Foliar application of diethyl aminoethyl hexanoate (DA‐6) alleviated summer bentgrass decline and heat damage to creeping bentgrass

Abstract Creeping bentgrass ( Agrostis stolonifera ) is sensitive to supra‐optimal temperature, which makes summer bentgrass decline (SBD) a main conundrum troubling turf manager. Diethyl aminoethyl hexanoate (DA‐6) is an artificial and bioactive plant growth regulator affecting tolerance to various abiotic stresses. It is commercially available for field application due to multiple advantages such as low cost, environmentally friendly compound, and sustainable effect. However, the positive effect and mechanism of DA‐6‐mediated heat tolerance in cool‐season grass species and SBD are not yet been explored. Objectives of the study were to screen the optimal dose of DA‐6 for improvement in thermotolerance and to investigate roles of DA‐6 in regulating photosynthesis, osmotic balance, and antioxidant homeostasis in two creeping bentgrass cultivars (heat‐tolerant 13 M and heat‐sensitive Seaside II) in controlled heat condition. Summer heat tolerance induced by the DA‐6 was further evaluated for 2 years under field conditions in a subtropical zone. Results demonstrated that the optimal dose of DA‐6 was screened as 0.1 mM based on analyses of chlorophyll content, photochemical efficiency, and cell membrane stability under heat stress. Foliar application of DA‐6 significantly alleviated heat‐induced leaf senescence by improving photosynthetic performance, accumulation of sugars (sucrose, fructose, and glucose) for osmotic homeostasis, and total antioxidant capacity for reactive oxygen species scavenging in the two cultivars. A 2‐year field test was further carried out to demonstrate that turf quality of the two cultivars was significantly improved after being treated by foliar DA‐6 during hot summer months in 2020 and 2021. Current findings suggested that DA‐6‐mediated thermo‐resistant mechanism was associated with photosynthesis, osmotic adjustment, and antioxidant in cool‐season grass species. Foliar application of DA‐6 could be a cheap, effective, and environmentally friendly strategy to alleviate SBD.