The relationship of inducing chilling tolerance by postharvest heat treatment and protection enzymes activity in loquat fruit

Effects of heat treatment on inducing chilling tolerance of loquat fruits during cold storage were studied. The loquat fruits were exposured to hot air (38 ℃ )for 15 hour, and then stored at 1～4 ℃. In order to find out the relations between heat treatment and chilling injury during storage under low temperature,the chilling injury rate,the chilling injury index,extractable juice rate, weight loss rate, respiration rate, MDA content and the parameters of enzymes such as peroxidase(POD), superoxide dismutase(SOD), polyphenol oxidase(PPO), lipoxygenase(LOX) , were examined periodly during storage. The resuhs showed that heat treatment inhibited chilling injury occurrence, improved the extractable juice rate, and reduced the weight loss rate , respiration rate and the content of MDA. It also improved the activity of POD, and maintained1 high activity of SOD in later storage period. The activity of PPO and LOX were inhibited. Heat treatment can enhance resistance to chilling injury of loquats and lighten the degree of chilling injury.