effect of sodium nitroprusside (snp) on some biochemical characteristics of barley seedlings (hordeum vulgare l. cv. sahra) under salinity stress

to find out the effect of sodium nitroprusside (snp) in reducing oxidative damage induced by salinity stress in barley seedlings, a crd based factorial experiment with three replications was conducted in agronomy laboratory of the faculty of agricultural sciences, university of guilan, in 2012. the experimental design consisted of two snp levels (0.1 and 0.2 mm snp; as nitric oxide (no) donor) and two amount of nacl (0 as control and 300 mm nacl). seven days after the onset of the experiment, superoxide dismutase (sod), peroxidase (pod), catalase (cat), ascorbate peroxidase (apx) and polyphenol oxidase (ppo) activities, lipid peroxidation (mda) and oxidation of proteins content in leaves were measured. results revealed that the highest pod (7.07 μm g-1 fw. min.) and cat (17.6 μm g-1 fw. min.) activity was related to the treatment snp0.1 in saline condition. no significant effect of salinity stress was seen on apx enzyme activity; however, highest of the sod and apx activity was attained in snp0.1. no significant effect of no treatment was seen on ppo enzyme. exogenous no, as an antioxidant, also reduced peroxidation of membrane lipids (mda) and delayed the oxidation of proteins. overall, it seems that the concentration of 0.1 mm no is the best concentration for barley seedlings under saline conditions which could increase resistance seedlings through the reduction salinity stress adverse effects by influence on the plant antioxidant defense system.