Effect of vineyard nitrogen management on Souviginer gris wine sensory quality and aromatic compounds

Abstract

Fungus-Resistant Grape (FRG) varieties represent a promising approach to address the challenges of climate change and sustainability in viticulture. Despite the growing availability of FRG wines on the market, detailed information on their characteristics is still scarce, as these varieties remain novel. One such variety, Souvignier Gris, is gaining popularity among winegrowers in Switzerland, Germany, and France. Notably, Souvignier Gris has been reported to produce must with low yeast assimilable nitrogen (YAN). To date, little is known about the connection between vineyard management practices, must nitrogen levels, and the implications for wine quality of this variety. This study aims to address this gap and provide vineyard managers with both short- and long-term strategies to optimize must nitrogen status with the goal of improving wine sensory characteristics.

The experiment evaluated the effects of five field treatments (undervine tillage, organic fertilizer, nitrogen-fixing cover crop, foliar fertilization, and a control) and four cellar treatments (0, 30, 90, and 180 g/hl of complex yeast nutrient additions) on YAN, volatile compounds, thiol content, and wine sensory attributes. Analytical methods included WineScan, volatile compound analysis, and sensory evaluation. Preliminary results indicate that foliar fertilization application and nitrogen-fixing cover crops significantly increased YAN compared to the control, leading to distinct aromatic profiles. While the nitrogen-fixing cover crop had an influence on common vigor markers with higher yield and lower sugar accumulation, foliar fertilization increased must YAN without affecting yield. As expected, nitrogen addition to fermentation had a shortening effect on fermentation time and reduced residual sugar levels. Consequently, fermentation was most efficient when YAN in must was increased in the vineyard, while also having the beneficial effect on increasing thiol content. Higher YAN values positively influenced aroma intensity and attributes exotic fruit, ripe fruit and vegetal. This study provides valuable insights into how vineyard management can directly influence wine aroma and overall quality.