The effects of shading and reflective mulch in the early stages of fruit development in kiwifruit

Kiwifruit vines are characterized by large canopies, which intercept most of the radiation in the upper part. However, leaves reach photosynthetic light saturation with only a fraction of the total radiation typical of clear sunny days in Mediterranean conditions. Since Actinidia chinensis is still largely managed following protocols developed for A. deliciosa, specific studies are needed to improve light management in A. chinensis orchards. This study aims at analyzing the effect of three different light micro-environments: i) a higher shading level (ca. 33%); ii) a white reflective mulch covering the orchard inter-row; iii) the commercial light management characterized by an anti-hail net with 18% shading (control). The trial was carried out on the ‘Jinyan’ (A. chinensis × A. eriantha) in 2023. Light influence on vine physiological parameters, such as leaf gas exchanges as well as water potentials were assessed. Fruit growth, its vascular flows as well as dry matter content were also monitored. Reflective mulch enhanced the diffused light within the canopy, leading to a slightly higher fruit transpiration. Preliminary results showed increased xylem flows to the fruit with reflective mulch during stage I (cell division). While dry matter gaining was lower in higher shading conditions. Therefore, fruit growth was influenced by the light environment. This study investigated the potential for further improvements in kiwifruit canopy light management, aimed at improving fruit growth and quality, specifically for A. chinensis.