Abstract: To explore the effects of high temperature stress on the senescence characteristics and the dynamics of endogenous hormones in leaves of cucumber at flowering stage, we established an artificial environment within which temperature was controlled and selected cultivar ‘Nan Za Ⅱ’ as experiment material. Four levels of daily/night temperature were treated as 42  ℃/32  ℃,39  ℃/29  ℃, 36  ℃/26  ℃, and 24  ℃/18  ℃ (control); the durations of treatment time were 1, 3, 5, and 7 d, respectively. The contents of chlorophyll a, chlorophyll b, carotenoids andchlorophyll a+b, the activities of SOD, POD and CAT, and the content MDA, ABA, IAA, GA-3 and ZT were measured. Treatment of 42  ℃/32  ℃ with a duration of 7 d significantly reduced the contents of leaf chlorophyll a, chlorophyll b, and carotenoids, the activities of POD and SOD, and the contents of IAA, GA3, and ZT by 16.61%, 23.17%, 73.33%, 17.89%, 56.90%,94.16%, 54.32%, 90.68%, respectively, but enhanced leaf MDA content (+62.66%), CAT activity(+28.06%), and ABA content (+294.35%) in apical bud. Our results showed that shortterm high temperature stress increased the chlorophyll content of cucumber leaves and that the chlorophyll b content decreased gradually with the increase of temperature and extension of stress time. Shortterm high temperature stress increased the activities of antioxidant enzymes in cucumber leaves, but decreased gradually with the increased intensity of high temperature stress. An increasing trend of ABA content in cucumber leaves was detected under high temperature stress, while the changes of IAA, GA3 and ZT contents showed an opposite trend. Results from this study provide scientific basis for temperature management of cucumber cultivation.

Key words: RbohC and RbohF genes, reactive oxygen, Brassica campestris, enzyme activity analysis, MAP kinase