Effects of high temperature stress on the physiological and biochemical characters of alfalfa.

High temperature is one of the important adverse environmental factors that limits alfalfa(Medicago sativa L.) extension and utilization and seriously affects production and quality.The physiological and biochemical indices of tested alfalfa varieties caused by high temperature stress were investigated in this study.The MDA contents.POD and SOD activities of alfalfa leaves during and after high temperature stress were detected.Results were that MDA content(P0.05) and POD activity(F0.01) significant increased under high temperature stress compared with control,while SOD activity first increased then decreased.The MDA content,POD and SOD activities of tested alfalfa varieties after high temperature period were higher than that before high temperature period.Integrated analysis showed Victoria variety was of the best heat resistance compared to other tested alfalfa varieties,and followed by Sidel variety.