemer, 1984; Nonn, 1994; Pietsch, 1989; Skirde, 1971).
Preliminary research supports the hypothesis that Supina bluegrass is more tolerant of
RLC than Kentucky bluegrass (P. pratensis L.) (Stier and Rogers, 1995) which is
commonly used in the United States but has poor shade tolerance (Beard, 1973). The
mechanism(s) for the apparent shade tolerance of Supina bluegrass is/are unknown.

In addition to the use of shade-tolerant turfgrasses proper management techniques are
also important for turf performance in RLC. Previous research has indicated the potential
for plant growth regulators (PGRS) which inhibit gibberellic acid (GA) biosynthesis to

improve turf quality in reduced light conditions (Rogers et al., 1996; Stier and Rogers,

101

102
1995). Turf treated with GA-inhibitors in RLC was more uniform with darker color and

increased density compared to untreated turf. While the GA-inhibitors effectively
suppressed shoot elongation, other mechanisms by which the GA-inhibitors improved
turf quality were unknown. Possibilities range from enhanced photosynthetic rates
(Gausman et al., 1991), increased carbohydrate production or partitioning (Hanson and
Branham, 1987; Wang et a1. 1985), increased chlorophyll levels (Wang et a1 1985,
Archbold and Houtz, 1988), increased protein/enzyme levels and/or activity (Wang et al.
1985), altered hormonal levels affecting foliar production (Gausman et al., 1991), to gene
expression (Gausman et al., 1991). Conversely, Archbold and Houtz (1988) reported
flurprimidol and paclobutrazol decreased photosynthetic rates and Rubisco activities in
strawberry plants. DeJong and Doyle (1984) found paclobutrazol reduced shoot growth
of nectarine trees but did not affect photosynthesis. Mefluidide, generally considered a
mitotic inhibitor which also may inhibit GA-biosynthesis (Wilkenson, 1982), consistently
reduced photosynthetic rates of ‘Baron’ Kentucky bluegrass while amidochlor
occasionally enhanced photosynthesis (Spokas and Cooper, 1991).

In the early 1990’s a new GA-inhibitior, trinexapac-ethyl (TE), was labeled for use on
turfgrasses, primarily to decrease mowing requirements by suppressing shoot growth
(Vitolo et al., 1990). The potential side effects of TE on plant physiology are relatively
unknown due to its recent release but may be different than other turf GA-inhibitors. TE
apparently blocks 3-B oxidation of the biologically inactive GAzo to form the biologically

active GA, as opposed to flurprimidol and paclobutrazol which inhibit ent-kaurene

103
oxidation oxidative steps earlier in the biosynthetic pathway (Coolbaugh et al., 1982;

Rademacher, 1991).

In normal (full sun) conditions GA-inhibitor effects on turfgrass can vary with
nitrogen (N) rate and turf species or cultivars. Watschke (1981) found differences in
responses of two Kentucky bluegrass culitivars (‘Merion’ and ‘Pennstar’) to
paclobutrazol and flurprimidol. Other studies showed high N rates reduced the effects of
flurprimidol on common bermudagrass [C ynodon dactylon (L.) Pers.] (Devitt and Morris,
1988) but not on ‘Tifway’ hybrid bermudagrass [Cynodon transvaalensis Burtt-Davy x
C. dactylon (L.) Pers.] (Johnson, 1988). Johnson (1994) corroborated the differences in
response to trinexapac-ethyl between common bermudagrass and ‘Tifway’ hybrid
bermudagrass. In RLC of approximately 5-6 mol photosynthetically active radiation
(PAR) day", medium to high N rates (48 and 96 kg ha" at four to six week intervals)
resulted in significantly better quality Kentucky bluegrass compared to low N rates (24
kg ha" at four to six week intervals) when flurprimidol was applied, although low and
medium N rates provided superior turf in the absence of flurprimidol (Chapter 1).

Due to the demand for improved turfgrasses and management schemes for turf in
RLC, studies were initiated to examine the effects of N rate, trinexapac-ethyl, and species
on turf photosynthesis in RLC. Two hypotheses were tested: 1) Supina bluegrass was
more tolerant of RLC compared to Kentucky bluegrass due to a greater carbon exchange
rate (CER), i.e., enhanced photosynthetic rate, and 2) Trinexapac-ethyl improved
turfgrass quality in RLC by enhancing CER. The objectives of this research were to

determine if differences in CER existed between Supina bluegrass and Kentucky

104

bluegrass and to determine the effects of trinexapac-ethyl on CER of the two species. A
second set of objectives were to determine the influence of nitrogen rate and trinexapac-

ethyl on the CER of Supina bluegrass.

MATERIALS AND METHODS
£11 111'! | 111'
x e ' ' 1

Portable plots were established outside in full sun conditions. Wooden boxes (1.2 x
1.2 x 0.15 m depth) were filled with a sandzpeat mixture (80:20 v/v) (Table 78,
Appendix). The pH was 7.8 with initial P and K levels of 85 kg ha" and 90 kg ha",
respectively. Sixteen holes (0.6 cm diam) were drilled on approximately 23 cm spacings
in the bottom of each box to provide drainage. Starter fertilizer (13-25-12) was applied to
the soil and supplied 76 kg N ha", 64 kg P ha", and 58 kg K ha". Ten plots each were
sodded in Sept. 1995 with Supina bluegrass ‘Supra’ or Kentucky bluegrass ‘Blacksburg’.
The sod had been grown in a composted wood mulch on polyethylene sheeting during the
summer of 1995 (Cairol and Chevallier, 1981). Plots were mowed two to three times
weekly to 3 cm height and irrigated as necessary to prevent moisture stress. Plots were
fertilized bimonthly with 48 kg ha'l N, 3 kg ha'l P, and 40 kg ha" K. To prepare plots for
testing in reduced light conditions (RLC), plots were fertilized with 48 kg N ha", 41 kg P
ha", and 38 kg K ha" on 26 Aug. 1996. Plots were fertilized thereafter on a biweekly

basis with 37 kg N ha", 3 kg P ha", and 30 kg K ha".

105
On 18 Sept. 1996 trinexapac-ethyl (0.19 kg ha") was applied to five plots each of

Supina bluegrass and Kentucky bluegrass. Plots were moved into the Covered Stadium
Simulator Facility (CSSF) on 4 October 1996 and arranged in a randomized complete
block (RCB) design with five replications. Air temperature was maintained at 15.9 C i
2.9 C (range was 10-20 C). Relative humidity was 55.4 i 8.7%.

High pressure sodium lamps (400 W), suspended 2.7 m above the turf surface,
provided a steady but reduced light condition of approximately 100 i 9 umol m'2 s" on a
12 h photoperiod (ppd) and provided approximately 4.3 mol PAR m'2 day", not including
ambient light (Table 62). Iprodione (3-(3,5-dichlorophenyl)-N-(1-methethyl)-2,4-dioxo-
1-imidazolidinecarboximide), 5.93 kg ha", was applied with a COz-powered backpack
sprayer on 2 November 1996 to control Microdochium patch (Microdochium nivale). An
open gas exchange system was used to determine photosynthetic rates (Sams and Flore,
1982) using a polycarbonate chamber (4.9 cm2, approximately 24 cm3) secured over the
turf surface. Gas exchange measurements, foliar characteristics, and chlorophyll
concentrations were determined 23-25 Nov. 1996 approximately seven weeks after the
turf was moved into the CSSF. Carbon exchange rates (CERs) were collected on 23 Nov.
between 1200-1600 h after C02 levels in ambient air had stabilized following large
fluctuations earlier in the day. Data were analyzed as a 2 x 2 factorial in a RCB design
with two species (Supina bluegrass and Kentucky bluegrass) and TE treatments (0.00 and

0.19 kg ha" trinexapac-ethyl) as main plots with five replications.

106

Table 62. Photosynthetically active radiation (PAR) of plots in the Covered Stadium
Simulator Facility (CSSF), Hancock Turfgrass Research Center, East Lansing, MI.

