Effect of Ca~(2+) ,La~(3+) and EGTA on reactive oxygen species metabolism in muskmelon seedlings under hypoxia stress

Effect of exogenous foliar spraying Ca 2+ ,plasma membrane Ca 2+ channel blockers La 3+ and Ca 2+ chelator EGTA on reactive oxygen species(ROS)contents and antioxidant enzymes activities in muskmelon seedlings was studied under root-zone hypoxia stress.The results showed that the activities of SOD,POD,CAT in roots and leaves treated by Ca 2+ were obviously higher than those of treated by hypoxia stress,but the contents of H2O2,MDA and production rate of were lower compared with treated by hypoxia stress,which induced higher hypoxia tolerance of muskmelon seedlings.Under the hypoxia stress,5 mmol·L -1 La 3+ and EGTA treatment remarkably inhibited the activities of CAT,SOD,POD,and aggravated the accumulation of ROS and membrane lipid peroxidation of muskmelon seedlings,which led to a lower hypoxia tolerance of seedlings.