Effects Of Exogenous ABA On Activities Of Different Varieties Of Kentucky Bluegrass Under Drought Conditions

Kentucky bluegrass is s a very important turfgrass species and used widly in landscaping, lawn and sports field in north China. It is suitable for damp and cold weather, but the drought resistance is poor. Drought is a limiting factor for turfgrass and green land quality. Therefore, turfgrass drought resistance and tolerance mechnism is crucial.Two "Midnight" and "Kenblue" different in drought tolerance were used to evaluate performances under soil drying processing and foliar spraying ABA treatment. Turfgrass physiological indexes, including the quality, water content of soil, relative water content of leaves, MDA content, antioxidant enzymes system APX, SOD, CAT, POD and ROS system, were compared to investigate drought tolerance of the two cultivars and the effect of foliar spraying ABA. This research was to evaluate key factors involved in drought adaptation and tolerance of Kentucky bluegrassThe results showed that, Midnight exhibited better drought resistance than Kenblue. Midnight has higher RWC, photochemical reaction efficiency and membrane stability during drought stress compared with Kenblue, and Midnight also has better turf quality Plants with ABA treatment showed that, both varieties with ABA have higher RWC than control plants during the drought stress, the extent of SOD activity reduction and MDA accumulation is smaller than that in control plants. With water stress intensifiing, ABA enhances CAT、APX、POD、SOD activity, especially for Kenblue, it suggested that ABA enhancement effect is remarkable to drought sensitive cultivar. During drought treatment period, MDA content in control plants increased significantly but ABA treatment slow down the rate of increasing. The result indicating that ABA can alleviate lipid perxidation under water stress. H2O2content is rising with drought stress proceeding in both cultivars of control plants and ABA treated plants. However, the foliar spraying ABA slowed down the process of H2O2increasing.·O2-content, like superoxide anion radical is increasing with drought stress proceeding too. The speed of·O2-content increasing in Midnight is very fastduringl0-20days of drought treatment, ABA foliar application inhibit the speed of·O2-content increasing. The research implied that exogenous ABA treatment enhances endogenous ABA content to improve Kentucky bluegrass aptation to drought stress.Midnight has better drought resistance than Kenblue. Foliar spraying ABA enhances their drought tolerance, especially for Kenblue. Through these experiments it helps us to explain turfgrass drought resistance mechanism in theory and toprovide basic information for turfgrass mangement strategy.