This paper presents data on the effect of mechanical pre-bloom basal shoot defoliation and on the effect of post-veraison mechanical apical shoot defoliation on Sangiovese vines.
The physiological basis of the pre-bloom basal shoot defoliation is linked to the fact that leaves located at the nodes near the clusters represent for the flowers the main source of nutrients (carbohydrates), which are essential for berry set. The elimination of basal leaves at the pre-bloom stage is easy and of limited cost and proved to be able to reduce the berry set and hence the total yield, without the necessity of the expensive hand cluster thinning, which in Sangiovese is generally done at veraison.
The second group of researches (post-veraison apical shoot defoliation) is based on the fact that due to the climate changes the harvesting of Sangiovese grapes, which in the past was normally done at the end of October, today should be anticipated of about two-three weeks, but often the grapes are already to high in sugar content, while the acidity is low and the phenolic maturation is not completed.
The physiological basis of this research is linked to the fact that during summer the younger apical leaves of the shoots are provided by the higher assimilation capacity. The mechanical elimination of one part of these leaves may reduce the sugar production and its transfer to the clusters and dilate the full ripening, maintaining a good level of acidity and a full phenolic maturation.
Cesare Intrieri – Università di Bologna - email@example.com