 

 

 

 

 

 

 

 

 

 

1996

Location October November

mol PAR day"
Outside)r
average 1 5.5 9.8
standard deviation 9.4 4.3
CSSF, ambient light 1
average 2.4 1.5
standard deviation 1.5 0.7
CSSF, supplemental light §
average 5.5 5.1
standard deviation 1.1 0.7

 

1' PAR was integrated daily using a pyranometer (Li-Cor, model PY 14226, Lincoln NE).
Radiometric units (Ly day'l ) were converted to quantum units (mol PAR rr1'2 day" )
based on the conversion units published by Thimijan and Heins (1983).

I PAR inside the CSSF was determined by measuring the percent of PAR transmitted
into the CSSF at turf level with a portable spectroradiometer (Li-Cor, model LI-1800,
Lincoln NE).

§ Supplemental light (approximately 100 umol m'2 s"; 12 h photoperiod) was supplied
with 400 W high pressure sodium lamps.

107

E . II' 1 1‘ E SE 1

Portable plots were established outside in full sun conditions. Wooden boxes (1.2 x
1.2 x 0.15 m depth) were filled with sand (Table 79, Appendix). Sixteen holes (0.6 cm
diam) were drilled on approximately 23 cm spacings in the bottom of each box to provide
drainage. Starter fertilizer (13-25-12) was raked into the upper 2 cm of the sand surface
to provide 76 kg N ha", 64 kg P ha", and 58 kg K ha". Sixteen plots were sodded 29
August 1996 with Supina bluegrass ‘Supranova’ washed sod. Plots were irrigated as
necessary to prevent moisture stress. Plots were mowed at 5 cm height at seven day
intervals for the first 14 days, after which mowing height was gradually reduced to 3 cm
height during the following 21 days. Thereafter, plots were mowed two to three times
weekly to 3 cm height. Beginning 18 Sept. 1996 plots were fertilized with either a low N
rate, 24 kg N ha" month", or a high N rate, 96 kg N ha" month" applied in split
applications biweekly at 48 kg N ha". Potassium was applied biweekly at 48 kg K ha" to
all plots.

On 18 Sept. 1996 trinexapac-ethyl (0.19 kg ha") was applied to four plots each
fertilized with low or high N rates. Plots were moved into the CSSF on 4 October 1996
and arranged in a randomized complete block (RCB) design with four replications. High
pressure sodium lamps (400 W) were suspended 2.7 m above the turf surface and
provided a steady but reduced light condition of approximately 100 i 9 pmol 1n‘2 5". The
lamps were on a 12 h photoperiod (ppd) which totalled approximately 5 mol PAR rn'2
day", including ambient light (Table 62). Iprodione (3-(3,5-dichlorophenyl)-N-(1-

methethyl)-2,4-dioxo-1-imidazolidinecarboximide), 5.93 kg ha", was applied with a

108
COz-powered backpack sprayer on 2 November 1996 to control Microdochium patch

(Microdochium nivale). Carbon exchange rates were determined 15 and 16 Nov. 1996
(one and two days after mowing, respectively) using an open gas exchange system with a
polycarbonate chamber (surface area = 27 cm2; volume approximately 200 cm3). The
same location on each plot was assayed on both dates. Leaf areas from CER sampling
areas were determined 16 Nov. 1996. Samples for chlorophyll analysis were collected 18
Nov. and analyzed 20 Nov. 1996. Carbon exchange rates were determined again on 26
Nov. (1 day after mowing) using a smaller polycarbonate chamber (surface area = 4.9
cm2; volume approximately 24 cm3) to determine the effects of a greater flow ratezsurface
area on the CER. Leaf areas were determined from the sample areas the same day.
Samples for chlorophyll analysis were collected 25 Nov. and analyzed 27 Nov.
Photosynthetic measurements were collected between 0900-1200 h on all dates.

Gas exchange and foliar data were analyzed as a 2 x 2 factorial with N rate (24 and 96 kg

ha" month") and TE (0.00 and 0.19 kg ha") as main plots with four replications.

Gas esehange measurements

Carbon dioxide assimilation and related parameters were measured using an open
system. The system was comprised of an ADC LCA2 infrared gas analyzer (IRGA), an
air supply unit (ASU) capable of delivering up to 600 ml min" flow, a Parkinson leaf
chamber (PLC) (Analytical Development Co. Ltd., Hoddesdon, England), and a
polycarbonate assimilation chamber (PLC). Semi-flexible polyethylene tubing was used
to connect the system components. Ambient air inside the CSSF was used as the air

source and was drawn from a distance of at least 4 m away from the experimental site to

109

minimize C02 fluctuations due to the investigator. Air was drawn from approximately
0.3 m above the asphalt floor from a comer of the facility subject to little air movement
which minimized C02 fluctuation. Air drawn from a height of 4 m inside the facility, or
from outside the facility, had serious C02 fluctuations due apparently to fumace-emitted
(heated) air. The COZ fluctuations prevented accurate measurements even when the air
was passed through containers up to 250 L in attempts to dampen the C02 fluctuations.
Ambient air (approximately C02 = 349 i 5 11L L" except on 26 Nov. when C02 = 427 i
1 1 11L L") was passed into the ASU which pumped at a flow rate of 500 ml min". The
air was passed into a dome-shaped polycarbonate chamber (either 4.91 cm2 opening,
volume approximately 24 cm3, or 27.3 cm2 opening, volume approximately 200 cm3)
through in inlet port midway at or slightly below the turf surface. The chamber was
secured over the turf surface using wire which was hooked over bolts at the chamber base
and inserted into the turf. An exit port near the top of the chamber passed air into the
IRGA for analysis of C02 concentration. Steady readings of C02 differential between the
chamber and ambient air were achieved within one to two minutes. Immediately
following gas exchange determination, a PLC was connected between the outlet port of
the assimilation chamber and the IRGA for temperature and relative humidity
measurements. The temperature and relative humidity of the ambient air were then
measured. The photosynthetic photon flux density (PPFD) was determined during
assimilation using a Li-Cor 19OS quantum sensor (LiCor, Lincoln, NE). Photosynthetic

parameters were calculated on both a turf surface area and leaf area basis using a BASIC

l 10
computer program (Moon and Flore, 1986). No attempt was made to inhibit the effects

of soil respiration on CER.

Leafareaanalxsis

Leaf area of the turf was determined using a Li-Cor 300 leaf area meter (Li-Cor,
Lincoln, NE). Leaf blades were excised from shoots and placed flat on sheet of clear
contact paper. The contact paper was taped inside a folded piece of transparency paper;
the sheets were then passed through the leaf area meter. The average of three readings
were collected for each sample and the “blank” area of the contact paper plus tape was

subtracted.

Chlamphxfljnalxsis

Sections (1 cm length) were collected from the middle of the youngest, fully expanded
leaf blades of 10 plants per plot. Leaf widths were measured for leaf area determination.
The mass of each 10 segment sample was determined to evaluate fresh leaf weight.
Chlorophyll was extracted according to the methods of Moran and Porath (1980) using
the extinction coefficients and formulae determined by Inskeep and Bloom (1985).
Chlorophyll was extracted from each 10 leaf segment sample in 3 ml N,N-
Dimethylformamide during incubation in the dark for 48 h at 4 °C. Absorbance values
were measured using a UV-Vis spectrophotometer to determine chlorophyll a,

chlorophyll b, and total chlorophyll concentrations.

ll 1
RESULTS

Ex 'm n

Species significantly affected CER, E, and g5 on a turf surface basis while trinexapac-
ethyl did not affect gas exchange parameters (Table 63). No interactions occurred
between species and TE on any gas exchange parameters. Supina bluegrass CER on a
turf surface area basis was over 50% greater than CER of Kentucky bluegrass and
significantly different at p=0.05 (Table 64). Higher transpiration rate and stomatal
conductance of Supina bluegrass corresponded with the greater CER compared to lower
values observed from Kentucky bluegrass. Trinexapac-ethyl did not significantly
enhance CER although CER was 36% greater in treated versus control plots. On a leaf
area basis neither species or TE affected CER (Table 65). Values of gas exchange
parameters were quite similar between the two species on a leaf area basis (Table 66).

