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PHYSIOLOGIC AND METABOLIC EFFECTS OF
SUPPLEMENTAL FRUCTOSE APPLIED TO VARIOUS
TURFGRASSES UNDER SHADE

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Tara E. Valentino

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2/05 p:/ClRC/DateDua.indd-p.1

PHYSIOLOGIC AND METABOLIC EFFECTS OF SUPPLEMENTAL FRUCTOSE
APPLIED TO VARIOUS TURFGRASSES UNDER SHADE

By

Tara E. Valentino

A THESIS
Submitted to
Michigan State University
in partial fulﬁllment of the requirements
for the degree of
MASTER OF SCIENCE

Department of Horticulture

2006

ABSTRACT

PHYSIOLOGIC AND METABOLIC EFFECTS OF SUPPLEMENTAL FRUCTOSE
APPLIED TO VARIOUS TURFGRASSES UNDER SHADE

By
Tara E. Valentino

Shaded conditions pose difﬁculties in establishing and maintaining high quality,
persistent and hardwearing turfs. Exogenous fructose applications and supplemental light
were examined as potential methods to counteract the negative effects of shade on turf.
The effect of supplemental and ambient light levels in combination with exogenous
fructose applications on chewings fescue (Festuca rubra v. commutata) ‘SRS 100’,
creeping red fescue (F estuca rubra v. rubra) ‘Dawson’, and Kentucky bluegrass (Poa
pratensis) ‘Cynthia’ was examined in a simulated dome, controlled growth chamber, and
greenhouse environment. Exogenous fructose applications had a signiﬁcant positive
impact on particular growth and metabolism variables of each of the three species.
Species under ambient light had reduced growth compared to supplemental light; fructose
and available light were not sufﬁcient for these species to maintain growth under extreme
shaded conditions. Light response curves suggest that exogenous fructose applications
under ambient light could not supplement carbohydrates needed for growth; thus
carbohydrate reserves were utilized to maintain respiration. Collectively, the
supplemental low light produced better quality plants than any other treatment, and was
sufﬁcient to maintain overall photosynthesis to support turfgrass growth over a limited

time interval.

ACKNOWLEDGEMENTS

I would like to thank N. Suzanne Lang for the opportunity and support throughout
my time as a Masters student at Michigan State University. I greatly appreciate your
assistance and friendship during my two years. In addition I would like to thank Dr. Bert
Cregg, Dr. Jim Flore, and Dr. John Rogers III for their guidance and patience as I worked
through my master’s project. I would also like to thank the Michigan Turfgrass
Foundation and Michigan Agriculture Experiment Station for funding and support of my
Masters research. In addition, I would also like to thank Andrea Mainguy, Tammy
Wilkinson, and Brian Tomaka for their help and friendship throughout my Masters
process. To Andrea, thank you for all your help throughout the two years. Your time and
patience was greatly appreciated and I appreciate your help immensely. To Tammy,
thank you for your help with my thesis and your advice. To all the people at the Hancock
Center, especially Frank Roggenbuck and Mark Collins, thank you for all your help and
advice throughout my time as a Masters student. To my parents and family, thank you
for your support, guidance, and encouragement. It was wonderful and reassuring
throughout the past years as a student at Michigan State University. Finally, to my
husband, Nicholas: thank you for your unwavering support, guidance, and patience (and
for Pita! l). I love you and I dedicate my thesis to you, for without you it could have not

been completed.

iii

TABLE OF CONTENTS

List of Tables ...................................................................... vi

List of Figures ..................................................................... ix

Chapter 1: Literature Review ..................................................... 1
Turfgrass Introduction ................................................... 1
Environmental Demands on Turfgrasses .............................. 2
Carbohydrates: F ructans ................................................. 8
Light Response Curves: Indication of Photosynthetic Efﬁciency. 10
Turfgrass Biology ......................................................... 13
Past Research .............................................................. 15
Objectives of Study ........................................................ 17
References .................................................................. 19

Chapter 2: Supplemental Fructose Applied to Chewings fescue ‘SRSlOO’, Creeping Red
F escue ‘Dawson’, and Kentucky bluegrass ‘Dawson’ Under Shaded

Conditions ........................................................................... 23
Abstract ..................................................................... 23
Introduction ................................................................ 24
Materials and Methods ................................................... 25
Statistical Analysis ........................................................ 30
Results ..................................................................... 30
Discussion .................................................................. 37
Conclusion ................................................................. 39
References .................................................................. 6 1

Chapter 3: Metabolic Effects of Supplemental Fructose Applied to Chewings fescue
‘SRSlOO’, Creeping Red Fescue ‘Dawson’, and Kentucky bluegrass ‘Dawson’ Under

Shaded Conditions in Growth Chambers ........................................ 63
Abstract ...................................................................... 63
Introduction .................................................................. 64
Materials and Methods ..................................................... 65
Statistical Analysis .......................................................... 69
Results ........................................................................ 70
Discussion .................................................................... 74
Conclusion ................................................................... 77
References .................................................................... 91

iv

Chapter 4: Quantifying Daily Light Integral and Metabolic Effects of Supplemental
Fructose on Chewings fescue ‘SR5100’, Creeping Red Fescue ‘Dawson’, and Kentucky

bluegrass ‘Dawson’ ................................................................. 93
Abstract ..................................................................... 93
Introduction ................................................................ 94
Materials and Methods ................................................... 95
StatisticalAnalysis..................... ................................... 100
Results ............................................................... - ....... 1 01
Discussion .................................................................. 107
Conclusion .................................................................. 109
References .................................................................. 123

Thesis Conclusion ................................................................... 124

Appendix I: Dome Experiment Signiﬁcant Tables .............................. 125

Appendix 11: Growth Chamber Experiment Signiﬁcant Tables ............... 128

Appendix III: Greenhouse Experiment Signiﬁcant Tables .................... 129

Appendix IV: Commercial Products and Suppliers ............................ 132

LIST OF TABLES

Table 2.1 Dome experiment A) analysis of variance, B) mean speciﬁc for clipping weight
at week ﬁfteen, and C) mean speciﬁc clipping weight by species.

Table 2.2 KB dome experiment A) analysis ‘of variance, B) mean speciﬁc for clipping
weight at week four, and C) mean speciﬁc clipping weight over time.

Table 2.3 Dome experiment A) analysis of variance and B) mean speciﬁc for density
over time.

Table 2.4 KB dome experiment A) analysis of variance and B) mean speciﬁc for density
over time.

Table 2.5 Dome experiment A) analysis of variance, B) mean speciﬁc water band index
at week ﬁfteen, and C) mean speciﬁc water band index over time.

Table 2.6 Dome experiment A) analysis of variance, B) mean speciﬁc photosynthetic
reﬂective index at week ﬁfteen, and C) mean speciﬁc photosynthetic reﬂective index
over time.

Table 2.7 Dome experiment A) analysis of variance, B) mean speciﬁc narrow band
vegetative index 695 at week ﬁfteen, and C) means speciﬁc narrow band vegetative index
695 over time.

Table 2.8 Dome experiment A) analysis of variance. B) mean speciﬁc narrow band
vegetative index 700 at week ﬁfteen, and C) mean speciﬁc narrow band vegetative index
700 over time.

Table 2.9 Dome experiment A) analysis of variance, B) mean speciﬁc red-edge
vegetative index at week ﬁfteen, and C) mean speciﬁc red-edge vegetative index over
time.

Table 2.10 KB dome experiment A) analysis of variance, B) mean speciﬁc for water band
index at week three, and C) mean speciﬁc water band index over time.

Table 2.11 KB dome experiment A) analysis of variance, B) mean speciﬁc for
photosynthetic reﬂective index at week three, and C) mean speciﬁc photosynthetic
reﬂective index over time.

Table 2.12 KB dome experiment A) analysis of variance. B) mean speciﬁc for narrow

band vegetative index 695 at week three, and C) mean speciﬁc narrow band vegetative
index over time.

vi

Table 2.13 KB dome experiment A) analysis of variance. B) mean speciﬁc for narrow
band vegetative index 700 at week three, and C) mean speciﬁc narrow band vegetative
index over time.

Table 2.14 KB dome experiment A) analysis of variance , B) mean speciﬁc for red-edge
vegetative index at week three, and C) mean speciﬁc red-edge vegetative index over
time.

Table 3.1 Growth chamber A) analysis of variance, B) mean speciﬁc for clipping weight
at week seven , and C) mean speciﬁc clipping weight over time and by species.

Table 3.2 Growth chamber A) analysis of variance, B) mean speciﬁc for density at week
seven, and C) mean speciﬁc density over time and by species.

Table 3.3 Growth chamber A) analysis of variance, B) mean speciﬁc for leaf area at week
seven, and C) mean speciﬁc leaf area over time and by species.

Table 3.4 Growth chamber A) analysis of variance, B) mean speciﬁc for maximum
assimilation at week seven, and C) mean speciﬁc maximum assimilation over time.

Table 3.5 Growth chamber A) analysis of variance, B) mean speciﬁc for quantum
efﬁciency at week seven, and C) mean speciﬁc quantum efﬁciency over time.

Table 3.6 Growth chamber A) analysis of variance, B) mean speciﬁc for light
compensation point at week seven, and C) mean speciﬁc light compensation point over
time.

Table 3.7 Growth chamber A) analysis of variance, B) mean speciﬁc for dark respiration
at week seven, and C) mean speciﬁc dark respiration rate over time and by species.

Table 4.1 Greenhouse A) analysis of variance, B) mean speciﬁc for clipping weight at
week seven, and C) mean speciﬁc clipping weight over time.

Table 4.2 Greenhouse A) analysis of variance, B) mean speciﬁc for density at week
seven, and C) mean speciﬁc density over time and by species.

Table 4.3 Greenhouse A) analysis of variance, B) mean speciﬁc for leaf area at week
seven, and C) mean speciﬁc leaf area over time and by species.

Table 4.4 Greenhouse A) analysis of variance, B) mean speciﬁc for maximum
assimilation at week seven, and C) mean speciﬁc maximum assimilation over time and

by species.

Table 4.5 Greenhouse A) analysis of variance, B) mean speciﬁc for light compensation
point at week seven, and C) mean speciﬁc light compensation point over time.

vii

Table 4.6 Greenhouse A) analysis of variance, B) mean speciﬁc for quantum efﬁciency at
week seven, and C) mean speciﬁc quantum efﬁciency over time and by species.

Table 4.7 Greenhouse A) analysis of variance, B) mean speciﬁc for dark respiration at
week seven, and C) mean speciﬁc dark respiration rate over time and by species.

Table I-I Dome experiment mean speciﬁc clipping weight at week ﬁfteen.

Table I-II Dome experiment mean speciﬁc clipping weight for week by fructose
interaction.

Table I-III Dome experiment mean speciﬁc density at week ﬁfteen.
Tale I-IV Dome experiment mean speciﬁc density for week by fructose interaction.
Table I-V KB experiment mean speciﬁc density at week four.

Table I-VI Dome experiment mean speciﬁc narrow band vegetative index 695 for
fructose and species interaction.

Table I-VII Dome experiment mean speciﬁc red-edge vegetative index for fructose,
week, and species interaction.

Table 11-1 Growth chamber experiment mean speciﬁc maximum assimilation for week
and ﬁ'uctose interaction.

Table II-II Growth chamber experiment mean speciﬁc maximum assimilation for week
by species interaction.

Table III-I Greenhouse experiment mean speciﬁc clipping weight for fructose and species
interaction.

Table III-II Greenhouse experiment mean speciﬁc clipping weight for fructose, species,
and week interaction.

Table III-III Greenhouse experiment mean speciﬁc density for week and species
interaction.

Table III-IV Greenhouse experiment mean speciﬁc maximum assimilation for week,
ﬁ'uctose, and species interaction.

Table III-V Greenhouse experiment mean speciﬁc quantum efﬁciency for week, fructose,
and species interaction.

viii

LIST OF FIGURES
Figure 1.1 Light response curve: example of indices measured.

Figure 2.1 Dome experiment daily light integrals (DLI mol rn’2 d'l): a) year I and b) year
11 under ambient, supplemental low light, and supplemental high light.

Figure 2.2 KB dome experiment DLI under ambient and supplemental low light.
Figure 2.3 Dome experiment CF and CRF clipping weight over time.

Figure 2.4 Dome experiment KB clipping weight over time.

Figure 2.5 Dome experiment CF and CRF density over time.

Figure 2.6 Dome experiment KB density over time.

Figure 3.1 Growth chamber DLI under ambient and supplemental low light.
Figure 3.2 Growth chamber clipping weight over time.

Figure 3.3 Growth chamber density over time.

Figure 3.4 Growth chamber leaf area over time.

Figure 3.5 Growth chamber light response curves under ambient light.

Figure 3.6 Growth chamber light response curves under supplemental low light.
Figure 4.1 Greenhouse clipping weight over time.

Figure 4.2 Greenhouse density over time.

Figure 4.3 Greenhouse leaf area over time.

Figure 4.4 Greenhouse 10 mol m'2 (1'1 light response curves.

Figure 4.5 Greenhouse 8 mol rn'2 (1'1 light response curves.

Figure 4.6 Greenhouse 4 mol rn'2 (1’1 light response curves.

ix

Chapter 1
Literature Review
Turfgrass Introduction

Turfgrasses when regularly mowed form a dense growth of leaf blades and roots
that are used for a variety of purposes. Multiple uses for turfgrasses range from home
lawns, sports/athletic ﬁelds, and utility (soil stabilization) (Turgeon, 2002). Turfgrasses
have been selected and bred for diverse environmental conditions. The underlying
criteria for the selection of turfgrasses have been based on their quality and performance
in the environmental and management system in which they are grown.

Domestication of livestock for agriculture was the ﬁrst step in the domestication
of turfgrasses (Casler and Duncan, 2002). Over time natural selection and breeding have
improved turfgrass varieties (Long, 1972). The goal of breeding was to develop varieties
that would perform best under certain turf situations. Turfgrasses were introduced to the
United States from other continents that were adapted for seeding ranges and pastures
(Hanson, 1972).

Turfgrasses are chosen based on their quality, ﬁrnctional utility, appearance, and
playability (Turgeon, 2002). The characteristics of turfgrass quality include: visual
quality, plant density, leaf texture, uniformity of the stand, color and smoothness, and
overall quality. All of these characteristics may be maintained by selecting a well-
adapted turfgrass that is compatible to the environment. Modifying the environment
through cultural practices for example, mowing and fertilization, to promote survival and
desired growth of the plants can alter turfgrass performance. Unfortunately the selected

turfgrass does not always match the demands and/or management system in which it is

grown. As the demand for turfgrasses under less than ideal conditions or cultural
practices increases, the margin of error to maintain acceptable turfgrass quality decreases
(Turgeon, 2002). Due to this continued demand for the highest quality turfgrass new and
innovative methods of improving turfgrasses performance have been investigated.
Environmental Demands on Turfgrasses

Light is essential for growth of turfgrasses, because it is the energy source for all
plant life. Solar radiation that supports plant growth is within the spectral wavelengths
from 400-700 nm known as photosynthetically active radiation (PAR) (Bell et al., 2000;
Lambers et al., 1998; Johnson, 1993). Photosynthesis utilizes PAR to manufacture
chemical energy using wavelengths from 400-500 nm, (blue light) and from 600-700 nm,
(red light) being the most photosynthetically active (Beard, 1973; Bell et al., 2000).

Light can be measured in different units: footcandle, lux, Langleys, microeinstein,
and micromole per second per square meter (Thimijan and Heins, 1983). Photosynthetic
active radiation micromoles per second per square meter (umol m'2 s") is the most
accurate unit when evaluating light energy. This unit of measure is based on the number
of photons within the wavelengths utilized to drive photosynthesis based on a deﬁned
unit of time and a deﬁned unit of area. The total quantity of light available over the
course of the day is deﬁned as the daily light integral (DLI mol rn'2 d'l). It is useful to
consider the total PAR that is available over an entire photoperiod due to the natural
variation that occurs in light energy due to weather events, season, and/or physical
obstruction. DLI can be directly correlated to plant growth and crop yield. Bunnel et al.
(2005a) used DLI to quantify the total amount of light needed to maintain Tiﬂiagle

berrnudagrass under golf green conditions. They found that as DLI declines there is a

negative decline to growth, quality, and metabolic responses in TifEagle. In addition,
they also found that as DLI decreases so does the growth responses of Tifway, TifSport,
and Celebration bermudagrass as well as Meyer zoysiagrass (Bunnell et al., 2005b).

DLI is an important measure of light intensity (photo ﬂux density) because of its
direct relationship with the rate of photosynthesis and ultimately carbohydrate
accumulation. Turfgrass genera and species vary in their ability to survive or even
maintain acceptable quality under different environmental stresses, including very low
light. Even species that can withstand “low light” conditions can become stressed when
they are grown under extremely low light, because a plant cannot survive when light
intensity is below a threshold level needed to meet its respiratory requirements. The light
intensity at which photosynthesis and respiration are at equilibrium is deﬁned as the light
compensation point (LCP). Plants maintained at PAR below their LCP can support the
metabolic processes until carbohydrate reserves are exhausted; after which they die. The
LCP for most cool-season turfgrasses is 2-3 % of ﬁlll sunlight (2000 umol m'2 s") (Fry
and Huang, 2004). Conversely, the maximum photosynthetic rate (Amax) of individual
turfgrass leaves occurs at light intensities about 30% of full sunlight (Beard, 1973). The
LCP and Amax vary dependent on species as well as the environment in which they are
acclimated. Thus, both the species and environment to achieve high quality turfgrasses
must be considered.

Shade is a major problem in turfgrass management because it associated with
decreasing light absorption, quality and intensity. There are many reasons shade occurs
on managed turfgrass sites such as buildings, trees, or shrubs. Shade caused by buildings

result in an equal loss of intensity of all wavelengths, and shade caused by vegetation

results in a loss of only certain wavelengths. Beard (1973) estimated that at least 20 to
25% of the existing turfgrasses are maintained under some degree of shade. As shade
increases, the light quality is altered and light intensity is decreased. Shade shifts light
quality so that more blue and less red reaches the turf canopy; and red light is necessary
for good plant health (Gaskin, 1964).

Phytochromes are the pigments that monitor various features of the light
environment. They perceive the presence, the spectral composition, the direction, and the
duration of light (Lambers et al., 1998). Phytochrome A absorbs far-red light, and
phytochrome B absorbs red light (Lambers et al., 1998; Bell et al., 2000). In shaded
conditions far-red light is available in greater proportions than other wavelengths under a
canopy because PAR (400 to 700 nm) is less and far-red (730 nm) is more substantial
(Lambers et al., 1998). This increase in the proportion of far-red light results in a
reduction of carbohydrates for plant growth, because far-red light is less effective in
photosynthesis compared to other wavelengths (Dunn et al., 1999). F ar-red light also
causes greater growth in the direction towards the light; resulting in a morphological trait
of shade plants, stem elongation (Lambers et al., 1998; Bell et al., 2000).

Density of shade and the source of the shade are factors determining the
magnitude of the change in both light quality and light intensity. For example, light
transmittance through tree canopies can be less than 10% of full sunlight, resulting in a
lower ration of red to far-red light (Lambers et al., 1998). For turfgrasses under
vegetative shade, the amount of blue light decreased 1% while far-red light increased 2%

compared to building shade (Bell et al., 2000). These results suggest that photosynthetic

performance was affected by both shade density and shade source when vegetative shade
and building shade.

The impact of turfgrasses growing under shade results in decreased plant vigor,
increased susceptibility to disease, reduced Wear tolerance, and reduced turfgrass canopy
density (McBee and Holt, 1966; Dudeck and Peacock, 1992). Many of these decreases in
quality and performance are directly related to reduced photosynthesis that results in a
decrease in available carbohydrates and stored total nonstructural carbohydrates (TNC)
(Koh et al., 2003). As percent shade increased the levels of TNC decreased, which in
turn resulted in low quality ratings, because low carbohydrate reserves also limit the
growth of roots, shoots, rhizomes, and stolons (Burmel, 2003). In addition, on ‘Coastal’
Bermudagrass roots and rhizomes decreased as shade increased (Burton et al., 1959).
Carbohydrates are limited both by reduced biosynthesis via photosynthesis and because
reserves are used at night during respiration (Beard, 1973; Burton et al., 1959; Johnson,
1993). When carbohydrate reserves are depleted because PAR is below the turfgrass
LCP, plant quality declines. Interestingly, turfgrasses that are physiologically adapted to
low light conditions have higher chlorophyll content per unit area to maximize the
capability for light absorption compared to turfgrasses grown in full sunlight which may
maximize the capability for light absorption and lower respiration rates which in turn
lowers LCP, allowing the turfgrass to maintain positive rates of photosynthesis at lower
light levels (Beard, 1973). This lower concentration in carbohydrate reserves due to
lower photosynthesis rates triggers a cascade of changes in plant metabolism that include:
lower carbohydrate-to-nitrogen ratio due to less nitrogen ﬁxation; reduced transpiration

rate due to reduced stomatal conductance; and higher tissue moisture content (Beard,

1973). Although plants possess similar responses, the responses can differ among plant
or species. For example, LCP of ‘Chardonnay’ grapevine plants grown under three
different levels of shade decreased as shade increased. Shaded leaves approached LCP
more quickly and had reduced dark respiration rates compared to sun leaves, indicating
that shaded leaves used available light more efﬁciently (Vanden Hueval et al., 2004).
Kentucky bluegrass ‘Merion’ and red fescue ‘Pennlawn’ were also grown under three
different levels of shade as both species LCP decreased as shade level increased
(Wilkinson et al., 1974). Collectively, these results suggest that plants respond
differently physiologically when under shade and the ability of a plant to adjust to its
photosynthetic system is desired when choosing a plant for shaded sites.
Morphologically turfgrasses grown in shade are taller with thinner stems, lower
dry weights, and decreased plant density than turfgrasses grown in full sun-light (Dudeck
and Peacock, 1992; McBee and Holt, 1966). Anatomically grasses grown in shade
display decreased cuticle thickness and stomatal density (Dudeck and Peacock, 1992)
which results in more succulent leaves that are more susceptible to injury. The observed
increase in disease infection for turfgrasses grown under low light intensities may be
caused by germination of fungal spores in high humidity that is prevalent under shaded
environments. The impact of disease tends to be the highest cause of death of turfgrasses
under shade. This is because under shade there is a longer dew period, low
evapotranspiration (ET) rate, and more succulent plant tissue all of which favor disease
establishment and growth (Beard, 1973). Beard (1965) observed that the prominence of

disease, enhanced by shade, reduced overall turfgrass performance.

Turfgrass species or cultivar selection, establishment, and maintenance of shade
tolerant grasses are critical for producing high quality turfgrass (Tanskerly, 1999). Using
the correct grass for a speciﬁc site will enhance the odds of better quality turf. In
addition, there are many other key principles (mowing, trafﬁc management, and nutrient
and/or water applications) that must be considered when managing turfgrasses under
shade. The management of the shaded site is as important as the adaptation capabilities
of a speciﬁc turfgrass species. Raising the cutting height (5- 10 cm) allows more leaf
area for absorption of light and productions of carbohydrates (Beard, 1973). Controlling
trafﬁc in a shaded site is important due to tissue weakness and sparse grth of turf
under shade (Dunn et al., 1999; Tankersley, 1999). Also avoiding excess nitrogen
fertilization is key since turfgrass growth rate is lower in shaded sites (Michigan State
University (MSU) Extension Bulletin; GT1062, 1998). Burton et a1. (1959) suggests that
with heavy shade, high nitrogen fertilization decreased plant density and leaf area,
contributing to a carbohydrate deﬁciency. Turfgrasses in shade posses’ lower
evapotranspiration rates so irrigate deeply and infrequently to control potential wet
conditions (Danneberger, 2003). Irrigation techniques are important because large
amounts of water on a shaded site may cause disease or other problems.

The management of trees and/or shrubs shading the site by pruning decreases
shade canopy density to allow more sunlight to ﬁlter through for increased light reaching
the turf (Beard, 1973; Tankserly, 1999). Pruning is the number one recommendation for
reducing the negative impact of shade on turfgrass because of the increase in light
penetration through the canopy, but also because it increases wind movement which

assists the reduction of standing water on the turfgrass and high heat pockets due to

stagnant air movement (Beard, 1973; Danneberger, 2003; Dunn et al., 1999; Tankserly,
1999). All of these management practices are important because managing all parts of
the turfgrass microenvironment is crucial to maintain better quality turf.
Carbohydrates: Fructans

When considering overall plant health and quality, carbohydrates are essential to
turf growth and development. Carbohydrates are a source for re-growth and recovery, as
well as survival when utilization exceeds supply and demand (Smith, 1972).
Carbohydrates accumulated in excess of the level required for assimilation are called
carbohydrate reserves (Beard, 1973). Fructans and oligosaccharides are the primary
constituents of carbohydrate reserves in cool-season turfgrasses and contribute up to 45%
of dry weight (Groteluxhen and Smith, 1968). Fructans also regulate: sucrose pool size
in photosynthetic tissue, sucrose metabolism during phloem unloading, osmoregulation
of cellular water potential, adaptation to low-temperature photosynthesis, and lowering of
the freezing point of tissue water upon depolymerization to fructose (Nelson and
Gorharn, 1987; Pollock, 1986; Beard, 1973).

Fructans are made up of short-chain and long-chain fructosans. Long-chain
fructose molecules are predominantly found in the lower sheath, lower intemodes, and
roots of cool-season turfgrass species, and act as the storage units for the carbohydrates
(Smith, 1967 and 1972). Altemately, short-chain fructose molecules can be found in leaf
blades and stem bases (Smith, 1967 and 1972), and are utilized for growth and
maintenance of plant tissues.

The availability of these reserves and the concentration that are allocated to

individual plant parts vary depending on tissue age, season of the year, environmental

factors that control supply and demand, and turfgrass management. Accumulation of
carbohydrates is greatest during periods of minimal shoot growth and high light intensity
as well as during late fall hardening prior to winter dormancy (Beard, 1973). The
exhaustion of the reserves can occur when the plant is actively growing. Accumulation is
favored by conditions like long photoperiods, infrequent cutting or grazing, low
temperatures, and low amounts of fertilizer, and will be minimized with the opposite
environmental and management conditions (Pollock, 1986).

When light intensities are below the optimum for efﬁcient growth, carbohydrate
reserves are utilized for respiration (Beard, 1973; Lambers et al., 1998). At medium light
intensity, the rate of carbohydrate production can be less than 50% of that at high
intensity, and that at low intensity there was almost no carbohydrate formation (Alberda,
195 7). This supports the assumption that at higher light intensities, more photosynthesis
takes place, which in turn creates more carbohydrates. When plants under experimental
conditions are subjected to no light, there is a dramatic decline in available carbohydrates
(Burris et al., 1967). Tomato plants placed in darkness stopped growing after 30-40
hours due to depletion of their carbohydrate reserves (J uhren and Went, 1949). However,
when squash plants were grown in light then transferred to a darkroom, the plants were
greatly affected by the amount and intensity of light that they had beforehand (Juhren and
Went, 1949). This suggests that prior light intensity determines a plant’s future due to
the amount of allocated reserves that are then available to support metabolism under

reduced light conditions.

