Abstract: The study was conducted to investigate the effect of exogenous nitric oxide on growth of cucumber seedlings, membrane lipid peroxidation and photosynthesis under low temperature conditions of 9℃/9℃ (day /night). The results showed that the growth of cucumber seedlings was significantly restrained under low temperature. Accompanying the great decreases in dry weight, fresh weight, chlorophyll content and net photosynthesis rate, the membrane permeability and content of MDA markedly increased in low temperature treatment. However, spraying of 100 μmol·L-1 SNP, a donor of nitric oxide, to surface of leaves significantly alleviated the injuries from low temperature, the decrease of chlorophyll content and net photosynthesis rate as well as the increase of membrane permeability and content of MDA were also significantly alleviated as compared to the non-SNP-treated counterpart. There were no obvious effects of exogenous nitric oxide on seedlings under normal temperature conditions.

Key words: low temperature, nitric oxide, cucumber, physiological characters