The effect of summer pruning time and severity on antioxidant capacity and storage quality of Hayward kiwifruit

BACKGROUND Summer pruning of kiwifruit has an important effect on fruit quality and storability. OBJECTIVE: The present study was conducted to investigate the effects of summer pruning time and severity on some quantitative and qualitative characteristics and storability of Hayward kiwifruit. METHODS: The present study was conducted to evaluate summer pruning time (one week after fruit set [1WAFS] and four weeks after fruit set [4WAFS]) and pruning severity (1 - no pruning [control], 2 - shoot pruning after the third or fourth leaf after the last fruit [common pruning], 3 - tip squeezing, and 4 - zero leaf pruning in 20% of fruit-bearing shoots with unlimited growth) on Hayward kiwifruit in 2020 and 2021. RESULTS: The results showed that, at harvest time, the highest average fruit weight and total acid were 124.00 g and 1.74% in the tip squeezing treatment observed in the 4WAFS pruning time in 2021. Zero leaf pruning produced fruits with the highest firmness and antioxidant capacity in 2020 and the highest vitamin C and total phenols in 2021. At the end of 90 days of cold storage, in the tip squeezing treatment, fruit firmness at 4WAFS pruning time was higher than in 1WAFS pruning time in the second year, and the highest antioxidant capacity was in 1WAFS pruning time in the first year. In the second year, the highest vitamin C, firmness, and dry matter were obtained in the zero leaf pruning treatment. In this treatment, the highest total phenols and antioxidant capacity were 133.96 mg GAE/100 g FW and 86.75% , respectively, observed in 4WAFS pruning time in the second year. CONCLUSIONS: Overall, tip squeezing and zero leaf pruning at the time of 4WAFS improved the quantitative and qualitative characteristics at the harvest and cold storage.