Species and TE both significantly affected LAI, fresh leaf weight, and chlorophyll
levels (Table 67). There were no significant interactions between species and TE.
Supina bluegrass turf had a greater LAI and lower fresh leaf weight but less chlorophyll
compared to Kentucky bluegrass (Table 68). Trinexapac-ethyl resulted in greater LA]
and increased chlorophyll levels in both species. Chlorophyll azb was not affected by any

treatment.

Experiment 11: Nitregen x PGR study

Nitrogen and trinexapac-ethyl did not have a significant effect on CER or other gas
exchange parameters of Supina bluegrass when evaluated on a turf area basis (Table 69).

A higher than normal (approximately 350 11L L" COZ) ambient C02 level and decreased

112

.xocomoao own .833
MS? 60:90:28 £3088 . aw . N00 .5qu BEBE .5 ”8:826:00 .858on am ”coumufimgb .m ”88 owcwnoxo c880 JED +
66153365 85 65 a 38%me ..

 

 

8.8 3.; 3A: 3. G 3.5. 8.9. .x. .>o
m2: at? ESQ: 3:: 83 ES ccem
owed $2 82% 6%.: $0.0 9.2 m: x m
$2 $3 $32 9.2M 33 Red Am: 35668965:
22 $2: 3552 52.3” as? .. _ m2 A5 66ch
E: 83 32.82 macs em; 22 eccecsacm
A To”: BE Now 35 A em as 655 A moo as Now .255 A em as 35.5 A _.m as .655 A we N.E N8 .655 856m
a: a _ .MSB em 6 .w m 5.5

 

.003 con8o>oz mm £23 38 85.35 E A 18¢ add 38 m bofigxoaamv mcoEwcoo Em: 3268
E coESEmE 3.5th: 50 .Amhoonqu osofiimoaosa so Efiobamxosg 98 86on mo gumbo 5:253: 28 88:3 S82 .8 £th

113

.82 .acm 2 BE? M:
305650 3: :89:

#53 60:30:28 @0382: . aw . NOD 5:2 358:: :0 60:80:28 3:806 aw Hatfifimgb .m 6:: owSono :2th J50 A.
:32 £5365 85 65 a “seemed: ..

 

mmN owe: ooém oodwm mod 3: H Ed

mm; mud owém mmdom mud MA: cod

 

A 7:: mos 3:663:55;

 

cm: A? .. :2: wag .. _ no .85 $882: 3635:

a: Sm o : .Nm 2.8m 33 a: sewage eeaem

lwmmemmw

A :05 BE N00 .25 A12: 6:55 ALoE 36:5 A19: 683 ATm ~-E EEEV Avm NE BEE 3258:.
L: x : :23 em .w d m .. mm:

 

doo— BnEo>oZ mm £me no.8 ooflSm E A 7.3: fixed 38
m bofiéxoammv 325:8 Em: 30:3: 5 323:3 3035M :5 mmflwofin «Egm :oozzon gangsta: ocofiimowonm .vc 2an

114

$05650 om: 83>»
M53 6288350 $3338 , em a NOD m3— EEBE “AU ”8:80:38 338on am ”couahmmcmb .m ”38 omSono A8928 .mmu +
.132 Essen 3o 2: a Hfiofiawa ._,

 

 

3% S? 32 3% 8.8 :.mm .x. ,>u
8: 83 @382 §qu 2A; :3 85
mod :2 .323 $2 8A; 08.0 m; x m
o A 2 :56 as. A 2 03. 3 omod 53 Am: 350-8385
82 83 83% £9: 8A; 8A; Amv Exam
on: 83 ESE 8; ~56 *mmod 8:8:an
A Tom: as N8 35 A _.m we 35.5 A moo BE N8 .023 A _.m N.5 .255 A _.m N.5 35.5 A _.m we N8 353 85cm
we x A m5? em 6 mm m mmu

 

603 “38302 mm Emma. «Em man: A 19% M<m 38 m AAABQEAxoammV 256650 Em: 3268
5 3:84:88 mmfiwfia mo Ambfifiedm ozoficxmowosq so ESoémmmxofib ER 360% go acute Hosanna can 831% :32 .mo 28;

115

$2 .aom A: BAAAAAA:
226850 cm: 883

£33 6880330313388 . aw . NOU awo— AmEBE 40 60530358 39:06 am Eosfifimcmb .m $58 092235 conao rmmu 4A

 

mmN om; 05m aodwm Ed 36 Had

NM: w_._ wow mmdam mmd mmd cod

 

A 7m: wvc 35068305;

 

EN 2._ one ASSN w A .o N3 88323 53352
SA w A .A AA; 2.8». A3 26 323:3 2&6
86on

A TONE BE NOD _oEv A 7.9: .355 A 19: .955 A 10:. BE: A_-m N.E AoEEv A _.m N.E 3&3
1: x A .mDB em mm U m A mmu €258;

 

.002 528962 mm .2me 83 .32 .A 18% Mai AoEm
bufifiioammv £82950 Ew: 3268 5 $8333 3035M was $8333 «£96 5353 moocvobE ocoficxmowonm .00 033.

116

533838“ £32 bzfimnoa 56 28 mod 2: E “53$:me .1 .*

 

 

:3 mm.» 3.2 N; 30 as .x. .>u
8.0 33 23 ONE $2 33 82m
cm; 2&2 Emma 33 Rod 53 E x m
:3 :23.va .1288 1.5.02 :3? amow Amt aeoaamxoafi
god $03.2: $02.? .2; 5.2; $2 :83 av 860%
Sad $2. G 3.8.N “imam :MGN $3 cassava
am so 39 so a Eu a 20 f8 we .5 850m
95 EB 50$

 

Aosmmu ‘82 was was 253.520

 

6mg .>oZ 3. .A 1A3 Mai 38 m buEEQoEnmv 2836.80 Em: 3262 E 83888“ go 5:868:00

=bfi€oEo EB .EwBB :32 28¢ .AZ‘C x09: 83 b8— 20 303.3 62585 mo oogomawmm new 8833 532 So Bash

117

.82 .aom M: 883 J,

$838880 a20>2 ham—29088 Ed was mod 05 00 8.000—mama 3.. J.

 

 

 

03 3.2.3. :20 :3: 13.0 33 +2.0

:.m Ea 8s 8. a OS Nam 8.0

A 70: wxv 35003082;

03 15% toms 1 _ 3m in? 12.». 38033 303500

c; 3.3 8.0 88 N2 03 $8083 2&3

880%

as :0 89 20 a 20 a 20 £8 3 :3 0:258;
05> ~02 200.5

 

A0320 82 N.80 way $38820

 

.82 .32 a #5 ~20 as m

308828890 £82980 Em: 000800 E mommfiwfia 80 2038820 08 08:8 8 7300-0mmmxocg 08 0.200% .8 mwoubm .3 2an

118

 

 

 

 

 

 

30.0 83 2 2; 03. 5 .950 08.0 me x 2
20A 2 3 33% «.3? 23 80.0 at afloaamxocfi
mag 83 $0.02 93.3 23 £00 90 508:2
35 $3 £32: 838 $3 23 cosmoiom
852: 5% a E 602 .32 8
8:52? .8323:me «80 ad
3.9 330 8.3 8.3 2.? 8.3 g ,>0
:2 08.3. $0.2 2: .2: ~80 $20 8:0
33 $2 83% 02.3? 08.0 38 me x 2
$30 53 82 was :50 08.0 at @0908me5
:3: N32: 23 30.202 30.0 0:3 20 508:2
3? SEN a: 80002 80.0 .83 8082030
wage 5% a we £2 .32 S
3.2 $.02 52 3.2 3.2 mm? .x. “>0
3: E? $3 335 wood $3 5:0
38 iv. a :55. $0.3? “ago 330 me x z
320 N 0 2: $3: m 2 3%. 80.0 ”8.0 m5 150-8385
83 N28 32 $20 08.0 08.0 20 50802
£3 82: 20.0 $2.50 33 80.0 808800
0:505 5% a «N .32 .82 2
8:85.? 8:23:08 «80 mfiu
ACNE :88 ~00 .25 A _-_0E 88:: A 10.: BEEV A 108 .083 A _-m N.E SEE A _.m $8 863 00.50m
me x 2 “023 am mm .0 m 80

