Abstract:In this work，to investigate the mechanism by which 1-methylcyclopropene （1-MCP） affected the reactive oxygen metabolism and softening of 'Hongxiang No.1' guava fruits （Psidium guajava L.），the hardness，indexes of reactive oxygen metabolism and cell wall metabolism from samples in storage were studied. The results showed that when stored for 10 d，the hardness of 1-MCP-treated guavas was 66.88% higher than that of guavas in the control group. Compared to the guavas in the control group，the 1-MCP-treated guavas manifested higher hardness，activities of superoxidase dismutase，peroxidase，catalase，and ascorbate peroxidase，and content of ascorbic acid，and glutathione，but a lower production rate of superoxide anion radical and content of malondialdehyde. Furthermore，1-MCP-treated guavas displayed higher dry weight of cell wall materials and content of protopectin，soluble pectin and cellulose，but maintained lower activities of polygalacturonase，β-glucosaccharase and cellulase. The above results suggested that，as 1-MCP treatment could decrease the level of reactive oxygen in fruit cells so that the activity of degrading enzymes of cell wall materials could be mitigated，thereby prolonging the degradation of cell wall materials，1-MCP treated guavas could have a prolonged postharvest softening process and a higher hardness compared to those in the control group.