Responses of Warm Season Turfgrass Cultivars to Different Light Intensities.

Shade is a major abiotic stress that poses challenges for the turfgrass manager. Understanding the influence of shade on turfgrass water use and performance among different cultivars can provide valuable information for turfgrass cultivar selection by consumers and improved selection in breeding programs. As a promising species for use in shaded environments, eleven zoysiagrass (Zoysia Willd.) cultivars (‘Empire’, ‘UltimateFlora’, ‘JaMur’, ‘EI Toro’, ‘Palisade’, ‘Cavalier’, ‘Zorro’, ‘Emerald’, ‘Zeon’, ‘PristineFlora’, and ‘Geo’) were evaluated in the greenhouse under 0%, 30%, 60% and 90% shade for water use, visual ratings, growth rate, and canopy spectral reflectance.  For comparison purposes, three St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze.) cultivars (‘Floratam’, ‘Palmetto’, and ‘Captiva’) also were evaluated. Differences were found among species and cultivars for all parameters. Zoysiagrass had better color and quality, higher NDVI (normalized difference vegetation index) and LAI (leaf area index calculated as R₉₃₀/R₆₆₀) than St. Augustinegrass as shade levels increased to 90%. Water use was decreased by 20% under 30% shade; 36% under 60% shade, and 60% under 90% shade among all cultivars. Zorro and Emerald zoysiagrass used less water than JaMur and PristineFlora, but they were not different for visual quality. The water use was higher for cultivars with higher NDVI and LAI.