Effects of Girdling treatment and Forchlorfenuron spray on quality and storage life of Hayward kiwifruit (Actinidia deliciosa cv. ‘Hayward‘)

Increasing fruit yield and improving fruit size along with high dry matter percentage, is the main goal of kiwifruit growers in the worldwide. There are deferent techniques to access exportable fruit size with high dry matter content in kiwifruit including summer pruning, root pruning and flower and fruit thinning. Furthermore, trunk girdling and plant growth regulators such as Forchlorfenuron (CPPU) are widely used in modern kiwifruits orchards to increase fruit yield and quality.

In this study, the effect of vine trunk girdling at different times (spring, summer, autumn), CPPU (10 mg L-1 of active ingredients in water), combined effect of CPPU and summer girdling as compared to control (without girdling and CPPU treatments) on fruits quality of Hayward kiwifruit at harvest and the end of cold storage was evaluated in complete randomized block design in 1398. Fruits were harvested based on soluble solids index and fruit quality was measured immediately after harvest and after three months storage at 1o°C.

The results showed that the summer girdling with CPPU, CPPU alone and spring girdling increased 37.99, 32.19 and 22.11% of kiwifruit weight compared to control respectively. Application CPPU increased fruits weight, length and diameter, but decreased fruits dry matter percentage and the ratio of soluble solids content to titratable acidity (SSC/TA) the compared to control. No significant differences were found between CPPU treated fruits and control for fruit tissue firmness, soluble solids content at harvest time and after three months storage in cold storage. The summer trunk girdling together with CPPU spray increased fruit weight (38% as compared to control). In addition, this treatment showed the highest fruit dry matter percentage, soluble solids and SSC/TA at harvest time and the lowest fruit weight loss (0.66%) with the highest fruits tissue firmness (3.96 kg force) at the end of three months storage time. Summer girdling showed the highest fruit weight loss (2.54%) at the end of storage, while no significant difference was found between autumn and spring girdling treatments compared to the control.

Overall, the results showed that summer vine trunk girdling with CPPU spray not only improved kiwifruit size and yield but also improved fruit quality by increasing fruits dry matter percentage and soluble solids content. Such fruits showed the longer postharvest life as compared to control and other treatments. Therefore, it is recommended for improving fruit size and quality in Hayward kiwifruit, CPPU spray was applied with summer vine trunk girdling.