The« Sigales’ method »

The goal of this work was to determine the spatial variability of terroir using the isotope composition of wine. Carbon (δ13C) and oxygen (δ18O) stable isotope composition was measured in wines from Tempranillo (Vitis vinifera L.) vineyard, located in Rioja Appellation (Spain). Stable isotope composition, leaf area, vigour, yield components, grape and wine composition were determined in a grid of 85 geo-referenced points, that was drawn across the 5 ha vineyard area

Climate influence on grapevine physiology is prevalent and this influence is only expected to increase with climate change. Although governed by a general determinism, climate influence on grapevine physiology may present variations according to the terroir. In addition, these site-specific differences are likely to be enhanced when climate influence is studied using farm data. Indeed, farm data integrate additional sources of variation such as a varying representativity of the conditions actually experienced in the field. Nevertheless, there is a real challenge in valuing farm data to enable grape growers to understand their own terroir and consequently adapt their practices to the local conditions. In such a context, this article proposes a framework to site-specifically study climate influence on grapevine physiology using farm data. It focuses on improving the analysis of time series of weather data. The analytical framework includes the synchronization of time series using site-specific thermal indices computed with an original method called Extended Growing Degree Days (eGDD). Synchronized time series are then analyzed using a Bayesian functional Linear regression with Sparse Steps functions (BLiSS) in order to detect site-specific periods of strong climate influence on yield development. The article focuses on temperature and rain influence on grape yield development as a case study. It uses data from three commercial vineyards respectively situated in the Bordeaux region (France), California (USA) and Israel. For all vineyards, common periods of climate influence on yield development were found. They corresponded to already known periods, for example around veraison of the year before harvest. However, the periods differed in their precise timing (e.g. before, around or after veraison), duration and correlation direction with yield. Other periods were found for only one or two vineyards and/or were not referred to in literature, for example during the winter before harvest.

The French vine selection partners network is currently made up of 40 regional partners, grouped around IFV (French Institute for Vine and Wine) and INRAE (national research institute for agriculture and environment), whose missions are preservation, selection, and innovation of our varietal diversity. The originality of this device is based on a 3-level organisation: – varietal diversity preservation, with the world reference: the INRAE’s vine genetics resources centre of Vassal-Montpellier (Marseillan, France), the world’s largest ampelographic collection, which includes nearly 6 000 accessions of cultivated Vitis vinifera from 54 countries, as well as rootstocks, interspecific hybrids, wild vines (lambrusques) and wild American and Asian species.

The concept of Appellation d’Origine Contrôlée (AOC) is based on the existence of a link between the characteristics of the terroir and the quality and typicality of the production (DELAS, 2000). If for a long time, this link only appeared as the fruit of empiricism, the research undertaken recently has made it possible to scientifically establish the complex relationships between the functioning of natural environments and the ability to produce quality.

Climate change and harvest date decisions have led to the evolution of must quality over the last decades. Increases in must sugar concentrations are among the most obvious consequences, quantitatively. Saccharomyces cerevisiae is a robust and acid tolerant organism. These properties, its sugar to ethanol conversion rate and ethanol tolerance make it the ideal production organism for wine fermentations. Unfortunately, high sugar concentrations may affect S. cerevisiae and lead to growth inhibition or yeast lysis, and cause sluggish or stuck fermentations. Even sublethal conditions cause a hyperosmotic stress response in S. cerevisiae which leads to increased formation of fermentation by-products, including acetic acid, which may exceed legal limits in some wines.