Ethylene Signals Involved in Salicylic Acid to Improve Cold Resistance of Postharvest Plum Fruits

In order to study the effect of salicylic acid on the cold resistance of postharvest plum fruits and its relationship with ethylene signal,in this study,medium-maturation(Bulang)plum fruits were used as materials. It were treated with 1.0 mmol/L SA and 1.0 μL/L 1-MCP separately and in combination,and treated with distilled water as a control group. The effects of the above treatment on the chilling injury rate,chilling injury index,peroxidase(POD),polyphenol oxidase(PPO),cell membrane permeability,malondialdehyde(MDA)content,superoxide dismutase(SOD)and catalase(CAT)activities of plum fruits under storage conditions at 4℃ were analyzed. The results showed that SA treatment could significantly reduce the chilling injury rate and chilling injury index(P<0.05),delay the increase of POD and PPO activity,delay flesh browning,mitigate chilling injury symptoms. Moreover,it could also augment the activities of SOD and CAT(P<0.05),and maintain lower levels of cell membrane permeability and MDA. Thereby,it had a certain inhibitory effect on the occurrence of cell membrane lipid peroxidation. The experiment also found that SA combined with 1-MCP treatment significantly inhibited the occurrence of chilling injury in the middle of storage(P<0.05),but the accumulation rate of chilling injury was higher than that of SA treatment,and 1-MCP treatment accelerated the accumulation of chilling damage. The above results indicate that the appropriate concentration of exogenous SA treatment can enhance the cold resistance of plum fruit after harvest,and ethylene signal participates in the process,but it is not a dependent factor.