Drought Performance and Physiological Responses of Bermudagrass and Seashore Paspalum

Drought is a major abiotic stress that affects turfgrasses, leading to progressive declines in plant health and eventual death of turf areas. A collection of bermudagrasses (Cynodon spp.; 'Celebration', 'TifTuf', and 'Tifway') and seashore paspalums (Paspalum vaginatum Swartz; 'SeaIsle I', 'SeaStar', and UGA1743) were used to determine differences in drought performance and associated mechanisms. Plants were exposed to drought trials during the 2016 and 2017 growing seasons using an automatic rainout shelter. Performance was assessed by measuring visual turf quality, normalized difference vegetation index, and green cover via digital image analysis. Additional measures including membrane stability, canopy temperature difference, relative water content, osmotic adjustment, and canopy respiration rates were also taken to better understand the underlying physiology responsible for differences in drought performance. Results showed a range of drought performance among cultivars, with Tiftuf consistently being the top performer with quality ratings of 6 and 5 in 2016 and 2017, respectively, and SeaStar consistently being the most drought sensitive with quality ratings of 4 or less for both years. The other bermudagrass and paspalum cultivars had similar performance to each other during drought. TifTuf was able to maintain lower canopy temperatures and higher relative water content and had the greatest accumulation of osmolytes during drought. Drought decreased respiration rates and membrane stability more in paspalum than bermudagrass cultivars. Understanding mechanisms responsible for differences among cultivars and how these mechanisms are affected by environmental conditions is essential for improving drought performance in turfgrasses.