Effects of the application of exogenous NO at different growth stage on the physiological characteristics of peanut grown in Cd-contaminated soil

A pot experiment was conducted to study the effects of sodium nitroprusside (SNP, a nitric oxide [NO] donor) on cadmium (Cd) toxicity in peanut plants. SNP solution was poured into Cd-contaminated soil at sowing, seedling, flowering, and pod setting stages, respectively. The results showed that exogenous NO increased the biomass and yield of peanuts and improved chlorophyll content, photosynthesis (P-n), and transpiration (T-r). Cd-induced oxidative damages were eliminated by exogenous NO, reflected by decreased accumulation of superoxide anion (O-2(center dot-)), hydrogen peroxide (H2O2), and malondialdehyde (MDA). Moreover, exogenous NO increased Cd-decreased activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and soluble protein and proline contents also reached a normal level. Furthermore, exogenous NO improved the uptake of nutrient elements and reduced Cd accumulation in the roots, shoots, and kernels under Cd stress. These data suggest that SNP application at sowing and seedling stages had better alleviation effects on Cd toxicity in peanut plants.