[Effects of exogenous Ca2+ on leaf photosynthetic apparatus and active oxygen scavenging enzyme system of chrysanthemum under high temperature stress].

Taking cut flower chrysanthemum 'Jinba' as test material, the effects of exogenous Ca2+ on its photosynthetic system and antioxidant enzyme activities under high temperature stress were investigated, with the possible action mechanisms of Ca2+ discussed. The results showed that under high temperature stress, Ca2+ addition greatly inhibited the net photosynthesis rate (P(n)) and quantum yield of PS II electron transport (phi(PS II)). After 24 h treatment, the P(n) and psi(PS II) were increased by 31.11% and 21.88% , respectively, and the initial fluorescence (F(o)) decreased by 13.19%, compare with the control. Ca2+ addition also greatly enhanced the activities of SOD, POD and CAT, and thus, the active oxygen was scavenged timely. After 24 h treatment, the MDA accumulation and REC were 29.20% and 35.81% lower than the control, respectively. In conclusion, Ca2+ addition could efficiently protect chrysanthemum leaves from the damage in photosynthetic apparatus under short-term high temperature stress.