Research On The Impacts Of High Temperature And Drought On Korla Fragrant Pear Photosynthetic Characteristics

This thesis taked Korla fragrant pear as the material,the effect of high temperature and drought on photosynthetic characteristics in Kor la fragrant pear were measured with 3 different treatments which were included high temperature and drought, watered, sprayed at 36℃ high temperature conditions.The results are as follows:1. The variation curve of Korla fragrant pear net photosynthetic rate presented double-apex with a phenomenon of photosynthetic “noon breaking” and net photosynthetic rate of each time period were less than irrigation treatments in the high temperature and drought condition.2. The variation curves of stomatal conductance and transpiration rate showed the same, which displayed a hollow pattern and the stomatal conductance of each time period were less than irrigation treatments in the high temperature and drought condition.3. The variation curves of intercellular CO2 may be influenced by the net photosynthetic rate showed a decreasing trend at noon in the high temperature and drought condition; the variation curves of intercellular CO2 appeared smaller change under the condition of irrigation.4. High temperature and drought treatment led to a prominent drop in the contents of Chl-a,Chl-b and Chl a+b.The watered and sprayed treatment can improve the chlorophyll content.5. High temperature and drought compared with watered and sprayed,the content of starch decreased and with extension of treatment, the content showed a decreasing trend; The content of soluble sugar and the activity of SOD, CAT showed a increasing trend, and in the meantime the content of soluble protein and the activity of POD significantly increased. With the extension of treatment, soluble protein and POD showed a decreasing trend.6. The content of starch increased at five minutes after the water ed and then dropped to the level at watered after thirty minutes; The content of soluble sugar、soluble protein and POD contrary; The activity of SOD, CAT showed a decreasing trend under the condition of sprayed.7. The content of soluble sugar and starch and soluble protein with extension of treatment, the content showed a increasing trend;The activity of SOD, POD,CAT showed a flat trend under the condition of irrigation.The results indicated that Korla fragrant pear photosynthesis reduced and the adjustment mechanism also decreased. It caused hazards to plants under the high temperature and drought treatment.Sprayed cannot alleviate the damage of high temperature and drought on Korla fragrant pear.Irrigation can reduce the active oxygen concentration. It showed that Korla fragrant pear be able to maintain normal physiologic function under the condition of irrigation. Irrigation can protect Korla fragrant pear over-summering safety.