Effects of Plant Growth Hormones on Drought Tolerance and Post-Drought Recovery in Creeping Bentgrass.

Drought is an important abiotic stress that causes decreased growth in plants and is a major concern for cool-season turfgrass stands during periods of prolonged water deficit. Water use restrictions or lack of irrigation causes turf to go dormant and rapid recovery from dormancy once rainfall or irrigation resumes is important for regrowth and reestablishment of drought-stressed turfgrass in order to maintain both physiological and aesthetic qualities. Production of plant hormones within drought-stressed plants can be associated with rapid recovery and exogenous applications of plant growth hormones have been found to improve plant tolerance to drought. However, information regarding the mechanisms behind plant growth hormone effects on post-drought recovery on turfgrass is not fully understood. This study focused on the drought recuperative ability that exogenous applications of synthetic plant growth hormones, including cytokinin (6-BA), gibberellic acid (GA₃), and 6-BA and GA₃ in combination, could have on the rehydration or regrowth of leaf tissue upon re-watering of drought-stressed creeping bentgrass (Agrostis stolonifera cv. Barracuda). Improvement in overall turf performance was observed in both the rehydration of older leaf tissue and the regrowth of new tissue to a greater extent in plants treated with GA₃ or 6-BA in combination with GA₃ compared to those treated with either water or 6-BA alone. This was reflected at leaf levels by increased leaf water content, canopy height, turf quality (TQ), and normalized difference vegetation index (NDVI), as well as at root levels by enhanced root growth. The results suggest that exogenous applications with GA₃ could have desirable recuperative abilities for promoting rapid recovery from drought stress once the plants are re-watered.