Bud fertility of ‘Malbec’ and ‘Syrah’ grapevines subjected to double-pruning management in Central-West Brazil

Resumen

Knowledge of bud condition and vegetative vigor in grapevines is essential for making sound pruning decisions, directly
affecting both yield and fruit quality. This study evaluated bud fertility and the influence of shoot characteristics on bud differentiation in
‘Malbec’ and ‘Syrah’ grapevines subjected to double-pruning management in the Central-West region of Brazil, where viticulture has been
expanding. Based on visual assessment, buds collected from ‘Malbec’ and ‘Syrah’ grapevines from vineyards in Goiás State (GO) and the
Distrito Federal (DF) were classified as fruitful, vegetative, dead, or absent. Vigor was estimated using shoot and bud diameter and internode
length. The proportions of fruitful buds (53.4% in ‘Malbec’ and 48.4% in ‘Syrah’), vegetative buds (21.4% and 26.4%, respectively), and
absent buds (11.1% and 19.2%, respectively) were similar between cultivars. Fruitful buds were concentrated in the basal portion of the shoots,
up to position 8, with mean values ranging from 47.5% to 70.6%, whereas their frequency declined markedly at positions 14 and 15, with
means ranging from 0.8% to 5.3%. The number of fruitful buds was inversely related to variables associated with shoot vigor, indicating that
excessive vigor impairs fruitful bud development.