Abstract:The effects of exogenous ascorbic acid (AsA) and methy jasmonate (MeJA) on rice (Oryza sativa) leaf senescence induced by ethephon was investigated using wild type of cultivar line Zhonghua 11(ZH-11) and the mutant line GI-2 with down-regulated GLDH gene,which GLDH was a key enzyme in AsA biosynthesis path.The results showed that exogenous AsA increased ascorbic acid content in GI-2.Likewise,the contents of Rubisco protein and chlorophyll contents increased significantly after treated by AsA,and the descending rate of photosynthetic parameters decreased,while AsA treatment had no significant effects on ZH-11.In both cultivars,MeJA significantly decreased the contents of ascorbic acid,Rubisco protein and chlorophyll after treatment,while increased the descending rate of photosynthetic parameters,and had a stronger effect on ZH-11 than GI-2.Therefore,it was demonstrated that exogenous AsA plays an effective role in alleviating the early-senescence of rice leaf induced by ethephon,while MeJA has the opposite effects.