Effect of Preharvest Spray Salicylic Acid on Antioxidant Compond and Maintaining Postharvest Quality of Kiwifruit (Actinidia deliciosa)

Different concentration of salicylic acid foliar spraying on antioxidant system and postharvest quality attributes of kiwifruit were investigated. For this purpose, Hayward cultivar was used and SA treatment, at 0 (control), 0.5, 1 and 1.5 mM, were applied at two times of final steps of during [A1] fruit development (125 and 145 days after flowering). Fruits were harvested at commercial maturity (TSS=6.2 Brix) and stored at 1.5±1°C and 90±5% relative humidity for 14 weeks. Different characteristics of the fruit were evaluated at 0 (before storage), 11 and 14 weeks after harvesting. The results show that, the highest firmness of fruit tissue was related to 1.5 mM SA and its lowest was related to the control. In addition, kiwifruit treated with SA has higher significantly total chlorophyll content, L*, and b* values and lower a* value, pH and total soluble solids (TSS) than the control. Preharvest SA treatment reduced the microbial activity (log CFU g-1) of kiwifruit during storage. Also, the higher amount of total phenol, ascorbic acid was related to 0.5 mmol SA and the higher amount of antioxidant capacity was related to 1 mmol SA, in which SA improved the antioxidant compounds of kiwifruit. Ultimately, it seems that preharvest treatments with SA could be a promising strategy to maintain postharvest quality and improve the health benefits of kiwifruits consumption by increasing the antioxidant capacity.