Effect of exogenous ethylene on quality and PPO activity of loquat fruit

Effects of varying concentrations of exogenous ethylene stress on the flesh firmness、titratable acidity (TA)、total soluble sugars(TS) and polyphenol oxidase(PPO) activity of"Jiefangzhong"loquat were studied. The results showed that the flesh firmness increased 11%and 35.7%respectively after 20 d and 40 d storage with 50～60 mgL-1 of exogenous ethylene,but control group increased 29.9%and 49.4%;While,it could inhibit the consumption of TS and TA,which were better than control group after 40d storage;The activity of PPO could be excited with 10～20 mgL-1 exogenous ethylene in the early storage,but it was inhibited with 50～60 mgL-1.