Light Response Curves: Indication of Photosynthetic Efficiency

Although research is abundant on the interaction of shade and turfgrasses growth
responses, the impact on turfgrass metabolism is not as well understood. Measuring
photosynthesis of plants under shade provides an indication of the efﬁciency of the
photosynthetic system (Peck and Russek-Cohen, 2002). In addition to light response
curves (LRC), leaf reﬂectance measurements from a plant canopy detect plant stress
(Carter and Miller, 1994). These indices provide information on the metabolic properties
of a plant under shaded conditions.

Light response curves are used to measure a plant’s photosynthetic responses to
light by measuring carbon dioxide (C02) ﬁxation in intact leaves at increasing light units
(umol rn'2 s"). The LRC provides information on the photosynthetic properties of the
plant to the changing light levels. The properties described by this series of
measurements are the light compensation point (LCP), assimilation (A), apparent
quantum efﬁciency ((p), dark respiration (Rd), and maximum assimilation or
photosynthetic rate (Amax) (Figure 1.1). The response curves are calculated and ﬁtted
by the equation using Photosyn Assist Version 1.1 2004 (Dundee Scientiﬁc, Scotland,

UK):

 

A = (.90 + Amax - \/((pO + Amax)2 -4g_pOkAmax - Rd
2k

The (p is the linear portion of the curve and reveals the relationship between given light-
dependent product and the number of absorbed photons known as quantum yield. These
yields can vary from 0, where none of energy is used in photosynthesis, to 1, where all

absorbed light is used (Taiz and Zeiger, 2002). The Rd is the measurement of C02 given

10

off by the plant due to respiration. As PAR continues to increase the photosynthetic
response rate levels off and when the system becomes saturated Amax measures the
photosynthetic response at the point where A no longer increases at a speciﬁc light level.
At this point electron transport rate, rubisco activity, or the metabolism of triose
phosphates, have become limiting to photosynthesis (Taiz and Zeiger, 2002).

Photosynthesis and LCP will vary depending on the light environment and plant
species. For example, LCP of sun-grown light energy level plants ranges from 10-20
umol In2 5'1 and shade grown light energy level plants the LCP ranges from 1-5 umol rn'2
s'I (Taiz and Zeiger, 2002). When photosynthetic rates of six different turfgrasses were
compared, turfgrass genera varied (p-value < 0.05) in net photosynthetic rate. The
differences were related to the individual features of growth habit: leaf elongation and
surface cover, and carotenoid and chlorophyll content of the different genera (Van
Huylenbroek and Van Bockstaele, 2001). Speciﬁcally, Amax was signiﬁcantly higher
for zoysiagrass compared to bentgrass, resulting in higher dry matter production in
zoysiagrass (Agata et al., 1989). Thus, it is very important to consider the efﬁciency of
genera and/or species photosynthetic apparatus when considering whether a turfgrass is
suited for establishment for shaded sites.

There are three fates for light that is intercepted by a leaf: absorption, transrnition,
and/or reﬂection. Based on the fact that a fraction of the intercepted light is reﬂected,
speciﬁc differences in reﬂected light quality between turfgrasses grown under
environmental conditions which support normal metabolic conditions and turfgrasses
grown under conditions in which induce stress metabolism can be used as an indication

of metabolic efﬁciency or stress. Leaf reﬂectance measurements have been used to

11

measure wavelengths that correlate to plant stress (Carter and Miller, 1994). The
following indices are used to provide information about various aspects of plant stress:
water band index (WBI), narrow band index (NDVI), red-edge stress vegetation index
(RVSI), and photosynthetic reﬂectance index (PR1). The WBI (WBI= R900/R970)
values have been correlated with leaf water content, thus the values measure water-
induced stress. The NDVI (NDV11695= (R970-R695)/(R760+R695) and NDVIl700=
(R840-R700)/(R840+R700)) measures the difference in reﬂected near infrared and red
bands, and divided their sums, which have been positively related to plant health. The
RVSI (RVSI= (R714+R759)/ 2-R733) value measures stress, which as the values become
more negative this indicates reduced stress. The PR1 (PRI= (R531-R570)/ (R531+R570))
values indicate photosynthetic radiation efﬁciency, which become increasingly negative
with reduced radiation efﬁciency. Carter (1993) ﬁrst deﬁned the wavelengths at which
leaf reﬂectance was most responsive to stress using plant competition in pines, disease on
euonymus, fungi infection on pine, and oak senescence. The results suggested that
changes in the wavelengths within the green and red areas of the spectrum increased in
response to stress, and were most consistent over each stress regardless of plant genera
(Carter, 1993). The usefulness of these indices in detecting and quantifying plant stress
has been illustrated on a variety of plant systems. On soybeans, differences in leaf
reﬂectance were measured in narrow stress-sensitive wavebands after herbicides were
applied, showing that these measurements increased with herbicide damaged canopies
(Carter and Miller, 1994). In addition, Lang et a1. (2000) used leaf reﬂectance
measurements to measure plant stress in relation to black leaf in grapes, and Penuelas et

a1. (1997) used the indices to measure plant stress in relation to water concentration.

12

Collectively, these studies suggest that leaf reﬂectance is a non-destructive tool in
monitoring plant stress. Thus, combining LRC and leaf reﬂectance to explain the
metabolic impact of shade on turfgrass growth and overall plant quality may provide
important insights.
Turfgrass Biology

Selecting speciﬁc turfgrass species is important when growing turfgrass under
shade. Turfgrasses have been speciﬁcally bred for shaded sites, to improve turfgrass
performance by maintaining grth and quality better than previous turfgrasses
available. Fine fescues are cool season grasses that are composed of over 100 species
and cultivars within the F estuca tribe originating from Europe (Beard, 1973; Hanson,
1972). Fine fescues are known for their relatively high shade tolerance, not only due to
their ability to grow well in the shade but also their ability to compete with surrounding
plants. They are characterized as having a rhizomatous or “bunch type” growth habit,
moderate wear tolerance (ability of grass to overcome trafﬁc), good density (plants per
unit area), and ﬁne texture (estimate of leaf width). Fescues usually are grown in lawns,
parks, and areas with shade (Murphy, 1996). Fescues are divided into two types based on
leaf texture: coarse fescues or ﬁne fescue (Turgeon, 2002). Coarse fescues include: tall
fescue and meadow fescue. Fine fescues include creeping red fescue, chewings fescue,
hard fescue, and sheep fescue. The diversity of fescues is based on their unique
adaptation, cultural intensity, and plant description.

Chewings fescue (CF) (F estuca rubra v. commutata) is a ﬁne fescue that forms a
ﬁne textured, erect growing, and high-density turf. The chewings fescue cv. ‘SR 5100’ is

both shade and sun tolerant, which means this cultivar can grow well in sunny or shaded

13

sites (Beard, 1973). The cultivar has been evaluated in several research trials including
the 1998 National Turf Evaluation Program (NTEP) ﬁne fescue test (Morris, 2003).
NTEP tests for quality, color, texture, density, percent ground cover, seedling vigor,
drought tolerance, frost tolerance, and trafﬁc tolerance of different cultivars to help
breeders, researchers, and extension specialists determine what cultivar has the desired
characteristics for their individual needs of their clientele. ‘SR 5100’ was ranked 6 on a 0
to 9 scale of 80 ﬁne fescue cultivars that were evaluated (Graham Turf Seeds Ltd.,
Canada; Morris, 2003).

Creeping red fescue (CRF) (F estuca rubra v. rubra) is also a ﬁne fescue that has a
narrow texture, high shoot density, and good uniformity. The cultivar is a slender
creeping red fescue that grows well in shaded sites (Beard, 1973; Turgeon, 2002). Based
on the NTEP 1998 ﬁne fescue test ‘Dawson’ received highest quality rating, which
ranked it 16 out of 80 cultivars that were evaluated (Royal Brand Technical Report,
2003).

In Michigan, Kentucky bluegrass (KB) (Poa pratensis) is the most widely used
cool season turfgrass. The original species of Kentucky bluegrass introduced to the
United States originated from Eurasia (Beard, 1973). However, some scientists believe
native populations existed along Cascade-Sierra Nevada Cordillera, the Rocky Mountain
Cordillera, and northern Canada before the spread of European cultivars (Stebbins, 1972).
Within the Kentucky bluegrass species there are both common and improved cultivars.
Common cultivars are the original cultivars of Kentucky bluegrass, while improved
cultivars are more disease resistant and more vigorous than common cultivars, and

perform well in lawns under low maintenance (MSU Extension Bulletin; GT1062, 1998).

14

Its characteristics are: rhizomatous growth habit; medium wear tolerance (ability of grass
to overcome trafﬁc); 7-21 days to germinate; 1/ 8” leaf width; moderate to high thatch;
and good shade, heat, drought, cold tolerance (Royal Brand Technical Report, 2003).
Recommended cultural management for Kentucky bluegrass lawns include: mow
frequently (one to two times per week) at 2.54 or 5 cm, 10-20g/ m2 nitrogen fertilize in
split applications, and irrigate to replace evapotranspiration rate. Kentucky bluegrass
grows rapidly under cool and moist weather. The grass is widely used in lawns and also
for commercial sites, golf course fairways, tees, roughs, and athletic sites. Kentucky
bluegrass ‘Cynthia’ is a cultivar that was developed for its dark green color, ﬁne leaf
texture, and good density compared to other Kentucky bluegrass cultivars. The cultivar
also has moderate shade tolerance, disease resistance, low water requirements, good wear
recovery, and low input requirements.
Past Research

Extensive research has been done on turfgrasses grown in shade to correct
problems and stress that the turfs encounter. Researchers have used different types of
chemical applications to improve the quality of shade grown grasses. Types of chemical
applications include: nitrogen, iron, trinexapac-ethyl (TE), and soluble carbohydrates
such as sucrose, fructose, or combinations of each. Sucrose and fructose may supplement
low carbohydrate reserves and compensate for low light conditions. For example, in
tomatoes a 10% foliar sucrose solution increased dry weight, and in squash plants sucrose
increased survival of plant when grown in darkness (Went, 1944; Juhren and Went, 1949;
Berrie, 1960). Also in tomato plants, Went (1944) found that in darkness sucrose drops

essentially to zero within 24-48 hours, but rises again upon immersion of 10% sucrose or

15

light exposure of 1000 umol rn’2 s". Nelson and Gorham (1957) applied sucrose-C14 or
glucose-C14 to trace carbohydrate partitioning in soybean seedlings and leaves. In the
light they found that 1% of sucrose was translocated after 14 hours and that in dark 10%
of glucose was translocated in 3 hours. In clover, 0.5 and 1% glucose stimulated nodule
formulation both in absence and presence of light, and 2% glucose produced the highest
number of nodules (Van Schreven, 1959). More recently, fructose was combined with
post-emergent herbicides to enhance the action of the herbicide without decreasing
tolerance of a plant to the herbicide (Penner et al., 1999). Fructose in solution was taken
up in a plant between 125-11% weights per volume; however the combination of 1.25%
fructose with herbicide and organisilicone as an adjuvant was sufﬁcient to successfully
kill weeds (Penner et al., 1999).

Use of exogenous fructose applications to counter act the negative effects of
shade on turfgrass was ﬁrst investigated under a sports turf management system
(Sorochan, 2002). Due to the role of fructans as storage carbohydrate in cool season
grasses, fructose applications could potentially supplement inadequate biosynthesis of
fructans due to shaded environments and increase the quality of grasses grown under
reduced light conditions. In these studies, fructose dissolved in water with an
organisilicone adjuvant was applied on Supina bluegrass ﬁve times per week at 1.25%
weight per volume and was also applied once per week at 1,2,4,6, and 8 times the
application rate. Sorochan (2002) found that ﬁve applications per week caused leaf
damage and that once a week at 1x rate (1.25% weight/volume) provided least amount of
injury while demonstrating positive physiological responses. When investigating the

translocation of exogenously applied fructose, exogenous fructose was successfully taken

16

up by the plant and used for metabolic processes (Sorochan, 2002). The quality of
Supina bluegrass increased with exogenous applications of ﬁ'uctose compared to the
control. However, the broader use of exogenous fructose on other turfgrasses and under
varied shade conditions remains to be evaluated.

Growing turfgrasses in shade has been and currently is a challenge to the sports
ﬁeld industry as well as to the homeowner. Investigating innovative methods to increase
the quality and health of turfgrasses grown under shaded conditions needs to be
investigated. Knowledge about the effects of exogenous fructose on the metabolism is
important to the understanding of how fructose is being utilized in turfgrass and if the
fructose is producing a positive physiological response. Recommendations could also be
made on the minimum DLI for each turfgrass required for exogenous fructose to have a
positive response. The potential use of exogenous fructose applications and quantifying
DLI can have great impact on the management of turfgrasses under shaded conditions.
Objectives of Study

1. Determine effects of exogenous ﬁ'uctose on CF, CRF, and KB
2. Determine effects of supplemental and ambient light levels on CF, CRF, and KB
3. Test the direct effects of the interaction of exogenous fructose applications
and light level on CF, CRF, and KB
4. Determine metabolically (LRC and leaf reﬂectance) the effects of exogenous
fructose and light levels on CF, CRF, and KB
5. Determine if fructose can substitute for light to maintain growth under

supplemental and ambient shaded environments

17

 

Amax

 

 

 

LCP

 

Rd

 

 

 

 

>
O 2000
PAR

Figure 1.1 Light response curve: assimilation rate (A umol CO2 m.2 s“) measured over changing

photosynthetic active radiation (PAR pmol m'2 5“) levels. Amax: maximum assimilation; LCP:
light compensation point; Rd: dark respiration rate; and CD: quantum efﬁciency.

18

References

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International T urfgrass Research Conference, Tokyo 133-135.

Alberda, T. 1957. The effects of cutting, light intensity, and night temperature on grth
and soluble carbohydrate content. Plant and Soil VII], No. 3, 199-230.

Beard, J .B. 1965. Factors in the adaptation of turfgrass to shade. Agronomy Journal
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Beard, J.B. 1973. Turfgrass: science and culture. Englewood Cliffs, New Jersey: Prentice
Hall.

Bell, G.E., T.K. Danneberger, and MJ. McMahon. 2000. Spectral irradiance available for
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Berrie, A.M. 1960. The effect of sucrose sprays on the grth of tomato. Plant
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Bunnel, T., Lambert B. McCarty, James E. Faust, William C. Bridges, Jr., and Nihal C.
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Bunnel, T., Lambert B. McCarty, and William C. Bridges. 2005b. Evaluation of Three
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Bunnel, T. 2003. Evaluation of three bermudagrass cultivars and ‘Meyer’ zoysigrass to
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Burris, J .S., R.H. Brown, and RE. Blaser. 1967. Evaluation of reserve carbohydrates in
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Burton, G.W., J. E. Jackson, and F .E. Knox. 1959. The inﬂuence of light reduction upon
the production, persistence, and chemical composition of coastal bermudagrass, Cynodon
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Carter, GA. 1993. Response of Leaf Spectral Reﬂectance to Plant Stress. American
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Carter, G.A., and Richard L. Miller. 1994. Early Detection of Plant Stress by Digital

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Casler, M.D., and Ronny R. Duncan. 2003. Ch. 3 Origins of the Turfgrasses. In:
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Dudeck, A.E. and CH. Peacock. 1992. Shade and Turfgrass Culture. In Turfgrass.
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Dunn, John H., Brad S. F resenburg, and Erik H. Ervin. 1999. Grasses in Shade:
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Hanson, A.A. 1972. Breeding of Grasses. In Younger and McKell: The Biology and
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Johnson, S. 1993. Light as a Resource. In Danneberger: Turfgrass Ecology and
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effects on creeping bentgrass golf greens. Crop Science 43:2182-2188.

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and Long-Distance Transport. In Plant Physiological Ecology. Springer, New York.
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Biology and Utilization of Grasses. Academic Press, New York. 23: 318-333.

Sorochan, J .C. 2002. Sugars in Shade: The Effects of Exogenous Fructose Applications
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21

Tankersley, L. 1999. Managing Trees and Turfgrasses. Agriculture Extension Service
[University of Tennessee].

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Physiology, Third Edition. Sinauer Associates, Inc. Publishers.

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Affects Morphology, Dry-Matter Partitioning, and Photosynthetic Response of
Greenhouse-grown ‘Chardonnay’ Grapevines. HortScience 39(1):65-70.

Van Huylenboreck, J .M., and E. Van Bockstaele. 2001. Effects of Shading on
Photosynthetic Capacity and Growth of Turfgrass Species. International T urfgrass
Society Research Journal 9:353-359.

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Responses of Poa pratensis L. ‘Merion’ and F estuca rubra L. ‘Pennlawn’ to Reduced
Light Intensity. Agronomy Abstracts 102.

22

Chapter 2

Supplemental Fructose Applied to Chewings Fescue ‘SR5100’, Creeping Red Fescue
‘Dawson’, and Kentucky bluegrass ‘Dawson’ Under Shaded Conditions

Abstract

Shade poses difﬁculties in establishing and maintaining high quality, persistent
and hardwearing turfs. Exogenous fructose applications were examined as a potential
method to counteract the negative effects of shade on turf. We examined the effect of
supplemental and ambient light levels in combination with exogenous fructose
applications on chewings fescue (F estuca rubra v. commutata) ‘SRS 100’ (CF), creeping
red fescue (F estuca rubra v. rubra) ‘Dawson’ (CRF), and Kentucky bluegrass (Poa
pratnesis) ‘Dawson’ (KB). Exogenous fructose treatments had a signiﬁcant affect on KB
clipping weight under 14 and 32 umol m'2 s", on CF water content under 14 pmol m'2 s“,
on CRF photosynthetic efﬁciency under 73 umol rn'2 s", on CRF plant health under 14
umol m'2 s", on CF plant stress under 73 umol rn‘2 s", on KB photosynthetic efﬁciency
under 14 pmol rn'2 s", and on KB plant health under 32 pmol rn'2 s'l. Species grown
under supplemental light had positive physiological responses compared to species grown
under ambient light. This suggests that within the conditions of these experiments
exogenous fructose was not an effective supplement for decreased carbohydrate reserves
due to low rates of photosynthesis under ambient light. However, supplemental light (32
or 73 umol rn'2 s") was sufﬁcient to maintain turfgrass growth of CF, CRF, and KB.
Species under ambient light became increasingly stressed compared to supplemental
light, thus suggesting that these species do not maintain quality and grth well under

extreme shaded conditions (40 to 200 pmol m'2 s").

23

Introduction

Shaded environments are a major management problem for establishing high
quality, persistent and hardwearing turfs (Wilson, 1997). Shading involves the partial or
complete interception of direct solar radiatiOn prior to being available for absorption by
plant tissue. Growing many genera and species of turfgrass under shade decreases plant
vigor, increases susceptibility to disease, reduces wear tolerance, and reduces density
(McBee and Holt, 1966; Dudeck et al., 1992). With reduced light intensity the rate of
photosynthesis is lowered, resulting in an immediate decrease in available carbohydrates
and carbohydrate reserves (Koh et al., 2003). In addition, total nonstructural
carbohydrates (TNC) decrease which are primarily stored in roots and crown tissue of
grasses. Reduced light intensities that result in reduced levels of PAR limit growth and
development of roots, stolons, shoots, and rhizomes (Dudeck and Peacock, 1992;
Johnson, 1993; Bell et al., 2000; Danneberger, 2003; Wilson, 1997; Beard, 1973).
Increasing the quality and health of turfgrasses under shaded conditions has been an
ongoing goal. Exogenous fructose applications have been one of the newest methods to
counteract the effects of turfgrasses grown in shade. It has been hypothesized that these
applications are a way of supplementing low carbohydrate reserves to compensate for
low light conditions (Sorochan, 2002).

In theory fructans may improve turfgrass growth since ﬁ'uctans have been
identiﬁed as the primary carbohydrate reserve in cool-season turfgrasses (Sorochan,
2002; Groteluxhen et al., 1968). F ructans are polymers of fructose with a single
molecule of glucose that forms a single molecule of sucrose as an end group. Fructose

and other carbohydrate concentrations are greatly affected by light intensity. At high

24

light intensities, photosynthesis increases, which in turn creates more carbohydrates, and
when plants are subjected to insufﬁcient light there is a general decline in available
carbohydrates (Burris et al., 1967). However, it remains unclear what threshold of light
is sufﬁcient to maintain turfgrass grth and development when supplemental ﬁ'uctose is
applied. The objective of this work was to investigate the effect of different light levels
in combination with exogenous fructose applications or no fructose applications on CF,
CRF, and KB.

Materials and Methods

Experimental Site

This work took place druing 2004 (year I) and 2005 (year 11) inside the dome
structure at the Hancock Turfgrass Research Center (HTRC) at Michigan State
University (MSU) in East Lansing, Mich. The dome simulates an indoor sports facility
that allows 2-10% of available photosynthetic active radiation (PAR) through ﬁberglass
fabric. (Birdair®, Birdair Inc., Amherst, NY.)

The experimental design was split block design with three factors and four
replications in year I, and four factors and three replications in year II. Replications
decreased in year II due to additional treatments amid the same number of modules. The
main factor was light level, which was a ﬁxed effect: ambient light (AL, 2-10% PAR or
40 to 200 mol m'2 5", depending on weather) with ambient photoperiod duration,
ambient light plus 73 pmol rn'2 3‘1 light supplemental high light (SHL) with 16-h
photoperiod using high pressure sodium (HPS) lights, and ambient light plus 32 mol m'2
s'1 supplemental low light (SLL) light with 16-h photoperiod using HPS lights. In year 11

only SLL and AL were tested. The supplemental light units were achieved by using

25

400W HPS lights located 2.3m above the turfgrass canopy. To achieve SHL a total of
ﬁve 400W HPS lights were placed to cover a 5m2 area of turf. To achieve SLL four
400W HPS lights were placed to cover a 6m2 area of turf. Light intensity was measured
with a CIRAS portable photosynthesis system (PP Systems, Amesbury, Mass.) at turf
canopy height three times under each light treatment in random areas to verify consistent
light intensity. A Watchdog Model 450 data logger (Spectrum Technologies, Plainﬁeld,
111.) recorded PAR under AL conditions instantaneously and calculated an average every
60-minutes. The output was used to calculate daily light integral (DLI mol m'2 d") under
AL over the duration of the experiment. Within each light treatment the second
experimental factor consisted of fructose applied once per week (F1) or no fructose (NF)
application (control). For the experiment initiated during year 11, fructose applied two
times per week (F2) was included as an additional treatment. The third experimental
factor in both experiments was turfgrass cultivar type: CF and CRF in both years and KB
in year 11.

Forty-eight movable turf modules (GreenTech Inc®, Roswell, Ga.) were used to
establish the CF, CRF, and KB. The modules measured four-by-four feet and 200m deep
creating a volume of 0.03m3. They are manufactured using high-density polyethylene
material with a perforated base, pallet channels for easy repositioning, and foot locator
pads for stability. The modules were placed in natural light outside the dome at the
HTRC on a concrete area for proper drainage during establishment for both experiments.
The modules contained a 5cm depth gravel base and 15cm soil depth that contained 10%
Oshtemo sandy loam topsoil mixed with 90% well-graded sand (Great Lakes Gravel,

Lake Odessa, Mich.) The turfgrass was seeded onto the modules at a rate of 15 g/ m2

26

(1000ft2) on 23 July in year I. A starter fertilizer (l6N-25P-13K) was applied at a rate of
3g phosphors (P)/ m2 on the day of seeding. On the same day as seeding, germination
blankets were placed over the top of the seeded area to accelerate germination and
removed on 5 August. For the duration of the entire establishment period (from 23 July
to 12 October) a total of 24g/ m2 of (21N-3P-18K) fertilizer was applied to the modules
on a weekly basis. Also during establishment, the modules were mowed starting 31
August at 7.6cm (3in) bench height, or set height of mower blades, with a Toro® walk
mower (Bloomington, Minn.) Until 31 August the turf was mowed only when the height
was 7.6cm tall and once per week thereafter until 16 October. Clippings were not
removed and until 16 October, the turf was watered using an automated irrigation system
four times a day for eight-minute periods.

Prior to moving the modules into the dome, all species were treated with a broad-
spectrum fungicide (BannerMaxx®, Sygenta Corporation, Wilmington, Del.) at a rate of
1.2mL/ m2 to prevent disease. Year I light and fructose treatments were initiated on 19
October 2005. Sixteen modules of CF or CRF per light treatment were placed inside the
dome. The Agriculture Research Manager (ARM) statistics system (Gylling Data
Management Inc., Brookings, S. Dak.) was used to randomly assign each module and
treatment to its speciﬁc light treatment. The KB modules were left on the concrete area
and were allowed to over winter under ambient outside light conditions.

In year 11 the KB modules were over seeded on 26 July at a rate of 10g/ m2 and
were fertilized with urea (46N-0P-0K) to increase coverage of KB at a rate of 5 g/ m2.
After urea application, the KB modules were then fertilized a total of 23 g/ m2 of (21N-

3P-18K) fertilizer applied weekly. Beginning 26 July the KB modules were watered four

27

times a day using an automated irrigation system and beginning 24 August KB was
mowed as described in year I. On 15 September the KB modules were randomly
assigned a light level and fructose treatment and placed into the simulated dome, as
described in year I.

For year 11 on 26 July the modules from year I were cleaned of the old CF and
CRF material and rebuilt with 90% sand and 10% soil mix. Once the modules were in
place, CF and CRF cultivars were seeded, fertilized, and watered beginning on 26 July;
mowing began on 6 September; and on 22 October the modules were randomly assigned
a light level and fructose treatment and placed into the simulated dome, as described in
year I.

Fructose Treatments

 

Fructose (Isoclear®, Cargill Sweeteners, Naperville, Ill.) treatments began on 21
October year I, 15 September year H KB, and 22 October year II CF and CRF. The
treatments were applied once per week (year I and II) and twice per week (year H) to the
corresponding modules. Fructose was mixed with an adjuvant (BreakThru®,
Goldschmidt Chemical Corporation, Hopewell, Va.) and double distilled water. Fructose
was applied at a rate of 1.25% v/v and the adjuvant was applied at a rate of 0.1% w/v
(Penner et al., 1998). A carbon dioxide backpack sprayer (R&D Sprayers©, Opelousas,
La.) was used to apply the fructose and adjuvant mixture to the corresponding modules.
Response Variables

Treatment effects were evaluated based on the interaction between light and
fructose on the cultivars by measuring: clipping yield, turf density, and leaf-reﬂectance

all species. Clippings were collected biweekly for CF and CRF in both years and weekly

28

for year 11 KB, and were stored at 5°C until placed in a forced air-drying oven. The
clippings were dried at 100°C for 3 days and dry weight was measured and expressed as
grams/m2 of the plot area. Core samples were taken biweekly for CF and CRF in both
years and weekly for year 11 KB with a 2.54cm diameter soil sampling tube to a depth of
3cm. For each sample the number of tillers were recorded and used to calculate turf
density (tillers cm'z).

