Study On Heat Tolerance Of Cowpea

The changes of growth and physiological characters of 18 cowpea (Vigna unguiculata W.) varieties commonly cultured in north China were studied. The fruit stage researches were actualized in farmland in summer and the seedling experiments were done in phytotron and light growth incubator. Two varieties which evidently different in their heat tolerance were selected, that is zaoyouNO.1 and youxuanzhijiang28-2. Seedlings of those two varieties were used to study the effects of heat stress on the membrane damage, changes of protective enzymes, non-enzyme antioxidants and photosynthesis. And the mechanism of high temperature endurance of cowpea was discussed. The main results were as follow:1. Heat-tolerance comparison of cowpea:Fruit stage experiment in farmland in summer was actualized first, and then the seedling experiments in phytotron and light growth incubator were done. The results showed that the heat-tolerance of zaoyouNo.1 was highest, but that of youxuanzhijiang28-2 was low relatively among the 18 varieties.2. Study on mechanism of cowpea heat-tolerance2.1 The suitable temperature range for photosynthesis of cowpea was 36℃～38℃, and different cowpea varieties behaved different.2.2 As time of heat-stress went by, heat index, relative conductivity and MDA content of cowpea increased, while the chlorophyll content decreased. But the heat index, relative conductivity and MDA content of zaoyouNo.1 were lower apparently than those of youxuanzhijiang28-2, while the chlorophyll content of zaoyouNo.1 was higher. It showed that under high temperature stress, the damages to plasma membrane and chloroplast of heat-tolerant cowpea variety were not more serious than to heat-sensitive variety.2.3 Under high temperature stress, the content of proline and soluble sugar of cowpea increased evidently, and those of zaoyouNo.1 were higher than those of youxuanzhijiang28-2, which showed that the ability of osmotic...