Abstract: The responses of seedling growth, physiological properties and PSⅡto low temperature among three genotype cucumbers were comparatively studied.The results showed that:Chilling injury of three genotypes pro-duced under low temperature stress, the dehydrate and chilling injury of EC 1 was the most light, and SWCC12 showed the serious.The contents of Malondialdehyde ( MDA) and electrolyte leakage in three cucumbers increased under cold treatment,the increase extent of two indices in EC1 was minimum,and in SWCC12 was maximal.Super-oxide dismutase ( SOD) in three cucumbers increased during treatment, especially in EC1 and Beijingjietou SOD were induced rapidly and efficiently.The change of peroxidase ( POD) and ascorbate peroxidase ( APX) activity in EC1 rose first and then fell, but were higher than pretreatment, and the contents of two enzymes in Beijingjietou first decreased the increased and had no significant change.While the activity of POD and APX in SWCC 12 increased under low temperature stress.Catalase(CAT) activity in EC1 could be activated by low temperature,reaching the peak in 2 d and then dropped to the former level, that in Beijingjietou and SWCC 12 had not changed much.The content of soluble protein increased before decreasing in three genotypes.And the change of soluble sugar in EC 1 and Beijingjietou as the same as that protein, and were higher than pretreatment, but in SWCC12 declined during stress.The contents of chlorophyll and carotenoid in three genotypes first increased and then decreased under low temperature.The high contents of two pigments in EC1 maintained longer time, declined slowly, while that in SWCC12 was contrary.Low temperature hurt the PSⅡ of cucumbers,the Fv/Fm,Yield and ETR in SWCC12 di-clined most seriously, while in Beijngjietou most slightly.

Key words: CucumbeR, Genotype, Low tempeRatuRe stRess, Antioxidant enzyme, PhotosystemⅡ

CLC Number: 

• S642.2