Leaf-reﬂectance measurements were collected as close to solar noon as possible
on a sunny day biweekly for CF and CRF both years and weekly for year II KB. Leaf-
reﬂectance quantiﬁes the amount and speciﬁc wavelength of light that is reﬂected off the
turf canOpy, which is then used to correlate to overall plant stress. The measurements
indicate the effect of treatments on photosynthetic efﬁciency, metabolism of the plant,
and the light absorbed that will be utilized for photosynthesis. A spectroradiometer
(FieldSpec® Pro, Analytical Spectral Devices, Inc., Boulder, Colo.) was used to measure
reﬂected light waves to calculate: water band index (WBI), narrow band index (NDVI),
red-edge stress vegetation index (RVSI), and photosynthetic reﬂectance index (PR1).
The WBI (WBI= R900/R970) values are correlated with leaf water content thus the
values measured water-induced stress. The NDVI (NDVIl695= (R970-
R695)/(R760+R695) and NDV11700= (R840-R700)/(R840+R700)) measured the
difference of near infrared and red bands, and divided their sums, resulting values are
positively related to plant health. The RVSI (RVSI= (R714+R759)/ 2-R733) values
indicate reduced stress and the greater negative numbers indicate reduced stress. The PRI
(PR1: (R531-R570)/ (R531+R570)) indicated photosynthetic radiation efﬁciency, and the

values decrease with reduced radiation efﬁciency.

29

Statistical Analysis

Species and fructose treatments for each light level were compared using Proc
ANOVA with Tukey’s adjustment (SAS, 2000). Measured light energy underneath all
conditions was calculated into daily light integral (DLI mol rrr‘2 d'l) and used for
statistical analysis for light treatment inﬂuence. Data from year I will only be reported
due to similar results between CF and CRF for both years. Pearson’s correlation was used
to test the interactions between response variables.
Results

The application of fructose had a signiﬁcant affect on KB clipping weight (grams
m'z) under AL and SLL (Table 2.2A), for PRI under AL (Table 2.11A), and NDVI695
under SLL (Table 2.12A). For CF and CRF, WBI, NDVI695, and NDVI700 were
signiﬁcantly different between ﬁ'uctose applications and control treatments under AL,
whereas PR1 and RVSI were signiﬁcantly different under SHL (2.5A, 2.6A, 2.7A, 2.8A,
2.9A). There were no signiﬁcant differences for CF and CRF clipping weight and tiller
production (density). Due to the application of fructose there were no signiﬁcant
differences for KB tiller production or for WBI, NDVI700, and RVSI (Tables 2.1A,
2.3A, 2.4A, 2.10A, 2.13A, 2.14A). There were signiﬁcant affects on grth and
metabolism of CF, CRF, and KB due to available light energy (PAR). There were also
signiﬁcant interactions between species, fructose, and time for each of the parameters that
were measured.
_D_aily Light Integral (DLI)

For each light treatment light levels were signiﬁcantly different over time (weeks)

(p-value < 0.05). Fluctuation in light levels was dependent on natural ambient conditions

30

(data not shown). There were no differences between the response parameters of the
different turfgrass species and fructose treatments under the various light levels.
However, SHL was found to have higher average DLI than SLL (Figure 2.1A), thus the
SHL treatment was not included as a treatment in year 11 (Figure 2.1B). Supplemental
low light treatments were also found to be more likely achieved under commercial
management situations. Due to the time of year the KB experiment was conducted DLI
was found to be higher than in both fescue experiments (data not shown). For KB light
levels were not signiﬁcantly different over time (weeks) (p-value < 0.01), however SLL
maintained a higher DLI than compared to AL (Figure 2.2).
Clipping Weight
CF and CRF Experiment

Clipping weights (grams m’z) for all species grown under all light energy levels
were signiﬁcantly different over time (weeks) (Table 2.1A). Clipping weights under AL
decreased for all species, while increasing over the duration of the experiment when
grown under SLL and SHL (Table 2.1B and Figure 2.3). There were signiﬁcant
differences between species when grown under AL and SLL (Table 2.1A); with CRF
maintaining 30% higher clipping weights compared to CF (Table 2.1C). In addition, for
plants grown under all light energy levels there was a signiﬁcant interaction between
species and time (Table 2.1A). Light energy available had a greater affect than
exogenous fructose as illustrated by the one to ﬁve fold increase in clipping weight as
light energy increased from AL to SHL (Table 2.18).

Clipping weights for both CF and CRF under AL were positively correlated to

density (p-value < 0.01 , r = 0.84). For both CF and CRF, clipping weight was negatively

31

correlated to respective light DLI (p-value < 0.0001, r = -0.67). Under AL CRF clipping
weight was positively correlated to NDVI695, NDVI700 and RVSI (p-value < 0.01, r =
0.503, 0.53, and 0.515 respectively).
KB Experiment

Exogenous fructose applications had a signiﬁcant affect on KB clipping weight
under AL and SLL (Table 2.2A). Under AL KB plants that received fructose had higher
clipping weights compared to controls (NF) (Table 2.2B). Under SLL KB control plants
(NF) had higher clipping weights than F2 and F1, respectively (Table 2.2B). Kentucky
bluegrass clipping weight signiﬁcantly differed over time (weeks) (Table 2.2A, C).
Clipping weights for KB under AL ﬂuctuated over time while clipping weights under
SLL decreased by week four (Figure 2.4). Kentucky bluegrass clipping weights were
20% greater under SLL than under AL (Table 2.2B). Kentucky bluegrass grown under
AL and SLL light levels maintained 25% higher clipping weights than both CRF and CF
(data not shown). Under AL KB clipping weight was positively correlated to NDVI695
and NDVI700 (p-value < 0.01, r = 0.59).
My
CF and CRF Experiment

Density (tillers cm‘z) was signiﬁcantly different over the duration of the
experiment for both CF and CRF species under both light energy levels (Table 2.3A),
with density for both species decreasing over time (Table 2.3B and Figure 2.5). When
CF and CRF were grown under SLL there was a signiﬁcant interaction between fructose,
species, and time (Table 2.3A). Each species responded differently to fructose

applications over the duration of the experiment. There were slight differences in density

32

between light levels, with turfgrass species grown under SLL and SHL generally having
higher densities than those grown under AL (Table 2.3B). For both CF and CRF density
was negatively correlated to AL DLI (p-value < 0.0001, r = -0.63). For turfgrasses grown
under AL density counts were positively correlated to clipping weight (p-value < 0.0001 ,
r = 0.74).
KB Experiment

There were signiﬁcant differences in density over time (weeks) for KB grown
under SLL (Table 2.4A). Density increased over the duration of the experiment (Table
2.4B and Figure 2.6). Tiller production was found to be two times greater under SLL
than under AL (Table 2.48).
Lgf Reﬂectance
CF and CRF Experiment
Water Band Index

For CF grown under AL exogenous fructose had a signiﬁcant affect on water
band index (WBI R900/R970) (Table 2.5A), with the control plants (NF) maintaining
higher WBI compared to F 1 (Table 2.5B). Chewings fescue that did not receive fructose
applications was less water-stressed compared to plants that received fructose
applications. When plants were grown under AL and SLL there were signiﬁcant
differences in WBI over time (weeks) (Table 2.5A). At all points in time WBI under AL
was consistently lower compared to measurements on turfgrasses grown under SLL

(Table 2.5C).

33

Photosynthetic Reﬂective Index

Under SHL for CRF exogenous ﬁ'uctose applications signiﬁcantly affected
photosynthetic reﬂective index (PR1 (R531-R570)/(R531+R570)) (Table 2.6A), with
control plants maintaining higher PR1 values compared to F1 plants (Table 2.6B). For
CRF that did not receive fructose utilized PAR more efﬁciently compared to plants that
received fructose applications. There was also a signiﬁcant difference between species
under SHL (Table 2.6A), with CRF maintaining one percent higher PR1 compared to CF
(Table 2.6D). Photosynthetic reﬂective index was signiﬁcantly different over time for all
species under all light energy levels (Table 2.6A). Photosynthetic reﬂective index was
found to decrease under AL and SHL and increase under SLL over the duration of the
experiment (Table 2.6C). Under AL conditions there was a signiﬁcant interaction
between species and time (Table 2.6A). Over time PR1 responded differently depending
on species type. Under SHL there was a signiﬁcant interaction between ﬁ'uctose, species,
and time (Table 2.6A). For both the control plants and F1 plants PR1 decreased for both
species over the duration of the experiment (data not shown).
Narrow-Band Vegetative Index

Exogenous fructose applications signiﬁcantly affected narrow-band vegetative
index 695 and 700 (NDVI695 and 700 (R970-R695)/(R970+R695) and (R840-
R700)/(R840+R700)) for CRF grown under AL (Table 2.7A and 2.8A). Control plants
maintained higher NDVI values than plants that received fructose (Table 2.7B and 2.83).
There were signiﬁcant differences in NDVI under all light energy levels over time
(weeks) (Table 2.7A and 2.8A), with NDVI decreasing over the duration of the

experiment (Table 2.7C and 2.8C). For CF and CRF grown under SHL there were

34

signiﬁcant differences in NDVI695 between species (Table 2.7A). Creeping red fescue
possessed 1% higher NDVI values than CF (Table 2.7B). For CF and CRF grown under
AL there was a signiﬁcant interaction between fructose and species for NDVI695 (Table
2.7A). For plants grown under SHL there was a signiﬁcant interaction between species
and time for both NDVI695 and 700 (Tables 2.7A and 2.8A), with values decreasing over
the duration of the experiment (Table 2.7C).

Under all light conditions NDVI695 and NDVI700 were highly correlated to one
another (p-value < 0.0001, r = 0.94). For turfgrasses grown under SHL, NDVI695,
NDVI700, and RVSI were all highly positively correlated (p-value < 0.0001, r = -0.83).
Red-edge Vegetative Index

Exogenous fructose applications for CF grown under SHL signiﬁcantly affected
red-edge vegetative index (RVSI (R714+R759)/(2-R733)) (Table 2.9A), with the control
plants maintaining one point ﬁve percent higher RVSI vales than plants that received
fructose (Table 2.9B). There were signiﬁcant differences in RVSI over time for all
turfgrass species and light conditions (weeks) (Table 2.9A). Red-edge vegetative index
values were found to increase over the duration of the experiment (Table 2.9C). Under
AL there was a signiﬁcant interaction between species and fructose (Table 2.9A). Under
SLL and SHL there was a signiﬁcant interaction between fructose applications and
species (Table 2.9A). Under all AL and SLL there was a signiﬁcant interaction between
fructose applications, species, and time (Table 2.9A). Each species responded differently

over the duration of the experiment and to exogenous ﬁ'uctose (Appendix I).

35

KB Experiment
Water Band Index

Water band index (WBI) under both light energy levels signiﬁcantly differed over
time (weeks) (Table 2.10A), with WBI decreasing under AL and increasing under SLL
(Table 2.10C). Water band index under AL maintained slightly higher values compared
to WBI under SLL (Table 2.10B). Kentucky bluegrass grown under AL was under
greater water stress than compared to KB grown under SLL.
Photosynthetic Reflective Index

Exogenous fructose applications for KB grown under AL signiﬁcantly affected
photosynthetic reﬂective index (PR1) (Table 2.11A). Plants that received fructose once
per week (F l) maintained higher PR1 values followed by NF and F2, respectively (Table
2.11B). Kentucky bluegrass that received F1 utilized PAR more efﬁciently than the two
other treatments. Under both light energy levels there were signiﬁcant differences in PR1
over time (weeks) (Table 2.11A). Photosynthetic reﬂective index decreased over the
duration of the experiment (Table 2.11C). Kentucky bluegrass grown under SLL
maintained one percent greater PR1 values compared to KB grown under AL (Table
2.11B).
Narrow-Band Vegetative Index

For KB grown under SLL exogenous fructose had a signiﬁcant affect on narrow-
band vegetative index 695 (NDVI695) (Table 2.12A), with control plants maintaining
higher NDVI695 than plants that received fructose applications (Table 2.12B). Under
both light energy levels, NDVI695 and 700 were signiﬁcantly different over time (weeks)

(Table 2.12A and 2.13A). Narrow-band vegetative index 695 and 700 decreased over the

36

duration of the experiment (Table 2.12C and 2.13C). Narrow-band vegetative index 695
values under both light levels were one to two percent higher than NDVI700 values
(Table 2.12B and 2.13B). Under both AL and SLL NDVI695 and NDVI700 were
positively correlated (p-value < 0.0001, r = 0.97).
Red-Edge Vegetative Index

Red-edge vegetative index (RVSI) was signiﬁcantly different under both light
energy levels over time (weeks) (Table 2.14A). Red-edge vegetative index increased
over the duration of the experiment (Table 2.14C). Stress increased under both light
levels over time. Red-edge vegetative index values were similar under both AL and SLL
levels (Table 2.14B).
Discussion

Exogenous ﬁ'uctose had a signiﬁcant affect on response variables measured under
all light energy levels. For CF and CRF exogenous fructose applications negatively
affected the plants when grown under ambient light by increasing water stress as
measured by WBI and reducing health measured by NDVI compared to plants that did
not receive exogenous fructose. When grown under supplemental high light, CF and
CRF control plants utilized PAR more efﬁciently and were less stressed compared to
plants that received exogenous fructose. These results suggest that under the light
conditions within this experiment exogenous fructose may not have beneﬁcial effects on
the metabolic mechanisms of CF and CRF. In contrast, when KB was grown under
ambient light exogenous fructose applications increased clipping weight and increased
how efﬁcient KB utilized PAR. However, when KB was grown under SLL fructose

applications decreased overall health based on leaf reﬂectance indices. These results

37

indicate that exogenous fructose applications may have beneﬁcial effects on growth and
metabolism dependent on species and PAR light conditions.

When supplemental light was added under low light energy conditions higher
positive responses in plant grth occurred compared to plants grown under ambient
light. Thus, in contrast to previous work (Sorochan, 2002) supplementing ambient light
under these simulated sports dome conditions with or without exogenous fructose,
improved growth for CF, CRF, and KB over long periods of time.

Turfgrasses within this study were able to maintain consistent clipping weight and
tiller production values under low supplemental light (daily light integral 3 A: 2 mol m'2 d'
l). This suggests that carbohydrates in CF, CRF, and KB produced by photosynthesis
may have been preferentially allocated to shoots rather than tillers. This is consistent
with Sorochan’s (2002) data that suggested exogenous fructose applied to Supina
bluegrass was allocated within the plant and was used for metabolic processes to support
growth. However, clipping weights from CF, CRF, and KB turfgrasses grown under AL
decreased early on and did not recover over time, suggesting that carbohydrates were
rapidly depleted under this level of PAR and even exogenous fructose could not
supplement for the required carbohydrate concentrations for grth (i.e. dry weight
accumulation).

Under AL all leaf reﬂectance values decreased over time. This suggests that the
metabolic processes of CF, CRF, and KB became increasingly less efﬁcient as the
duration of shaded conditions was extended. Turfgrasses grown under AL non-fructose
plants had higher NDVI values than fructose treated plots. In addition, Rd increased as

exogenous fructose applications increased for turfgrasses grown under AL. These results

38

suggests that exogenous ﬁ'uctose treatments under AL may have contributed to the
turfgrasses overall stress by reducing health and increasing respiration, possibly
contributing to reduced photosynthetic efﬁciency by altering other metabolic processes
(i.e. mitochondrial respiration) resulting in overall reduced growth. Trinexapac-ethyl
(TE) treatments on Supina and Kentucky bluegrass in ambient light conditions reduced
clipping weights in comparison to plots not treated with TB, indicating increased stress
on TE treated plots (Stier, 2001). A treatment intended to reduce one speciﬁc stress
actually triggers another, but related metabolic stress was observed in Stier’s work
(2001). In this work under SLL and SHL for CF and CRF and under SLL for KB species
leaf reﬂectance indicated water stress index and overall stress (RVSI) increased while
overall plant health (NDVI) and radiation efﬁciency (PR1) decreased over time,
regardless of fructose treatment. Based on light reﬂectance data, all species were
continually metabolically stressed; they were still able to maintain some shoot grth
under these conditions. In addition, DLI was positively correlated to overall plant health,
which supports the general hypothesis that with higher DLI there is a positive effect on
plant health. Collectively, the correlations suggest that when species had better overall
health, then overall growth was higher, regardless of fructose treatment.
Conclusion

In summary, exogenous ﬁ'uctose treatments had a positive effect on some
response variables for all three turfgrass species. However, light energy (PAR) had a
greater positive affect on growth compared to exogenous ﬁ'uctose although turfgrasses
responded differently to exogenous fructose treatments. Some species (KB) achieve a

better physiological status than other species (CF and CRF) with fructose applications. In

39

addition, supplemental PAR as low as 3-10 i 2 mol m'2 5'1 appears to be sufﬁcient to
maintain overall growth and quality of the KB, CF, and CRF species tested in this
experiment. This research causes one to speculate how exogenous fructose impacts
different metabolic responses within the plant and how the application of exogenous

fructose interacts with light.

40

Table 2.1A Analysis of variance for clipping weight (grams m2) under ambient light (AL 5-10 pmol
m'2 s I.) supplemental low light (SLL 32 pmol m 31), and supplemental high light (SHL 73 pmol
m 2 s ) for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) and creeping red fescue
"Dawson (CRF Festuca rubra v. rubra).

 

 

 

 

 

 

 

.A_L_ _L_L %
Source df MS F df MS F df MS F
F 1 1.01 1.79ns 1 0.48 0.38ns 1 0.006 Ons
W 5 46.3 75.6" 5 22.1 17.3" 5 8.69 6.70"
S 1 26.1 42.6“ 1 28.7 22.5” 1 0.33 0.26ns
F‘W 5 1.80 295* 5 1.37 1.08ns 5 1.60 1.23ns
PS 1 0.005 0.01ns 1 0.77 0.61ns 1 0.23 0.18ns
S*W 5 15.36 25.1" 5 14.8 11.6“ 5 3.99 3.08“
F‘W’S 5 0.09 0.15ns 5 0.25 0.18ns 5 1.31 1 .01ns
Error 72 0.61 72 1 .27 72 1 .29
Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;

*", p < 0.01.
F, fructose; W, week; 8, Species.

.-—-----—----------------------_-__--____-—_---_---__--_--_-__---_--_----------------—-----------u----------------

Table 2.18 Means speciﬁc clipping weight (grams m) over time (week) under ambient light (AL
5-10 umol m'2 s 1), supplemental low light (SLL 32 pmol m'2 s1), and supplemental high light (SHL
73 pmol m’2 s1)for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) and creeping
red fescue ‘Dawson’ (CRF Festuca rubra v. rubra).

 

 

& §Ll= .$_HL

Week CF CRF CF CRF CF CRF

1 2.068 6.98 1.71 ab 6.328 1.99b 3.24b
3 0.62b 2.1b 1.628b 3.52b 3.2381) 3.658b
5 0.25b 0.1OC 0.89b 0.77c 1.83b 1 .15b
9 0.23b 0.200 1.58b 1.460b 4.27ab 2.54ab
12 0.34b 0.40bc 1.748 1.21cb 2.13ab 2.2080
15 0.19b 0.200 2.588 1.71cb 2.228b 2.368b

 

 

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

.---------_---------—------------__-_--------------__--------------—-----------------------------—-—--------------

Table 2.1C Means speciﬁc clipping weight (grams m '_2by2) species under ambient light (AL 5-10
pmol m'2 81,) supplemental low light (SLL 32 pmol m s1.) and supplemental high light (SHL 73
pmol m 2 s ) for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) 8nd creeping red
fescue ‘Dawson’ (CRF Festuca rubra v. rubra).

 

Species A}; SLL SHL
CF 0.62b 1.67b 2.168
CRF 1.668 2.778 2.498

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

41

Table 2. 2A Analysis of variance for clipping weight g grams m 2) under ambient light (AL 5-10 pmol
m2 s ) and supplemental low light (SLL 32 pmol m s ) for Kentucky bluegrass ‘Cynthia’ (KB

 

 

Poa pratensisL

AL S_LL_
Source df MS F df MS F
F 2 6.02 3.71 * 2 7.80 6.23“
W 3 19.05 11.8" 3 27.4 21.9“
F‘W 6 0.50 0.31 ns 6 0.30 0.24ns
Error 36 1.62 36 1.25

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
*", p < 0.01.
F, fructose; W, week; S, species.

Table 2. 28 2Means speciﬁc for clipping weight (grams m) at 21week four under ambient light (AL 5-
10 pmol m2 s ) and supplemental low light (SLL 32 pmol m2 s1)for Kentucky bluegrass
Qnthia’ (KB Poa pratensis).

 

AL SAL
Trt re re
F1 2.528 3.53b
F2 2.468b 3.87b
NF 1.790 4.728

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F 1, fructose 1x/week; NF, no fructose (control).

a------------------—---—-——----——-----—--------——-—-----c----------_----------------------c-c-----—--------------.

Table 2. 20 Means speciﬁc for clipping weight (grams m 2)ov1er time under ambient light (AL 5-10
pmol m2 s1)8nd supplemental low light (SLL 32 pmol m s1)for Kentucky bluegrass ‘Cynthia’
(KB Poa pratensis).

 

 

Week AL SLL

1 4.988 2.75c
2 3.62b 3.65bc
3 4.818b 6.308
4 2.26c 4.04b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

42

Table 2. 3A Analysis of variance for density (tillers cm 2) under ambient light (AL 5-10 pmol m2 2's
1), supplemental low light (SLL 32 pmol m2 s 1,) and supplemental high light (SHL 73 pmol m2 s
1)for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) and creeping red fescue
‘Dawson ’(CRF Festuca rubra v. rubra).

 

 

AL S_LI= S_HL

Source df MS F df MS F df MS F

F 1 0.74 0.12ns 1 0.47 . 0.99ns 1 0.88 0.22ns
W 3 13.4 22.6" 3 5.11 10.5“ 3 3.03 7.74"
S 1 0.32 0.54ns 1 0.29 0.61ns 1 0.09 0.22ns
F*W 3 0.02 0.03ns 3 0.21 0.44ns 3 0.12 0.31ns
F*S 1 0.38 0.64ns 1 0.02 0.05ns 1 0.62 1.59ns
S*W 3 0.06 0.11ns 3 0.29 0.61ns 3 0.86 0.22ns
F*W‘S 3 1 .48 2.49ns 3 1.41 292* 3 0.30 0.78ns
Error 48 0.59 48 0.48 48 0.39

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
“, p < 0.01.
F, fructose; W, week; S, Species.

—--—----------------—----—-—---------------—-----—--—---—-----—-—--cc--_----------------—------—---------—--------

Table 2. 38 Means speciﬁc density (tillers czm ) over time under ambient light (AL 5-10 pmol m2 s
1.) supplemental low light (SLL 32 pmol m2 51,) and supplemental high light (SHL 73 pmol m2 s
1)for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) and creeping red fescue
"Dawson (CRF Festuca rubra v. rubra).

 

& SI; ELL
Week CF CRF CF CRF CF CRF
1 3.168 3.508 3.118 3.108 2.998b 3.038
5 1.63b 1.70b 2.578b 2.608 3.268 3.168
10 1.68b 1.70b 2.298b 2.308 2.668b 2.398
15 1 .18b 1.30b 1.48b 2.008 2.458b 2.278

 

 

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

43

Table 2.4A Analysis of variance for density tillers cm'2) under ambient light (AL 5-10 umol m'2 3'1)
and supplemental low light (SLL 32 pmol m' s‘1) for Kentucky bluegrass ‘Cynthia’ (KB Poa
pratensis).

 

AL S_LL
Source df MS F df MS F
F 2 0.10 1.83ns 2 0.006 0.12ns
W 3 0.002 0.40ns 3 , 0.59 12.7"
F*W 6 0.02 0.35ns 6 0.04 0.82ns
Error 36 0.06 36 0.46

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
*", p < 0.01.
F, fructose; W, week; 3, species.

Table 2.48 Means speciﬁc density (tillers cm'2) over time under ambient light (AL 5-10 pmol m'2 s'
1) and supplemental low light (SLL 32 umol m' s") for Kentucky bluegrass ‘Cynthia’ (KB Poa

 

 

pratensis).

Week AL SLL
1 0.588 0.5%
2 0.628 0.54b
3 0.538 0.51 b
4 0.558 0.998

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

44

Table 2. 5A Analysis of variance for water band index (R900/R970) under ambient light (AL 5-10
pmol m2 51,) supplemental low light (SLL 32 pmol m2 51,) and supplemental high light (SHL 73
pmol m'2 s1)for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) and creeping red
fescue ‘Dawson’ (CRF Festuca rubra v. rubra)

 

A_L & Sli

Source df MS F df MS F (ii MS F

F 1 0.04 4.44” 1 0.002 0.57ns 1 0.001 0.45ns
W 4 0.14 15.5" 4 0.03 11.2" 4 0.006 1.81ns
S 1 0.13 1.42ns 1 0.00009 0.03ns 1 0.0003 0.10ns
F*W 1 0.009 0.93ns 1 0.006 2.22ns 1 0.007 2.05ns
F*S 4 0.005 0.51ns 4 0.01 3.40ns 4 0.007 2.18ns
SW 4 0.009 1.07ns 4 0.002 0.65ns 4 0.001 0.22ns
F*W'S 4 0.009 0.99ns 4 0.003 1.14ns 4 0.001 0.53ns
Error 219 0.009 219 0.003 219 0.003

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *. p < 0.05;
**, p < 0.01.
F, fructose; W, week; S, Species.

w.-------------Q-------------u--------------------n----—-----n------------------n-----¢--—---'---.-

Table 2.58 Mean speciﬁc water band index (R900/R970) azt week ﬁfteen under ambient light (AL
5- 10 umol m2 51,) supplemental low light (SLL 32 pmol m2 51,) and supplemental high light (SHL
73 pmol m2 s ) for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) 8nd creeping
red fescue ‘Dawson’ (CRF Festuca rubra v. rubra).

 

AL & §_H_L
Trt Qﬁ CRF if CRF CF CRF
NF 0.938 0.898 1.018 1.028 0.988 1.018
F1 0.94b 0.908 0.998 1.018 0.998 1.028

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF, no fructose (control); F 1, fructose 1x/week.

ou-onaonnooncnpccaco----~-----~-—-----—-~-----v—.-u------m----—--—-~---—u--a..--n-‘cncac-n-n-I-q-u—u-u—cno- ooooooooooo

Table 2. 250 Mean speciﬁc water band index (R900/R970)2 over time under ambient light (AL 5-10
umol m2 s1)and supplemental low light (SLL 32 pmol m2 s 1)forchewings fescue ‘SR 5100’ (CF
Festuca rubra v. commutata)and creeping red fescue D‘awson’ (CRF Festuca rubra v. rubra).

AL SLL
Week CF CRF CF CRF
3 1.028b 1.028 0.97bc 0.978b
6 1 .038 1 .048 1 .028 0.998b
9 1.058 1.058 0.96bc 0.96b
12 1.058 1.008 0.940 0.97ab

15 0.93b 0.90b 1.008b 1.028
Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

 

 

45

Table 2. 6A Analysis of variance for photosynthetic reﬂective index ((R531 -RS71)/(R5131+R570))
under ambient light (AL 5-10 pmol m2 s 4,2) supplemental low light (SLL 32 umol m 51,) and
supplemental high light (SHL 73 umol m s ) for chewings fescue ‘SR 5100’ (CF Festuca rubra v.
commutata) and creepinwd fescue ‘Dawson’ (CRF Festuca rubra v. rubra).