 

.293 008 00280 E .A 1920 Mai 88 m 3088288qu 825080 Em: 20003000 5 28 c0802:

98 350008825 3 02028 mmfiwoin «Easm mo +0202888020 0302028088 mo 302mm 80880.3 28 008:3 822 do 2an

119

305650 mm: 833
MS? 502803300 $2382: asw ”NOD buo— EEBE .5 60530528 fiflmaowm aw ”coumbmmcm: ,m ”28 09855 55.60 JED +
$338232 £32 $23.3qu Ed can mod 05 «a Emommcflm .I. 3..

 

vwdm aqmm wad 3.3 wadv wodm o\o .>U
wmmg shod wmnénm mth—N god coho “ohm

A383 3 2E

120

assimilation areazflow rate ratio (smaller versus larger chamber) did not result in different
treatment effects although the CER, E, and g5 rates were higher than on previous dates at
a “typical” ambient C02 level (Table 70). Small and large chamber sizes (flow rate
approximately 500 ml min") resulted in similar values when compared between the
species x PGR and nitrogen x PGR studies.

Carbon exchange rates on a turf area basis were lower at the high N rate compared to
the low N rate although treatment effects were not significant at p=0.05 (Table 70).
Carbon exchange rates 48 h after mowing were slightly greater compared to 24 h after
mowing but there were still no significant differences among treatments. An interaction
occurred on 15 Nov. 1996 between species and TE on E and g8 when gas exchange
parameters were determined on a turf area basis. Twenty-four hours after mowing, E and
gS of turf maintained at high N and treated with TB were significantly greater than
untreated, high N turf or low N turf regardless of treatment (Table 71). This interaction
was not significant on a leaf area basis and was not observed when the experiment was
repeated on 26 Nov. 1996.

On a leaf area basis nitrogen was the only treatment effect to produce any significant
effects (Table 72). TE had no effect and there were no interactions. The high nitrogen
rate increased CER, E, gs, and gm although the results were only significant for CER
(p=0.10), E, and gS on one date 24 h after mowing and were not significant 48 h after
mowing (Table 73).

Both nitrogen rate and TE significantly affected LAI and chlorophyll content of

Supina bluegrass (Table 74). There were no significant interactions on foliage or

121

 

mod :8 3.; vamm wed wmd 3d

 

dm.m wmd 2.6m §de mud mmd odd

ATE mos TAfioémmmxoctH
aim 3.0 we. _ m 2.03. wed ANN do
KM dds Nddm $.de vnd wmd vm

 

 

mi 7m we .85 2 a we .60 Ease“ L .3 : a 5. .332: 5% g cm .82 .32 8 A 7588 72 me: some?
3:823 55:—:53“ «So dd

 

 

 

 

 

dm.m 9% we.» 05%— mmd m: 3d
mm.m wad mod 3&3 mmd mo; ddd
ATE mod Rfioéagocth

tame dd.m wwd mo. _ E omd wad do
dmd dmdfi 2: 3.20.2 mmd mm; vm
5a Twas 3&1 a a NS .60 2835“ L .3 N a SM .3308 new a a. .82 .82 2 p-588 72 was some?
$6 dfim om: $.de de 3d d 3d
mud mms nmd mddofi Ed omd odd
ATE we: 350-8%xocth

D; :1. mm.\. dqmdm dmd 5d do
Ed 36 3.0 .3. SN dmd dad vm

 

 

mi _.m we .8; M: a w: .60 305% L .3 m a 8m .3255 5% a E .32 .52 2 E7558 .2 was Emofiz

a 335.23 zeta—25mm." «Eu «:5

 

 

AONI 19: ~00 38V A12: .355 A108 BEEV A_-_oE 3&3 A_-m N.E 7:55 A _.m N-E 3&3 “sogmofit
a: x _ .mDB aw .m d m Mao

 

Emma 33 oofiSm $3 .AZAmd ~33 38 m bofiemxoammv
mcoEdcoo Em: 3262 E mmfiwogn «Edam do .mLBoEEmQ ozoficxmouosa no 735-3%on: 28 coon: do 38am d5 2an

122

.32 .aom M: 8:93 a
.5208 some 82333an

bxooBB O25 SE 5% $3 38 LE: 2: influx: x83 .58 “a 8:ng 33 BE 32 2: .35 8 coming 33 5on Z F
.mofid =m so Engage Eon 5:85 738 A md 33 88 32m w.
$25650 35 83>»
MS? 60:80:38 23338 :Em ”NOD as“: BEBE .5 62583280 33:85 am ”coumbamcwb .m ”88 owcwnoxo c0258 .mmo H
.EE fifisoa o3 2: a agoumcwmm .2

.5253 E 038.

123

Table 71. Interaction of N rate and trinexapac-ethyl on transpiration (E) and stomatal
conductance (gs) of Supina bluegrass maintained in reduced light conditions of
approximately 5 mol PAR day".

 

ambient co2 = 346 i 3 uL L"

 

 

 

 

 

 

 

E gs
trinexapac-ethyl (kg ha'I ) T
N rate (kg ha'1 ) 0.00 0.19 0.00 0.19
24 0.22 0.18 7.62 6.15
96 0.13 0.27 4.92 9.57
LSD (0.05) 0.10 4.2

 

1 Applied 18 Sept. 1996.

124

 

 

 

 

 

 

RS ooo.o Koo $5.3 ooo.o ooo.o Sum
ooo.o E _.o ooo.o 2 S; ooo.o too me x z
“:2” 83 Show oooém ooo.o ooo.o Amt 3538985
sumo 52o om: ooo.ofl ooo.o ooo.o Azo Sweoz
ooo.o ago 24.2 35:2 ooo.o ooo.o Snoozoom
m5 7... we 6:3 2 a of a8 2225 L .3 : a 5. .woosoe 8% ; om .82 .32 om
hogan—.9 gag—Emma «:8 ad
59. oo.ov ommo No.3 too oo. 8 so .>u
:3 $2 Goo oo _ .23. ooo.o ooo.o Sum
33 ooo.o zoo ooo.o»? ooo.o ooo.o m: x z
ooo.o ooo.o ooo.o ooo.o ooo.o oo.o Amt assoaoxoofi
$3: 82 wow: 33%: Soo o_o.o 9o Emoaz
ooo.o 2 2 oo: ooo.oomm ooo.o Goo 8:8:on
m5 7... we as: 2 a of a8 Basso L .3 N a to. .mosse 5% o oo .32 .82 2
oo.om oo.o: oo.o... 3.2 a2 2.3 so .>o
ow: ooo.o ooo.o £35 ooo.o foo Sum
32 ooo.o oo: $2989. ooo.o oo.o E x z
ooo.o ooo.o ooo.o Smoom ooo.o ooo.o at 350-8385.
ooo.o ooo.oo .53 84.8 :mooo Kmoo 9o 38:2
$3 5.2 ooo.o *ooito ooo.o .mooo oooogaom
mi _.m we as: M: a o: .60 2285 L .3 m .+. so .waaoe 5% o om 32 5oz 2
3:82? 2523.33 «Eu MKN
ACNE LoE NOD 3.5 :35 38.5 ALE: .255 A12: .063 A m E .255 A _.m N.E 3&3 830m

M.oo x _ MS?

em

mw

d

_- N.

m

#50

 

Emma ooo.o won: A38 ~35 BE m boommeoaamv mcoEwcoo Em: 8968 E 88 somehow:
EB ifioéamxoqtu 3 wooootw mmmcmoin ocmmsm mo moumtooogfio ouofiqmmopona mo 38b... E0835 can 333?. :32 .NB 03m...

