Impacts of altered light spectral quality on warm season turfgrass growth under greenhouse conditions
Warm-season turfgrass quality declines under shade due to reduced photosynthesis, increased disease pressure, reduced carbohydrate production, tree root competition, and reduced lateral stem growth. Another factor limiting turfgrass growth and development under tree shade is variable qualities of light filtered by trees. However, effects of various filtered wavelengths on turfgrass performance are lacking and deserve research. Therefore, a greenhouse project investigated the physiological and morphological responses of ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.], ‘Sea Isle 2000’ seashore paspalum (Paspalum vaginatum Swartz.), and ‘Tifway’ and ‘Celebration’ bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] to variable light spectral qualities. Light treatments included a control without any shade cloths and four different color shade cloths filtering wavelengths 560 to 720 nm (blue shade cloth), 360 to 520 nm (yellow shade cloth), 360 to 560 nm (red shade cloth), and 360 to 720 nm (black shade cloth). The percent light reduction for each cloth was about 65% relative to the control. Data collected included visual turfgrass quality (TQ), relative clipping yield, relative chlorophyll concentration, relative shoot width, relative root biomass, relative root length density, relative specific root length, and root and shoot total nonstructural carbohydrates. Diamond was the least affected turfgrass by the color shade cloths, while Celebration and Sea Isle 2000 performed similarly. Tifway was the most sensitive turfgrass with the lowest TQ under color shade cloths. Yellow and red shades were least detrimental, while black shade most negatively inhibited parameters measured, followed by blue shade. This study implies different types of shade significantly impact the TQ of warm-season turfgrasses.