Physiological Responses Underlying the Interactive Effects of Trellis System and Lateral Shoot Management on Table Grape Quality

To establish precise canopy management strategies for high-quality table grape production, this study evaluated the interactive effects of trellis systems and lateral shoot management strategies on canopy microclimate, leaf physiology, and berry quality in two table grape cultivars. A two-factor experimental design (trellis sysem × lateral shoot management) was applied separately to each of two table grape cultivars: Vitis vinifera cv. Victoria and Vitis labrusca× V. vinifera cv. Kyoho. Two trellis systems, HTC (horizontal overhead trellis with horizontal canopy) and VTC (vertical trellis with V-shaped canopy), and three lateral shoot management strategies – S1 (early shoot topping), S2 (dynamic lateral shoot management), and S3 (single pre-harvest leaf removal) – were evaluated. Dynamic lateral shoot management (S2) generally optimized canopy microclimate, reducing the cumulative duration of high-temperature (≥35°C) exposure in the fruit zone, while enhancing leaf net photosynthetic rate and photosystem II efficiency. Berry quality responses to treatment combinations showed cultivar specific patterns. For “Victoria,” the VTC-S2 combination was associated with increased total soluble solids (TSS) and sugar/acid ratio; for “Kyoho,” the HTC-S2 treatment was associated with improved sugar/acid ratio, anthocyanin content, total phenolic content, and fruit coloration. Two-way ANOVA indicated that most physiological and quality parameters were significantly influenced by trellis system, lateral shoot management, and their interaction. Integrating dynamic lateral shoot management (S2) with cultivar‑adapted trellis systems may offer a promising approach for table grape production. These findings provide a basis for further investigation into cultivar‑specific canopy management strategies under similar conditions.