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

In resent years, with the greenhouse effect and the global air temperature gradually increasing, the high temperature gives birth to bad effects on growth and viability of foliage plants. Cyclamen is one kind of ornamental flowers, which is fond of coolness and could not endure high temperature. Cyclamen can easily suffer from the high temperature in planting. In this thesis, five experimental species of potted cyclamen were choosed, which are 1011, 1051, 2031, 1013 and Laizhou number 3. The effect of high temperature on the content of chlorophyll and MDA, electrolytic leakage of membrane, the activities of antioxidant enzymes, and the content of antioxidants of cyclamen were studied. Treatment with heat shock, Ca²⁺ and salicylic acid were taken to induce the thermotolerance of cyclamen under high temperature stress. The physiology and biochemical mechanism of high temperature on cyclamen and the treatment with heat shock, Ca²⁺ and salicylic acid on cyclamen under high temperature stress were also discussed. All above provided the base theory for cultivation and breeding of cyclamen. The results showed that:(1) Under high temperature stress, chlorophyll was decomposed, the electrolytic leakage of membrane was amplified, MDA content was accumulated in cyclamen. The activities of SOD, CAT and POD were increased at the beginning stage of high temperature and then decreased with long time stress in cyclamen under high temperature stress. APX had different changes and GR had little changes. Pro content was accumulated, ASA content increased at first stress time then decreased as the stress time lengthened. GSH content had different changes during all stress period.(2)Heat shock applied to cyclamen increased the thermotolerance of cyclamen 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 cyclamen was lower than those of the control under high temperature stress.(3) The MDA content and electrolytic leakage of cellular membrane in cyclamen treated with Ca²⁺ and salicylic acid severally was lower than control under high temperature. The antioxidant enzymes and antioxidants of cyclamen treated with Ca²⁺ were higher than those of control under high temperature.