125

 

$05650 mm: 663
db? moogosccoo :EQOmoE Em ”Nov .32 3585 .6 ”8932628 33:56 am HHS 538338“ .m ”88 owcmnoxo :onooo rmmu o.
503832 .222 bosfieo _o.o 2a oo.o .ofio 2: a ofiooema ...... ..

 

mwdm 3.3 3.: mod wmdv nmdm .X. .>U

3.253 No 22¢

I26

 

wad VNA wm.m vmfimm :d 3.0 03o

 

 

 

 

 

 

 

 

 

 

 

 

om.m 92 $8 $63 Ed ovd oo.o
A72 mos Axfiooamxocth
wim $2 oo.o 3.91m 26 omd co
Aha ANA Mod 3.31m 26 ovd vm
5a m we .83 2 4 oo_ .60 305.5 2 .3 : a E. oases 5% o om .32 5oz om A7588 woo mo 53232
52.8.2.9 Eta—mafia: «:8 ad
36 wmd mod 35:: oo.o 36 Ed
mNm omd mm.m $02: A: .o mvd oo.o
ATE my: Enuoéaoxocth
3N6. o A .N Ame mg. A 3.. N A .o mvd 00
one end wmd omA.mm_ oo.o nmd vm
mg was 3:3 a a NE .60 303:3 L .3 N a to .onoe 5% o oo doe .32 2 9.588 :2 mo some?
3: 8; SN mmwdom mod mmd a Ed
who cad ohm ova.wm_ oo.o mmd oo.o
A72 9: §5068mxocth
Sic mod Ema cawdom Imod ammo om
E? 31 oo.m 2%. SN oo.o wmd VN
min 98 3:3 M: a o: .60 255:3 L 3 m 3 SA .332: 5% o om 69.: .52 2 F588 72 mo 5332
.A hon—SEQ noun—Esau «Eu MEN
AONE 108 N00 BEV A Lee BEEV A 10:. 68.5 A 7.9: .083 A To N.E 62:5 A _.m N.E 6&3 “co—Emmi.
we x 2 .mSB so mm .o m mmu

 

233 «Pa .28— .AIAon MEL AoE m 3088905va
202980 Em: 3268 E mmfiwogn ocmmsm mo “£80883 ofioficxmooosm co TAfioéomoonb Ea cowobmc mo mooobm .mA. 035.

127

382050 um: BE?
ME? ”8:90:28 $3388 2% ”NOD awo— EEBE .5 60:90:28 338on am ”88 858E355 .m ”88 098588 conao JED H
52,8032 £32 253% :3 Es .86 .26 2: a 68%? I .... g

A383 m 23

128

53838“ .282 353% So as ,mod .26 2: a 88%.me .1 .*

 

 

 

cod $6 mos 36 3d mmém o\o .>U
wood :06 526 3.0:». wmod vomd 8th
29¢ 35% mnvd mnmd mowd owed m; x Z
mood * *mmo.R * * _ mwxm 3mm A .5“ *mvoé 30 A .N Am: 350-8355;
Cod :Novdfl “1.036 ivomdo mid ibmfim AZV 5&0me
wood *moAdm “AME: 33.2 0:; mg; :oswozmom
em EU BE .5 9 :5 a 20 f5 we :5 850m
A ~-Eo wlv $238220 is (32 amour,—

 

602 .>oZ : .A 19% Mag 38 m bofifimxoaamv mafia—Eco Em: 3038 E mmfiwoin «fiasm mo 2058:5800
:Emouoio cam ”£303 use. 23¢ .AFJV x09: moan awo— co 38am “58:85 mo oogomemm 98 38:3 :32 .3 2an

129
chlorophyll content. The high nitrogen rate significantly reduced LAI although

chlorophyll content was increased (Table 75). Trinexapac-ethyl significantly increased
LAI, fresh leaf weight, and chlorophyll concentration. The ratio of chlorophyll asb was
not affected by any treatment.

Although it was not a planned component of the study, N rate was observed to affect
Microdochium patch (Microdochium nivale) (Table 76). Microdochium patch severely
damaged turf maintained at high N rates while turf at low N rates sustained significantly

less damage (Table 77).
DISCUSSION

Carbon exchange rates (approximately 1 umol C02 m'2 s", turf area basis) were
comparable to results obtained using an open system to determine CER of Kentucky
bluegrass during sod establishment in similarly reduced light conditions of 150 umol m"2
s'1 PAR (Kamok and Augustin, 1981). Kamok and Augustin (1981) reported increasing
assimilation rates on a sward area basis with increasing days after mowing which
corresponded to increased shoot height. Since fine turf is normally mowed frequently
(e.g., one or two day intervals) the photosynthetic rate within one to two days following
mowing was deemed important in the current study.

Morgan and Brown (1983) concluded the optimal LAI of bermudagrass for
photosynthesis was approximately 4.7 at 1600-2000 umol m'2 s'1 PAR while lesser LAls
resulted in significantly lower CER. The optimal LAI for cool-season turfgrasses in

reduced light conditions is unknown but the higher LAI of Supina bluegrass was

130

32 .aom M: 3%:

reggae .232 Essoa So as ,2; .26 05 a :aéeam r. u or

 

 

 

 

 

v0.“ $9.5m 100$ imodm *3: .I.m Home
Nm.m Nm.mm Ks Ewm mo 0m oo.o

A 72 mos Efioomqwxoctb

com €523 1.3.x imndm 33 1:” 00
end Exam m2. No.3 3.0 m.m vm

A 75:2: Tm: we: cowobmz

as 20 33 Eu a Eu a :5 f5 we :5 access:

a? L32 5on
A $80 was =EmoHoEU

 

.ooofi .>oZ C ,ATAg ~33 BE m £03meonva £82980 Em: 3262 E mmfiwofin «Emsm mo
2235:8200 233820 98 Jammy? awo— nmofi .AZd x09: 33 .32 so “Afioommmxocg 98 88 come“? we mgoobm .m5 2an

131

Table 76. Mean squares and treatment effects on Microdochium patch (Microdochium

nivale) effects on Supina bluegrass in reduced light conditions (approximately 5 mol
PAR day"), 18 Nov. 1996.

 

 

 

Turfgrass
Source of variation Color Density Quality
Replication 0.099 421 .229 1.307
Nitrogen rate (N) 0.391 6123.063" 62.106"
Trinexapac-ethyl
(TE) 8.266” 742.563 8.266
N x TE 0.391 60.063 2.641
Error 0.488 175.229 5.307
CV, % 9.35 18.690 45.23

 

** Significant at the 0.01 probability level.

Table 77. Effects of nitrogen rate and trinexapac-ethyl on Microdochium patch
(Microdochium nivale) damage to Supina bluegrass in reduced light conditions
(approximately 5 mol PAR day'l), 18 Nov. 1996.

 

 

 

 

 

Turfgrass
Treatment Color;r Density: Quality§
Nitrogen rate (kg ha’l month)‘
24 7.3 90.4 7.1
48 7,6 512” 3.1"
Trinexapac-ethyl (kg ha'1 )
0.00 6.8 64.0 4-4
0.19 H 8.2“ 77.6 5.8

 

** Significant at the 0.01 probability level.

1‘ Color was rated visually on a one to nine scale, one = chlorotic, yellow turf, nine: dark
green turf color with 5 a minimum rating for acceptable color.

1 Percent turf cover, visual estimate.

§ Quality was rated visually on a one to nine scale, one=100% necrotic turf, nine=dense,
uniform, ideal turf with 5 a minimum rating for acceptable turf.

