Abstract: ObjectiveThe effects of exogenous hydrogen sulfide(H2S) on antioxidant metabolism of rice seeds germinated under drought stress and intrinsic mechanism of rice drought resistance were explored,so as to provide reference for improving drought resistance of rice.Method0.75 mmol/L hydrosulfide sodium was used as exogenous H2S donor,polyethylene glycol (PEG) as the drought stress simulated agent,and hydroxylamine (HA) as H2S synthesis inhibitor.Germination rate,germination potential,relative conductivity,malondialdehyde (MDA),soluble protein content,hydrogen peroxide content (H2O2),superoxide dismutase (SOD) activity,catalase (CAT) activity,peroxidase (POD) activity and ascorbate peroxidase(APX) activity of rice seeds treated with exogenous H2S under drought stress were determined.ResultThe germination rate and germination potential of rice seeds treated with NaHS were 82.30% and 43.10% respectively,which were significantly higher than those of untreated seeds(P<0.05).Exogenous H2S could effectively prevent the soluble protein content of rice seeds under drought stress from decreasing,lower osmotic potential,alleviate the harm caused by drought stress.It could effectively alleviate H2O2 accumulation in rice seeds,which helped to slow down cell senescence and disintegration.It also better maintained the stability of plasma membrane of rice seed during germination and alleviate the damage caused by drought.Exogenous H2S effectively reduced MDA content in rice seed,decreased permeability of plasma membrane;it also promoted the increase of SOD activity,POD activity,CAT activity and APX activity of rice during germination,and improved the ability of germinated rice seed countering drought.ConclusionThe treatment with exogenous H2S donor NaHS can significantly improve the activity of antioxidant enzymes in rice seeds,effectively remove reactive oxygen,reduce permeability of plasma membrane,alleviate oxidative damage,improve drought resistance of rice seeds,and effectively promote rice seed germination under drought stress finally.