Influence of pedoclimatic factors during berry ripening in Burgundy

Berry composition at ripeness can be explained by many factors. This study was carried out from 2004 through 2011 in a 60 block network in the Yonne region, Burgundy. The impact of the main components of terroir – vintage, soil, exposition, topography, varietal, rootstock, age, density and vine management- were studied simultaneously, during berry ripening. Berry composition during ripening was assessed each week by the sampling of 400 berries and the following analyses of grape-juice were carried out : sugar, total acidity, malic acid, tartaric acid, pH, and potassium. The variables total acidity, malic acid and tartaric acid were anti-correlated to sugar content. The potassium variable explained an important part of the grape composition variability in the network. Statistical analysis allowed ranking of the terroir factors in order of importance during ripening. The vintage, highly significant, was the major factor, followed by factors cultivar, exposition and soil, who all had statistically significant influence. Pinot noir reaches maturity earlier than Chardonnay. Blocks with a North exposition present a delay in maturation, especially on steep slopes. Grapes reach maturity earlier on South exposed slopes, although this does not lead to higher sugar accumulations. The shallow limestone soils on hard bead-rock, limit potassium accumulation, probably because of limited water supply. Among the colluvium soils, variability may be explained by the importance of soil depth. The wine-growers factor had also a great influence in this study.