Effects of Exogenous Nitric Oxide on Physiological Characteristics of Wax Gourd Seedlings under Osmotic Stress

SNP (sodium nitroprusside) was used in this experiment at three concentrations (0.1,0.3,0.5 mmol/L) to investigate the effects of exogenous nitric oxide on the physiological characteristics in osmotically stressed wax gourd (Benincasa hispida Cogn.) seedlings.20% PEG-6000 was used to produce the osmotic stress,under which the effects of SNP were measured on oxidative damage to the leaves and protective enzyme activities in wax gourd.The results showed that the damage to wax gourd caused by the osmotic stress of 20% PEG-6000 was significantly reduced in the presence of 0.1 mmol/L SNP.Specifically,the level of malondialdehyde (MDA) in the leaves decreased by 62.65%;the relative conductivity in the leaves decreased by 28.09%;the proline content and enzyme activities of POD,CAT and SOD in the leaves increased by 14.35%,146%,41.34% and 14.01%,respectively;When the concentration of SNP increased to 0.3 and 0.5 mmol/L,the oxidative damage to the leaves sustained and the protective enzyme activities decreased,and 0.5 mmol/L SNP suppressed the activity of POD and SOD.