Impact of bud load on vegetative growth, cluster characteristics and yield of Attika Seedless grapevines

This study examined the impact of varying bud load levels 45, 53, 61, 69, 77, and 85 buds per vine of Attika Seedless grapevines on the cluster characteristics, berry quality, bud behavior, and vegetative development characteristics over the 2022 and 2023 growing seasons. The experiment was conducted on vines grown in sandy soil, trained using a Gable supporting system, and spaced at intervals of two by three meters. In all treatments, spur-pruning was done by fixing two eyes per spur during the second week of December in both seasons. The results showed that while the bud fertility was adversely affected by high bud load levels in two seasons, the percentages of bud burst increased as the bud load levels/vine decreased. Additionally, while the yield/vine to pruning weight ratio (measured by the Ravaz index) increased, the high bud load levels markedly reduced vegetative growth characteristics and fruit quality. Furthermore, the chemical components of berries, including total soluble solids, the ratio of total soluble solids to acidity, total anthocyanin, and antioxidant activity, were negatively impacted by both low and high bud load levels. However, both the number of clusters per vine and the total acidity of grape berries had maximum values at high bud load levels. The findings suggest that maintaining a bud load of 53 or 61 buds per vine is optimal for Attika Seedless grapevines, balancing good yield with high fruit quality.