Growth and physiological effects of chitosan on heat tolerance in creeping bentgrass (Agrostis stolonifera)

High temperature is one of the major abiotic stresses limiting growth and development of cool-season grass species, but chitosan could effectively enhance heat tolerance and improve plant growth. The objective of this study was to determine the optimal concentration of chitosan that could alleviate heat stress in creeping bentgrass ( Agrostis stolonifera ) and investigate the effects of exogenous chitosan on photosynthesis and cell membrane stability under heat stress. Under heat stress (38/28 °C, day/night), different chitosan concentrations of 0, 50, 100 and 500 mg·L −1 were applied on the leaves of creeping bentgrass (cv. 'Penn-A4'). Foliar application of chitosan exhibited the positive effects on plant growth and the optimal concentration was 100 mg·L −1 which significantly improved turf quality, root length, root-shoot ratio as well as shoot and root biomass. Chitosan-treated plants subjected to high temperature stress had a lower decline in photosynthetic rate and photochemical efficiency as well as less increase in electrolyte leakage and malondialdehyde content. The results demonstrate that chitosan-improved heat tolerance as reflected by the superior growth performance of both shoot and root, photosynthesis and cell membrane stability in creeping bentgrass under heat stress.