Development of Bermudagrass Cultivars with Improved Drought Performance.

Selection and identification of drought resistant bermudagrass cultivars under acute or chronic drought stress is important for sustainable turfgrass management and water conservation. The objective of this research was to identify differences in overall field drought performance of selected industry standard and OSU experimental bermudagrass entries. This research was conducted at the Oklahoma State University (OSU) Turfgrass Research Center in Stillwater, OK. Twenty-three clonal standard cultivars and experimental genotypes were used for this study including: Celebration, Premier, Tifway, Tifsport, SIU U-3 (Southern Illinois University source), TGS U-3 (Tulsa Grass and Sod farm source), NC U-3 (Northcutt sod farm source), Patriot and OSU experimental OKC 70-18, OKC 1119, OKC 1134, #2, #4, #12, #16, #17, #18, #20, #22, #24, #25, #26, and #27.  The experimental design was a strip-plot with four replications, 23 bermudagrass entries and four irrigation treatments. Four levels of irrigation were used according to reference evapotranspiration (ET_o) where: 0% ET_o, 33% ET_o, 66% ET_o, 100% ET_o, control treatment. A consecutive 28 days of drought stress was applied, and 60 days of recovery period was observed upon re-watering. Leaf firing and turf quality ratings were collected once per week throughout the study period. Turfgrass color was measured using an NDVI (normalized difference vegetative index) meter. All statistical analysis was completed at a P=0.05 significance level. Based on the overall results from this study, the hypothesis that there were no differences in vegetative bermudagrass entries for their field drought performance was rejected. At the 0% ET_o irrigation level, the OSU experimental bermudagrasses that performed lower than Celebration but better than all other entries for leaf firing, turf quality, % living cover, turf quality recovery, and NDVI were #2, #12, #16, #24, and #27. At the 33% ET_o irrigation level, Celebration, #2, #12, and #27 performed better for leaf firing, turf quality, % living cover, turf quality recovery, and NDVI than all other bermudagrass entries.  Future work should assess the drought tolerance and/or drought avoidance mechanisms of these entries.