The Study On The Physiological Effects And Thermotolerance Induction Of Kiwifruit Under High Temperature Stress

The effect of high temperature on the content of chlorophyll and malondialdehyde(MDA), electrolytic leakage of membrane, the activities of antioxidant enzymes, and the content of antioxidants of kiwifruit were studied. The measures of treatment with heat shock, Ca2+, salicylic acid and ascorbic acid were taken to induce the thermotolerance of kiwifruit under high temperature stress in this thesis. The physiology and biochemical mechanism of high temperature on kiwifruit and the treatment with heat shock, Ca2+, salicylic acid and ascorbic acid on kiwifruit under high temperature stress were discussed. All aboved provided the base theory for cultivation and breeding of kiwifruit. The result showed that chlorophyll was decomposed, the electrolytic leakage of membrane was amplified, H2O2 and MDA content were accumulated in kiwifruit under high temperature stress. The activities of superoxide dimutase(SOD), catalase(CAT), peroxidase(POD), ascorbic peroxidase(APX) and glutathione reductase(GR) were incited by first period of high temperature and then decreased with long time stress in kiwifruit under high temperature stress. Pro content was accumulated, ascorbic acid(ASA) content decreased during all stress period, glutathione content increased at first stress time then decreased as the stress time lengthened. Heat shock proteins were induced in kiwifruit under high temperature stress. Heat shock applied to kiwifruit increased the thermotolerance of kiwifruit compared with the control. Brief heat shock applied before high temperature stress inhibited the decomposition of chlorophyll, decreased the electrolytic leakage of cellular membrane under high temperature stress. Heat shock enhanced the activities of antioxidant enzymes and the antioxidants were higher than the control. In contrast, the MDA content in heat shock kiwifruit was lower than those in the control under high temperature stress. Kiwifruit treated with Ca2+ inhibited the decomposition of chlorophyll, lower the MDA content and electrolytic leakage of cellular membrane under high temperature. The antioxidant enzymes and antioxidants of kiwifruit treated with Ca2+ were higher than those in the control under high temperature. Kiwifruit treated with salicylic acid(SA) also lower MDA content and electrolytic leakage of cellular membrane under high temperature stress. Not only the antioxidant enzyme activities but also antioxidants increased in kiwifruit treated with salicylic acid under high temperature. Compared to the control, the kiwifruit treated with ascorbic acid maintain higher levels of antioxidant enzyme activities, inhibited the electrolytic leakage of membrane, and diminished the content of MDA in kiwifruit under high temperature stress.