 

 

ILL §LL_ 31L
Source df MS F df MS F df MS F
F 1 0.04 6.11ns 1 0.00009 0.01ns 1 0.97 4.53*
W 4 0.71 121" 4 0.18 23.2“ 4 3.27 153"
S 1 0.0004 6.11" 1 0.00006 0.01ns 1 0.13 4.53"
F*W 1 0.003 0.58ns 1 0.003 0.42ns 1 0.03 1.55ns
F*S 4 0.0002 0.05ns 4 0.002 0.24ns 4 0.07 3.46ns
S*W 4 0.01 2.43“ 4 0.008 1.02ns 4 0.04 1.85ns
F*W‘S 4 0.01 2.02ns 4 0.006 0.76ns 4 0.09 4.21“
Error 219 0.006 214 0.008 222 0.02
Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;

**, p < 0.01.
F, fructose; W, week; S, Species.

------------_-----c-------g------—------------—--——-------------u----—----------—------------u-u----------—-. .....

Table 2. 68 Mean speciﬁc photosynthetic reﬂzective index ((R531 -RS71)/(R531+R570)) at week
ﬁfteen under ambient light (AL 5- 10 umol m2 51), supplemental low light (SLL 32 pmol m'2 31,)
and supplemental high light (SHL 73 umol m2 s ) for chewings fescue ‘SR 5100' (CF Festuca
rubra v. commutata) 8nd creeping red fescue Dawson’ (CRF Festuca rubra v. rubra).
& & S_HL

Trt CF CRF CF CRF _C_3_F_ CRF

NF -0.138 -0.158 -0.058 -0.098 -0.17a 0078

F1 -0.098 -0.098 -0.128 -0.088 -0.148 —0.11b

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF, no fructose (control); F1, fructose 1x/week.

 

 

Table 2. 6C Mean speciﬁc photosynthetic reﬂective index ((R531-R571 )/(R531+R570))1 over time
under ambient light (AL 5-10 umol m2 s1), supplemental low light (SLL 32 umol m2 81), and
supplemental high light (SHL 73 pmol m s1)for chewings fescue ‘SR 5100’ (CF Festuca rubra v.
commutata) 8nd creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra).

 

& S_L_L ﬂ
Week CF CRF CF CRF CF CRF
3 0.048 0.048 -0.04b -0.04b 0.368 0.348
6 0.058 0.028 -0.09b -0.06b -0.41d -0.33d
9 0.018 -0.018 -0.04b -0.05b -0.04 bc 0.07b
12 -0.25c -0.26c -0.04b -0.05b -0.02b 0.01 be
15 -0.12b -0.12b 0.098 0.098 -0.16c -0.090

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

46

Table 2. 7A Analysis of variance for narrow band vegetative index 695 ((R970-
R695)/(R9710+R695)) under ambient light (AL 5-10 umol m’: 51,) supplemental low light (SLL 32
umol m2 51,) and supplemental high light (SHL 73 pmol m2 s1)for chewings fescue ‘SR 5100’
(CF Festuca rubra v. commutata) 8nd creeping red fescue ‘Dawson’ (CRF Festuca rubra v.
rubra).

 

 

& & §L1L
Source df MS F df MS F df MS F
F 1 0.05 8.9“ 1 0.00003 Ons 1 0.01 1 .41ns
W 4 0.28 50.3“ 4 0.25 35.9“ 4 4.82 585"
S 1 0.007 1.28ns 1 0.001 0.17ns 1 0.04 5.31 *
F*W 1 0.009 1.58ns 1 0.004 0.61ns 1 0.003 0.35ns
F*S 4 0.02 4.3‘ 4 0.002 0.25ns 4 0 Ons
S*W 4 0.007 1.35ns 4 0.004 0.59ns 4 0.03 3.06“
F*W‘S 4 0.009 1.67ns 4 0.004 0.56ns 4 0.006 0.75ns
Error 219 0.006 214 0.007 222 0.008

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *,
**, p < 0.01.
F, fructose; W, week; S, Species.

p<00a

Table 2. 78 Mean speciﬁc narrow band vegetative2 index 695 ((R970- R695)/(R970+R695)) at
week ﬁfteen under ambient light (AL 5- 10 pmol m2 51,) supplemental low light (SLL 32 umol m2
51,) and supplemental high light (SHL 73 pmol m2 s1)for chewings fescue ‘SR 5100’ (CF
Festuca rubra v. commutatﬁ and creepigg red fescue Dawson’ (CRF Festuca rubra v. rubra).

 

PL S_LL §ﬂL
Trt g: CRF g CRF g: CRF
NF 0.51a 0.63b 0.628 0.648 0.01a -o.02a
F1 0.588 0.57a 0.618 0.588 -0.07a -o.10a

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF. no fructose (control); F1, fructose 1x/week.

Table 2. 70 Mean speciﬁc narrow band vegetative index 695 ((R970- R695)/(R970+R6952)) over
time under ambient light (AL 5- 10 umol m s 1) supplemental low light (SLL 32 umol m2 51,) and
supplemental high light (SHL 73 pmol m2 s ) for chewings fescue ’SR 5100’ (CF Festuca rubra v.
commutata) and creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra).

 

AL SI; _$_H_L
Week CF CRF CF CRF CF CRF
3 0.748 0.758 0.668b 0.698b 0.698 0.688
6 0.60b 0.61 b 0.698 0.698 0.668 0.618
9 0.738 0.718 0.55d 0.52d 0.698 0.698
12 0.708 0.698 0.54cd 0.53cd 0.658 0.628
15 0.54b 0.59b 0.61bc 0.61bc 0.04b 0.10b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

47

Table 2. 8A Analysis of variance for narrow band vegetative index 700 ((R840-
R700)/(R8410+R700)) under ambient light (AL 5-10 umol m2 31,) supplemental low light (SLL 32
umol m2 51), and supplemental high light (SHL 73 pmol m2 s1)for chewings fescue ‘SR 5100’
(CF Festuca rubra v. commutata) 8nd creeping red fescue ‘Dawson (CRF Festuca rubra v.
rubra).

 

& & S_li

Source df MS F df MS , F df MS F

F 1 0.05 15.7“ 1 0.002 0.56ns 1 0.02 3.83ns
W 4 0.32 94.0“ 4 0.16 37.7" 4 5.34 958"

S 1 0.004 1.27ns 1 0.005 1.23ns 1 0.04 7.35“
F*W 1 0.006 1 .49ns 1 0.003 0.80ns 1 0.003 0.60ns
F*S 4 0.008 2.41 ns 4 0.00001 Ons 4 0.00003 0.06ns
S*W 4 0.003 0.98ns 4 0.0008 0.21ns 4 0.01 2.60‘

F*W'S 4 0.007 2.04ns 4 0.005 1.11ns 4 0.002 0.33ns

Error 219 0.003 241 0.004 222 0.005

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
", p < 0.01.
F, fructose; W, week; S, Species.

.c-------—-ooo~—-—-—ocal—n-u-----------~----o-—-u-u-u--—--u-an-a.--onu-nu-..-—uo-c-ou-a-uopoocqoan-cnnnu-np ..........

Table 2. 88 Mean speciﬁc narrow band vegetative2 index 700 ((R840- R700)/(R840+R700)) at
week ﬁfteen under ambient light (AL 5-10 pmol m'22 s1), supplemental low light (SLL 32 umol m2
s1.) and supplemental high light (SHL 73 umol m2 s ) for chewings fescue ‘SR 5100’ (CF
Festuca rubra v. commutata) and creeping red fescue ‘Dawson‘ (CRF Festuca rubra v. rubra).

 

AL. §L_L ﬂ
Trt CF CRF CF CRF CF CRF
NF 0.468 0.548 0.578 0.558 -0.078 0.128
F1 0.508 0.48b 0.578 0.598 -0.138 -0.198

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF, no fructose (control); F1, fructose 1x/week.

Table 2. 80 Mean speciﬁc narrow band vegetative index 700 ((R840- -R700)/(R840+R700)) over
time under ambient light (AL 5-10 umol m 51,) supplemental low light (SLL 32 pmol m2 s 1,) and
supplemental high light (SHL 73 pmol m2 s1)for chewings fescue ‘SR 5100’ (CF Festuca rubra v.
commutata) and creepinﬂed fescue "Dawson (CRF Festuca rubra v. rubra).

 

EL & ﬂ
Week CF CRF CF CRF CF CRF
3 0.698 0.718 0.628b 0.648 0.688 0.678
6 0.57c 0.57c 0.648 0.648 0.58b 0.540
9 0.67ab 0.668b 0.520d 0.51c 0.648b 0.638b
12 0.62bc 0.62b 0.51 d 0.54bc 0.60b 0.58bc
15 0.47d 0.51d 0.57bc 0.57c 0.10c 0.10d

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

48

Table 2. 9A Analysis of variance for red-edge vegetative index ((R714+R759)/(12- R733)) under
ambient light (AL 5-10 umol m2 51,) supplemental low light (SLL 32 umol m2 51), and
supplemental high light (SHL 73 umol m2 s1)for chewings fescue ‘SR 5100’ (CF Festuca rubra v.
commutata) 8nd creemeLred fescue Dawson’ (CRF Festuca rubra v. rubra).

 

AL §_L_L _S_HL
Source df MS F df MS F df MS F
F 1 0.00008 0.95ns 1 0.0001 1.56ns 1 0.004 4.1"
W 4 0.003 32.1“ 4 0.003 37.9“ 4 0.10 100"
S 1 0.0001 1.79ns 1 0.000002 0.02ns 1 0.003 2.88ns
F*W 1 0.00006 0.68ns 1 0.004 5.1 ** 1 0.0003 0.23ns
F*S 4 0.0006 639* 4 0.00009 1 .16ns 4 0.0008 0.90ns
S*W 4 0.00005 0.62ns 4 0.0003 3.81" 4 0.009 9.71"
F*W‘S 4 0.0002 2.74' 4 0.0001 2.47" 4 0.004 0.51ns
Error 219 0.00009 214 0.00008 222 0.0009

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
**, p < 0.01.
F, fructose; W, week; 8, Species.

Table 2. 98 Mean speciﬁc red edge vegetative index ((R714+R759)/(2- -R733)) at week ﬁfteen
under ambient light (AL 5—10 pmol m2 51,2) supplemental low light (SLL 32 pmol m2 31), and
supplemental high light (SHL 73 pmol m s1)for chewings fescue ‘SR 5100’ (CF Festuca rubra v.
commutata) and creepingred fescue D‘a’wson (CRF Festuca rubra v. rubra).

 

& §LL ﬂ'LL
Trt Q CRF CF CRF CF CRF
NF -0.03a -0.03a -0.048 -0.058 0.02b 0.03b
F1 -0.038 -0.028 -0.038 -0.048 0.078 0.098

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF, no fructose (control); F1, fructose 1x/week.

Table 2. QC Mean speciﬁc red edge vegetative index ((R714+R759)/(2- R7332) over time under
ambient light (AL 5- 10 pmol m2 51,) supplemental low light (SLL 32 pmol m 81,) and
supplemental high light (SHL 73 pmol m2 s1)for chewings fescue S‘R 5100’ (CF Festuca mbra v.
commutata) and creeping red fescue ‘Dawson (CRF Festuca rubra v. rubra).

 

& S_LL §ﬂ
Week CF CRF CF CRF CF CRF
3 -0.038 -0.028 -0.028 -0.028 -0.05b -0.04b
6 -0.028 -0.028 -0.03a -0.028 -0.06b -0.05b
9 -0.04b -0.04b -0.028 -0.028 -0.03b -0.03b
12 -0.04b -0.04b -0.038 -0.028 -0.04b -0.04b
15 -0.038 -0.038 -0.04b -0.04b 0.058 0.068

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05

level. Mean differences were determined by Tukey’s studentized range test.

49

Table 2.10A Analysis of variance for water band index (R900/R970) under ambient light (AL 5-
10 pmol m'2 3'1) and supplemental low light (SLL 32 umol m'2 s'1) for Kentucky bluegrass
‘glnthia’ (Poa platensis).

 

 

& S_LL
Source df MS F MS F
F 2 0.001 2.76ns 0.003 3.96ns
W 2 0.001 3.51* 0.02 26.2“
F*W 4 0.0007 1.89ns 0.0002 0.30ns
Error 99 0.0004 0.0008
Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;

**, p < 0.01.
F, fructose; W, week.

Table 2 108 Mean speciﬁc water band index (R900/R970) at2 week four under ambient light (AL 5-
10 umol m2 s 1)and supplemental low light (SLL 32 umol m2 s ) for Kentucky bluegrass
Qnthia’ (P08 pratensis).

 

 

Trt A]: SLL

NF 1.068 1.058
F1 1.078 1.038
F2 1.078 1.058

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF, no fructose (control); F1, fructose 1x/week; F2, fructose 2x/week.

a-coguuuuuung-nncc--n—n-------—-——---u-u---a--c-u--cg-----------u--—---cc-n--o-a-n----_---------------—-----—-----o

Table 2.10C Mean speciﬁc water band index (R900/R97 02) over time under ambient light (AL 5-10
umol m2 s1)8nd supplemental low light (SLL 32 pmol m s1)for Kentucky bluegrass ‘Cynthia’

 

 

(Poa pratensis).

Week AL SLL
1 1 .068 1 .088
2 1 .068 1 .03b
3 1 .078 1 .04b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

50

Table 2.11A Analysis of variance for photosynthetic reﬂective index ((R531-
R571)/(R531+R570)) under ambient light (AL 5- 10 umol m2 s1)and supplemental low light (SLL
32 umol m2 s1)for Kentucg bluggrass ‘Cynthia’ (P08 pratensisL

 

 

AL &
Souce df MS F MS F
F 2 0.05 4.99" 0.003 0.42ns
W 2 0.37 40.5" 0.85 - 128"
F*W 4 0.01 1.50ns 0.004 0.66ns
Error 99 0.009 0.007
Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;

**, p < 0.01.
F, fructose; W, week.

----------—--—--------—----—------------------_----_------------------_--—-------------—---—----------------------

Table 2.118 Mean speciﬁc photosynthetic2 reﬂective index ((R531-R571)/(R531+R570)) at week
four under ambient light (AL 5—10 umol m2 s ) and supplemental low light (SLL 32 umol m2 s 1)
for Kentucky bluegrass ‘Cynthia’ (Poa pratensis).

 

Trt AL s5;
NF -0.08a -0.01a
F1 -0.19b -0.0068

F2 -0.108b -0.0098

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF, no fructose (control); F 1, fructose 1x/week; F2, fructose 2x/week.

-------------------_----------_------------------—--------uoo----go---n-o-o-u-n-n-n-nn-ncnuu-pg-------------—-----

Table 2.11C Mean speciﬁc photosynthetic reﬂective index ((R531-R571)/(R531+R570) over time
under ambient light (AL 5-10 umol m2 s 1)and supplemental low light (SLL 32 pmol m s1)for
Kentucky bluegrass ‘Cynthia’ (Poa pratensis).

Week AL SLL

 

1 0.048 -0.38
2 -0.2b 0.03b
3 -0.1b 0.02b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

51

Table 2. 12A Analysis of variance for narrow band vegetative index 695 ((R970-
R695)/(R9720+R695)) under ambient light (AL 5- 10 umol m2 s 1)and supplemental low light (SLL
32 pmol m2 s1)for Kentucky bluegrass ‘Cynthia’ E08 pratensis).

 

 

AL _S_L_L
Source df MS F MS F
F 2 0.0006 0.45ns 0.007 3.20“
W 2 0.01 8.31“ 0.06 33.4“
F*W 4 0.0006 0.45ns 0.001 0.66ns
Error 99 0.001 0.002
Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; ‘, p < 0.05;

*“, p < 0.01.
F, fructose; W, week.

Table 2.128 Mean speciﬁc narrow band vegetative index 695 ((R970-R695)/(R970+R695)) at
week four under ambient light (AL 5-10 umol m2 s ) and supplemental low light (SLL 32 umol m
s ) for Kentucky bluegrass ‘Cny nthia’ (P08 pratensis).

 

Trt ALF SLL

NF 0.818 0.818
F1 0.838 0.78b
F2 0.818 0.77b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF, no fructose (control); F1 , fructose 1x/week; F2, fructose 2x/week.

Table 2.12C Mean speciﬁc narrow band vegetative index 695 ((R970- R695)/(R970-l-R695))_2 over
time under ambient light (AL 5-10 pmol m2 s1)8nd supplemental low light (SLL 32 umol m2 s 1)
for Kentucky bluegrass ‘Cynthia’ (P08 pratensis).

 

 

Week AL SLL

1 0.858 0.878
2 0.848 0.80b
3 0.82b 0.79b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

52

Table 2.13A Analysis of variance for narrow band vegetative index 700 ((R840-
R700)/(R8420+R700)) under ambient light (AL 5-10 umol m2 s 1)and supplemental low light (SLL
32 umol m2 s1)for Kentucky bluegrass ’Cynthia’ (P08 pratensis).

 

 

AL S_LL
Source df MS F MS F
F 2 0.0006 0.36ns 0.006 2.97ns
W 2 0.01 5.77“ 0.08 . 38.2“
F*W 4 0.001 0.61ns 0.001 0.58ns
Error 99 0.002 0.002
Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; ‘, p < 0.05;

**, p < 0.01.
F, fructose; W, week.

Table 2.138 Mean speciﬁc narrow band vegetative index 700 ((R840- -R700)/(R840+R700)) at
week four under ambient light (AL 5- 10 pmol m2 s 1)and supplemental low light (SLL 32 umol m2
s) for Kentucky bluegrass ‘Cynthia’ (P08 pratensis).

 

Trt AL SLL
NF 0.73a 0.74a
F1 0.77a 0.71a
F2 0.74a 0.71a

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF, no fructose (control); F1, fructose 1x/week; F2, fructose 2x/week.

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

Table 2.13C Mean speciﬁc narrow band vegetative index 700 ((R840- R700)/(R840+R700)).2 over
time under ambient light (AL 5- 10 pmol m2 s ) and supplemental low light (SLL 32 umol m2 s 1)
for Kentucky bluegrass ‘Cynthia’ (P08 pratensis).

 

Week AL SLL

1 0.78b 0.808
2 0.778b 0.72b
3 0.758 0.72b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

53

Table 2.14A Analysis of variance for red-edge vegetative index ((R714+R759)/(2-R733)) under
ambient light (AL 5-10 umol m'2 3'1) and supplemental low light (SLL 32 pmol m'2 s'1) for Kentucky
Mass ‘Cynthia’ (Poa pratensis).

& _LL
Source df MS F df MS F
F 2 0 0.03ns 2 0.00005 0.63ns
W 2 0.001 22.9" 2 0.0009 » 11.6"

F*W 4 0.00003 0.47ns 4 0.00006 0.72ns

 

 

Error 99 0.00006 99 0.00008
Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
“', p < 0.01.

F, fructose; W, week.

oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo

Table 2.148 Mean speciﬁc red-edge vegetative index ((R714+R759)/(2-R733)) at week four
under ambient light (AL 5-10 pmol m'2 5'1) and supplemental low light (SLL 32 umol m'2 s'1) for
Kentucky bluegrass ‘Cynthia’ foa pratensis).

 

Trt AL SLL

NF -0.03a -0.03a
F1 -0.03a -0.03a
F2 -0.03a -0.03a

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
NF, no fructose (control); F 1, fructose 1x/week; F2, fructose 2x/week.

Table 2.14C Mean speciﬁc red-edge vegetative index ((R714+R759)/(2-R733)) over time under
ambient light (AL 5-10 umol m'2 s’ ) and supplemental low light (SLL 32 umol m‘2 s'1) for Kentucky
bluegrass ‘Cynthia' (Poa pratensis).

 

Week AL SLL

1 -0.038 -0.028
2 -0.04b -0.03b
3 -0.038 -0.03b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

54

 

 

 

 

 

 

 

 

 

 

+AL
--O-~SHL
o "O.
o _.o-- o 1 O O
,..-O
O o 0 v
3- /‘ 1'2 2' 112/
,\ 2V~1
2‘ A /
x ' 1'
1..
0..
Nb 0 2 4 6 8 10 12 14 16
.E 6
_5 +AL
5-
4.1
3‘ o ................. o
O ................. O .................. O
21
k
1..
N
o T 1 1 1
0 2 4 6 8 10
Week

Figure 2.1 A) Year I beginning October 19, 2004 8nd 8) year ll beginning October 24, 2005 over
time (week) daily light integrals (DLI) mol m'2 (1'1 under ambient light (AL 40-200 mol m'2 s'1
ambient photoperiod); supplement high light (SHL ambient light plus 73 umol m' s'1 16-h
photoperiod using high pressure sodium (HPS) lights); and supplemental low light (SLL ambient
light plus 32 pmol m‘ s’1 16-h photoperiod using HPS lights).

55

 

 

 

 

 

6
+AL
5" “O"SLL
4-
O .............. 0.,
To 0 .............. O .............. O
0.1 3‘
E
B
E
2‘ ./.\\
#— A
1-1
0 1 F l l l
0 1 2 3 4 5 6
Week

Figure 2.2 Kentucky bluegrass ‘Cynthia’ (K8) (Poa pratensis) daily light integral (DLI) mol m'2 d'1
ambient light (AL 40-200 umol m' s'1 ambient photoperiod) and supplemental low light (SLL
ambient light plus 32 umol rn'2 s'1 16-h photoperiod using high pressure sodium lights) over time

(week).

56

 

 

 

 

 

 

 

 

 

+AL
--O--SLL
6d—T—SHL
44
2.
1E
(I) 02
E
S
a) A
:5) 8 I I I I I I I
a:
3
a:
c
'5.
e 6.
O
4.1
_O
//'\N‘\ ———--"“"V
2« / 2'
O ................ O
0* #—OF/\~O
B
0 2 4 6 8 10 12 14 16

Week

Figure 2. 3 A) Chewings fescue “SR 5100’ (Festuca rubra v. commutata) 8nd 8) creeping red
fescue ‘Dawson’ (Festuca rubra v. rubra) clipping weight (grams m) under ambient light (AL 40-2
200 pmol m2 s18mbient photoperiod), supplemental low light (SLL ambient light plus 32 umol m2
s1-16 h photoperiod using high pressure sodium lights), and supplemental high light (SHL
ambient light plus 73 umol m2 s1-16 h photoperiod using HPS lights) over time (week).

57

 

 

 

 

 

+AI.
.0,

q 64 .- -.
E
(D
E
e
O)
76 4-
CD
3
U)
.5
Q.
E}
o

2.1

O T T l l

0 1 2 3 4 5

Week

Figure 2.4 Kentucky bluegrass ‘C nthia’ (P08 pratensis) clipping weight (grams m'2) under
ambient light (AL 40-200 pmol m' s'1 ambient photoperiod) and supplemental low light (SLL
ambient light plus 32 umol m'2 s'1 16-h photoperiod using high pressure sodium lights) over time
(week).

58

Density: tillers cm'2

 

4.0 d

3.5 e

3.0 d

2.5 ~

2.0 -

1.5~

 

 

 

3.5 -

2.5 -

2.0 ~

1.5-

 

 

 

1.0

 

 

Week

—I

10

12

14

16

Figure 2. 5 A) Chewings fescue ’SR 5100’ (Festuca rubra v. commutata) and 8) creeping red
fescue ‘Dawson’ (Festuca rubra v. rubra) density (tillers cm 2) under ambient light (AL 40-2002
pmol m2 s18mbient photoperiod), supplemental low light (SLL ambient light plus 32 umol m2 s1
16- h photoperiod using high pressure sodium lights), and supplemental high light (SHL ambient

light plus 73 umol m2 s1-16 h photoperiod using HPS lights) over time (week).

59

1.1

 

 

 

 

 

1.0 ‘1 O
+ AL
0.9 —
0.4 0.8 '1
E
0
1’3
g 0.7 .
2}
'Z’
a; 0.6 “
C)
0.5 1
0.4 I I I I
0 1 2 3 4 5

Week

Figure 2. 6 Kentucky2 bluegrass ‘Cynthia’ (P08 pratensis) density (tillers cm 2) under ambient light
(AL 40- 200 2pmol m2 s18mbient photoperiod) and supplemental low light (SLL ambient light plus
32 umol m2 s11-6 h photoperiod using high pressure sodium lights) over time (week).

60

References

Beard, James B. 1973. Turfgrass: science and culture. Englewood Cliffs, New Jersey:
Prentice Hall.

Bell, G.E., T.K. Danneberger, and M.J. McMahon. 2000. Spectral irradiance available for
turfgrass growth in sun and shade. Crop Science 40:189-195.

Burris, J .S., R.H. Brown, and RE. Blaser. 1967. Evaluation of reserve carbohydrates in
rnidland bermudagrass (Cynodon dactylon L.). Crop Science 7:22-24.

Danneberger, T. Karl. 2003. Maintaining turf in shade: A Tough Environment. 73rd
annual Michigan turfgrass Conference Proc. Vol. 32, 2003, 21-22.

Dudeck, A.E. and CH. Peacock. 1992. Shade and Turfgrass Culture. In Turfgrass.
Agronomy No. 32.

Groteluxhen, RD. and Dale Smith. 1968. Carbohydrates in Grasses- III Estimations of
degree of polymerization of the fructosans in the stem bases of timothy and bromegrass
near seed maturity. Crop Science 82210-212.

Johnson, Samuel. 1993. Light as a Resource. In Danneberger: Turfgrass Ecology and
Management. F ranzak and Foster, Cleveland. 2: 25-34.

Koh, K.J., G.E. Bell, D.L. Martin, and NR. Walker. 2003. Shade and airﬂow restriction
effects on creeping bentgrass golf greens. Crop Science 43:2182-2188.

McBee, George G., and EC. Holt. 1966. Shade Tolerance studies on bermudagrass and
other turfgrasses. Agronomy Journal 58:523-525.

Morris, Kevin, Executive Director. National Turfgrass Evaluation Program (NTEP)
10300 Baltimore Ave. Bldg. 003, Rm. 218 Beltsville Agricultural Research Center-West,
Beltsville, Maryland 20705.

Penner, Donald, Richard Burow, and Frank Roggenbuck. 1998. Use of Organosilicone
Surfactants on Agrichemical Adjuvants in Silicone Surfactants. Surfactant Science
Series, Vol. 86: 241-258.

Sorochan, John C. 2002. Sugars in Shade: The Effects of Exogenous Fructose
Applications to Turfgrass under Reduced Light Conditions. Ph.D. Dissertation Michigan
State University, East Lansing.

Stier, John C. 1997. The Effects of Plant Growth Regulators on Kentucky bluegrass (Poa

pratnesis) and Supina bluegrass (Poa supina Schrad.) in Reduced Light Conditions.
Ph.D. Dissertation Michigan State University, East Lansing.

61

Stier, John C., and J .N. Rogers, III. 2001. Trinexapac-Ethyl and Iron Effects on Supina
and Kentucky Bluegrass Under Low Irradiance. Crop Science 41:457-465.

Wilson, J .R. 1997. Adaptive responses of grasses to shade: relevance to turfgrass for low
light environments. Int. T urfgrass Soc. Res. J. 8:575-591.

