Abstract: To understand the effects of gummy stem blight on retardation of early-senescence of muskmelon, dynamic changes of activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), the contents of chlorophyll (Chl) and soluble protein (Pr) in Xiami and Yugu on different nods were analyzed after inoculation by Didymella bryoniae. The results showed that, SOD and CAT activities rapidly increased after inoculated 1 day (d), and then reduced, the SOD and CAT activities were higher in xiami than in Yugu. The POD activities increased with the leaf age until the physiological function of muskmelon leaves lost, and the POD activities of xiami were weaker than Yugu. The contents of Chl and soluble Pr decreased quickly, which decreased more quickly in Yugu than in xiami. Leaves of different nods showed different premature senescence degree after inoculation and the low nods of leaves were strongly affected by gummy stem blight．

Key words: muskmelon, gummy stem blight, retardation of early-senescence