11 Nitrogen was applied as urea

T'l‘ Applied 18 Sept. 1996.

132

apparently responsible for most or all of the difference in CER between the two species a
sward area basis. There were no significant gas exchange differences between species on
a leaf area basis. Supina bluegrass plants have a prostrate growth habit and stolons with
short intemodes and numerous tillers which apparently provided a greater leaf area for
photon capture and gas exchange compared to Kentucky bluegrass which exhibits an
increasingly more vertical growth habit as PPFD declines (Wilkinson and Beard, 1973).

The high N rate did not increase photosynthesis on a turf area basis because the
amount of foliage was significantly decreased. High disease incidence associated with
the high N rate may have caused a reduction in foliage although areas which appeared to
be relatively unaffected by disease were chosen for CER measurements. The direct
relationship between N rate and photosynthesis in non light-limiting situations appears to
be largely dependent on the increased leaf biomass stimulated by higher N rates which
affect carbon partitioning (Belanger et al., 1994; Gastal and Belanger, 1993; Nelson et al.,
1993; Walker and Ward, 1973). In the current study, the high N rate may have stimulated
excessive shoot growth early on after being placed in the reduced light conditions and
depleted the carbohydrate pool necessary to sustain foliar growth and development. The
high N rate may also have stimulated respiration which would have depleted the pool of
nonstructural carbohydrates and resulted in reduced tillering.

On a leaf area basis, the high N rate had a tendency to increase photosynthesis
although this was significant only on one of the three dates. This result concurs with
Walker and Ward (1973) who reported photosynthetic rates of centipedegrass

[Eremochloa ophiuroides (Munro) Hack.] were directly dependent on N rate. The higher

133

N rate may have resulted in greater enzyme, particularly Rubisco, production (Ogata et
al., 1983; Stitt and Schulze, 1994) and/or greater mesophyll conductance (gm) (Bolton and
Brown, 1980).

The lack of significant effect of TE on photosynthesis in RLC is not surprising. GA-
inhibitors (paclobutrazol, flurprimidol) which act to inhibit ent—kaurene oxidation to ent-
kaurenoic acid have been associated with both increases and decreases in photosynthetic
rates in strawberries (Archbold and Houtz, 1988). Trinexapac-ethyl, however, inhibits
the latter stages of GA biosynthesis, primarily by inhibiting hydroxylation at the 38
position of GAZOto produce a biologically active GAl (Rademacher, 1991). Several other
differences exist between trinexapac-ethyl and other GA-inhibitors commonly used on
turf which may influence their effects on plant physiology: 1) trinexapac-ethyl is foliar-
absorbed (Vitolo et al., 1990), while paclobutrazol and flurprimidol are drenched into the
ground for root uptake (Watschke et al., 1992), and 2) trinexapac—ethyl may be less
phytotoxic than paclobutrazol and flurprimidol (Watschke and DiPaola, 1995).

It is important to understand the mechanism(s) by which trinexapac-ethyl affects
turfgrass growth and physiology in order to successfully use trinexapac-ethyl to maintain
high quality turf in RLC. Green et a1. (1990) reported flurprimidol significantly reduced
the ET rate of St. Augustinegrass for 5 weeks after application. Although the ET
components were not split into the respective components of evaporation and
transpiration, it was implied the reduced leaf extension rate was responsible for lowering
the ET. Such data are important as decreased transpiration in RLC will further inhibit

photosynthate production, an undesirable effect.

134
TE did significantly enhance leaf area and chlorophyll concentrations of both species

and of Supina bluegrass across nitrogen rates but did not signficantly affect CER, even on
a sward area basis. The effects of TE on photosynthesis may have been complicated by
reduced senescence and increased LAI since increased leaf age and greater canopy
development have been reported to reduce individual leaf photosynthetic rate (Morgan
and Brown 1983).

The improved turf quality associated with TE on turf in RLC may be related only to
darker green leaf color and increased leaf area and/or tillering. Reduced leaf senescence
rate and additional tillering could have been stimulated by TE side effects on other
hormones or by TE altering carbohydrate levels and partitioning in the plants. GA-
inhibitors have been shown to affect levels of other hormones such as abscisic acid in
wheat (Buta and Spaulding, 1990) but their effects on hormones in turf is not known.
Research on PGR effects on carbohydrate partitioning in turf is scarce. The key
publication in the area, produced prior to the release of TE, indicates even GA-inhibitors
with similar modes of action (paclobutrazol and flurprimidol) vary in their effect on
assimilate partitioning (Hanson and Branham 1987). It is interesting to note that both
paclobutrazol and flurprimidol did significantly decrease photoassimilate partitioning to
roots four weeks after treatment (Hanson and Branham, 1987) although this may have
been a transient response and not resulted in long-term effects. In the long term, reduced
photoassimilate partitioning to roots could decrease turf quality and growth due to
reduced root production. Studies on root growth of turf treated with flurprimidol or TE

indicated these compounds had either no effect or had a beneficial effect on root growth

135
(Demoeden, 1984; Elam, 1993; McCarty etal., 1990). Studies on the effects of GA-

inhibitors on photosynthate partitioning and hormone levels in turfgrass in RLC are
warranted.

Chlorophyll concentration did not affect photosynthetic rates (r2 = 0.07). Differences
in chlorophyll concentration were often statistically significant at p=0.05 when analyzed
between species, between N rates, and between TE and untreated plots, but were not great
enough to result in different photosynthetic rates. The quantity of photosynthetically
active radiation, not chlorophyll, limited the CER. Species and TE did have a significant
role in turf color (Ch. 2), however, and for practical reasons species and TE must be
considered when managing turf in reduced light conditions. Chlorophyll a:b ratios were
typical of “sun” plants, approximately 3 (Nobel, 1991), and were not affected by any

treatments.

CONCLUSION

The relative shade tolerance of Supina bluegrass compared to Kentucky bluegrass
appeared to be related to a greater LAI and not to superior gas exchange properties (e. g.
CER, transpiration, stomatal resistance). The high N rate did not sufficiently enhance
Supina bluegrass photosynthetic rates to offset problems associated with the lower LAI
compared to the low N rate or the problem of the increased Microdochium patch
incidence (Microdochium nivale). Trinexapac-ethyl did not seem to affect gas exchange

parameters of photosynthesis. It is likely TE improved turf quality in RLC by

136

mechanisms other than enhanced photosynthesis, possibly by altering photosynthate

partitioning.

APPENDIX

137
Table 78. Particle size analysis of sand used in sandzpeat mixture (80:20) .

 

 

 

 

 

 

Description
Very
Gravel coarse Coarse Medium Fine Very fine Silt & clay
diameter (m)

> 2 2-1 1-0.5 0.5-0.25 0.25-0.l 0.1-0.05 < 0.05

Percent (%)
1.5 1.3 11.6 70.8 14.4 0.35 0.05
2.8 82.4 14.8

 

 

 

Table 79. Particle size analysis of sand used in Experiment 11: Nitrogen x PGR study

 

 

 

 

 

(Chapter 3).

Description
Very
Gravel coarse Coarse Medium Fine Very fine Silt & clay
diameter (m)

> 2 2-1 1-0.5 0.5-0.25 0.25-0.1 0.1-0.05 < 0.05

Percent (%)
0.9 6.7 32.0 40.0 16.2 1.6 0.5

 

7.6 72.0 18.3

 

 

 

LIST OF REFERENCES

LIST OF REFERENCES

Anonymous, 1995. The Kohlerdome. Panstadia International 2(2):70-71.

Archbold, DD, and KL. Houtz. 1988. Photosynthetic characteristics of strawberry plants
treated with paclobutrazol or flurprimidol. HortScience 23(1):200-202.

Beard, J .B. 1973. Turfgrass: Science and culture. Prentice-Hall, Englewood Cliffs, NJ.

Belanger, G., F. Gastal, and RR. Warembourg. 1994. Carbon balance of tall fescue
(F esuca arundinacea Schreb.): Effects of nitrogen fertilization and the growing
season. Annals of Bot. 74(6): 653-659.

