Effect of vine nitrogen status on grape berry aromatic potential and on wine aroma

Abstract

The interactions between climate, soil, genetic factor and viticultural practices affect grapevine physiology and berry metabolism. Among the elements that vines pick up from the soil, nitrogen has the strongest impact on its development, grape composition and organoleptic characteristics. The aim of this study was to investigate the effect of nitrogen on the synthesis of key compounds that have important sensory value, like IBMP (3-isobutyl-2-methoxypyrazine) responsible for green pepper aroma and volatile thiols i.e. 3SH (3-sulfanylhexan-1-ol) and their S-conjugates precursors responsible for grapefruit aroma. Untreated Sauvignon blanc vines, grown in a commercial vineyard or in 10 L pots, were compared to vines fertilized with nitrogen. Secondary metabolites were measured in grape berries, musts and in wines. Yeast available nitrogen and leaf color measurements were significantly affected by the treatments. In the vineyard, the analysis of aroma compounds showed an increase in the content of the glutathionylated precursor of 3SH in berries and musts when nitrogen fertilizer was supplied. The same effect was observed on the concentration of 3SH in wine. In contrast, under the same experimental conditions, nitrogen did not affect IBMP content. In pots, in addition to the positive effect of nitrogen on 3SH glutathionylated precursor in berries, a possible impact of the interaction rootstock x nitrogen status on both 3SH precursors was observed. This study will allow a better management of nitrogen in vineyards, and allow a better control of grape berry quality potential.