Abstract:The effects of different concentrations of 1-methylcyclopropene （1-MCP） on the postharvest quality and reactive oxygen species metabolism of tomatoes harvested at the green mature stage and stored at low temperatures were studied. The fruits of the tomato variety 'Tianci 575' were fumigated with 0.5，1.0，1.5 μL/L 1-MCP for 24 h and then placed at（12±1） ℃. The quality and reactive oxygen metabolism indexes of tomatoes during storage were measured regularly. The results showed that 1-MCP significantly reduced the weight loss rate，attenuated the decreases in hardness and vitamin C content （P＜0.05），inhibited the degradation of chlorophyll，and delayed the ripening and senescence of tomatoes harvested at the green mature stage. At the same time，1-MCP increased the activity of superoxide dismutase，slowed down the production of superoxide anion，and inhibited the formation of hydrogen peroxide，the accumulation of malondialdehyde，and the increase of cell membrane permeability. The above results showed that 1-MCP regulated the metabolism of reactive oxygen species and maintained the postharvest quality of tomatoes stored at low temperatures.