Study the Characters of Physiological and Biochemical Index of the Alfalfa in High Temperature Stress

The characters of physiological and biochemical index of Alfalfa in high temperature stress (42/33℃)is studied. The results showed that with prolongation of the time of high temperature, cell membrane penetration and the content of malondialdehyde (MDA) increased, the content of chlorophyll decreased, the change of solubility sugar and POD enzyme activity were enhanced at first and followed decreased. At the same time the reason of this change is discussed. All these characters provided the scientific basis for seeking the high temperature resistant species of Alfalfa.