Drought response of zoysiagrass with varying leaf texture under progressive deficit irrigation

Improving drought resistance in Zoysiagrass (Zoysia spp.) is a target for both private and public breeding programs. The performance of 26 elite experimental zoysiagrasses was compared under progressive drought stress with Palisades, Diamond, and Zeon. Environmental conditions were warmer and drier in 2020 (66 days) than 2021 (45 days). Irrigation was applied once weekly using potential evapotranspiration (ETo) rates and crop coefficients (Kc) of 0.6 (non-stress), or 0.40, 0.30, and 0.25 deficit treatments. Turfgrass quality, leaf wilt, normalized difference vegetative index, normalized difference red edge, and volumetric water content were recorded weekly. Genotypes with the highest means (statistical "a" group) contributed to a turfgrass performance index (TPI). Elite zoysiagrass with TPI >= Palisades (19) were Zoysia japonica Steud. ecotypes DALZ 1311 (22), 1601 (19), and 1603 (21), and finer textured interspecific hybrids, DALZ 1701 (18), 1713 (26), 1714 (18), and 1801 (24). Relative to an irrigation schedule using a 0.6 Kc, these genotypes survived extreme deficit irrigation, which conserved 40.1% (45,859.6 L) and 66.4% (44, 592.2 L) of water in 2020 and 2021, respectively. Overall, this study demonstrated that significant water consumption could be reduced with proper cultivar selection and deficit-based irrigation management while maintaining an acceptable turfgrass quality under drought conditions. Genetic variation exists in zoysiagrass for quality, leaf wilt, and green cover under soil drying conditions. Some Zoysia japonica ecotypes and hybrids exhibited high quality and low leaf wilt equal to or better than Palisades. Afternoon leaf wilt predicted turfgrass quality in zoysiagrass under water-deficit conditions. Within 3 weeks of resuming irrigation, most zoysiagrasses recovered to acceptable quality.