Effects of High Temperature Stress on Photosynthesis Rate, Contents of Chlorophyll,Ca~(2+)-ATPase,Mg~(2+)-ATPase in Chloroplast and Ca~(2+) Distribution in Peanut Seedlings

Peanut seedlings potted after tank farming were cultured at 42℃ in incubator, and the photosynthesis rate, contents of chlorophyll, activities of Ca2+-ATPase, Mg2+-ATPase in chloroplast were measured regularly and the Ca2+ distribution in young leafage was observed accordingly. The results show that under high temperature stress, the photosynthesis rate and contents of chlorophyll decreased, and were positively correlated. Moreover, activities of Ca2+-ATPase, Mg2+-ATPase in chloroplast increased early and then decreased later, and the sensitivity to heat of Ca2+-ATPase was higher than Mg2+-ATPase. In addition, most of Ca2+ was transferred to cytosol and chloroplast across the plasmalemma, and Ca2+ could stabilize the structures of membrane and chloroplast under high temperature stress.