EFFECTS OF HIGH TEMPERATURE STRESS ON MEMBRANE DAMAGE AND ACTIVITIES OF PROTECTIVE ENZYMES IN COWPEA SEEDLING LEAVES

Two cowpea varieties(Vigna unguiculata W.,var.zaoyouNo.1 and youxuanzhijiang28-2) were used to study the membrane damage and the activities of protective enzymes in cowpea seedling leaves under high temperature (45℃/33℃).The results showed that under high temperature stress,activities of SOD、POD、CAT and Pro content of both varieties increased at different level,activities of SOD、POD、CAT and Pro content of zaoyouNo.1 were to the maximum point after 3 days' stress without exception,while activities of SOD、POD、CAT and Pro content of youxuanzhijiang28-2 were to the maximum point after 1 day,1 day,3 days' and 3 days' stress.Then all of them decreased,and still decreased after 2 days' recovery under 35℃.MDA content and relative conductivity of both varieties increased all along during the stress,to the maximum point after 5 days' stress.The activities of SOD,POD and CAT and content of Pro of zaoyouNo.1 were higher distinctly than those of youxuanzhijiang28-2,however the MDA content and relative conductivity of it were lower apparently than those of the latter.The results indicated that under the high temperature stress,the membrane stability of zaoyouNo.1 was higher;the active oxygen quenching ability of its protective enzyme was also higher.