Effect of salicylic acid pretreatment on the postharvest response of hardy kiwifruit during storage.

Hardy kiwifruit (Actinidia arguta) is a climacteric fruit, a characteristic contributing to its short shelf life. Plant phytohormones such as salicylic acid (SA) are well known for their role in regulating the postharvest fruit ripening processes. Here, we investigated, for the first time, the effect of SA pretreatment on postharvest responses in the hardy kiwifruit cultivar 'Autumn Sense' during cold storage. SA pretreatment effectively maintained fruit firmness and titratable acidity during the first two weeks of storage, whereas both parameters declined sharply in untreated control fruits. Moreover, no ethylene production was detected in SA-pretreated fruits during the same period, likely due to modulation of gene expression in the ethylene biosynthetic pathway. These results suggest that SA pretreatment suppresses the early phases of ripening, thereby delaying fruit softening in hardy kiwifruit during cold storage. In addition, antioxidant activity and ascorbic acid content were significantly upregulated in fruits treated with 0.1 mM SA during the first week, indicating enhanced antioxidant accumulation. Overall, these findings provide valuable insights into the postharvest physiology of hardy kiwifruit and support the use of SA pretreatment as a strategy to extend shelf life and improve fruit quality in commercial storage and distribution.