Effects of Trinexapac-Ethyl and Acibenzolar-s-Methyl on Drought Tolerance in Hybrid Bermudagrass Fairways.

Plant growth regulators are a common component of turfgrass management systems, where they are used to reduce mowing requirements, reduce seedheads, and enhance stress tolerance. Although there are numerous plant growth regulators available in the turfgrass market, trinexapac-ethyl has been the most widely used due to its broad safety across a range of species and the positive effects it can have on turfgrass performance. One area that has received limited attention is how a product such as trinexapac-ethyl might influence the drought tolerance of warm-season grasses such as bermudagrass. The objective of this study was to determine the effects of trinexapac-ethyl and acibenzolar-s-methyl, a plant defense activator, on the performance of bermudagrass fairway under restricted irrigation. This study was conducted on Tifsport hybrid bermudagrass maintained at 1.27cm. Four applications of treatments were made on 21 day intervals throughout the growing season. All treatments were exposed to a drought cycle three days after the second and fourth applications and a movable rainout shelter was used to insure drought conditions. The untreated plots began to lose turfgrass coverage after 21 days, and levels were near 50%. Plots treated with acibenzolar sustained at least 75% green turf coverage three weeks into the drought cycle. Green coverage of the AB treated plots continued longer than the controls, TE alone, and plots treated with a combination of TE and AB. Through the early stages of drought, all TE and AB treatments had higher soil volumetric water content when compared to the untreated control. These results suggest that considerable water savings might be realized on bermudagrass fairways through the use of PGRs such as trinexapac-ethyl and products like the plant defense activator acibenzolar. The delay in the onset of drought stress for up to several weeks in AB-treated bermudagrass suggests that numerous irrigation cycles might be avoided over a single growing season when using this product.