The Impact of Bud Load on Berry Quality, Yield, and Cluster Compactness in H4 Strain Grapevines

The Thompson Seedless (Sultanina) seedless variety of grapes is an important crop in Egypt, both for local consumption and export. In recent years, the H4 strain of this grape variety has gained popularity due to its high productivity. However, a drawback of this strain is that the grape clusters become densely packed, resulting in small berries and reduced overall quality. A study was conducted to investigate the impact of pruning severity and bud load on the growth, yield, and quality of H4 grapes. The study included several different treatments, namely T1 Control: (10 canes × 12 buds), T2: (8 canes × 6 buds), T3: (8 canes × 8 buds), T4: (8 canes × 10 buds), T5: (8 canes × 12 buds), T6: (6 canes × 13 buds), T7: (8 canes × 13 buds), T8: (10 canes × 13 buds), and T9: (12 canes × 13 buds). The behavior of the buds, vegetative growth, yield, and quality of the grapes were analyzed. The results showed that pruning of the H4 strain with either 8 canes and 10–12 buds per cane, or 6 canes with 13 buds, produced the best results in terms of managing excessive fruit production, achieving a balance between vegetative growth and yield, and improving the physical and chemical characteristics of the grape clusters and berries. Overall, maintaining 8 canes with 10–12 buds per cane or 6 canes with 13 buds is recommended for obtaining maximum crop yield and quality.