Abstract: The effects of NaCl stress (0, 50, 100 and 150 mmol·L^-1) on the growth, photosynthesis and chlorophyll fluorescence parameters of three cucumber rootstock seedlings (Cucurbita moschata Duch. 'Chaoji Quanwang', Cucurbita ficifolia 'Heizi Nangua', Lagenaria siceraria Standl. var. clavata Makino 'Chaofeng 8848') were investigated. The results showed that the dry and fresh mass of shoot, plant height, leaf number, net photosynthetic rate, stomatal conductance and transpiration rate of three cucumber rootstock seedlings decreased gradually with increasing of NaCl concentrations. The initial fluorescence yield (Fo) of 'Chaoji Quanwang' and the photochemical quenching (qP) of 'Heizi Nangua' decreased significantly, whereas qP of 'Chaofeng 8848' increased significantly under higher salt stress (150 mmol·L^-1 NaCl). The maximal photochemical efficiency of PSⅡ (Fv/Fm) did not decrease and there was no significant difference in the quantum efficiency of PSⅡ photochemistry (ΦPSⅡ) under NaCl stress. The chlorophyll a/b ratio of 'Chaoji Quanwang' and 'Heizi Nangua' seedlings did not change significantly under NaCl salt stress, whereas that of 'Chaofeng 8848' decreased significantly.

Key words: Cucumber, NaCl stress, Rootstock, Plant growth, Photosynthesis, Chlorophyll fluorescence parameters