Effects of Low Temperature on Physiological Properties of Eggplant Seedlings and Selection of Cold-Tolerance Indicators

Effects of low temperature stress on the physiological and biochemical properties as well as the antioxidant enzyme activities of the eggplant seedlings and the correlation among the indicators for the cold-tolerance of the plants were studied. The results indicated that cold stress reduced the content of chlorophyll in leaves but increased those of MDA, proline, soluble protein and soluble sugar in the seedlings.Meanwhile, the electric conductivity and the activities of SOD, POD and CAT also increased significantly. By moving the stressed seedlings back into normal temperature, the chlorophyll content increased slightly but remained lower than control, while the other indicators declined to the levels still higher than those of control.There were ery significant correlations existed among the indicators. The highest correlation coefficient was found between the electric conductivity and the MDA or soluble sugar content. It appeared that a day/night low temperature exposure at 10℃/5℃ would irreversibly damage the normal metabolism of the seedlings.The electric conductivity, MDA and soluble sugar seemed to be appropriate for evaluating the cold-tolerance of eggplant seedlings.