Hormone-containing products' impact on antioxidant status of tall fescue and creeping bentgrass subjected to drought

This study was conducted to determine whether the plant endogenous antioxidant concentration is responsive to exogenous hormone-containing products (HCPs) in two turfgrass species subjected to drought. Two-week-old seedlings of tall fescue (Festuca arundinacea Schreb.) and creeping bentgrass (Agrostis palustris Huds. A.) were treated with two HCPs, seaweed extract (SWE) at 326 g ha(-1) or humic acid (HA, 25% a.i,) at 5 L ha(-1), applied alone or in combination and grown under either -0.03 or -0.5 MPa soil moisture for 5 wk. Growth and antioxidant status of leaves were determined subsequently. The HCP treatments significantly improved leaf water status (LWS) and shoot and root growth of the grasses grown under high (-0.03 MPa) and low (-0.5 MPa) soil moisture. alpha-Tocopherol concentration increased significantly and ascorbic acid concentration remained unchanged for drought-stressed compared with nonstressed turfgrass. The HCP treatments significantly increased alpha-tocopherol and ascorbic acid concentration of the grasses grown under high and low soil moisture. Positive correlation between antioxidants and shoot or root growth was found in the two grass species. Improvement of growth and LWS of turfgrass treated with HCPs may be related to its high antioxidant concentration.