effect of post-harvest treatments wax and methyl salicylate some enzymes activity related to chilling injury in two cultivars of orange(moro and thomson)

treated with different coating and application of methyl salicylate and salicylic acid are used for reduce chilling injury and maintain the quality of citrus fruit during storage. this experiment was carried out in order to study enzyme activity that involved in reducing chilling injury and maintain the fruit quality based on split plot design with three replications. fruits was treated and then placed in the cool storage at 5 ° c and 95% relative humidity(rh) for 80 days. each 20 days with sampling investigated fruit enzyme activity was measured.results showed the highest pal enzyme activity was in fruits treated with methyl salicylate and the lowest was in fruits coated with the bretix wax .the highest sod enzyme activity related to moro fruits which treated with methyl salicylate is in the first 20 days of storage (23/19 umg-1fw). the apx enzyme activity in increased in both cultivars thomson and moro during storage. relatively, treatments used caused is the change in apx, sod and pal enzyme activity.