Plant Growth Regulator Effects on Drought Tolerance of 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 an experimental product on the ability of bermudagrass fairways to perform under restricted irrigation. This study was conducted on Tifsport hybrid bermudagrass maintained at 1.27 cm. 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 application and a movable rainout shelter was used to insure drought conditions. The untreated plots and plots that were treated with the experimental compound alone began to lose turfgrass coverage after 21 days, and levels were near 50%. Plots treated with TE alone were superior and sustained over 80% coverage. The advantage of TE over untreated plots was sustained for the duration of the drought cycle. These results suggest that considerable water savings might be realized on bermudagrass fairways through the use of PGRs such as trinexapac-ethyl. The delay in the onset of drought stress for up to several weeks in TE-treated bermudagrass suggests that numerous irrigation cycles might be avoided over a single growing season when using a PGR to regulate growth of the bermudagrass.