Effect of Time of Girdling on Leaf Photosynthetic Performance and Kiwifruit Quality Characteristics at Harvest and Post-Storage

The present study investigated the impact of cane girdling on the ‘Hayward’ kiwifruit cultivar, both in terms of leaf physiological functions and fruit quality attributes, at harvest and post-storage. Four treatments were conducted: the control cane girdling conducted separately in August (GA), in September (GS), and both in August and September (double girdling) (GAS), using different canes. The results indicated that the carbon assimilation rate was reduced in girdled canes. Nevertheless, girdling resulted in increased fruit dry matter (by 1.7%), weight (by 6.4%), and dimensions without altering fruit shape. Additionally, fruits produced on girdled canes exhibited higher total soluble solids content (by almost 13%) and TSS-to-TA ratio post-storage. There were no significant differences in chlorophyll and carotenoid concentrations, organic acids, and most sugars assessed, both at harvest and post-storage. There were no significant differences among the treatments at harvest regarding total phenolic compounds, except for total flavonoids, which were lowest in the GA treatment. Post-storage, girdling (especially GAS and GS) was found to enhance the fruits’ total phenols and total flavanols, as well as its antioxidant capacity (1.88 μmol equiv. Trolox g−1 FW based on DPPH assay under GS versus (0.53 μmol equiv. Trolox g−1 FW under control). Overall, cane girdling can improve the quality of kiwifruit in terms of both fruit size and functional fruit properties.