Abstract: The effects of different concentrations of 6-BA on gas exchange and chlorophyll fluorescence parameters in different cucumber types under low light stress in greenhouse were studied. The results showed that application of optimal concentrations of 6-BA could obviously alleviate the decrease of net photosynthetic rate, stomatal conductance and transpiration rate under low light stress, indicating 10 μmol·L^-1 was suitable for cross combination of Huanan type 07QP56 and 2, 5 μmol·L^-1 was suitable for cross combination of European mini type 07QP56. Meanwhile, 10 μmol·L^-1 6-BA could also alleviate the decrease of Fv/Fo, Fv/Fm in 07QP56 under low light stress as well. It was also indicated that 07QP51 showed higher resistance to low light stress compared to 07QP56, and 07QP51 was more sensitive to the higher concentration of 6-BA．

Key words: 6-BA, low light stress, cucumber, gas exchange parameters, chlorophyll fluorescence