The behaviour of four red grapevine varieties of Val de Loire according to climatic variables

Abstract

The behaviour of 4 grapevine varieties - Cabernet franc, Cabernet Sauvignon, Gamay noir and Grolleau noir – was studied from 1988 to 1998 at the INRA experimental Station, in Montreuil-Bellay, France. Very contrasted climatic years occurred within this period. The study of some phenological stages allowed to classify the varieties in 2 groups of maturation : early for Gamay and Grolleau, late for Cabernets. The former had large berries (>2 g), the latter small berries (<1,5 g). Sugar content of Cabernets and Gamay was much higher than for Grolleau, respectively >190 g/L and <170 g/L. For a same maturity index, titratable acidity of Gamay was higher than Grolleau, and Cabernet Sauvignon higher than Cabernet franc. Malic acid was identified as explaining better the acidity level. The anthocyanin content and polyphenolic index of late varieties was superior to those of the precocious ones. The variety and the climate of the vintage play an important role on final grape composition. Berry weight, sugar content, titratable acidity and malic acid could be explained by simple climatic variables, mainly temperature and rainfall during the vegetative cycle as well as wind velocity before harvest. For the phenolic compounds, the analysis looked more complex ; it seemed that the climatic variables had only a minor effect after veraison, but the role of each one of them before this stage is still to be understood.