62

Chapter 3

Physiologic and Metabolic Effects on Various Turfgrasses Under Shaded Conditions
within a Growth Chamber

Abstract

Maintaining growth and quality of turfgrasses under shaded conditions is
challenging. Exogenous fructose applications were tested under low ambient light (14
umol m'2 5'1) and supplemental low light (40 pmol m'2 s'1) levels using chewings fescue
‘SR 5100’ (F estuca rubra v. commutata), creeping red fescue ‘Dawson’ (F estuca rubra
v. rubra), and Kentucky bluegrass ‘Cynthia’ (Poa pratensis) as model plant systems.
Results from this experiment suggest exogenous fructose applications had an effect on
density and dark respiration for the three species. Overall growth was positively affected
by supplemental low light compared to ambient light regardless of species. In addition,
light response curves suggest that exogenous ﬁ'uctose applications decrease
photosynthesis over time (week) regardless of light level. These data suggest that
exogenous fructose applications under ambient light (14 umol rn‘2 s'1) could not
supplement carbohydrates needed to maintain growth; and thus carbohydrate reserves
were being utilized to maintain respiration. Overall, supplemental low light (35 umol rn'2
s'1) produced better quality plants than any other treatment, suggesting the light energy
level was sufficient to maintain overall grth and photosynthesis. Species under
ambient light became increasingly stressed as indicated by metabolic indices, thus
suggesting that ambient light cannot sustain physiological and metabolic processes as

measured by these indices.

63

Introduction

Low light conditions impact physiological and metabolic qualities of turfgrasses.
Growing under shade decreases plant vigor, increases susceptibility to disease, reduces
wear tolerance, and reduces density (McBee, 1966; Dudeck et al., 1972). These changes
are associated with reduced light intensity because photosynthesis is reduced resulting in
a decrease in available total nonstructural carbohydrates (TNC) (Koh, 2003; Bunnel],
2005). Reduced light intensities (e. g. photosynthetic active radiation (PAR)) result in
detrimental growth and development that limit grth of roots, stolons, shoots, and
rhizomes (Dudeck et al., 1992; Johnson, 1993; Bell, 2000; Danneberger, 2003; Wilson,
1997; Beard, 1973).

To counteract the effects of low light conditions, applications of exogenous
fructose have been examined as a way to supplement low amount of carbohydrates. In
turfgrasses, fructans are the primary carbohydrate reserve in cool-season turfgrasses
(Sorochan, 2002; Groteluxhen et. al., 1968). Exogenous fructose applications may
supplement the loss of carbohydrates, speciﬁcally fructans, due to reduced photosynthesis
in low light conditions.

Understanding the impact of low light energy level can be difﬁcult in a ﬁeld-type
environment because there are many other factors that may interact with each other.
Thus, using controlled environments (8. g. growth chambers) to study reduced light
conditions on turfgrasses allows one to isolate the inﬂuence of speciﬁc environmental
factors on growth. For example, when Kentucky bluegrass and Zoysiagrass were grown
under three different PAR levels (11.1, 2.2, and 0.9 mol m“2 d'1) clipping weights were

directly related to daily light integral (DLI); clipping weights decreased as DLI decreased

64

(Cockerharn et al., 2002). The objective of this experiment was to examine the direct
interaction of light level, species, and exogenous fructose treatments on chewings fescue
‘SR5100’ (F estuca rubra v. commutata), creeping red fescue ‘Dawson’ (F estuca rubra v.
rubra), and Kentucky bluegrass ‘Cynthia’ (Poa pratensis) under controlled light
environments.

Materials and Methods

Experimental Site

Experiments were conducted using Econair® (Ecological Chambers Inc.,
Manitoba, Canada) growth chambers located on Michigan State University (MSU)
campus in East Lansing, Mich. The experiment was replicated in time with experiment I
initiated on 24 October 2005 and concluding 7 weeks later, experiment 11 initiated on 5
December 2005 and concluding 7 weeks later. The experiment was a split block design
with ﬁxed blocks and repeated measures.

Fifty-four four-inch square plastic pots (volume 1.05L) were ﬁlled with an 80:20
soil to sand mix and placed into research greenhouses on 26 September and 14 November
for experiment I and II, respectively. The greenhouse was set to 21°C and 45% RH. To
provide a constant soil temperature of 13°C the pots were placed onto a germination pad
that was thermostatically controlled. The pots were seeded with chewings fescue
‘SRSlOO’ (CF), creeping red fescue ‘Dawson’ (CRF), and Kentucky bluegrass ‘Cynthia’
(KB) at a rate of 15 g/ m2. At seeding a starter fertilizer was applied at a rate of 3g
phosphors (P)/ m2 and biweekly fertilizing (16N-25P-13K) took place thereafter. CF and
CRF species germinated within three weeks and KB germinated within three and half

weeks of seeding. During germination the pots were watered two to three times per week

65

to maintain consistent soil moisture. Each pot within each turfgrass species was
randomly assigned to a corresponding treatment. The treatments consisted of no fructose
(control- NF), exogenous fructose application one time per week (F1); and exogenous
ﬁ'uctose application two times per week (F2). Once the grasses were 75% germinated, or
3A of the pot was covered with turfgrass, the pots were placed into the grth chamber
and treatments were initiated. The pots were randomly placed into their respective light
level and allowed to acclimate for one week to their environment, prior to response
variable measurements, which began after the acclimation period. The growth chamber
was set to a temperature of 10°C, relative humidity of 70%, and a 12-hour photoperiod
using four 400W high-pressure sodium (HPS) lights. Inside the growth chamber two
structures were built so that shade cloth could be arranged for speciﬁc light energy levels.
The light energy levels achieved were 14 umol rn'2 s'1 using 70% shade cloth (Ludvig
Svennson, Charlotte, NC.) folded over twice (ambient light - AL) and 40 umol m'2 s'1
using 70% shade cloth folded over once (supplemental low light- SLL), both of which
correspond to light energy levels that were obtained under a simulated sports dome
environment (Chapter 2). A hand-held light meter (Spectrum Technologies, Model
BQM, Plainﬁeld, 111.) was used to verify consistent light energy levels for each light
treatment. There were three replications of each treatment and turfgrass species giving a
total of nine pots per grass and 27 pots per light treatment.
Fructose Treatment

Fructose (Isoclear®, Cargill Sweeteners, Naperville, Ill.) treatments began on 24
October and 5 December for experiments I and II, respectively, and were applied once or

twice per week depending on treatment speciﬁcation. Fructose was mixed with an

66

adjuvant (BreakThru®, Goldschmidt Chemical Corporation, Hopewell, Va.) and double
distilled water. The fructose was applied at a rate of 1.25% v/v and the adjuvant was
applied at a rate of 0. 1% w/v. A hand held 2mL sprayer was used to apply the fructose
and adjuvant mixture to the turfgrass canopy of designated pots.

Resgonse Variables

 

The following data were collected to determine the interaction between DLI,
fructose treatment, and/or turfgrass species: clipping yield, density, leaf area, and light
response curves. Collection of data began on 25 October and 5 December for
experiments I and II, respectively. Clipping yields correspond to cutting each individual
pot to a pre-determined height of 7.620m above the soil line of the container. Although
the pots were cut weekly, clippings were collected for analysis on a biweekly basis. The
clippings were then dried at 100°C in an oven for three days and weighed for dry content
that is expressed as grams/m2. To measure density tillers per cm2 were counted on an
identical pre-determined section measuring 5x5 cm of the 10.16xlO.16 cm pot biweekly.

Light response curves were evaluated using a LICOR 6400 portable
photosynthesis system biweekly beginning on 24 October and 5 December for
experiments I and II, respectively (LICOR® Biosciences, Lincoln, Nebr.). These
measurements are a non-destructive technology to evaluate the affects of fructose on
photosynthetic responses to varying light energy levels. The parameters of the LICOR
cuvette were: chamber 2x3 cm opaque needles light emitting diode (LED) light source,
carbon dioxide (C02) maintained at 400 umol/mol constant concentration, 10°C constant
temperature, and ﬂow rate 250 parts per million Qapm). These speciﬁc parameters were

used because the “needle” chamber measures a small amount of area, which corresponds

67

to the small area of turfgrass leaves measured. Six turfgrass leaves from each pot were
placed within the chamber of the LICOR and subjected to the AutoProgram ‘Light
Curve’ to determine photosynthesis rates at varying light levels. The program parameters
for each light level were: 1) photosynthetic active radiation (PAR) 500 250 100 60 45 30
15 0 mol m'2 3'1, 2) minimum wait time 30 seconds, 3) maximum wait time 100
seconds, 4) coefﬁcient of variation (total CV%) 0.05 to maintain mean stability, and 5)
match if reference C02 0 ppm different ﬁ'om C02 sample.
Gas exchange measurements were converted for actual leaf area since the grasses

did not cover the entire leaf chamber. Six leaves in the chamber were removed from each
plant and stored for calculation of leaf area. Leaf area was calculated by measuring the
width of the leaves under a dissecting microscope set at 64x for each leaf and an average
was calculated to determine leaf area per plant. The leaf area equation used to determine
correction factors is as follows:

100 units at 64x= A m

B units x (A mm/100)= Cmm/10=D cm

6 leaves x D cm x 3cm (width chamber) = E cm2
A corresponds to millimeter length of samples as measured by the microscope; B
corresponds to how many units the sample measured from the microscope ruler; C
corresponds to the sample measurement now in millimeters; D corresponds to the sample
in centimeters; and E corresponds to the total sample area within the chamber. Each
individual correction was recorded for used to process LICOR output for each

measurement.

68

Once all measurements were taken using the LICOR AutoProgram, the data was
downloaded using the LICOR software and inputted into Microsoft Excel (Microsoft
Corp., Redmond, Wash). The following parameters were calculated using the LICOR
‘Light Curve’ program: photosynthetic rate (photo), area 2cm2 constant, and
photosynthetically active radiation (PAR) in (PARi).

Once all leaf measurements were calculated, light response curves were

determined using the following equation:

 

A = (90 + Amax - \/((00 + Amax)2 -4(kaAmax - Rd
2k

with Photosyn Assistant (Dundee Scientiﬁc, Scotland, UK). From the ‘Light Curve’
output from Excel photo, PARi, and light level (Q umol m‘2 s'1) were used to determine
assimilation (A pmol C02 rn'2 s'1): apparent quantum efﬁciency ((0 umol C02 ﬁxed/mol
PPF), maximum assimilation (Amax mmol C02 m'2 3'1), convexity (k), dark respiration
(Rd umol m‘2 S"), and light compensation point (LCP umol C02 m'2 5'1). Using the
variables calculated and the ‘Light Curve’ output, Photosyn Assistant calculated
corresponding light response curves for each turfgrass.

Statistical Analysis

 

Species and fructose treatments were compared within each light energy level
using Proc ANOVA with Tukey’s adjustment (SAS, 2000). The light energy level
measured was calculated into daily light integral (DLI mol m'2 d'1) and used for statistical
analysis for light treatment inﬂuence. Clipping weights between experiments I and H
were signiﬁcantly different. However, over time experiments I and H showed similar

trends, therefore, only results from experiment I will be reported. There were no

69

signiﬁcant differences between experiments I and II for all other variables, therefore
means were combined. In addition, Pearson’s correlation coefﬁcients were prepared to
assess the relationship of the response variables (SAS, 2000).
Results

The application of exogenous fructose had a signiﬁcant affect on CF, CRF, and
KB tiller production (density) and dark respiration (Rd) under AL (Tables 3.2A and
3.8A). However, there were no signiﬁcant differences in clipping weight, leaf area, net
photosynthesis (Pn), maximum photosynthetic rates (Amax), and quantum efﬁciency (Q)
for turfgrass species treated with exogenous fructose (Tables 3.1A, 3.3A, 3.4A, 3.5A,
3.6A, 3.7A). There were signiﬁcant affects on growth and metabolism of CF, CRF, and
KB due to available light energy (PAR). There were also signiﬁcant interactions between
species, fructose, and time for each of the parameters measured.
Daily Light Integral

Daily light integral (DLI mol m'2 d'1) was not signiﬁcantly different over time
(weeks) regardless of experiment and light level (data not shown). SLL had two point
ﬁve percent higher DLI values than AL regardless of week (Figure 3.1). Under AL DLI
was positively correlated to turfgrass leaf area for CF (r = 0.76) and KB (r = 0.74) (p-
value < 0.0001) and negatively correlated to turfgrass quality for CF (p-value < 0.0001, r
= -0.53); and under SLL DLI was positively correlated to leaf area for KB (p-value <
0.01, r = 0.55).
Clipping Weight

Clipping weights (gm m'2) were signiﬁcantly different for all species over the

duration of the experiment when grown under AL and SLL (Table 3.1A). Clipping

70

weights for all species decreased over time under both light levels (Table 3.1C and Figure
3.2). Species was signiﬁcantly different under SLL (Table 3.1A). Kentucky bluegrass
maintained greater clipping weights compared to CF and CRF (Table 3.13). There was a
two fold increase in clipping weights as light energy level increased from AL to SLL for
all turfgrass species (Table 3.1B). Under AL clipping weight was negatively correlated
to leaf area for species CRF (p-value < 0.01, r = -0.51).

Dim

Tiller production (density) for plants grown under AL responded signiﬁcantly to
the application of exogenous fructose (Table 3.2A). For CF, density was greatest for the
control plants (NF), followed by F1 and F 2, respectively (Table 3.2B). Density for CRF
and KB was greatest for plants that received F1 treatments, followed by F2 and NF
treatments, respectively (Table 3.28).

For plants grown under SLL tiller production was signiﬁcantly different over the
duration of the experiment (Table 3.2A). Densities for all species increased over time
(Table 3.2C and Figure 3.3). Under both light levels there was a signiﬁcant difference
between species (Table 3.2A). Kentucky bluegrass maintained two percent higher tiller
production then CF and CRF (Table 3.2B). Under both light levels there was a
signiﬁcant interaction between fructose applications and species (Table 3.2A). Available
light had a greater impact on density than exogenous fructose applications as illustrated
by the one to three fold increase in density as light energy level increased from AL to
SLL (Table 3.2B). Under SLL density was positively correlated to turfgrass leaf area for
CRF and KB (p-value < 0.0001, r = 0.53), suggesting that under SLL as density

increased, turfgrass leaf area was positively affected.

71

Leaf Area

Leaf area (cm2) for all plants grown under AL and SLL were signiﬁcantly
different over the duration of the experiment (Table 3.3A and 3.3C). Leaf area for both
CF and CRF decreased over time under both light energy levels. While KB grown under
AL decreased and KB grown under SLL increased over time (Table 3.3C and Figure 3.4).
Under both light energy levels there was a signiﬁcant difference between species (Table
3.3A). Kentucky bluegrass maintained one to two percent greater leaf area than CF and
CRF (Table 3.3B). There was an approximate two fold increase in leaf area as light
energy level increased from AL to SLL for CRF and KB (Table 3.3B). Under AL, leaf

area was negatively correlated to clipping weight CRF (p-value < 0.01, r = -O.51).

 

I_._ight Response Curves
Amax

Maximum assimilation (Amax mmol C02 rn'2 s'1) for plants grown under AL was
signiﬁcantly different over time (weeks) (Table 3.4A and 3.4C). Maximum assimilation
decreased for CF and KB and increased for CRF over the duration of the experiment
(Table 3.4C). The interaction between exogenous fructose applications and time for
plants grown under SLL was signiﬁcant (Table 3.4A). Maximum assimilation increased
over time for plants applied with fructose once per week and the controls, while Amax
decreased for plants applied with ﬁ'uctose two times per week (Appendix II). There was
a signiﬁcant interaction between species and time for plants grown under SLL (Table
3.4A). Maximum assimilation increased within the ﬁrst week and then decreased over
the following weeks of the experimentation (Appendix 11). Under each light energy

level, KB maintained two percent higher Amax compared to CF and CRF (Table 3.4B).

72

There was a one to four fold increase in Amax as light energy level increased from AL to
SLL for all species (Table 3.48).
Quantum Eﬁ‘iciency

Plants grown under AL had a signiﬁcant difference in quantum efﬁciency (Q
umol C02 m'2 s'1/mol PPF) over time (weeks) (Table 3.5A). The efﬁciency of quantum
utilization decreased over time for all species (Table 3.5C) under the earlier speciﬁed
levels of PAR. There were slight differences in Q between AL and SLL for all turfgrass
species (Table 3.5B).
Light Compensation Point

Light compensation point (LCP umol m'2 s'1) for plants grown under AL was
signiﬁcantly different over time (weeks) (Table 3.6A). Light compensation point
increased for all species over the duration of the experiment (Table 3.5C). There was a
one to three fold increase in LCP as light energy level increased from AL to SLL for KB
and CF (Table 3.6B).
Dark Respiration

Dark respiration (Rd pmol C02 m'2 5'1) for KB grown under AL responded
signiﬁcantly to applications of exogenous fructose (Table 3.7A). The control (NF) plants
maintained greater Rd rates, followed by F l and F2, respectively (Table 3.7B). Dark
respiration rate for plants grown under AL were signiﬁcantly different over time (weeks)
(Table 3.7A and 3.7C). Dark respiration rate decreased within the ﬁrst two weeks and
then increased over the following experimentation (Table 3.7C). There were signiﬁcant
differences between species Rd (Table 3.7A). Kentucky bluegrass maintained two to ﬁve

percent higher Rd rates when grown under AL, and maintained two percent higher Rd

73

rates when grown under SLL than CF and CRF (Table 3.7B). There was a ﬁve fold
increase in Rd as light energy level increased from AL to SLL for all species (Table
3.7B).

Light Response Curves

Under AL all turfgrasses were able to maintain positive assimilation (A umol C02
m'2 5'1) rates through week ﬁve of the experiment (Figure 3.5). However, each individual
turfgrass species varied in A rates week by week. At week three and ﬁve there were no
signiﬁcant differences in A between the three turfgrass species (data not shown). At
week three CF maintained higher A rates compared to KB and CRF (Figure 3.5A). By
week ﬁve all three species decreased in A (Figure 3.5B). By week seven, there were
signiﬁcant difference in turfgrass species (p-value < 0.01), with CRF and CF possessing
two point ﬁve percent higher A rates compared to KB (Figure 3.5C).

Under SLL all turfgrass species were able to maintain positive rates of
photosynthesis through the seven weeks of the experiment (Figure 3.6). Over the
duration of the experiment there were signiﬁcant differences between turfgrass species
(p-value < 0.01) (data not shown). At week three CF possessed two percent higher A
rates compared to both KB and CRF (Figure 3.6A). By week ﬁve KB possessed one
point ﬁve percent higher A rates compared to CRF and three percent higher A rates
compared to CF (Figure 3.6B). By week seven CRF and KB possessed three percent
higher A rates compared to CF (Figure 3.6C).

Discussion
Exogenous fructose treatments had a positive affect on plant density and dark

respiration rate under 14pmol m’2 s'1 for all three turfgrass species. Dark respiration was

74

highest for the control plants of all three species, suggesting that exogenous fructose
applications assisted the turfgrass species adaptation to extreme low light conditions.
This supports the improved metabolic efﬁciency of the species under simulated dome
conditions (Chapter 2).

Turgrass growth increased as available PAR increased; when the turfgrasses were
grown under supplemental light of 40 umol m'2 s'1 a greater signiﬁcant positive response
occurred. As measured under simulated dome conditions, the minimum critical PAR for
turfgrass maintenance and grth appears to be greater than 3-10 umol rn'2 s'1 and may
fall between the light energy level provided in the AL (14 pmol m'2 3'1) and SLL (40
umol m’2 s'1) levels.

When the three turfgrasses were grown under AL, KB initially had improved
efﬁcient utilization of available PAR compared to CF and CRF. Over time CF and CRF
were able to acclimate to the low light conditions within this experiment, while KB did
not acclimate as illustrated by the negative assimilation rates obtained by KB by week
seven. This supports the research of the turfgrasses under shaded conditions that showed
the photosynthetic features of the turfgrass species were associated with differences in
shade tolerance (Van Huylenbroeck and Van Bockstaele, 2001). This suggests that the
idea that species selection may be the largest factor in determining turfgrass success for
shaded conditions.

When turfgrasses were grown under supplemental low light for long periods of
time they were able to maintain positive assimilation rates over the duration of the
experiment. The results from this work supports similar results from sports simulated

dome work (Chapter 2), which showed that growth and metabolism of turfgrasses grown

75

under the light energy level of SLL were higher than the same variable measured under
lower (AL) light energy (Chapter 2). In addition, total non-structural carbohydrates were
greatly inﬂuenced by turfgrass species under shaded conditions supporting the idea that
improved photosynthetic capacity of the individual species greatly affects improved
shade tolerance (Bunnell, 2003). This is supported by the fact that under both AL and
SLL the individual A rates of the three turfgrass species decreased as the experiment
lengthened (Figure 3.5 and 3.6), suggesting that the three turfgrass species adapted to the
low light conditions (AL), thus decreasing their individual potential Amax.

In addition, it was observed that the LCP for each individual turfgrass decreased
as the experiment lengthened. This result is expected, since an adaptation to low light
conditions (i.e. shade) is lower LCP and ultimately lower Amax potential (Beard, 1973).
In fact, Kentucky bluegrass ‘Merion’ and red fescue ‘Pennlawn’ grown under three
different levels of shade had decreased LCP values as shade level increased (Wilkinson et
al., 1974). The differences in photosynthetic rates between species may be due to total
leaf area of each turfgrass species. Jones (2006) found that net photosynthesis (umol
C02 m'2 s'1) of various ﬁrs (Abies spp.) increased with needle thickness and shape,
resulting in different photosynthetic measurements among species. In this study, KB had
larger leaf area and consistently higher photosynthetic rates than either of the fescue
turfgrasses regardless of light treatment.

The results combined suggest that KB grown under shaded conditions initially
was able to maintain photosynthesis more efﬁciently than the other turfgrasses and that
carbohydrate reserves were being utilized to maintain growth, regardless of exogenous

fructose treatment and light energy level. Collectively, the results suggest that SLL is

76

more efﬁcient to maintain growth regardless of species and treatment, and that increasing
light levels at these low PAR values have a positive effect on the plant.
Conclusion

In summary, exogenous fructose applications positively affected density and dark
respiration rate of the turfgrass species under AL, but did not signiﬁcantly affect any of
the other response variables measured under the two light energy levels within this work.
Supplemental low light was sufﬁcient to maintain overall grth of the species, although
initially KB performed better than CF and CRF, thus species can be a large factor in
determining light and exogenous ﬁ'uctose application efﬁciency.

Light response curve data suggests CF and CRF were able to acclimate to ambient
light (14 umol m'2 s'1) conditions compared to KB regardless of exogenous fructose
applications. Additionally, the data indicate that under supplemental low light (40 umol
rn'2 s") all three turfgrass species within this experiment were able to maintain overall
photosynthesis over the duration of the experiment, thus increasing growth compared to
turfgrasses grown under ambient light (14 umol m’2 s'1).

In conclusion, exogenous fructose applications had little positive physiological
response regardless of species under ambient light (14 pmol m'2 5'1). Species type and
light energy level to drive photosynthesis had the most inﬂuence on growth and
metabolism and suggest that species is a contributing factor in determining overall
grth and quality under shaded conditions. This research suggests there may be a light
energy level threshold between 14 and 40 umol m'2 s'1 that exogenous fructose

applications may be most efﬁcient in increasing growth of the three species.

77

Table 3.1A Analysis of variance for clipping2 weight (grams m 2) under ambient light (14 umol m2

s ) and supplemental low light (40 pmol m2 s ) for chewings fescue ‘SR 5100’ (CF Festuca rubra
v. commutata), creeping red fescue ‘Dawson (CRF Festuca rubra v. rubra), and Kentucky
bluggrass ‘Cynthia’ (K8 P08 pratensis).

 

AL 5;
Source df MS F MS F
F 2 7.2 0.84ns 4.56 1.06ns
W 2 143.6 16.8" 23.6 5.51 *
S 3 16.6 1.94ns 55.0 12.8"
F*W 6 17.2 2.01 ns 1.37 0.32ns
F*S 4 0.73 0.08ns 4.50 1.05ns
SW 6 7.24 0.84ns 6.90 1.61 ns
F*W‘S 12 5.02 0.59ns 2.25 0.53ns
Error 180 8.57 4.29

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; ', p < 0.05;
", p < 0.01.
F, fructose; W, week; S, species.

Table 3.18 Mean speciﬁc clipping weight (grams m) at week seven under ambient light (14 pmol
m2 s1)and supplemental low light (40 pmol m2 s1)for chewings fescue ‘SR 5100’ (CF Festuca
rubra v. commutata), creeping red fescue ‘D’awson (CRF Festuca rubra v. rubra), and Kentucky
blugrass ‘Cynthia’ (K8 Poa pratensis).

& iL
Trt CF CRF K8 CF CRF K8
NF 0.618 0.418 0.698 1.698 1.848 3.968
F1 0.388 0.548 0.618 1.188 2.468 4.268
F2 0.258 0.358 0.498 0.818 1.788 3.608

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F 1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

o---------nun-------------------n-u---onn---ocouo-----------------------------uncnouccnunocouccnoco. uuuuuuuuuuuuuu

Table 3.1C Mean speciﬁc clipping weight (grams m) over time and by species under ambient
light (14 umol m2 s1)and supplemental low light (40 pmol m2 s1)for chewings fescue ‘SR 5100'
(CF Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra),
and Kentucky bluegrass ‘Cynthia' (K8 Poa pratensis).

 

 

Week AL SLL Species AL SLL
1 4.048 3.788 CF 1.928 1.93b
3 2.668 2.858b CRF 1 .638 2.948
5 0.98b 2.39b K8 2.568 3.678
7 0.47b 2.36b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

78

Table 3. 2A Analysis of variance for 21density (tillers cm 2) under ambient light (14 umol m2 s ) and
supplemental low light (40 umol m2 s ) for chewings fescue ‘SR 5100’ (CF Festuca rubra v.
commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra), and Kentucky
bluegrass ‘Cynthia’ (K8 Poa pratensis).

 

AL &
Source df MS F MS F
F 2 1.04 6.44” 0.18 1.00ns
W 2 0.30 1.84ns 6.00 33.7*
S 3 9.13 56.4“ 19.5 109*
F*W 6 0.22 1.37ns 0.05 0.31ns
F*S 4 0.65 3.99" 0.91 5.13"
SW 6 0.07 0.42ns 0.26 1.45ns
F'W“S 12 0.15 0.90ns 0.09 0.53ns
Error 180 0.16 0.18

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
“, p < 0.01.
F, fructose; W, week; S, species.

Table 3. 28 Analysis of variance for density (tillers cm) at week seven under ambient light (14
umol m2 s1)8nd supplemental low light (40 pmol m2 s1)for chewings fescue ‘SR 5100’ (CF
Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra), and
Kentucky bluegrass ‘Cynthia’ (K8 Poa pratensis).

 

 

& §LL
Trt g CRF K8 CE CRF _K§
NF 0.978 0.54b 1.62b 1.518 1.168 2.048
F1 0.908b 0.998 1 .598 1 .268 1 .298 2.648
F2 0.65b 0.578 1.218b 1.158 1.318 2.728

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

Table 3. 20 Analysis of variance for density (tillers cm 2) over time and by species under ambient
light (14 pmol m2 s 1)and supplemental low light (40 pmol m2 s1)for chewings fescue ‘SR 5100’
(CF Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra),
and Kentucky bluegrass ‘Cynthia’ (K8 P08 pratensis).

 

 

Week AL SLL Species AL SLL

1 0.848 0.86c CF 0.80b 1.00b
3 0.998 1.25b CRF 0.64b 0.95b
5 0.888 1.31 b K8 1.328 1.878
7 1 .008 1 .688

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

79

Table 3. 3A Analysis of variance for leaf area (cm2 ) under ambient light (14 pmol m2 s1)and
supplemental low light (40 pmol m2 s1)for chewings fescue ‘SR 5100’ (CF Festuca mbra v.
commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra), and Kentucky
bluegrass ’Cynthi8’(KB Poa pratensis).

