Modélisation du régime thermique des sols de vignoble du Val de Loire : relations avec des variables utilisables pour la caractérisation des terroirs

Climate change has become a reality that is becoming more and more apparent every day, with changes in the physico-chemical composition of grapes and an increase in the alcohol content of finished wines. These higher alcoholic degrees are not without consequences for the success of alcoholic and malolactic fermentation. Correcting the alcohol content (-20% of the initial alcoholic strength) is also part of an approach designed to meet consumer expectations for healthier, lighter or lower-alcohol wines (9 to 13% vol.). Correcting the alcohol content of wines also rebalances the mouthfeel by reducing the alcohol’s burn.

Wine consumers generally demand wines having a perception of softer tannins and less ripe, having a heaviness and richness on palate (full-body wine) with a limpid and stable color. However, polyphenol
(tannins)-rich wines have been also correlated with unpleasant taste properties such as astringency and
bitterness when perceived at high intensities. Modulating these unpleasant properties could be important for consumer’s approval of wines.

Wine quality is a complex concept determined by multiple factors, including vineyard management, winemaking operations, and the sensory perception of key attributes.

The Languedoc-Roussillon wineries are facing a decline in wine yields particularly PGI yields due to many factors. Climate change is just ones, but is expected to increase in the future. There is also structurally a large heterogeneity of yield profiles among terroirs, varieties and strategies. This work investigates the link between yield, competitiveness and resilience to explore how resilient winegrowers have been in the recent past. To this end two approaches have been combined; (i) an accountancy database analysis at estate scale and (ii) municipality level competitiveness analysis. A new resilience indicator that characterizes the capacity of an estate to absorb yield variation is also defined. The FADN database between 2000 and 2018 of ex-Languedoc-Roussillon (France) and other data are used to analyse the current situation and the past evolution of competitiveness and resilience by type of estate (type of farm: PGI and/or PDO & type of commercialization: bulk and/or bottles). The net margin, which defines competitiveness, is not correlated to yield for all types but depends on the type of commercialization and the level of specialisation. The resilience indicator shows that the net margin of estates specialized in PGI is particularly sensitive to yield declines. We also show that price evolutions seem to compensate the effect of yield losses for the majority of types. Municipality scale analysis shows the links between local pedoclimate, yield, commercialization strategies and price. Overlapping a PDO with a PGI does not always increase a municipality’s PGI competitiveness. It is difficult to make links between causes and effects due to the complexity of the wine production system. Production diversification may be a solution. Resorting to the two level of analysis helps resolving the data gap that is necessary to explore the links between yield and economic performance of the wine estates in the long term.

Today’s viticulture faces a considerable challenge dealing with fungal diseases and limitations on the use of plant protection products (PPP) have increased the pressure to find more sustainable alternatives. One strategy may be the development and cultivation of disease-resistant grapevine varieties (PIWI) that could maintain crop productivity and quality while reducing dependence on PPP. In this work a set of 9 PIWI varieties (5 white and 4 red) deploying genes for resistance to powdery and downy mildew were evaluated in two consecutive years in Valdegón, La Rioja, with Tempranillo and Viura as controls. The objective was to correlate agronomic performance and disease incidence with the presence of disease resistance genes in two different seasons: with (2023) and without disease pressure (2022).