Exogenous choline chloride improves heat and drought stress tolerance of creeping bentgrass

Abstract Choline is a primary precursor of glycine betaine, which is an important osmoprotectant. Choline may improve plant tolerance to abiotic stress, but little study was reported on the effects of choline on drought and heat tolerance in cool‐season turfgrass species. The objective of this study was to determine the effects of choline chloride on drought and heat tolerance associated with antioxidant metabolism and root viability in creeping bentgrass ( Agrostis stolonifera L.). The four treatments, including control, choline chloride at 38, 76, and 152 mg m −2 , were applied biweekly to the foliage, and treated grass was subjected to heat and drought stress conditions in a growth chamber for 56 days. The choline chloride applications at 76 and 152 mg m −2 improved turf quality ratings by 11.9% and 16.9%, respectively; photochemical efficiency by 8.9% and 7.8%, respectively; and chlorophyll content by 28.4% and 29.7%, respectively, when compared to the control at the end of the trial. The choline chloride treatments at 76 mL m −2 and 152 mg m −2 enhanced antioxidant enzyme superoxide dismutase, catalase, and ascorbate peroxidase activity when compared to the control as measured at the end of the trial. Choline chloride treatments at 76 and 152 mL m −2 also enhanced leaf proline content and root biomass relative to the control. The choline chloride applications at 76 mL m −2 and 152 mg m −2 improved root viability by 124.6% and 93.0% relative to the control. Data suggest that exogenous choline chloride may improve drought and heat tolerance by enhancing leaf antioxidant enzyme activity, root growth and viability, and protecting photosynthetic function. The results of this study suggest that foliar application of choline chloride at 76 and 152 mg m −2 may improve creeping bentgrass performance during the summer months in the US transition zone and other regions with similar climate.