Effect of acute shade on the canopy morphology and evapotranspiration rates of three turfgrasses

Understanding the comparative evapotranspiration (ET) rates of commonly used turfgrass species in a shaded environment would improve irrigation scheduling recommendations and contribute towards urban water conservation. The objectives of this study were (a) to compare the ET rates of selected turfgrasses under two irradiance levels and (b) to determine if shade-induced changes in ET rates were related to changes in leaf morphology. An 8-wk greenhouse experiment was conducted in fall 2017 with ‘Latitude 36 Turf Bermudagrass’ hybrid bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon Transvaalensis Burtt Davy], ‘Falcon IV’ tall fescue [Schedonorus arundinaceus (Schreb.)] ‘Dumort., nom. cons.’, and ‘Meyer’ Japanese lawngrass (Zoysia japonica Steud.) grown in lysimeters 15 cm in diameter. Plants were subjected to shaded conditions (55% nominal shade fabric) or a control (ambient greenhouse conditions plus supplemental lights). Plants were evaluated for specific leaf area, clipping yield, and ET rate over the study period. Turfgrass ET rates for tall fescue, Japanese lawngrass, and hybrid bermudagrass declined under shade by 12.8, 23.1, and 28.9%, suggesting that the ET rate for tall fescue is less sensitive to changes in light intensity. These results suggest irrigation scheduling methods for shaded landscapes may be influenced by species response to changes in light intensity.