Rooting Characteristics and Antioxidant Pigment Responses of Three Hybrid Bermudagrass

128 Pages·2017·2.79 MB·English

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Cory Alan Yurisic
University of Tennessee - Knoxville, [email protected]
Follow this and additional works at: https://trace.tennessee.edu/utk_gradthes
Part of the Plant Biology Commons
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Yurisic, Cory Alan, "Rooting Characteristics and Antioxidant Pigment Responses of Three Hybrid
Bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt- Davy] Cultivars Exposed to
Drought. " Master's Thesis, University of Tennessee, 2016.
https://trace.tennessee.edu/utk_gradthes/3822
This Thesis is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and
Creative Exchange. It has been accepted for inclusion in Masters Theses by an authorized administrator of TRACE:
Tennessee Research and Creative Exchange. For more information, please contact [email protected].
To the Graduate Council:
I am submitting herewith a thesis written by Cory Alan Yurisic entitled "Rooting Characteristics
and Antioxidant Pigment Responses of Three Hybrid Bermudagrass [Cynodon dactylon (L.)
Pers. × Cynodon transvaalensis Burtt- Davy] Cultivars Exposed to Drought." I have examined the
final electronic copy of this thesis for form and content and recommend that it be accepted in
partial fulfillment of the requirements for the degree of Master of Science, with a major in Plant
Sciences.
John C. Sorochan, Major Professor
We have read this thesis and recommend its acceptance:
Jim T. Brosnan, Dean A. Kopsell, John C. Stier
Accepted for the Council:
Carolyn R. Hodges
Vice Provost and Dean of the Graduate School
(Original signatures are on file with official student records.)
Rooting Characteristics and Antioxidant Pigment Responses of Three Hybrid
Bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt-
Davy] Cultivars Exposed to Drought

A Thesis Presented for the
Master of Science
Degree
The University of Tennessee, Knoxville

Cory Alan Yurisic
May 2016
DEDICATION

To my parents, Karen and Mark for their support in my decision to return to school to pursue my
passion.

To my beloved best friend, Whitney. Thank you so much for always being there to encourage
me during the times when I felt overwhelmed.

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ACKNOWLEDGEMENTS
Many thanks to my committee members: Dr. Jim Brosnan, Dr. Dean Kopsell, and Dr.
John Stier for their guidance and support throughout all stages of working toward my graduate
degree at the University of Tennessee. A special thanks to my advisor, Dr. John Sorochan for
introducing me to the world of turfgrass research, and for providing me the mentorship and
advice to become a better scientist.
Thank you to all of the undergraduate student assistants, James Adams, Sam Douglas,
Ryan Hammit, Hunter Salts, and Patrick Wright. Without your help, there is absolutely no way I
could have managed all of the work that went into making my research possible. A special
thanks to Dr. Adam Thoms for your scientific advice and for helping to manage my research
plots during my absences. Thank you to the farm management team at ETREC for providing the
space and tools needed to put forth this research. Thank you to Phil Flanagan for providing me a
space at the UTIA greenhouses to conduct my research.
Finally, thanks to my fellow graduate students, Jesse Benelli, Kyley Dickson, Eric
Reasor, and David Shell for providing me with some good laughs along with your valuable
insight.

