Effects of exogenous nitric oxide on growth, active oxygen species metabolism, and photosynthetic characteristics in cucumber seedlings under NaCl stress

Abstract

The study was conducted by means of nutrient solution culture to investigate the effects of exogenous nitric oxide (NO) on growth of cucumber seedlings, active oxygen species metabolism and photosynthetic characteristics in cucumber leaves under 50 mmol/L NaCl stress. The results showed that 10–400 µmol/L exogenous sodium nitroprusside (SNP), especially 100 µmol/L SNP, significantly alleviated the injury to seedlings and increased seedling growth. The activity of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), and the contents of photosynthetic pigments and proline also increased under 50 mmol/L NaCl stress. Similarly, net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) also increased significantly. However, exogenous nitric oxide application markedly decreased membrane permeability, rate of O 2 .− production, the contents of malondialdehyde (MDA) and H2O2, and intercellular CO2 concentration (Ci) under 50 mmol/L NaCl stress.