 

 

& .3;
Source df MS F MS F
F 2 0.002 0.13ns 0.002 0.17ns
W 2 0.07 6.30“ 0.06 5.16“
S 2 0.09 7.72" 0.23 18.3"
F*W 4 0.01 0.90ns 0.01 0.65ns
F*S 4 0.02 1 .47ns 0.01 0.87ns
SW 4 0.01 0.73ns 0.01 0.86ns
F*W‘S 8 0.01 0.70ns 0.01 0.95ns
Error 135 0.01 0.01
Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; ", p < 0.05;
". p < 0.01.

F, fructose; W, week; S, species.

Table 3. 38 Mean speciﬁc leaf area 2(cm2 )8t week seven under ambient light (14 umol m2 s1)and
supplemental low light (40 umol m2 s ) for chewings fescue ‘SR 5100’ (CF Festuca rubra v.
commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra), and Kentucky
bluegrass ‘Cynthia’ (K8 Poa pratensis).

 

& ﬂ-L
Trt CF CRF K8 CF CRF K8
NF 0.408 0.348 0.478 0.438 0.418 0.538
F1 0.458 0.408 0.438 0.398 0.398 0.488
F2 0.408 0.338 0.508 0.398 0.378 0.638

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey‘s studentized range test.
F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

Table 3. 3C Mean speciﬁc leaf area (cm2 )over time and by species under ambient light (14 pmol
m2 s1)and supplemental low light (40 umol m2 s1)for chewings fescue ‘SR 5100' (CF Festuca
mbra v. commutata), creeping red fescue Dawson’ (CRF Festuca rubra v. rubra), and Kentucky
bluggrass ‘Cynthia’ (K8 Poa pratensis).

 

 

 

Week AL SLL Species AL SLL

3 0.478 0.508 CF 0.42b 0.43b
5 0.391) 0.44b CRF 0.380 0.41b
7 0.41b 0.44b KB 0.478 0.538

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

80

Table 3. 4A Analysis of variance maximum assimilation (mmol 002 m2 s 1) under ambient light (14
pmol m2 s1)and supplemental low light (40 pmol m2 s )for chewings fescue ‘SR 5100’ (CF
Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. mbra), and
Kentucky blugrass ‘Cynthia’ (K8 Poa pratensis).

 

AL &
Source df MS F MS F
F 2 0.63 1.76ns 1 .44 1 .77ns
W 2 2.73 7.67" 1.79 2.20ns
S 2 0.05 0.01ns 0.68 0.84ns
F’W 4 0.38 1.06ns 3.03 3.72'
F*S 4 0.25 0.69ns 0.59 0.72ns
S*W 4 0.34 0.97ns 2.9 3.60“
F*W‘S 8 0.43 1 .22ns 0.34 0.42ns
Error 135 0.36 0.81

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
“, p < 0.01.
F, fructose; W, week; S, species.

.oonnao----------------------o---—---—--------------_-_------------------_--u—-u-_--o-n-----o-----p----------o---a

Table 3.48 Mean speciﬁcz maximum assimilation (mmol CO2 m2 s ) at week seven under
ambient light (14 pmol m2 s1)and supplemental low light (40 umol m2 s1)for chewings fescue
‘SR 5100’ (CF Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v.
rubra), and Kentucky bluegrass ‘Cynthia’ (K8 P08 pratensis).

AL §_LL
Trt CF CRF K8 CF CRF K8
NF 0.718 0.488 0.528 0.688 0.888 1.238
F1 0.468 1.458 0.418 0.568 1.618 1.518
F2 0.478 0.248 0.288 0.738 0.918 1 .088

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F 1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

*0---¢-‘GOG------OOCCC‘CCCOCD—OD-‘0b-.-0--.-0G.-00--O---In-O-O-OuaoﬂoOOCQCOC-s.OOO--9O-QCOQC‘OOOO-Qﬂ-‘OD-O‘.-OC .....

Table 3. 40 Mean speciﬁc maximum assimilation (mmol CO2 m2 s ) over time under ambient light
(14 pmol m2 s 1)chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata), creeping red
fescue ‘Da’wson (CRF Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (K8 Poa
gatensisL

 

Week AL

3 0.718
5 0.26b
7 0.558b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

81

Table 3. 5A Analysis of variance quantum efﬁciency (umol CO2 m2 3 1/mol PPF) under ambient
light (14 umol m s1)and supplemental low light (40 umol m2 s1)for chewings fescue ‘SR 5100’
(CF Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra),
and Kentucky bluegrass ‘Cynthia’ (K8 Poaﬁatensis).

 

& &

Source df MS F MS F

F 2 0.004 0.08ns 5429 1.00ns
W 2 0.51 10.9“ 5388 1.00ns
S 2 0.01 1 0.24ns 5422 1.00ns
F*W 4 0.003 0.07ns 5396 1 .0008
F‘S 4 0.01 0.27ns 5422 1.00ns
S*W 4 0.01 0.21ns 5403 1.0008
F*W‘S 8 0.01 0.30ns 5399 1 .0008
Error 135 0.47 5407.

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
“, p < 0.01.
F, fructose; W, week; S, species.

oooounocuua—uuoooocquonun—vo----—-.~—-———---—--—-_---p--—------------a-----unno-¢~-----------u-u-u-u-ocoooonnoooc .....

Table 3. 58 Mean speciﬁc 2quantum efﬁciency (umol CO2 m2 s1lmol PPF) at week seven under
ambient light (14 umol m2 s ) and supplemental low light (40 pmol m2 s1)for chewings fescue
‘SR 5100’ (CF Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v.
rubra), and Kentucky bluegrass ‘Cynthia’ (K8 P08 pratensis).

 

& &
Trt CF CRF KB 95 CRF K8
NF 0.068 0.0018 0.00048 0.0078 0.148 0.028
F1 0.0018 0.018 0.0018 0.158 0.018 0.288
F2 0.0018 0.00018 0.0018 0.018 0.018 0.018

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

.------------------------------------------—-----------_-u-------u-------------~------—-—-------------—-----------

Table 3. 50 Mean speciﬁc 2quantum efﬁciency (umol CO2 m2 s1/mol PPF) over time under
ambient light (14 pmol m2 s) for chewings fescue ‘SR 5100’ (Festuca rubra v. commutata),
creeping red fescue ‘D’awson (Festuca rubra v. rubra), and Kentucky bluegrass C‘ynthia’ (Poa
pratensis).

 

Week AL

3 0.01b
5 0.178
7 0.01 b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

82

Table 3. 6A Analysis of variance light compensation point (pmol m'2 s'1) under ambient light (14
pmol m2 s ) and supplemental low light (40 umol m s'1) for chewings fescue ‘SR 5100’ (CF
Festuca rub/8 v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra), 8nd
Kentuckyblueggss ‘Cynthia’ (K8 Poa pratensis).

 

 

& 8_LL
Source df MS F MS F
F 2 1402 0.72ns 1643 1.92ns
w 2 10074 5.19* 79.9 0.09ns
S 2 307 0.16ns 55.2 0.06ns
F*W 4 1693 0.87ns 565 0.66ns
F*S 4 1484 0.76ns 694 0.81ns
S*W 4 743 0.38ns 416 0.49ns
F*W*S 8 594 0.31ns 265 0.31ns
Error 85 1942 855
Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
", p < 0.01.

F, fructose; W, week; S, species.

.------_---------_-----——-___-———-—----------------------—-—------o—o--——-u--o--------o-a-oo----------------------

Table 3. 68 Mean speciﬁc light compensation point (umol m2 s'1)18t week seven under ambient
light (14 umol m2 s'1)8nd supplemental low light (40 pmol m2 s1)for chewings fescue ’SR 5100’
(CF Festuca rubra v. commutata), creeping red fescue ‘Dawson' (CRF Festuca rubra v. rubra),
and Kentucky bluegrass ‘Cynthia’ (K8 Poa pratensis).

& &
Trt CF CRF K8 CF CRF K8
NF 45.68 24.58 28.38 25.28 22.38 16.88
F1 71.88 71.68 69.88 11.08 33.18 39.48
F2 32.38 65.48 39.58 35.38 31.88 24.38

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey's studentized range test.
F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

Table 3. 60 Mean speciﬁc light compensation point (umol m2 s ) over time under ambient light
(14 umol m2 s1)for chewings fescue ‘SR 5100’ (Festuca rubra v. commutata), creeping red
fescue ‘Dawson’ (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (Poa pratensis).

Week AL

 

3 23.4b
5 21 .8b
7 52.88

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

83

Table 3. 7A Analysis of variance for dark respiration gu umol C02 m2 s 1) under ambient light (14
umol m2 s1)8nd supplemental low light (40 umol m s1)for chewings fescue ‘SR 5100’ (CF
Festuca rubra v. commutata), creeping red fescue "Dawson (CRF Festuca rubra v. rubra), and
Kentucky bluegrass ‘Cynthia’ (K8 P08 pratensis).

 

& _LL
Source df MS F MS F
F 2 0.27 405* 0.17 1.10ns
w 2 1.25 18.7“ 0.06 Ons
S 2 0.22 3.26“ 0.06 0.38ns
F*W 4 0.11 1.64ns 0.0001 0.29ns
F*S 4 0.05 0.79ns 0.26 1.69ns
S*W 4 0.04 0.61ns 0.05 0.30ns
F*W‘S 8 0.03 0.46ns 0.10 0.64ns
Error 135 0.67 0.16

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
*“, p < 0.01.
F, fructose; W, week; S, species.

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

Table 3. 78 Mean speciﬁc dark respiration (umol CO2 m2 2's ) at week seven under ambient light
(14 pmol m2 s1)and supplemental low light (40 umol m2 s1)for chewings fescue ‘SR 5100’ (CF
Festuca rubra v. commutata), creeping red fescue ‘Dawson (CRF Festuca rubra v. rubra), and
Kentucky blugass ‘Cynthia’ (K8 P08 pratensis).

 

& &
Trt Q CRF K; g CRF ﬂ
N F 0478 -0.188 -0.65b -0.1 58 -0.218 -0.488
F1 -0.21a -0.24a -0.31 ab -0.128 -0.588 0198
F2 0188 -0.048 -0.138 -0.578 -0.228 -0.208

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

Table 3. 7C Mean speciﬁc2 da1rk respiration (umol CO2 m2 s ) over time and by species under
ambient light (14 pmol m2 s1)for chewings fescue S‘R 5100' (Festuca rubra v. commutata),
creeping red fescue "D8wson (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (Poa
matensis).

 

 

Week AL Species AL

3 -0.27 b CF 021 b
5 -0.01 a CRF -0.11 a
7 -0.27 b KB 023 b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

84

 

2.2

 

 

 

.O.
O ......
O O .......

2.0‘1'11111'017111110 "-0
f 1.8-
1E
E 1.6~
E1
C)
33 1.4“
.E
8
= 1.2-
3
"('6
O

1.0“

“O“SLL
0.6 l I l l j T I
o 1 2 3 4 5 5 7 8
Week

Figure 3.1 Daily light integral (DLI mol m'2 d'1) combined experiment means of ambient light (AL-
14 pmol m'2 3'1) and supplemental low light (SLL- 40 umol m'2 5'1) with 12 hour photoperiod using
high pressure sodium lights in Econair® growth chamber.

85

10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A
c)‘ a
E
(D
g
t. 8-4
C}
‘3‘.
.C
.9)
§ 6‘
C)
E
e 4‘
0
2-1
8-4
6—4
~-o
4—4
2—
C
——o
o ' I I V I V '
0 1 2 3 4 5 6 7 8

Week

Figure 3.2 Clipping weights (grams/m2) experiment I combined fructose and control treatment
under ambient light (AL- 14 pmol m'2 s") and supplemental low light (SLL- 40 pmol rn'2 s") for A)
chewings fescue “SR 5100’ (CF) (Festuca rubra v. commutata), B) creeping red fescue ‘Dawson’
(CRF) (Festuca rubra v. rubra), and C) Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

86

 

 

 

 

 

 

 

 

 

 

3.0
2.5-l
2.0-
15‘
..Q
10‘ ._._...o ...................... o
0,5~ I A
25‘
2.0-1
NI
E
an 1.5-
t—
: ........ 0..
a 1‘o-ﬁ O .............
8 _ W
Q 05‘ M
+AL B
"0- SLL
2.5— “O
2.0- ‘-
O ...................... O
1.5a
DIN/V.
1.0-l
0.5a C
00 I I I I T T I
O 1 2 3 4 5 6 7 8

Week

Figure 3.3 Density (tillers/cm? combined fructose and control treatment and experiment under
ambient light (AL- 14 pmol m' s“) and supplemental low light (SLL- 40 umol rn'2 s") for A)
chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), B) creeping red fescue ‘Dawson’
(CRF) (Festuca rubra v. rubra), and C) Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

87

 

0.55 a

0.50 —

0.45 -l

0.40 -‘

 

 

0.55 d

0.50 -

0.45 d

0.40 ~

 

Leaf Area: cm2

+AL
“O“ SLL

 

 

 

0.55 -‘

0.50 -

 

0.45 a

0.40 -

0.35 — C

 

 

q
.1

 

0.30 r
2 3 4 5 6 7 8

Week

Figure 3.4 Leaf area (cm2) Combined fructose and control treatments and experiment under
ambient light (AL- 14 pmol m'2 s") and supplemental low light (SLL- 40 pmol rn'2 s") for A)
chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), B) creeping red fescue ‘Dawson’
(CRF) (Festuca rubra v. rubra), and C) Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

.4

88

 

 

 

 

 

 

 

 

 

 

 

 

1.0 «
0.5 1
_,O ..................... o. .....................
O ————— M;
0.0
0 A
-05 a
A
'7 1.0 — ——0— KB
0)
E —v—- CRF
o“
0 0.5 a
E
V
< 0.0
B
0.5 a
1.0 —
0.5 ~
’I‘V ————————— a
__ )fo—r ....... o ......................................
Coo/9.. o
0.0 001/7
7'
F 4
.ﬁ‘” C
-05 -
o 100 200 300 400 500 600

PAR (umol m'2 s")

Figure 3. 5 Combined experiment and fructose and control treatments assimilation (A pmol 002

s )rates under ambient light (AL- 14 pmol m‘2 s )at A) week three, B) week ﬁve, and C)
week seven for chewings fescue ‘SR 5100' (CF) (Festuca rubra v. commutata), creeping red
fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa
pratensis) over photosynthetic active radiation (PAR umol rn'2 s ).

89

 

 

05 -

00

 

 

1.0-l

 

A (umol 002 m'2 s")

00

 

 

 

 

 

 

 

 

 

-05 ~
10 4

/::::—/—————7’.
0.5-4 I ”on

"O
00
C
-05 “
0 100 200 300 400 500 600

PAR (umol rn'2 s")

Fmigure 3. 6 Combined experiment and fructose and control treatment photosynthesis (A pmol CO;

5 )rates under supplemental low light (SLL- 40 umol rn‘2 s )at A) week three, B) week ﬁve,
and C) week seven for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping
red fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa
pratensis) over photosynthetic active radiation (PAR pmol m‘2 s ).

9O

References

Beard, J .B. 1973. Turfgrass: science and culture. Englewood Cliffs, New Jersey: Prentice
Hall.

Bell, G.E., T.K. Danneberger, and M.J. McMahon. 2000. Spectral irradiance available for
turfgrass grth in sun and shade. Crop Science 40:189-195.

Bunnel, T., L.B. McCarty, J .E. Faust, William C. Bridges, Jr., and Nihal C. Rajapakse.
2005a. Quantifying a Daily Light Integral Requirement of a ‘TifEagle’ Bermudagrass
Golf Green Crop Science 45:569-5 74.

Bunnel, T., L.B. McCarty, and WC. Bridges. 2005b. Evaluation of Three Bermudagrass
Cultivars and ‘Meyer’ Zoysiagrass Grown in Shade. International T urfgrass Society
Research Journal 10:826-834.

Cockerham, S.T., S.B. Ries, G.H. Riechers, and Victoria A. Gibeault. 2002. Turfgrass
Growth Responses Under Restricted Light: Growth Chamber Studies. California
T wfgrass Culture 52:13-20.

Danneberger, T.K. 2003. Maintaining turf in shade: A Tough Environment. 73rd annual
Michigan turfgrass Conference Proc. Vol. 32, 2003, 21-22.

Dudeck, A.E. and CH. Peacock. 1992. Shade and Turfgrass Culture. In Turfgrass.
Agronomy No. 32.

Groteluxhen, RD. and D. Smith. 1968. Carbohydrates in Grasses- III Estimations of
degree of polymerization of the fructosans in the stem bases of timothy and bromegrass
near seed maturity. Crop Science 8:210-212.

Johnson, S. 1993. Light as a Resource. In Danneberger: Turfgrass Ecology and
Management. Franzak and Foster, Cleveland. 2: 25-34.

Jones, Grant. 2006. Interspeciﬁc Variation in Adaptative Traits of True Firs (Abies spp.).
Master’s Thesis. Michigan State University, East Lansing.

Koh, K.J., G.E. Bell, D.L. Martin, and NR. Walker. 2003. Shade and airﬂow restriction
effects on creeping bentgrass golf greens. Crop Science 43:2182-2188.

McBee, G.G., and EC. Holt. 1966. Shade Tolerance studies on bermudagrass and other
turfgrasses. Agronomy Journal 58:523-525.

Morris, Kevin. Executive Director. National Turfgrass Evaluation Program (NTEP)

10300 Baltimore Ave. Bldg. 003, Rm. 218 Beltsville Agricultural Research Center-
West, Beltsville, Maryland 20705.

91

Sorochan, J .C. 2002. Sugars in Shade: The Effects of Exogenous Fructose Applications
to Turfgrass under Reduced Light Conditions. Ph.D. Dissertation Michigan State
University, East Lansing.

Wilson, J .R. 1997. Adaptive responses of grasses to shade: relevance to turfgrass for low
light environments. Int. T urfgrass Soc. Res. J. 8:575-591.

Wilkinson, J .F ., J .B. Beard, and J .V. Krans. 1974. Anatomical and Physiological

Responses of Poa pratensis L. ‘Merion’ and F estuca rubra L. ‘Pennlawn’ to Reduced
Light Intensity. Agronomy Abstracts 102.

92

Chapter 4

Physiologic and Metabolic Effects Due to Three Daily Light Integrals and

Supplemental Fructose on Various Turfgrasses Under Shaded Conditions
Abstract

It is difﬁcult to maintain overall quality and growth of turfgrasses under shaded

conditions. Exogenous fructose applications were tested under low ambient light and
supplemental low light levels using chewings fescue (Festuca rubra v. commutata)
‘SRSlOO’, creeping red fescue (F estuca rubra v. rubra) ‘Dawson’, and Kentucky
bluegrass (Poa pratenesis) ‘Dawson’ as model plant systems. Results from this
experiment suggest that exogenous fructose did not have signiﬁcant impact on clipping
weight for any of the three genera, although, fructose treatments signiﬁcantly interacted
with species clipping weight under 8 mol m'2 d'1 for KB and CF with clipping weight
decreasing for CF as fructose was applied and increasing for KB as ﬁ'uctose was applied.
Fructose treatments did have a signiﬁcant affect on density on KB under 8 and 4 mol m’2
d‘1 and for CRF under 4 mol m‘2 d], increasing tillers cm'z. Species grown under daily
light integral’s (DLI) of 8 and 10 mol m'2 (1'1 light levels were able to maintain and
increase overall growth and photosynthesis over time for all species. In contrast, data
suggest that exogenous fructose applications under a DLI of 4 mol In2 (1’1 could not
supplement carbohydrates needed to sustain essential metabolic functions and that
carbohydrate reserves were being utilized to maintain respiration. Collectively, the
results suggest there is a threshold light level between 4 and 8 mol m'2 (1'1 light energy
required to maintain grth and photosynthesis for the species and genera included in

this work.

93

Introduction

The amount of light energy a plant receives during the course of a day has a major
impact on its grth and quality. One way of measuring the total amount of light energy
a plant receives during the photoperiod is based upon daily light integral (DLI), which
accounts for the total moles of light energy per day per squared meter (mol m'2 d")
(Faust, 2004). In greenhouse studies, the recommended DLI to support growth and
development is 10 moles per day on various types of ﬂoriculture plants (Faust, 2004).
Plants grown in less than 10 moles per day may have enough light to support adequate
growth for a limited time, but extended periods under low light eventually will have
negative physiology impacts on the metabolism of the plant that translates into reduced
growth and resistance to stress. This is because low light conditions not only decrease
plant vigor, but also increase susceptibility to disease, reduces wear tolerance, and
reduces density (McBee, 1966; Dudeck et al., 1972). With reduced light intensity the rate
of photosynthesis is lowered resulting in a decrease in available carbohydrates,
carbohydrate reserves, and total nonstructural carbohydrates (TNC) (Koh, 2003; Bunnell
etaL,2005a)

Maintaining growth and quality of turfgrasses under low light conditions (<10
mol m'2 d'l) remains a challenge. Growth of turfgrasses is dependent upon carbohydrates
that are produced via the light-dependent reactions of photosynthesis. Bunnell et al.
(2005b) found that as DLI decreased for three Bermudagrass cultivars and ‘Meyer’
Zoysiagrass there was a corresponding decrease in total non-structural carbohydrates
(TNC) in both roots and shoots. This relationship is important to consider when

determining how turfgrass growth can be enhanced under low light conditions.

94

Application of exogenous fructose has been examined as a way to supplement the
low amounts of carbohydrates due to low light conditions. Sorochan (2002) found that
on Supina bluegrass, applications of exogenous fructose one time per week had positive
physiological impacts, i.e. increased grth (clipping weight-grams/mz) and quality,
under low light conditions (400 :1: 40 umol m'2 s"), and that the carbon from the
exogenous fructose was partitioned to different locations within the turfgrass. However,
further studies using chewings fescue ‘SRS 100’, creeping red fescue ‘Dawson’, and
Kentucky bluegrass ‘Cynthia’ suggest exogenous fructose applications did not improve
growth and quality under low light conditions, but had some beneﬁcial effects under
supplemental low light conditions (Chapter 2 and 3). Thus, the hypothesis that there is a
threshold light energy level in which exogenous fructose applications would beneﬁt
turfgrasses needs to be tested. The objective of this work was to measure the effects of
three low light energy daily light integrals (DLI- mol m'2 d'l) levels that can occur under
ambient shaded environments in combination with exogenous fructose applications to
determine physiologic and metabolic impacts for chewings fescue ‘SRS 100’ (F estuca
rubra v. commutata) and creeping red fescue ‘Dawson’ (F estuca rubra v. rubra) which
are two shade tolerant turfgrass species, as well as Kentucky bluegrass ‘Cynthia’ (Poa
pratensis) that is commonly grown in North Central United States.

Materials and Methods
Experimental Site

The investigation took place within Michigan State University (MSU) research

greenhouses located in East Lansing, Mich. The experiment was replicated in time with

experiment one (I) initiated 27 October 2005 and concluding 7 weeks later, and

95

experiment two (11) initiated 12 December 2005 and concluding 7 weeks later.
Supplemental lights were used to ensure identical light energy and photoperiod duration
for both experiments. The experiment was a split block design with ﬁxed blocks (light
energy level) and repeated measures.

Eighty-one four-inch square pots (volume 1.05L) were ﬁlled with an 80:20 sand
to soil mix and placed into the research greenhouses on 26 September and 14 November
for experiments I and II, respectively. The greenhouse was set to at 21°C and 45% RH.
To obtain a constant soil temperature of 13°C the pots were placed onto a germination
pad that was thermostatically controlled. The pots were seeded with chewings fescue
‘SR5100’ (CF), creeping red fescue ‘Dawson’ (CRF), and Kentucky bluegrass ‘Cynthia’
(KB) at a rate of 15 g/ m2. At seeding a starter fertilizer (16N-25P-13K) was applied at a
rate of 2.5g/ m2 and biweekly fertilizing took place thereafter. CF and CRF species
germinated within three weeks and KB germinated within three and half weeks of
seeding. During germination the pots were watered two to three times per week to ensure
media retained uniform moisture. Each pot within the speciﬁc turfgrass species was
randomly assigned to a corresponding treatment. The treatments consisted of no ﬁ'uctose
(control- NF), exogenous fructose application one time per week (F1); and exogenous
fructose application two times per week (F2); and then randomly assigned to one of three
benches. The three benches were set to obtain the following daily light integrals (DLI
mol m"2 d"): 10 mol m'2 (1'1 using high pressure sodium (HPS) lights with a 16-h
photoperiod; 8 mol m'2 (1'1 using incandescent lights with a 16-h photoperiod; and 4 mol
m‘2 (1’1 using HPS lights and 50% shade cloth (Ludvig Svennson, Charlotte, NC.) with a

16-h photoperiod. Once the grasses were 75% germinated, or 3/4 of the pot contained

96

turfgrass, the pots were placed under the DLI treatments that have been described
previously to initiate the experiment. Greenhouse indices were maintained by an
environmental computer (Priva CD 750 Computer System, Vineland Station, Ontario),
that controlled roof vents, exhaust fans, evaporative cooling pads, and heating as needed,
to maintained temperature at 20 i 5°C during both experiments. Light intensity was
maintained by quantum sensors (Apogee Instruments, Logan, Utah) that were located at
plant height on each bench. Hourly averages were recorded by a CR-lO datalogger
(Campbell Scientiﬁc, Logan, Utah). The three light energy levels of 10, 8, and 4 mol rn'2
d’1 were used to determine a threshold light energy level that could beneﬁt from
exogenous fructose treatments. The pots were assigned a light energy level and randomly
placed onto each bench and allowed to acclimate to their assigned light energy level for
one week, in which response variable measurements began after the acclimation period.
Each bench contained three replications of each fructose treatment for each grass species
giving a total of nine pots per grass and 27 pots per bench.
Fructose Treatment

Fructose (Isoclear®, Cargill Sweeteners, Naperville, Ill.) treatments began on 27
October and 9 December for experiments I and II, respectively, and were applied once or
twice per week depending on treatment speciﬁcation. Fructose was mixed with an
adj uvant (BreakThru®, Goldschmidt Chemical Corporation, Hopewell, Va.) and double
distilled water. The fructose was applied at a rate of 1.25% v/v and the adjuvant was
applied at a rate of 0.1% w/v. A hand held 2 L sprayer was used to apply the fructose and

adj uvant mixture to the corresponding pots.

97

Response Variables

Data were collected to determine the interaction between DLI, fructose treatment,
and/or turfgrass species: clipping yield, density, light response curves, and leaf area.
Data collection began on 1 November and 13. December for experiment I and II,
respectively. Clipping yields correspond to cutting each individual turfgrass species to a
pre-determined height of 7.62cm above the soil line of the container. Although the
turfgrass species were cut weekly, clippings were collected for analysis on a biweekly
basis. The clippings were dried at 100°C in an oven for three days and weighed for dry
content that is expressed as grams/m2. To measure density tillers per cm2 were counted
on an identical pre-determined section measuring 5x5cm of the 10.16x10. 1cm pot
biweekly.