Bemer, P. 1980. Characteristics, breeding methods, and seed production of Poa supina
Schrad. p. 409-412. In J .B. Beard (ed.) Proc. 3rd Int. Turfgrass Res. Conf.,
Munich, Germany. 11-13 July 1977. Int. Turfgrass Soc. and ASA, CSSA, and
SSSA, Madison, WI.

Bemer, P. 1984. Entwicklung der Léigerrispe (Poa supina Schrad) zum Rasengrass.
Rasen-Turf-Gazon 15(1):3-6.

Bolton, J .K., and RH. Brown. 1980. Photosynthesis of grass species differing in carbon
dioxide fixation pathways. 5. Response of Panicum maximum, Panicum milioides
and tall fescue (F estuca arundinacea). Plant Physiol. 66(1):97-100

Brueninger, J .M., T.L. Watschke, and L.D. Tukey. 1983. Effect of PP-333 and
flurprimidol (EL-500) on tall fescue in an apple orchard. Proc.
NEWSS 372372-375

Burton, G.W., J .E. Jackson, and FE. Knox. 1959. Influence of light reduction upon the
production, persistence, and chemical composition of coastal bermudagrass

(Cynodon dactylon). Agron. J. 51 :537-542.

Buta, J .G., and D.W. Spaulding. 1990. Effect of paclobutrazol on abscisic acid levels in
wheat seedlings. J. Plant Growth Regul. 10:59-61.

138

139

Cairol, D., and C. Chevallier. 1981. The use of turfgrass sod grown on pine bark for
repairing sports fields. p. 137-141. In R.W. Sheard (ed.) Proc. 4th Int. Turfgrass
Res. Conf., Guelph, ON, Canada. 19-23 July. Int. Turfgrass Soc., and Ontario
Agric. Coll., Univ. of Guelph, Guelph, ON.

Carrow, RN, and B.J. Johnson. 1990. Response of centipedegrass to plant growth
regulator and iron treatment combinations. Appl. Agric. Res. 5(1):21-26.

Coolbaugh, R.C., D.I. Swanson, and CA. West. 1982. Comparative effects of ancymidol
and its analogs on growth of peas and ent-kaurene oxidation in cell-free extracts
of immature Marah macrocarpus endosperm. Plant Physiol. 69:707-711.

Cooper, R.J., A.J. Koski, J .R. Street, and PR. Henderlong. 1985. Influence of spring
mefluidide on the carbohydrate status of Poa annua L. p. 115. In Agronomy
abstracts. ASA, Madison, WI.

Dejong, T.M., and J .F. Doyle. 1984. Leaf gas exchange and growth responses of mature
‘Fantasia’ nectarine trees to paclobutrazol. J. Amer. Soc. Hort. Sci.
109(6):878-882.

Demoeden, PH. 1984. Four-year response of a Kentucky bluegrass-red fescue turf to
plant growth retardants. Agron. J. 76:807-813.

Devitt, DA, and R.L. Morris. 1988. Growth and water consumption of common
bermudagrass as influenced by plant growth regulators, soil type and nitrogen
fertility. HortScience 23(1):30.

Diesburg, KL, and NE. Christians. 1989. Seasonal application of ethephon,
flurprimidol, mefluidide, paclobutrazol, and amidochlor as they affect Kentucky
bluegrass shoot morphogenesis. Crop Sci. 29:841-847.

Dudeck, A.E., and CH. Peacock. 1992. Shade and turfgrass culture. p. 269-284. In D.V.
Waddington, R.N. Carrow, and RC. Shearman (ed.) Turfgrass. ASA, CSSA, and
SSSA, Madison, WI.

Elam, P. 1993. Plant growth regulators and their effect on rooting in newly sodded turf.
Calif. Turfgrass Cult. 43(1-4):3-6.

Eriksen, F .1., and AS. Whitney. 1981. Effects of light intensity on growth of some
tropical forage species. 1. Interaction of light intensity and nitrogen fertilization on

six forage grasses. Agron. J. 73:427-433.

F reeborg, RP. 1983. Growth regulators. Weeds, Trees Turf 21(6):46.

140

Gastal, F ., and G. Belanger. 1993. The effects of nitrogen fertilization and the growing
season on photosynthesis of field-grown tall fescue. Annals of Bot.
72(5):401-408.

Gausman, H.W., J .E. Quisenberry, and H. Yokoyama. 1991. Introduction to effects of
plant growth regulators. p. 1-16. In H.W. Gausman (ed.) Plant biochemical
regulators. Marcel Dekker, Inc., New York, NY.

Glinski, D.S., R.N. Carrow, and K.J. Karnok. 1992. Iron fertilization effects on shoot/root
growth, water use, and drought stress of creeping bentgrass. Agron. J. 84:496-503.

Green, R.L., K.S. Kim, and J .B. Beard. 1990. Effects of flurprimidol, mefluidide, and soil
moisture on St. Augustinegrass evapotranspiration rate. HortScience
25(4):439-441.

Hanson, K.V., and BE. Branham. 1987. Effects of four growth regulators on
photosynthate partitioning in ‘Majestic’ Kentucky bluegrass. Crop Sci.
27:1257-1260.

Inskeep, WP, and PR. Bloom. 1985. Extinction coefficients of chlorophyll a and b in
MN-dimethylformamide and 80% acetone. Plant Physiol. 77:483-485.

Johnson, B.J. 1988. Influence of nitrogen on the response of ‘Tifway’ bermudagrass
(Cynodon dactylon) to flurprimidol. Weed Techno]. 2:53-58.

Johnson, B.J. 1994. Influence of plant growth regulators and mowing on two
bermudagrasses. Agron. J. 86:805-810.

Kaufmann, J .E. 1986a. The role of PGR science in chemical vegetation control. Proc.
Plant Growth Regul. Soc. Am. 13:2-14.

Kaufmann, J .E. 1986b. Growth regulators for turf. Grounds Maint. 21(5):72.

Kamok, K.J., and B.J. Augustin. 1981. Growth and carbon dioxide flux of Kentucky
bluegrass (Poa pratensis L.) during sod establishment under low light. p. 517-
526. In R.W. Sheard (ed.) Proc. 4th Int. Turfgrass Res. Conf., Guelph, ON,
Canada. 19-23 July. Int. Turfgrass Soc., and Ontario Agric. Coll., Univ. of
Guelph, Guelph, ON.

Keirle, D. 1995. A moving story. Panstadia International 2(1):54-55.

Kock, L., and A. Walch. 1977. Natfirliches vorkommen von [’00 supina auf s
sportplatzrasen in Tirol. Rasen-Turf-Gazon 2:44-46.

 

141

Leinauer, B., H. Jacob, and H. Schulz. 1991. EnfluB der dauer von trockenperioden auf
die regeneration einiger rasengrasarten. Rasen-Turf-Gazon 2:30-3 7.

Liesecke, H.J., and U. Schmidt. 1978. Scherfestigkeit und scherfesrtigkeitsmessungen an
rasentragschichten. Das Gartenamt 27(2):70-80.

McCarty, L.B., L.C. Miller, and D.L. Colvin. 1990. Tall fescue root growth rate
following mefluidide and flurprimidol application. HortScience 25(5):581.
McNitt, AS. 1994. Effects of turfgrass and soil characteristics on traction. MS.
Thesis. Pennsylvania State Univ., University Park, PA.

Moon, J .W. Jr., and J .A. Flore. 1986. A BASIC computer program for calculation of
photosynthesis, stomatal conductance, and related parameters in an open gas
exchange system. Photosynthesis Res. 7:269-279.

Moran, R., and D. Porath. 1980. Chlorophyll determination in intact tissues using N,N-
dimethylformamide. Plant Physiol 65:478-479.

