Abstract: In order to study the effect of high temperature on the senescence of strawberry leaves,five artificial environmental control experiments and one basis experiment were designed in artificial climate chamber in Nanjing University of Information Science & Technology from December in 2010 to February in 2011.The control experiments were set at 30,32,34,36,38℃,respectively,and the basis experiment was set at 25℃.At each experiment,we measured physiological indices closely related to leaf senescence such as leaf superoxide dismutase(SOD),peroxide(POD),catalase(CAT),malondialdehyde(MDA),soluble protein and chlorophyll content of strawberry(Fragaria ananassa Duch.cv Toyonak)leaves.The results showed that MDA content increased as temperature and observed time increased.Soluble protein,SOD,POD,CAT activity after 30-34℃ treatments were all higher than those in the control treatment.SOD and POD activity reached highest after 3 days in the 34℃ treatment,while soluble protein and CAT activity reached highest after 5 days in the 34℃ treatment.After the 36℃ and 38℃ treatments,soluble protein,SOD,POD,CAT activity were lower than those in the control treatment (P＜0.05).As the high temperature duration time increased, chlorophyll a,chlorophyll b and carotenoid decreased.The study suggested that high temperature stress reduced protective enzyme activity and antioxidant ability,resulted in amount of active oxygen accumulated and the senescence of strawberry leaves increased.The finding is possible to provide scientific basis for defense of high temperature meteorological disaster for greenhouse strawberry.

Key words: High temperature, Strawberry, Superoxide dismutase(SOD), Peroxide(POD), Catalase(CAT), Malondialdehyde(MDA), Soluble protein, Cytochrome