Combined influence of bud load and bud position along the cane on vegetative and reproductive parameters of grape cv. Grillo

Cultivar Grillo vines are characterized by problems with flower biology (the fertility of basal buds) and fructification (millerandage). In this study, to manage the variability in bunch weight with winter pruning and to program others canopy management practices (i.e. early defoliation), three different treatments of bud load were set up by leaving the cane with 3, 6 or 10 buds. The effects of bud load and cane length were studies regarding bud fertility, shoot leaf area, and the number of flowers and berries, as well as the relationship between leaf area and percentage of fruit set, leaf area/flower and percentage of fruit set, and the number of hens and chicks berries. Shoots in the distal position had higher values of fertility and inflorescences with a greater number of flowers, while no ‘apical’ effect of the buds emerged. A good relationship was found between fruit set and the number of flowers, leaf area at flowering and yield, and square centimeters/flower and percentage of fruit set. Cane length was found to be a valid tool for managing bunch weight variability; the value of the leaf area/flower can be used to program early defoliation practice carried out to manage berry set .