Morgan, J .A., and RH. Brown. 1983. Photosynthesis and growth of bermudagrass
swards. 1. Carbon dioxide exchange characteristics of swards mowed at weekly
and monthly intervals. Crop Sci. 23:347-352.

Nelson, C.J., N. Hicks, and J .H. Coutts. 1983. Growth responses of tall fescue to
nitrogen. p. 141. In Agronomy abstracts, ASA, Madison, WI.

Nobel, PS. 1991. Physicochemical and environmental plant physiology. Academic Press,
Inc., San Diego, CA.

Nonn, H. 1994. Erkenntnisse aus der Praxis mit Saatgutrnischungen und Soden mit
Lagerrispe (Poa supina Schrad.) auf golfplatzen. Rasen-Turf-Gazon 4: 101-104.

Ogata, S., T. Kubo, K. F ujita, and K. Kouno. 1983. Studies on interaction between carbon
and nitrogen metabolism in C3 and C4 plants. 1. Effects of nitrogen nutrition on
photosynthetic rates, and ribulose-1,5-bisposphate carboxylase and phosphoenol-
pyruvate carboxylase activities. J. Jap. Soc. of Grassland Sci. 29(1):l-8.

Pietsch, R. 1989. Poa supina (Schrad.) und seine bedeutung fiir sport-und
gebrauchsrasen. Zietschrift fiir vegetationstechnik 12:21-24.

Rademacher, W. 1991. Biochemical effects of plant growth retardants. p. 169-200. In
H.W. Gausman (ed.) Plant biochemical regulators. Marcel Dekker, Inc., New

York, NY.

Rogers, J .N., 111. 1994. In from the cold. The World and 1. 9(12): 1 92-199.

 

142

Rogers, J .N., 111, and D.V. Waddington. 1990. Effects of management practices on
impact absorption and shear resistance in natural turf. p. 136-146. In R.C. Schmidt
ed al. (ed.) Natural and articficial playing fields: characteristics and safety
features. ASTM STP 1073. ASTM, Philadelphia, PA.

Rogers, J .N. 111 and D.V. Waddington. 1992. Impact absorption characteristics on turf
and soil surfaces. Agron. J. 84:203-209.

Rogers, J .N., 111, and J .C. Stier. 1993. Effect of plant growth regulators on traffic

tolerance of indoor sports turf. p. 163. In Agronomy abstracts. ASA, Madison,
WI.

Rogers, J .N., 111, J .C. Stier, J .R. Crum, T.M. Krick, and J .T. Vanini. 1996. The sports turf
management research program at Michigan State University. p. 132-144. In Earl
F. Hoemer, (ed.) Safety in American Football. ASTM STP 1305. ASTM,
Conshohockan, PA.

Sams, GE, and J .A. Flore. 1982. The influence of age, position, and environmental

variables on net photosynthetic rate of sour cherry leaves. J. Amer. Soc. Hort. Sci.
107:339-344.

Schmidt, RE, and RE. Blaser. 1967. Effect of temperature, light, and nitrogen on

growth and metabolism of ‘Cohansey’ bentgrass (Agrostis palustris Huds.). Crop
Sci. 72447-451.

Shearing, SJ, and SJ. Batch. 1982. Amenity grass retardation - some concepts
challenged. p. 467-483. In J. McLaren (ed.) Chemical manipulation of crop
growth and development. Butterworth Sci., London.

Skinner, RH, and OJ. Nelson. 1995. Elongation of the grass leaf and its relationship to
the phyllochron. Crop Sci. 3524-10.

Skogley, CR, and CD. Sawyer. 1992. Field Research. p. 589-614. In D.V. Waddington,
R.N. Carrow, and RC. Shearman (ed.) Turfgrass. Agron. Monogr. 32. ASA,
CSSA, and SSSA, Madison, WI.

Skirde, W. 1971. Beobachtungen an Poa supina Schrad. Rasen-Turf-Gazon 2:58-62.
Spokas, LA, and R]. Cooper. 1991. Plant growth regulator effects on foliar

discoloration, pigment content, and photosynthetic rate of Kentucky bluegrass.
Crop Sci. 31:1668-1674.

 

143

Stier, J .C., J .N. Rogers, 111, J .R. Crum, and PE. Rieke. 1993. An indoor sports turf
research facility for World Cup 1994. p. 164. In Agronomy abstracts. ASA,
Madison, WI.

Stier, J .C., J .N. Rogers, III, J .R. Crum, and PE. Rieke. 1994. Turfgrass response to
nitrogen, plant growth regulators, and traffic treatments in reduced light
situations. p. 185. In Agronomy abstracts, ASA, Madison, WI.

Stier, J .C., and J .N. Rogers, 111. 1995. Response of Poa supina and Poa pratensis to plant
growth retardant and iron treatments under reduced light conditions. p. 145. In
Agronomy abstracts, ASA, Madison, WI.

Stitt, M., and D. Schulze. 1994. Does Rubisco control the rate of photosynthesis and

plant growth? An exercise in molecular ecophysiology. Plant Cell Environ.
17:465-487.

Thimijan, R.W., and RD. Heins. 1983. Photometric, radiometric, and quantum light units

of measure: a review of procedures for interconversion.
HortScience 18(6):818-822.

Tracinski, B. 1993. The turfcon team. SportsTURF 9(12)214-15,19.

Vargas, J .M., and J .B. Beard. 1981. Shade environment-disease relationships of Kentucky
bluegrass cultivars. p. 391-395. In R.W. Sheard (ed.) Proc. 4th Int. Turfgrass Res.
Conf., Guelph, ON, Canada. 19-23 July. Int. Turfgrass Soc., and Ontario Agric.
Coll. Univ. of Guelph, Guelph, ON.

Vitolo, D.B., E. Kerber, C. Somody, L. Stahlberd, J. Hensley, and J. Kollenkark. 1990.
CGA-l63935--A new plant growth regulator for use in northern turf. Proc.
Northeast. Weed Sci. Soc. 44:116.

Walker, RH, and CY. Ward. 1973. Influence of N and K nutrition on net
photosynthesis, dark respiration, and carbohydrates in centipedegrass. p. 196-208.
In E.C. Roberts (ed.) Proc. 2nd Int. Turfgrass Res. Conf., Blacksburg, VA. 19-21
June 1973. ASA and CSSA, Madison, WI.

Wang, S.Y., J .K. Byun, and G.L. Steffens. 1985. Controlling plant growth via the
gibberellin biosynthesis system- 11. Biochemical and physiological alterations in
apple seedlings. Physiol. Plant 63:169-175.

Watschke, T.L. 1976.Growth regulation of Kentucky bluegrass with several growth
retardants. Agron. J. 68:787-792.

Watschke, TL. 1981. Effects of four growth retardants on two Kentucky bluegrasses.
Proc. Northeast Weed Sci. Soc. 352322-330.

 

144

Wilkenson, RE. 1982. Mefluidide inhibition of sorghum growth and biggerellin
precursor biosynthesis. J. Plant Growth Regul. 1:85-94.

Wilkinson, J .F., and J .B. Beard. 1973. Morphological responses of Poa pratensis and
F estuca rubra to reduced light intensity. In E.C. Roberts (ed.) Proc. 2nd Int.
Turfgrass Res. Conf., Blacksburg, VA. 19-21 June 1973. ASA and CSSA,
Madison, WI.

Wilkinson, J .F., and J .B. Beard. 1975. Anatomical responses of ‘Merion’ Kentucky

bluegrass and ‘Pennlawn’ red fescue at reduced light intensities. Crop Sci.
15:189-194.

Wu, L., D. Huff, and W. B. Davis. 1985. Tall fescue turf performance under a tree shade.
HortScience 20(2)2281-282.

Yust, A.K., D.J. Wehner, and T.W. Fermanian. 1984. Foliar application of N and Fe to
Kentucky bluegrass. Agron. J. 76:934-938.

 

HICHanN STATE UNIV. LIBRARIES
1|111111111111111““1111NIH“ll11111111111111“
31293014271732