| The object of the present work was to investigate the effects of 1-MCP treatment on control of gray mold in postharvest ‘Red Fuji’ apple under normal and low temperature, as well as the resistance mechanism of 1-MCP treatment on postharvest gray mold for ‘Red Fuji’ apple by analyzing the changes of defense related enzyme activities and phenolic compounds.1. 1 μL/L 1-MCP effectively limited the development of lesion diameter of gray mold rot and significantly reduced the incidence caused by B.cinerea. At normal temperature, the incidence rate of CK was more than 90% after five days storage, however, the incidence of1-MCP treatment was less than 70% at the end of observation period of 9th day. At low temperature, the incidence of 1-MCP was only 26.5% on the 10 th day after inoculation,which was 53.86% lower than that of CK, and the difference was significant.2. 1-MCP treatment remarkably promoted the activities of phenylalanine ammonia-lyase(PAL), polyphenol oxidase(PPO), peroxldase(POD), β-1,3-glucanase(GLU) and chitinase(CHI), reduced the degree of membrane lipid peroxidation, decreased the production of MDA, and increase the disease resistance of fruit. In addition to GLU, the induction of1-MCP to the normal temperature on PAL, POD, PPO and CHI was more obvious than the low temperature, and the MDA production rate of the low temperature was slower than that of the normal temperature.3. Low temperature storage test, 1-MCP treatment promoted the accumulation of mono-phenols in apple fruit, improve the content of catechin, epicatechin, chlorogenic acid,rutin and quercitrin-3-rhamnoside in varying degrees. It can be known that 1-MCP can strengthen the metabolism of phenolic substances in apple fruit.4. 1-MCP treatment increased the rapid synthesisand accumulation of phenolics compounds, flavonoids and lignin, and the induction of 1-MCP to the normal temperature on total phenolics and flavonoids was more obvious than the low temperature, but the lignin was just the opposite. Besides, the content of chlorogenic acid, rutin and quercitrin-3-rhamnosidewere significantly increased, but there was no remarkably significant effect on catechin and epicatechin. And the content of mono-phenol at normal temperature was higher than that at low temperature. The increase of antimicrobial substances decreased the incidence and prevented lesion expansion. The results suggested that postharvest 1-MCP treatment induced disease resistance in apple fruit by activating the metabolism of phenolic substances. |
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