Effects of ABA on membrane lipid peroxidation and protective enzyme activities of cucumber seedlings leaves under alkaline stress

By spraying abscisic acid(ABA 5×10-5 mol·L-1)on cucumber seedlings leaves,the effects of alkaline stress on malondialdehyde (MDA) content,membrane permeability,superoxide dismutase (SOD),peroxidase (POD),catalase (CAT) and ascorbate peroxidase (APX) activities were studied.The results indicated that,at following 4,8,12,16 d of ABA application,the MDA content of the leaves of cucumber seedlings under alkaline stress decreased by 22.52 %,30.87 %,27.28 %,27.56 % respectively; and the membrane permeability decreased by 18.96 %,14.09 %,20.03 %,22.86 % respectively; but the activities of SOD,POD,CAT and APX increased in certain degree.These results suggested that ABA enhanced alkaline resistance by increasing antioxidant capacity of cucumber seedlings and alleviating membrane damage.