Stress coefficients for hybrid bermudagrass in the transition zone

Abstract

AbstractThe use of drought tolerant turfgrass cultivars is desirable due to greater water use efficiency and sustained acceptable turfgrass quality during times of drought stress. Crop coefficients (Kc) have traditionally been utilized to assist in reducing irrigation by comparing reference evapotranspiration (ETo) to actual evapotranspiration (ETa) of specific crops. However, Kc values are most relevant during times of nonlimiting conditions and do not quantify the amount turfgrasses restrict evapotranspiration (ET) under moderate drought stress. Stress coefficients (Ks) estimate water needs while maintaining minimally acceptable turfgrass quality. The objective of this study was to derive Ks values for four bermudagrass (Cynodon spp.) cultivars managed in the transition zone. Direct measurements of actual evapotranspiration were made through weighing lysimetry during a 2‐year field study. Experimental units were allowed to naturally dry down near wilting point and maintained at a steady level of soil moisture to calculate Ks for each cultivar. A lower Ks value indicates increased turfgrass tolerance to water stress; whereas a Ks value ≥1 suggests higher soil moisture levels are required to sustain turfgrass quality. ‘TifTuf’, ‘Latitude 36’ and ‘Tifway’ were the best performing cultivars with mean Ks values of 0.747, 0.766, and 0.796, respectively. ‘Celebration’ had the highest Ks value of 0.944. The results indicate certain bermudagrass cultivars can maintain quality with less soil water, and the reduced water requirements may be used to schedule efficient irrigation applications.