Abstract: 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.

Key words: high temperature stress, peanut seedlings, photosynthesis speed, chlorophyll, chloroplast, Ca²⁺-ATPase, Mg²⁺-ATPase, Ca²⁺ distribution