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ABSTRACT
With recent changes in global climate, water use and its conservation have become
important topics of discussion. Turfgrasses for lawns, parks, and other recreational areas are
often perceived negatively due to the need for irrigation. The identification of turfgrasses
possessing an improved ability to withstand water deficit is an important goal in science to curb
irrigation requirements in the landscape. Newly released cultivars of hybrid bermudagrass (C.
dactylon L. x. C. transvaalensis Burtt-Davy) have demonstrated improved tolerance to stresses
such as cold, traffic, and water deficit; however, drought resistance mechanisms of these new
cultivars have been largely uninvestigated. Drought resistant plant species are often
characterized by deep and extensive root systems and improved antioxidant defense mechanisms
that can reduce the damaging effects of reactive oxygen species. Several studies in a variety of
different species of turfgrass have focused on root architecture, while others have examined
changes in enzymatic antioxidants. However, investigations into the roles of antioxidant
pigments in turfgrasses exposed to stress are quite limited. This research examined drought
resistance aspects of three commonly known hybrid bermudagrass cultivars. Experiments at two
locations utilizing lysimeter-grown plants were designed to evaluate differences in rooting
characteristics and changes in antioxidant pigment composition among cultivars exposed to
drought stress. Hybrid bermudagrass plants were grown in 45-cm tall lysimeters and subjected
to 28 days of drought stress under natural field conditions by withholding all water during the
summer of 2015. Lysimeters were arranged in a completely randomized experimental design
with three replications at two locations. Pigments were extracted from leaf tissue using high
performance liquid chromatography at four day intervals during the experiments. At the end of
the study, plant roots were washed and analyzed for root length, mass, and architecture for three
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separate soil depths. Cultivars exhibited significant differences for antioxidant pigment
composition and rooting characteristics. Cultivars evaluated in this study included ‘TifTuf’,
‘Latitude 36’, and ‘Tifway’. The TifTuf cultivar demonstrated superior drought resistance which
was characterized by increased root weight, surface area, and volume at deeper soil depths, and
greater antioxidant pigment concentrations and xanthophyll cycle activity at the later stages of
drought.

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PREFACE

“I have written of dawn, of the moon, and the trees;
Of people, and flowers, and the songs of the bees;
But over those things my mind would pass,
And come to rest among the grass.”

-Mable Duggan

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TABLE OF CONTENTS

CHAPTER I - LITERATURE REVIEW ....................................................................................... 1
Introduction ............................................................................................................................... 2
Water Issues and Use in the U.S. ........................................................................................ 2
Bermudagrass ...................................................................................................................... 5
Water Relations and Drought.................................................................................................... 6
Water Movement in Plants: ................................................................................................ 6
Drought in Plants ................................................................................................................ 7
Rooting and Drought................................................................................................................. 8
Rooting Studies in Turfgrass .............................................................................................. 9
Oxidative Stress and Carotenoids ........................................................................................... 10
Formation of ROS ............................................................................................................. 10
Antioxidant Systems ......................................................................................................... 11
Non-enzymatic Antioxidant System – the Xanthophylls.................................................. 12
Non-enzymatic Photoprotection Studies........................................................................... 13
Justification and Objectives .................................................................................................... 15
CHAPTER II - ROOTING CHARACTERISTICS OF THREE HYBRID BERMUDAGRASS
CULTIVARS EXPOSED TO DROUGHT ...................................................................... 17
Abstract ................................................................................................................................... 18
Introduction ............................................................................................................................. 19
Materials and Methods ............................................................................................................ 21
Plant Culture ..................................................................................................................... 21
Plant Propagation .............................................................................................................. 22
Rainout Box ...................................................................................................................... 24
Experimental Design ......................................................................................................... 24
Drought Conditions ........................................................................................................... 25
Data Collection ................................................................................................................. 25
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Results ..................................................................................................................................... 28
Discussion ............................................................................................................................... 30
CHAPTER III - ANTIOXIDANT PIGMENT RESPONSES OF THREE HYBRID
BERMUDAGRASS CULTIVARS EXPOSED TO DROUGHT .................................... 34
Abstract ................................................................................................................................... 35
Introduction ............................................................................................................................. 36
Materials and Methods ............................................................................................................ 44
Plant culture ...................................................................................................................... 44
Rainout box ....................................................................................................................... 46
Drought Conditions ........................................................................................................... 47
Experimental Design ......................................................................................................... 47
Data Collection ................................................................................................................. 49
Statistical analysis ............................................................................................................. 51
Results and Discussion ........................................................................................................... 52
CHAPTER IV - CONCLUSIONS ............................................................................................... 63
REFERENCES ............................................................................................................................. 67
APPENDIX ................................................................................................................................... 77
VITA ......................................................................................................................................... 109

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