Abstract: With different concentrations of Putrescine (Put)for rice-soaking, we investigated its effects on seed germination at sub-optimal and optimal temperatures.The resultls showed that Put-treatment(0.010.1mmol/L)enhanced seed germination and index of germination and rigour of the rice seed at sub-optimal temperature(16±1℃),but no effects at optimal temperature(28±1℃).It was found that the effect of Put on the germination of rice seed was connected with temperature.In mean time,we also found that Put-treatment enhanced the synthesis of α-amylase,increased the ATPcontent and the respiration intensity during seed germination at sub-optimal temperature(16±1℃).