Effects of NaCl Stress on Filling,Antioxidant Enzyme Activities and Reactive Oxygen Metabolism in Seeds of Vegetable Soybean

Using vermiculite culture,the effects of 100 mmol·L-1 NaCl stress on filling,activities of antioxidant enzymes and reactive oxygen metabolism were studied in seeds of vegetable soybean [Glycine max(L.) Merr.].The results showed that seed size(including length,width and thickness),seed fresh mass and dry mass,pod fresh mass and dry mass were reduced significantly at later stages of salinization.The reduction stage of seed dry mass was later than that of pod.NaCl stress increased activities of antioxidant enzymes in varying degrees with different starting stages.Activities of peroxidase(POD) and ascorbate peroxidase increased remarkably in comparison with the control during 3-6 d and at the 6th day of salinization,while the activities of superoxide dismutase(SOD) and catalase(CAT) increased during 9-12 d and at the 12th day of stress respectively,which indicated that the responsive speed of antioxidant enzymes to salt stress was different.Under NaCl stress,O·-2 producing rate and the contents of H2O2 and malondiadehyde(MDA) increased significantly when compared to the control during the treated period except for the third day of salinization when their activities had no significant difference in comparison with the control.These results indicated that NaCl stress induced the accumulation of reactive oxygen in seeds of vegetable soybean,which resulted in membrane lipid peroxidation and the inhibition of seed filling.