Light response curves under the environmental conditions that have been
described were measured using a LICOR 6400 portable photosynthesis system biweekly
beginning on 1 November and 13 December for experiment I and II, respectively
(LICOR® Biosciences, Lincoln, Nebr.). These measurements are a non-destructive mean
of evaluating the effects of fructose and light energy level on photosynthetic responses of
each turfgrass species. The parameters of the LICOR were: chamber 2x3 opaque needles
light emitting diode (LED) light source, carbon dioxide (C02) maintained at 400
umol/mol constant concentration, temperature constant 20°C, and ﬂow rate 250 parts per
million (ppm). Six turfgrass leaves from each pot were placed within the chamber of the
LICOR and subjected to the AutoProgram ‘Light Curve’ to determine photosynthesis
rates at varying light levels. The program parameters were: 1) photosynthetic active

radiation (PAR)- 2000, 1000, 500, 250, 100, 60, 45, 3o, 15, o umol m'2 s'1 and PAR- 500,

98

250, 100, 60,45, 30, 15, 0 mol in2 s“; 2) minimum wait time 30 seconds; 3) maximum
wait time 100 seconds; 4) coefﬁcient of variation (total CV%) 0.05 to maintain mean
stability; and 5) match if C02 sample 0 ppm different from C02 reference.

After measurements the six leaves in the chamber were removed from each plant
and stored for calculation of leaf area correction for each measurement. Leaf area
correction was calculated by using a microscope set at 64x; leaf width was recorded for
each leaf and an average was calculated to determine leaf area per plant. The following
equation was used to determine corrected leaf area:

100 units at 64x= A m

B units x (A min/100) = Cmm/10=D cm

6 leaves x D cm x 3cm (width chamber) = E cm2
A corresponds to millimeters length of samples as measured by the microscope; B
corresponds to how many units the sample measured from the microscope ruler; C
corresponds to the sample measurement now in millimeters; D corresponds to the sample
in centimeters; and E corresponds to the total sample area within the chamber. Each
correction was recorded for use to process LICOR output for each measurement.

Once all measurements were taken using the LICOR program, the data was
downloaded using the LICOR software and inputted into Microsoft Excel (Microsoft
Corp., Redmond, Wash.). The following parameters were calculated using the LICOR
‘Light Curve’ program: photosynthetic rate (photo), conductance (cond), internal C02
concentration (Ci), leaf vapor pressure deﬁcit Wde), leaf area 2cm2 constant, stomatal

ratio (StrnRat), air temperature (Tair), leaf temperature (Tleaf), block temperature (TBlk),

99

reference C02 (C02R), sample C02 (C02S), reference H20 (H20R), sample H20 O-I2OS),
ﬂow, photosynthetically active radiation (PAR) in (PARi), and PAR out (PARo).

Once all leaf measurements were collected with the LICOR photo, PARi, and
light energy level (0 mmol m'2 s") were used, to calculate light response curves. The data
were ﬁtted to the following equation to calculate total photosynthesis or assimilation rates

(A umol C02 m'2 s") at the various light levels:

 

A = (90 + Amax - «(90 + Amax)2 -4q)0kAmax - Rd
2k

using Photosyn Assistant (Dundee Scientiﬁc, Scotland, UK.)
The following indices were used to calculate A and to determine the effects of light level
and fructose treatments on the various turfgrasses: apparent quantum efﬁciency ((p umol
C02 ﬁxed/mol PPF), maximum assimilation (Amax mmol C02 m'2 s"), convexity (k),
dark respiration (Rd umol C02 m'2 s”), and light compensation point (LCP umol C02 rn'2
3").
Statistical Analysis

To test the objectives of the experiment species and fructose treatments within
each light level were compared using Proc AN OVA with Tukey’s adjustment.
Experiment I and II were signiﬁcantly different for clipping weight (p-value < 0.01), with
experiment I containing signiﬁcantly higher clipping weights compared to experiment 11.
This difference may be due ambient light levels due to time of year (October vs.
December) the experiments began. Although, trends between experiments I and II were
similar, so only experiment I clipping weight representative data are presented. All other

variables were not signiﬁcantly different between experiment I and 11, thus, means were

100

combined and presented together. In addition, Pearson’s correlation coefﬁcients were
prepared to assess the relationship of the response variables (SAS, 2000).
Results

The application of exogenous fructose had a signiﬁcant affect on KB and CF
clipping weights (grams m '2) and tiller production (density) (Tables 4.1A and 4.2A).
However, there were no signiﬁcant differences in leaf area, net photosynthesis, maximum
photosynthetic rates (Amax), quantum efﬁciency (0), or dark respiration (Rd) due to the
application of exogenous fructose to the canopies of these three turfgrass species (Tables
4.3A, 4.4A, 4.5A, 4.6A, 4.7A, and 4.8A). There were signiﬁcant affects on the grth
and metabolism of KB, CF, and CRF due to available light energy (PAR) and signiﬁcant
interactions between species, fructose, and time that will be reported for each of the
parameters that were measured.
Clipping Weight

Plants grown under a daily light integral (DLI) of 10 mol m '2 (1'1 did not
signiﬁcantly respond to the application of fructose (Table 4.1B). However, for CF and
KB plants that received 8 mol m '2 d'1 PAR clipping weights were greatest for the
controls (NF), followed by F l and F2 treatments, respectively (Table 4.18). The same
pattern occurred for CF plants that received 4 mol m '2 d'1 PAR. There was a signiﬁcant
interaction between species and exogenous fructose for turfgrass grown under 8 mol m ’2
(1’1 indicating that the three species responded in different ways to the availability of an
exogenous supply of carbohydrate (Appendix III).

Additionally, there were signiﬁcant differences in clipping weights over the

duration of the experiment (Table 4.1A), with clipping weights for all species increasing

101

over time under both the 10 and 8 mol m '2 d'l DLI energy levels (Table 4.1C and Figure
4.1). Under 4 mol m '2 d'1 clipping weights did not signiﬁcantly change over the duration
of the experiment (Figure 4.1). There was a signiﬁcant interaction between fructose
applications, species and time (weeks) for plantsgrown under 8 mol m '2 d'l PAR (Table
4.1A), which suggests that clipping weights for all species increased as exogenous
fructose application continued over the duration of the experiment. However, light had a
greater impact on clipping weights than exogenous fructose applications as can be seen
by the two to 15 fold decrease in clipping weights as PAR decreased from 10 mol m '2 d"1
to 4 mol m '2 d'1( Table 4.1B).

_IEnSiLV.

Plants grown under 8 and 4 PAR of 10 mol m '2 (1'1 did have signiﬁcant
differences in density (tiller production) under all fructose application rates compared to
controls (NF, no fructose) (Table 4.2A). For plants grown under 4 mol m '2 d'l both CRF
and KB plants that received exogenous fructose had higher density compared to controls.
Once again, ﬁ'uctose applications did not signiﬁcantly inﬂuence turfgrass density under a
PAR of 10 mol m '2 (1'1 (Tables 4.2A and 4.2B). There was a signiﬁcant difference
between species with KB possessing 1.5% greater densities compared to CF and CRF
under all light energy levels (Table 4.2C).

There were signiﬁcant differences in densities over the duration of the experiment
(Table 4.2A), with densities for all species increasing over time under both the 10 and 8
mol m ’2 (1'1 light energy levels (Table 4.2C and Figure 4.2). Under 4 mol m '2 (1'1 there
was a signiﬁcant interaction between species and time (weeks), which suggests that each

species tiller production responded differently over the duration of the experiment (Table

102

4.2A). Both CF and CRF maintained similar densities over the duration of the
experiment, while KB tiller production increased over the duration of the experiment
(Figure 4.2). Light had a greater impact on density than exogenous ﬁ'uctose applications
as can be seen with the one to three fold decrease in density as light energy decreased
from 10 to 4 mol m '2 d" (Table 4.23).
Leaf Area

There were signiﬁcant increases in leaf area (cm2) for plants grown under 10 and
8 mol m '2 (1'1 (Table 4.3A), with all species increasing in leaf area over the duration of
the experiment (Figure 4.3). There was a signiﬁcant interaction between species and
time (weeks) for plants grown under 10 and 8 mol m '2 (1'1 (Table 4.3A). Each species
responded differently to their respective light treatment over the duration of the
experiment (Table 4.3 C). Plants grown under 4 mol m '2 d'1 maintained consistent leaf
areas over the duration of the experiment, although KB increased slightly over the
duration of the experiment while CF and CRF decreased (Figure 4.3). There were
signiﬁcant differences in leaf area under all light energy levels between species (Table
4.3A). Kentucky bluegrass maintained two to three percent higher leaf areas compared to
CF and CRF under all light energy levels (Table 4.3B and C), which is most likely
inﬂuenced by the morphological differences in KB and ﬁne leaf fescue turfgrass species.
As found for other growth responses, available light energy had a greater impact on leaf
area than exogenous fructose applications as seen by the one point ﬁve to greater than
two fold decrease in leaf area as light energy decreased from 10 to 4 mol m ’2 (1'1 (Table

4.33).

103

Light Response Curves
Amax

For all species grown under DLI of 10 and 8 mol m ’2 (1'1 maximum assimilation
(Amax mmol C02 rn‘2 s”) was signiﬁcantly different over time (weeks) (Table 4.4A),
with Amax increasing under both light energy levels (Table 4.4C; Figures 4.4 and 4.5).
Under 4 mol m '2 cl‘l Amax decreased over the duration of the experiment for all species
(Figure 4.6). Species was signiﬁcantly different under all light energy levels (Table
4.4A), with KB maintaining one to three times higher Amax compared to CF and CRF
(Table 4.4C). There was a signiﬁcant interaction between exogenous fructose, time, and
species for plants grown under 10 mol m '2 (1'1 (Table 4.4A).
Light Compensation Point

There were signiﬁcant differences in the light compensation point (LCP umol m'2
s") for plants grown under DLI of 10 and 8 mol m'2 (1'1 over time (weeks) (Table 4.5A),
with KB and CF decreasing in LCP and CRF increasing over time (Table 4.5C; Figures
4.4 and 4.5). For all species grown under 4 mol m '2 d'1 the LCP increased for CF and
KB and decreased for CRF over the duration of the experiment (Figure 4.6).
Quantum Eﬂiciency

There were signiﬁcant differences in quantum efﬁciency (Q umol C02 m'2 s'l/mol
PPF) over time (weeks) (Table 4.6A), with 0 increasing over time for all species grown
under DLI of 10 and 8 mol m'2 d'1 and decreasing for all species grown under DLI of 4
mol m'2 (1'1 (Table 4.6C; Figure 4.4, 4.5, and 4.6). The three species grown under DLI of
10 and 8 mol In2 (1'1 had a signiﬁcant difference in Q between species and there was a

signiﬁcant interaction between species and time (Table 4.6A). Under both of the higher

104

light energy levels the efﬁcient use of light energy to drive Pn increased over time for all
species, although KB maintained three to ﬁve percent higher 0 compared to CRF and CF
respectively (Table 4.6B and C). For plants grown under 4 mol m'2 d'1 there was a
signiﬁcant interaction between exogenous fructose, species, and time (Table 4.6A),
suggesting that each species responded differently to the various treatments over the
duration of the experiment.
Dark Respiration

For plants grown under 10 mol m‘2 (1'1 dark respiration rate (Rd umol C02 m“2 s")
was greatest for the controls (NF), followed by F2 and F 1 treatments respectively (Table
4.7B). In contrast, for plants grown under DLI of 4 mol m'2 d’1 Rd was greatest for
treatment F 1, followed by F2 and NF, respectively (Table 4.7B). For all species grown
under 10 and 8 mol m'2 d'1 DLI Rd signiﬁcantly decreased over the duration of the
experiment (Table 4.7C; Figures 4.4 and 4.5). In contrast, for plants grown under 4 mol
m ’2 (1‘1 Rd increased over the duration of the experiment (Figure 4.6). There was a
signiﬁcant difference in Rd between species under all light energy levels (Table 4.7A),
with KB possessing three to six percent higher Rd rates compared to CF and CRF (Table
4.7C). In addition, for plants grown under 10 mol In2 (1'1 there was a signiﬁcant
interaction between species and time (weeks) (Table 4.7A).
Light Response Curves

Under DLI of 10 mol m'2 d'1 all turfgrasses were able to maintain positive
assimilation (A umol C02 m'2 s") rates throughout the seven weeks of the experiment.
However, each individual turfgrass species varied in A rates over time. At week three

there were no signiﬁcant differences in A between the three turfgrass species, with all

105

species maintaining similar A rates at all PAR intensities (Figure 4.4A). By week ﬁve
there were signiﬁcant differences in turfgrass species (p-value < 0.01), with CRF
possessing two percent higher A rates compared to KB and ﬁve percent higher A rates
compared to CF (Figure 4.4B). By week seven, there were signiﬁcant differences in
turfgrass species (p-value < 0.01), with KB possessing two percent higher A rates
compared to CF and CRF (Figure 4.4C).

Under DLI of 8 and 4 mol m'2 d”1 all turfgrasses were able to maintain positive A
rates throughout the seven weeks of the experiment. However, each individual turfgrass
species varied in A rates over time. Under both of these DLI levels at week three there
were no signiﬁcant differences between turfgrass species, with all turfgrasses responding
similarly to the changing PAR levels (Figure 4.5A and 4.6A, respectively). Kentucky
bluegrass was able to maintain 0.5% higher A rates compared to CF and CRF under both
light energy levels (Figures 4.5A and 4.6A). By week ﬁve, there were signiﬁcant
differences between the three turfgrass species (p—value < 0.01). Under 8 and 4 mol m'2
d'1 DLI KB possessed l-3%, respectively, higher A rates compared to CRF and CF
(Figure 4.58 and 4.6B, respectively). By week seven, there were signiﬁcant differences
between the turfgrass species (p-value < 0.01), with KB possessing three point ﬁve
percent higher A rates under 8 mol rn'2 d'1 and two percent higher A rates under 4 mol m'
2 (1'1 compared to CF and CRF (Figure 4.5C and 4.6C, respectively). As expected, for all
turfgrass species A rates were higher under DLI of 10 and 8 mol m'2 (1‘1 compared to DLI

of 4 mol In2 (1'1 (data not shown).

106

Discussion

As with the simulated dome and control environment, exogenous fructose had a
signiﬁcant positive inﬂuence on growth under different DLI. When KB and CRF were
grown under 8 and 4 mol tn2 (1'1 there was a signiﬁcant effect of fructose on clipping
weight and density. Clipping weight decreased with increasing exogenous fructose
applications while density increased, suggesting that carbohydrates from exogenous
ﬁ'uctose applications were allocated to the tillers rather than the shoots of KB and CRF.
This is in contrast to previous results where carbohydrates were allocated to the shoots
rather than the tillers (Chapter 2; Sorochan, 2002), and similar to previous results where
carbohydrates were allocated to tillers rather than shoots (Chapter 3).

Daily light integral impacted growth and metabolism as illustrated by the increase
in response variables as light energy level increased across the three DLI (4 to 10 mol m“2
d’l). Under DLI of 10 and 8 mol in2 (1'1 light energy had a positive effect on the
metabolism of the three species. Although, the lowest DLI (4 mol m’2 d”) was able to
maintain some growth over time (week), this amount of light energy was not enough to
incur a positive physiological or metabolic response for any of the turfgrass species. For
all species clipping weight, density, and leaf area increased over time under DLI of 10
and 8 mol rn'2 d'l, while under a DLI of 4 mol rn‘2 (1'1 grth remained static in value
over time or sometimes even decreased. This response is similar to other common
observations of turfgrass growth responses to extreme shaded conditions. Under these
shade conditions the number of leaves were reduced was directly related to reduced

clipping weight and tillers (Dudeck and Peacock, 1992). In the present work KB had

higher response variable than CF and CRF regardless of light level or treatment. These

107

results are similar to the sports simulated dome experiment and the growth chamber
experiment, where all variables measured were higher for KB compared to CF and CRF
(Chapter 2 and 3).

In addition, KB possessed higher Rd, 0, Amax, LCP, and A than CF and CRF in
all light levels suggesting that photosynthesis for KB was driven by higher respiration
rates (Rd) and use additional carbohydrates to maintain growth over time in shaded
conditions. For all species, net photosynthesis increased over time under 10 and 8 mol m’
2 (1'1 while remaining similar over time in 4 mol m'2 d'l, suggesting a threshold light level
between 4 and 8 mol m'2 d". Also, light response curves under 10 and 8 mol In2 (1",
regardless of species that received fructose and control treatments that did not receive
fructose, possessed higher photosynthetic rates for all PAR levels compared to 4 mol m'2
d". This relationship supports the previous observation that shaded plants approach the
light compensation point more quickly and net photosynthesis is lower in shaded verses
full sun plants (Vanden Hueval et al., 2004; Wilkinson et al., 1974). Again, KB
maintained higher photosynthetic values than CF and CRF for all PAR points over time
regardless of light level and treatment, which may indicate a difference in the genetic
potential of photosynthesis among the species that were compared.

The present work indicates CF and CRF did not possess a surplus of carbohydrate
reserves regardless of exogenous fructose applications in quantities that were sufﬁcient to
maintain acceptable growth under all light levels, although all species performed better
under higher DLI (10 and 8 mol rn'2 d'l) than DLI compared with extreme shaded
conditions (4 mol rn'2 d'l). These results support the hypothesis that various types of

turfgrasses under shaded conditions show that the photosynthetic capacity of the turfgrass

108

species determines differences in shade tolerance (Van Huylenbroeck and Van
Bockstaele, 2001). Collectively, the outcome of the present work suggests that some
turfgrasses grown under DLI within the 10 and 8 mol In2 (1'1 treatments were able to
maintain and/or increase grth over time. Additionally, threshold light level for these
species may exist between 10/8 mol tn2 (1'1 and 4 mol rn'2 d'l.
Conclusion

In summary, exogenous ﬁ'uctose impacted growth and development as shade
tolerant turfgrass species. In addition, the results suggest that DLI within 10 and 8 mol
m'2 d'1 were sufﬁcient to maintain acceptable growth for all species. Light response
curve data suggests that species grown under 4 mol In"2 (1'1 light level could not produce
enough carbohydrates through photosynthesis to reach acceptable growth over time.

Exogenous fructose had some affects on the physiologic and metabolic response
on species grown under low light shaded conditions of this experiment. Speciﬁc DLI
research is essential to understand the minimum light levels these turfgrasses can

maintain and increase overall growth, quality, and photosynthetic capabilities.

109

Table 4.1A Analysis of variance for clipping weight (grams m'2) under 10, 8, 4 mol rn'2 d'1 for
chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson’

(CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

 

 

 

10 mol m'2 d’1 8 mol rn'2 d'1 4 mol m‘2 (1'1
Source df MS F MS F MS F
F 2 187 0.41ns 116 1.09ns 29.72 1.20ns
W 3 44546 96.60“ 10238 g 96.80" 229.1 9.25“
S 2 669 1 .45ns 205.3 1.94ns 21 .1 0.85ns
F*W 6 62.4 0.14ns 36.7 0.35ns 11.5 0.46ns
F*S 4 620 1 .34ns 558.1 5.28" 33.2 1.34ns
S*W 6 288 0.62ns 235.6 2.23“ 24.3 0.98ns
F*W‘S 12 224 0.49ns 249.8 2.36" 15.2 0.62ns
Error 180 461 105.7 24.7

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; * p < 0.05;
and ** p < 0.01.
F, fructose; W, week; S, species.

un----c-----——--—---------------—----—-—---—-u-ucongng---u---c---—----o—u—p-----------—--------------—-—------n---

Table 4.1B Mean speciﬁc clipping weight (grams m'2) at week seven under 10, 8, 4 mol rn'2 d'1
for chewings fescue “SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson‘
(CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

 

 

 

10 mol rn‘2 d'1 8 mol m'2 d'1 4 mol m'2 d’1
Trt 95 CRF Q g: CRF & gﬁ CRF kg_
F1 72.98 55.38 80.18 29.68b 37.38 54.68 4.428b 7.128 10.98
F2 62.88 57.58 82.88 20.3b 33.28 51 .381) 2.631) 6.258 10.18
NF 74.98 83.28 64.38 46.78 40.48 29.9b 10.68 7.758 7.438

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

Table 4.10 Mean speciﬁc clipping weight (grams m'2) over time under 10, 8, 4 mol m'2 d'1 for
chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson'
(CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

 

 

Week 10 mol m'2 d’1 8 mol rn'2 d'1 4 mol rn'2 9;:
1 11.1 bC 9.538 9.641)
3 8.966 5.18b 10.8b
5 21.31) 5.311) 11 .6b
7 70.2a 7.46ab 38.2a

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

110

Table 4.2A Analysis of variance for density (tillers cm'z) under 10, 8, 4 mol rn'2 d'1 for chewings
fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF)
(Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia' (KB) (P03 pratensis).

 

 

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Source df MS F MS F MS F
F 2 0.50 0.84ns 7.05 9.29" 1.49 3.32”
W 3 81.6 88.1 ** 15.5 34.2" 8.51 18.9“
S 2 20.9 22.6“ 25.9 ' 20.5" 17.3 38.6“
F*W 6 0.44 0.82ns 0.77 2.15ns 0.26 0.75ns
F*S 4 1.49 0.17ns 1.63 2.15ns 0.97 0.08ns
SW 6 0.50 0.77ns 0.43 0.56ns 1.01 0.04'
F*W‘S 12 0.09 1.00ns 0.47 0.62ns 0.15 0.98ns
Error 180 0.92 0.76 80.8

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
and "'*, p < 0.01.
F, Fructose; W, week; S, species.

Table 4.2B Mean speciﬁc density (tillers cm") at week seven under 10, 8, 4 mol m'2 d'1 for
chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson’
(CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Trt CF CRF KB CF CRF KB CF CRF KB
F 1 4.323 1.613 4.663 2.763 2.713 4.433 1.613 1.603 3.083
F2 3.883 1 .603 4.193 2.403 1 .963 3.023b 1 .603 1 .263b 2.953b
NF 4.503 1 .833 4.043 2.793 2.043 2.24b 1.833 0.83b 2.28b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

Table 4.2C Mean speciﬁc density (tillers cm'z) over time and by species under 10, 8, 4 mol rn‘2 d'1
for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson’
(CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

Week 10 mol m”2 d'1 8 mol m'2 d'1 4 mol rn'2 d'1

1 1.12c 1.04c 0.98b
3 1.59c 1 .61b 1.683
5 2.51 b 1.93b 1.663
7 3.93 2.713 1.893

 

§gecies 10 mol rn'2 d'1 8 mol m'2 d" 4 mol m'2 11.

CF 2.493 1.76b 1 .44b
CRF 1.67b 1.39c 1 .130
KB 2.693 2.323 2.093

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

111

Table 4.3A Analysis of variance for leaf area (cm2) under 10, 8, 4 mol rn'2 d“1 for chewings fescue

‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF) (Festuca

rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

 

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Source df MS F MS F MS F
F 2 0.0003 0.66ns 0.0005 0.6ns 0.003 1 .12ns
W 2 0.04 78.4" 0.02 24.1 ** 0.002 0.76ns
S 2 0.07 126" 0.017 19.3" 0.02 6.21'
F*W 4 0.009 1.86ns 0.0001 0.14ns 0.006 1.74ns
F*S 4 0.003 0.67ns 0.0003 0.37ns 0.005 1 .63ns
SW 4 0.008 15.7“ 0.004 4.86* 0.007 2.33ns
F’W’S 8 0.0006 1.16ns 0.0005 0.51ns 0.002 0.72ns
Error 135 0.0005 0.0009 0.003

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
and “, p < 0.01.
F, Fructose; W, week; S, species.

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

Table 4.3B Mean speciﬁc leaf area (cm2) at week seven under 10, 8, 4 mol m'2 d'1 for chewings
fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF)
(Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia' (KB) (Poapratensis).

 

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Trt JOE CRF KB CF CRF KB CF CRF KB
F1 0.083 0.083 0.173 0.063 0.083 0.133 0.05b 0.043 0.083
F2 0.073 0.073 0.163 0.093 0.073 0.143 0.04b 0.053 0.093
NF 0.093 0.083 0.183 0.083 0.083 0.143 0.073 0.153 0.093

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

Table 4.38 Mean speciﬁc leaf area (cm2) over time and by species 10, 8, 4 mol m'2 d'1 for
chewings fescue ‘SR 5100' (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson’
(CRF) (Festuca rubra v. rubra), and Kentucky blugqrass ‘Cynthia’ (KB) (Poa pratensis).

Week 10 mol m_2c_l: 8 mol ﬂ: 4 mol rn'2 d_”__

3 0.06c 0.060 0.063
5 0.0% 0.07b 0.073
7 0.113 0.103 0.083

 

species 10 mol m'2 d" 8 mol m‘2 d" 4 mol M221

CF 0.06b 0.06b 0.05b
CRF 0.07b 0.06b 0.073b
KB 0.133 0.103 0.093

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

112

Table 4.4A Analysis of variance for Amax (umol 002 m'2 5") under 10, 8, 4 mol rn'2 d'1 for
chewings fescue ’SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson’
(CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

 

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Source df MS F MS F MS F
F 2 10.2 3.14ns 0.71 1.88ns 0.08 1.03ns
W 2 33.2 10.2” 18.1 48.1 ** 0.22 2.84ns
S 2 14.7 4.49" 12.2 ‘ 32.7" 1.74 22.8“”r
F*W 4 4.9 1 .51ns 0.04 0.12ns 0.005 0.07ns
F*S 4 4.79 1.47ns 0.31 0.85ns 0.06 0.83ns
S*W 4 7.57 2.32ns 0.87 2.32ns 0.13 1.67ns
F‘W'S 8 6.72 2.06" 0.17 0.44ns 0.05 0.61ns
Error 132 3.26 0.37 0.08

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
and **, p < 0.01.
F, Fructose; W. week; S, species.

a-------------------------------—------—-—-------—------------g----------------—---------------------------------.

Table 4.4B Mean speciﬁc Amax (pmol CO2 rn'2 s") at week seven under 10, 8, 4 mol rn'2 (21’1 for
chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue ‘Dawson’
(CRF) (Festuca rubra v. rubra), and Kentucky bluegass ‘Cynthia’ (KB)(Poa pratensis).

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Trt CF CRF KB CF CRF KB CF CRF KB
F1 1.863 2.023 3.423 1.383 1.683 3.173 0.163 0.353 0.563
F2 1.453 1.923 3.253 1.263 1.353 2.773 0.393 0.313 0.583
NF 1.823 1.863 4.053 1.713 1.893 2.613 0.463 0.383 0.603

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F 1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

o----------------------o---C-O---u-c-----c---u-nu-------u---------------------------------------. .................

Table 4.4C Mean speciﬁc Amax (umol CO2 m'2 s") over time and by species under 10, 8, 4 mol
m"2 d'1 for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue
‘Dawson’ (CRF) (Festuca rubra v. rubraLand Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

Week 10 mol m'2 d”1 8 mol m'2 d'1 4 mol m'2 d'1

3 0.820 0.880 0.313
5 1.7230 1.080 0.423
7 2.413 1.983 0.428

 

gaecies 10 mol rn'2 d‘1 8 mol m'2 d'1 4 mol m'2 (1'1

CF 1.150 1.030 0.270
CRF 1.6730 1.100 0.290
KB 2.213 1.923 0.598

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

113

Table 4. 5A Analysis of variance for light compensation point (pmol rn'2 s ) under 10, 8, 4 mol m'2
d'1 for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue
‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

 

 

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Source df MS F MS F MS F
F 2 3.03 Ons 317 1.03ns 1341 0.58ns
W 2 16626 21 .9" 1331 4.58“ 3450 1 .49ns
S 2 1010 1.33ns 564 ‘ 1 .94ns 3285 1.42ns
F*W 4 174 0.23ns 41.8 0.14ns 1186 0.51ns
F*S 4 237 0.31ns 572 1 .97ns 1598 0.69ns
SW 4 58.7 0.08ns 80.3 0.28ns 1241 0.53ns
F*W‘S 8 201 0.27ns 28.7 0.98ns 1294 0.56ns
Error 132 757 290 2321

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
and **, p < 0.01.
F, Fructose; W, week; 8, species.

