Masters Theses

Date of Award

5-2016

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant Sciences

Major Professor

John C. Sorochan

Committee Members

Jim T. Brosnan, Dean A. Kopsell, John C. Stier

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 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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