Effect of antecedent drought stress on spring green-up in turf-type bermudagrasses

Winterkill is a major concern for turf-type bermudagrasses [Cynodon dactylon (L.) Pers. and C. dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] when cultivated in the US transition zone and frequently occurring drought conditions challenge bermudagrass management. Therefore, developing new bermudagrasses with both drought resistance and winter survivability are needed for the future sustainability of the turfgrass industry in the transition zone. How these two traits interact within bermudagrass populations is not widely reported. Accordingly, the objectives of this study were to estimate reliability for spring green-up (SG) (as an indicator of winter survivability) and drought response in turf-type bermudagrasses. A total of 77 experimental genotypes and 7 cultivars were planted in a randomized complete block design with 3 replications over 2 years in Goodwell, OK, USA. Substantial genetic variations were found for drought response and SG parameters when analyzed by year, but variations for SG parameters and leaf firing were not significant when analyzed across years. The reliability estimates for drought response ranged from low to moderate (i(2) = 0.24-0.61), whereas the subsequent estimates for SG were low (i(2) = 0.13-0.33), suggesting poor reliability. The low-to-moderate reliability values in SG were likely due to antecedent drought injuries, indicating that winter survivability and drought resistance may need to be evaluated in separate trials.