Table 4. 5B Mean speciﬁc light compensation point (umol m'2 s ) at week seven under 10, 8, 4
mol m 2"d for chewings fescue ‘SR 5100’ (CF) (Festuca mbra v. commutata), creeping red
fescue "Dawson (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa
pratensis).

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Trt CF CRF KB CF CRF KB CF CRF KB
F1 50.73 52.33 47.73 19.53 16.43 19.53 34.73 8.143 27.33
F2 57.73 57.73 50.73 23.93 24.53 12.53 24.03 33.83 15.93
NF 66.63 59.93 46.13 19.73 24.03 19.93 17.53 25.93 20.33

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

Table 4. SC Mean speciﬁc light compensation point (pmol rn'2 s ) over time under 10 and 8 mol m'
2°’d for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue
‘Dawson‘ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa pratensis).

Week 10 mol rn'2 d'1 8 mol rn'2 d'1

3 38.1 b 20.5b
5 19.3c 19.8b
7 54.43 28.93

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

114

Table 4. 6A Analysis of variance for quantum efﬁciency (umol 002 rn'2 s1/mol PAR) under 10.8.4
mol m 2'1d for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red
fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa
pratensis).

 

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Source df MS F MS F MS F
F 2 0.00002 2.78ns 0.000004 1 .31ns 0.01 0.94ns
W 2 0.0005 55.7“ 0.0002 ‘ 55.2“ 0.05 3.44’
S 2 0.0005 57.4" 0.0002 51.7" 0.02 1 .25ns
F*W 4 0.000004 0.28ns 0 0ns 0.01 1ns
F*S 4 0.000002 1 .41ns 0.00003 0.88ns 0.03 2.11ns
S*W 4 0.00005 6.43" 0.000002 4.85” 0.01 0.98ns
F*W'S 8 0.00004 1.73ns 0.000005 0.14ns 0.03 219*
Error 132 0.000008 0.000004 0.01

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
and ", p < 0.01.
F, Fructose; W, week; 8, species.

Table 4. 6B Mean speciﬁc quantum efﬁciency (umol C02 m‘2 s1/mol PAR) at week seven under
10, 8, 4 mol m 2'1d for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping
red fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia' (KB) (Poa
pratensis).

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Trt CF CRF KB CF CRF KB CF CRF KB

F 1 0.0043 0.0053 0.013 0.0043 0.0053 0.013 0.0023 0.0023 0.293
F2 0.0043 0.0063 0.013 0.0033 0.0043 0.013 0.0013 0.173 0.0053
N F 0.0053 0.0063 0.013 0.0043 0.0053 0.013 0.0023 0.0073 0.0033

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

--—-—-—-----------------------------—--------------—---—uu----u---c-u-gouge----c—u-a----—-----—-—-------------—---

Table 4. 60 Mean speciﬁc quantum efﬁciency (pmol CO2 rn‘2 s1/mol PAR) over time and by
species under 10, 8, 4 mol m 2d'1 for chewings fescue ‘SR 5100' (CF) (Festuca rubra v.
commutata), creeping red fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky
bluegrass ‘Cynthia’ (KB) (Poa pratensis).

Week 10 mol m'2 g; 8 mol rn‘2 d'1 4 mol m'2 (_1'_1_

3 0.002c 0.0020 0.001b
5 0.006b 0.003b 0.003b
7 0.0083 0.0063 0.053

 

Species 10 mol rn'2 g: 8 mol m3: 4 mol rn'2 g_1__

CF 0.0030 0.0030 0.0013
CRF 0.0040 0.0030 0.023
KB 0.0093 0.0063 0.043

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

115

Table 4.7A Analysis of variance for dark respiration rate (pmol 002 rn'2 s'1) under 10, 8, 4 mol rn'2
d'1 for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red fescue
‘Dawson' (CRF) (Festuca rubra v. rubra), and Kentucky bluqurass ‘Cynthia’ (KB) (Poa pratensis).

 

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1

Source df MS F MS F MS F

F 2 0.70 2.48ns 0.005 0.49ns 0.0009 0.2ns
W 2 1 .42 50.3" 0.06 5.94" 0.007 1.56ns
S 2 0.05 17.0" 0.09 9.19* 0.01 4.08"
F*W 4 0 1ns 0.005 0.48ns 0.003 0.61ns
F*S 4 0.02 0.07ns 0.01 1.11ns 0.005 1.18ns
S*W 4 0.18 6.65" 0.01 0.98ns 0.003 0.77ns
F*W’S 8 0.05 0.56ns 0.005 0.51ns 0.008 1.87ns
Error 132 0.03 0.01 0.004

 

Note: Signiﬁcance levels for repeated measures are given as probability: ns, p > 0.05; *, p < 0.05;
and "*, p < 0.01.
F, Fructose; W, week; S, species.

Table 4.78 Mean speciﬁc dark respiration rate (umol C02 m"2 s") at week seven under 10, 8, 4
mol rn'2 d'1 for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red
fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa
pratensis).

 

 

 

 

 

10 mol m-2 d-1 8 mol m-2 d-1 4 mol m-2 d-1
Trt Q CRF KB g CRF KB Q CRF KB
F1 0183 -0.223 -0.553 -0.073 -0.083 -0.203 -0.03a -0.063 -0.1 1 3
F2 0213 -0.293 -0.673 -0.013 -0.123 -0.113 -0.023 -0.063 -0.053
NF -0.31a -0.31a -0.64a -0.013 -0.053 -0.163 -0.023 -0.06a -0.07a

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

Table 4.7C Mean speciﬁc dark respiration rate (umol C02 m'2 s'1) over time and by species
under 10, 8, 4 mol rn‘2 d'1 for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata),
creeping red fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’
(KB) (Poa pratensis).

Week 10 mol rn'2 d'1 8 mol m'2 d'1 4 mol m'sz'1

 

3 -0.073 -0.043 -0.023
5 -O.123 -0.080 -0.033
7 -0.38 0 -0.11 ab -0.04 a

 

Species 10 mol m'2 d'1 8 mol m'2 d’1 4 mol m'2 (1'1

CF -0.123 -0.043 -0.023
CRF -0.153 -0.07 ab 0023
KB 031 b -0.13b -0.05b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

116

120

 

100 -

80-4

60*

20~

 

 

 

 

100 -

80-

60~

20*

Clipping Weight: grams rn'2

 

 

 

100 d

803

40‘

 

 

 

 

Week

Figure 4.1 Clipping weights (grams/1m2 )experiment l combined 2fru1ctose and control treatment
under1 bench one (B1- 10 mol rn'2 s1.) bench two (B2- 8 mol m'2 s1), and bench three (B3- 4 mol
m'2 s1)for A) chewings fescue ‘SR5100’ (Festuca rubra v. commutata) B) creeping red fescue
(Festuca rubra v. rubra), and C) Kentucky bluegrass ‘Cynthia’ (Poa pratensis).

ll7

 

 

+81
6 ‘ v~o-- B2
—v—B3

Density: tillers cm’2

 

 

 

 

 

 

 

 

Week

Figure 4.2 Density (tillers/cmz) combined fructose and control and experiment under bench one
(B1- 10 mol rn'2 s'1), bench two (B2- 8 mol m'2 s1), and bench three (B3- 4 mol rn’2 s'1) for A)
chewings fescue ‘SR5100’ (Festuca rubra v. commutata), B) creeping red fescue (Festuca rubra
v. rubra), and C) Kentucky bluegrass ‘Cynthia’ (Poa pratensis).

118

 

0.14 -

0.12 4

0.10 -I

 

0.04 -

 

0.16 4 + 81
+ 83
0.12-1

 

 

 

Leaf Area: cm2

 

 

 

 

 

.0
O
N
4

Week

Figure 4.3 Leaf area (cm2) from combined fructose and control treatment and experiment under
bench one (B1- 10 mol m'2 s‘1), bench two (BZ- 8 mol rn'2 5'1), and bench three (B3- 4 mol rn'2 s'1)
for A) chewings fescue ‘SR5100’ (Festuca rubra v. commutata), B) creeping red fescue ‘Dawson’
(Festuca rubra v. rubra), and C) Kentucky bluegrass ‘Cynthia’ (Poa pratensis).

119

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3 —1
2 -1
1 _.
0
A
-1
+ KB
3 ‘ 0 CF
+ CRF
2 _.
A
'7 1 -*
U)
“3
E
N 0
0
0 B
B
E -1
:1.
V
< 3 _
2 d
1 _
0
C
'1 I r 1' r I
0 500 1000 1500 2000 2500

PAR (umol rn'2 s‘1)

Figure 4.4 Combined fructose and control assimilation (A pmol 00 m'2 s'1) over varying
photosynthetic active radiation (PAR umol rn'2 s'1) under 10 mol m' d'1 light response curves at a)
week three, b) week ﬁve, and 0) week seven for chewings fescue ‘SR5100’ (CF) (Festuca rubra v.
commutata), creeping red fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass
‘Cynthia’ (KB) (Poa pratensis).

120

 

 

 

 

 

 

 

 

 

 

 

 

 

3 -I
2 _I
1 1 j
0 W
A
-1
.f" 3 4
'm + KB
945 ..o.. CF
—v— CRF
N 2 -
0
O
'5
E 1 -
3:
<
0
B
-1
3 _.
2 —1
1 _.
0
C
'1 I I I I I
0 500 1000 1500 2000 2500

PAR (umol rrI'2 s'1)

Figure 4.5 Combined fructose and control assimilation (A pmol CO2 rn'2 s'1) over varying
photosynthetic active radiation (PAR umol rn'2 s'1) under 8 mol rn'2 d’1 light response curves at A)
week three, 0) week ﬁve, and 0) week seven for chewings fescue ‘SR5100’ (CF) (Festuca mbra
v. commutata), creeping red fescue ‘Dawson’ (KB) (Festuca rubra v. rubra), and Kentucky
bluegrass ‘Cynthia’ (KB) (Poa pratensis).

121

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3 -1
2 _.
1-
o ————.oo-O¢‘—"1‘"—~'— I _——_—1_
A
A
'II- 1 j r
U)
N
1E 3 d + KB
0 + CRF
O 2 _
B
E
1
v
< 1‘
o
B
1 4 .
3 —1
2 -l
11
o
C
-1 I I T T I I
o 100 200 300 400 500 600

PAR (umol rn‘2 s'1)

Figure 4.6 Combined fructose and control assimilation (A umol C02 m'2 s'1) over varying
Photosynthetic active radiation (PAR umol rn'2 s'1) under 4 mol m'2 (1'1 light response curves at A)
Week three, b) week ﬁve, and c) week seven for chewings fescue ‘SR5100’ (CF) (Festuca rubra
V. commutata), creeping red fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky
bluegrass ‘Cynthia’ (KB) (Poa pratensis).

122

References

Bunnel, T., L.B. McCarty, J .E. Faust, W.C. Bridges, Jr., and Nihal C. Rajapakse. 2005a.
Quantifying a Daily Light Integral Requirement of a ‘TifEagle’ Bermudagrass Golf
Green Crop Science 45:569-574.

Bunnel, T., L.B. McCarty, and WC. Bridges. 2005b. Evaluation of Three Bermudagrass
Cultivars and ‘Meyer’ Zoysiagrass Grown in Shade. International T urfgrass Society
Research Journal 10:826-834.

Dudeck, A.E. and CH. Peacock. 1992. Shade and Turfgrass Culture. In Turfgrass.
Agronomy No. 32.

Faust, J. 2004. DLI Measurrnents: A Valuable Addition to Your Toolbox. Greenhouse
Product News (GPN) 40-46.

Koh, K.J., G.E. Bell, D.L. Martin, and NR. Walker. 2003. Shade and airﬂow restriction
effects on creeping bentgrass golf greens. Crop Science 43:2182-2188.

McBee, G.G., and EC. Holt. 1966. Shade Tolerance studies on bermudagrass and other
turfgrasses. Agronomy Journal 58:523-525.

Morris, K., Executive Director. National Turfgrass Evaluation Program (NTEP) 10300
Baltimore Ave. Bldg. 003, Rm. 218 Beltsville Agricultural Research Center-West,
Beltsville, Maryland 20705.

Sorochan, J .C. 2002. Sugars in Shade: The Effects of Exogenous Fructose Applications
to Turfgrass under Reduced Light Conditions. Ph.D. Dissertation Michigan State
University, East Lansing.

Vanden Heuvel, J .E., J. T.A. Proctor, K. H. Fisher, and J. Alan Sullivan. 2004. Shading
Affects Morphology, Dry-Matter Partitioning, and Photosynthetic Response of
Greenhouse-grown ‘Chardonnay’ Grapevines. HortScience 39(1):65-70.

Van Huylenboreck, J .M., and E. Van Bockstaele. 2001. Effects of Shading on
Photosynthetic Capacity and Growth of Turfgrass Species. International T urfgrass
Society Research Journal 9:353-359.

Wilkinson, J .F ., J .B. Beard, and J .V. Krans. 1974. Anatomical and Physiological

Responses of Poa pratensis L. ‘Merion’ and F estuca rubra L. ‘Pennlawn’ to Reduced
Light Intensity. Agronomy Abstracts 102.

123

Thesis Conclusion

Throughout each experiment exogenous fructose applications had a signiﬁcant
positive impact on particular growth and metabolism variables of each of the three
species under the various shaded growth environments (i.e. simulated dome, controlled
environment grth chamber, or greenhouse). Additionally, exogenous fructose
applications were found to increase photosynthesis initially after application under
supplemental light for chewings fescue ‘SR5100’, creeping red fescue ‘Dawson’, and
Kentucky bluegrass ‘Cynthia’. In these combinations, the effects of exogenous fructose
were species and light dependent.

Available light energy greatly impacted growth and metabolism in each
experiment, as illustrated by the increase in response variables from ambient or low light
conditions to supplemental or higher light conditions. These results indicate alight
threshold level required to maintain grth under shaded conditions, which is not
maintained under ambient light conditions under sports dome conditions. Also, this work
suggests the required light threshold may differ by species due to species being a
dependent factor.

This research raises many questions relating to exogenous fructose applications
on turfgrasses under shaded conditions. If exogenous fructose applications increase
photosynthesis initially, can we time the applications in the fall so that the stored excess
fructose from the applications will increase reserves in the spring? Can the previous
altering of storage reserves prior to winter dormancy determine how long fructose is
stored in the plant? Can timing of fructose applications provide practical usage for short

interval applications, with extended beneﬁts?

124

Appendix I

Dome Experiment Signiﬁcant Tables

Table l- I Means speciﬁc clipping weight (grams m) at week ﬁfteen under ambient light (AL 5-10
pmol m2 51,) supplemental low light (SLL 32 pmol m2 51), and supplemental high light (SHL 73
umol m 2 s ) for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) and creeping red

fescue "Dawson (CRF Festuca rubra v. rubra).

& i=1: §L1L
Fructose CF CRF CF CRF CF CRF
F1 0.223 0.173 2.363 3.143 1.893 2.303
NF 0.163 0.173 2.803 3.523 2.553 2.433

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F1, fructose 1x/week; NF, no fructose (control).

Table I- ll Means speciﬁc clipping we 2ght (grams m) week and fructose treatment interaction
under ambient light (AL 5-10 pmol m s1for chewings fescue ‘SR 5100’ (CF Festuca rubra v.
commutata) and creeping_r£d fescue ‘Dawson’ (CRF Festuca rubra v. rubra).

Week Fructose AL

 

1 F1 3.723
3 F1 1.54b
5 F1 0.280
9 F1 0.230
12 F1 0.290
15 F1 0.190
1 NF 5.243
3 NF 1.18b
5 NF 0.160
9 NF 0.180
12 NF 0.520
15 NF 0.160

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

W, week; F, fructose.

F 1, fructose 1x/week; NF, no fructose (control).

Table I- III Means speciﬁc density (tillers cm ) at 2we1ek ﬁfteen under ambient light (AL 510 umol
m2 s 1), supplemental low light (SLL 32 umol m2 51,) and supplemental high light (SHL 73 umol
m 2 s1)for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) and creeping red fescue
‘Dawson’ (CRF Festuca rubra v rubraL

& §Q ﬂ
Fructose CF CRF CF CRF CF CRF
F1 1.133 1.183 1.483 1.883 2.273 2.273
NF 1.233 1.433 1.493 2.173 2.223 2.273

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F 1, fructose 1x/week; NF, no fructose (control).

125

Table I- IV Means speciﬁc density (tillers2 cm) for week by fructose by species interaction
supplemental low light (SLL 32 pmol m2 s ) for chewings fescue ‘SR 5100’ (CF Festuca rubra v.
commutata) and creeping red fescue ”Dawson (CRF Festuca rubra v. rubra).

 

_sg

Week Fructose CF CRF

1 F1 2.863 3.553
5 F1 2.613 2.913
10 F1 2.763 2.073
15 F1 1.48b 1.870
1 NF 3.353 2.66ab
5 NF 2.513 2.22b
10 NF 1.82b 2.51ab
15 NF 1.48b 2.17b

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F1, fructose 1x/week; NF, no fructose (control).

.c—oooou—ccu------u-o---------------------------—-------------—-o--------_-—---——------------o----—---------- -----

Table l-V Means speciﬁc density (tillers cm) at 2week four under ambient light (AL 5- 10 umol rn'2
s1)and supplemental low light (SLL 32 pmol m2 s1)for Kentucky bluegrass ‘Cynthia’ (KB Poa
pratensis).

 

& §_LL
Fructose KL KB
F 1 0.543 1 .033
F2 0.593 1 .043
NF 0.493 0.883

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F1, fructose 1x/week; NF, no fructose (control).

Table l-Vl Means speciﬁc narrow band vegetative index 695 ((R970- R2695)/(R970+R695)) for
fructose and species interaction under ambient light (AL 510 umol m2 s ) for chewings fescue
‘SR 5100’ (CF Festuca rubra v. commutata) and creeping red fescue ‘Dawson’ (CRF Festuca
rubra v. rubra).

 

_A_L
Fructose CF CRF
F1 025 -0.24
NF -0.24 -0.28

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F 1, fructose 1x/week; NF, no fructose (control).

126

Table l-Vll Means speciﬁc red-edge vegetative index ((R714+R759)/(2-R733)) for week, fructose,
and species interaction under ambient light (AL 5—10 pmol m'2 5‘1) and supplemental low light
(SLL 32 pmol m’2 s'1) for chewings fescue ‘SR 5100’ (CF Festuca rubra v. commutata) and
creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra).

 

 

& .30

Week Fructose CF CRF CF CRF

3 F1 0023 -0.023 -0.02 a -0.023
6 F1 -0.023 -0.033 -0.02 a -0.033
9 F1 0040 -0.033 -0.02 a -0.023
12 F1 0050 -0.04b -0.03 a —0.023
15 F1 0033 -0.023 -0.04 b -0.04b
3 NF -0.033 -0.023 -0.02 3 —0.023
6 NF -0.033 -0.033 -0.02 a -0.023
9 NF -0.04b -0.04b -0.01 a -0.013
12 NF 0040 0040 -0.02 a -0.013
15 NF -0.04b -0.03a -0.04 b -0.023

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

F 1, fructose 1x/week; NF, no fructose (control).

127

Appendix 11

Growth Chamber Experiment Signiﬁcant Tables

Table ll-l Mean speciﬁc maximum assimilation (mmol 00;, m'2 s'1) for week by fructose interaction
under supplemental low light (SLL 40 umol m'2 s'1) for chewings fescue ‘SR 5100’ (CF Festuca
rubra v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra), and Kentucky
bluegrass ‘Cynthia’ (KB Poa pratensis).

 

_S_L_l=
Week F1 F2 NF
3 0.763 0.533 0.833
5 0.220 0.31b 0.27b
7 0.773 0.32b 0.57ab

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
F 1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

a-—-----—-----------Q---------o-‘m‘D-nnnun-_n-------h-----n---u-----oun------‘---—-------‘--‘---¢-------—----—----

Table Il-Il Mean speciﬁc maximum assimilation (mmol 0022 m’2 s'1) for week by species
interaction under supplemental low light (SLL 40 umol m' s") for chewings fescue ’SR 5100’ (CF
Festuca rubra v. commutata), creeping red fescue ‘Dawson’ (CRF Festuca rubra v. rubra), and
Kentucky bluegrass ‘Cynthia’ (KB Poa pratensis).

 

_S_l_.__l=
Week CF CRF KB
3 1.783 0.95b 1.093
5 0.71b 0.88b 1.213
7 0.66b 1.113 1.283

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

128

Appendix III

Greenhouse Experiment Signiﬁcant Tables

Table lIl-l Mean speciﬁc clipping weight (grams m'2) for fructose by species interaction under 8
mol m'2 d'1 for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red
fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa
pratensis).

 

 

8 mol m'2 d’1
Trt CF CRF KB
F1 15.73 18.98 22.38
F2 11.60 15.50 22.48
NF 20.23 18.33 12.90

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F 1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

------------------------------------------------------------------------------------------------------------------

Table Ill-ll Mean 5

peciﬁc clipping weight

(grams m‘2) for fructose, week, and species interaction

under 8 mol m'2 d' for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping
red fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa

 

 

pratensis).

Week Trt CF CRF KB

1 F1 11.60 15.50 4.90
3 F1 11.20 12.70 13.30
5 F1 10.30 9.480 16.50
7 F1 29.63 37.363 54.73
1 F2 8.390 7.310 10.10
3 F2 9.840 10.60 11.20
5 F2 8.110 10.80 17.10
7 F2 20.33 33.23 51.33
1 NF 9.290 8.390 10.90
3 NF 12.10 13.20 3.10
5 NF 12.70 11.30 7.80
7 NF 46.73 40.43 29.93

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F 1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

129

Table Ill-Ill Mean speciﬁc density (tillers cm'2) week and species interaction and by species under
4 mol m'2 d'1 for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping red
fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa

 

 

pratensis).

Week CF CRF KB

1 0.810 0.810 1.320
3 1.713 1.263 2.063
5 1.593 1.193 2.23
7 1.683 1.233 2.773

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.

Table lll-lV Mean speciﬁc Amax (umol 002 m'2 s'1) for week, fructose, and species interaction
under 10 mol m‘2 d’1 for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v. commutata), creeping
red fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky bluegrass ‘Cynthia’ (KB) (Poa

 

 

 

Katensis).
10 mol m'2 d'1

Week Trt CF CRF KB
3 F1 0.830 0.440 1.060
5 F1 0.890 0.680 1.660
7 F1 1 .860 2.033 3.433
3 F2 0.650 0.640 1.240
5 F2 0.880 0.790 1.830
7 F2 1 .453 1 .923 3.253
3 NF 0.660 0.690 1.480
5 NF 1.313 5.943 1.510
7 NF 1.813 1.860 4.043

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F1, fructose 1x/week; F2, fructose 2x/week; NF, no fructose (control).

130

Table Ill-V Mean speciﬁc quantum efﬁciency (umol 002 m'2 s'1/mol PAR) for week, fructose, and
species interaction under 4 mol m'2 d’1 for chewings fescue ‘SR 5100’ (CF) (Festuca rubra v.
commutata), creeping red fescue ‘Dawson’ (CRF) (Festuca rubra v. rubra), and Kentucky
bluegrass ‘Cynthia’ (KB) (Poa pratensis).

 

4 mol m'2 d’1

Week Trt CF CRF KB

3 F1 0.00080 0.0013 0.0010
5 F1 0.00080 0.0023 0.0040
7 F1 0.0013 0.0023 0.293
3 F2 0.00090 0.0010 0.0013
5 F2 0.0013 0.0020 0.0053
7 F2 0.0013 0.173 0.0043
3 NF 0.00080 0.00090 0.0033
5 NF 0.0013 0.0023 0.0043
7 NF 0.0013 0.0073 0.0033

 

Note: Means within column followed by the same letter are not signiﬁcantly different at the 0.05
level. Mean differences were determined by Tukey’s studentized range test.
Trt, treatment; F1, fructose 1x/week; F2, fructose 2x/week; NF , no fructose (control).

131

 

Appendix IV
Commercial Products and Suppliers
Apogee Instruments Inc. 82 Crockett Ave., Logan, Utah 84321. Phone: (435) 792-4700.

BannerMaxx®. Sygenta Corporation. 2200 Concord Pike, PO Box 8353, Wilmington,
Delaware 19803. Phone: (302) 425-2000.

BirdAir®. Birdair Inc. 65 Lawrence Bell Drive, Suite 100, Amherst, New York 14221.
Phone: (800) 622-2246.

BreakThru®. Western Farm Service Inc., PO Box 1168, Fresno, California 93715.

Campbell Scientiﬁc Inc. 815 West 1800 North, Logan, Utah 84321.
Phone: (435) 753-2342.

Dundee Scientiﬁc. l4 Menzieshill Road, Dundee DD2 1PW, Scotland, United Kingdom.
Photosyn Assist®.

FieldSpec® Pro. Analytical Spectral Devices, Inc., 5335 Sterling Drive, Boulder, Colo.
80310.

Graham Turf Seeds Ltd. 1702 Elm Tree Road, RRH, Lindsay, Ontario K9V-4RI, Canada.
Greentech, Inc. 470 Clubﬁeld Drive, Roswell, Georgia 30075. Phone: (804) 363-5048

Great Lakes Gravel Co. 7900 Woodland Rd., Lake Odessa, MI 48849. Phone: (616) 374-
3169.

Gylling Data Management Inc. Agriculture Research Manager (ARM). 405 Martin
Boulevard, Brookings, South Dakota 57006.

Isoclear®. Cargill Sweeteners. Box 1400A, Dayton, Ohio 45413. Phone: (937) 237-
1268.

LICOR® Biosciences, 4421 Superior St., Lincoln, NB 68504, USA.

Ludvig Svennson Inc. 1813 Associates Ln. Suite E., Charlotte, North Carolina 28217.
Phone: (704) 357-0457.

Microsoft Corporation. One Microsoft Way. Redmond, Wash. 98052.

PP Systems. CIRAS Portable Photosynthesis System. 110 Haverville Road, Suite 301,
Amesbury, Mass. 01913 Phone: (978) 834-0505.

132

Priva CD 750. Priva Computers Inc. 3468 South Service Road, Vineland Station,
Ontario, Canada. Phone: (905) 562-7351.

R&D Sprayers. 419 Highway 104, Opelousas, Louisiana 70570. Phone: (337) 942—1001.

SAS (Statistical Analytical Software). 2002. SAS Institute Inc., 100 SAS Campus Drive,
Cary, North Carolina 27513. Phone: (919) 677-8000.

Spectrum Technologies, Inc. Watchdog Data Logger Model 450. 12360 South Industrial
Dr., East - Plainﬁeld, Illinois 60585.

Toro Company. Consumer Division, 8111 Lyndale Avenue South, Bloomington, Minn.
55420.

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