Petiole phosphorus concentration is controlled by the rootstock genetic background in grapevine: is this a key for understanding rootstock conferred vigour?

Condensed tannins are widely distributed in plant‐derived foods and beverages like grape, red wine, nuts, tea, apples and chocolate in which they contribute to multiple sensorial properties such as flavor, color, and taste (astringency and bitterness). During the wine making process,

Due to the central role of the ripening timing in the evaluation of the varietal response to the environmental resources, a method to manage maturation curves has been developed. The method produces an index of veraison precocity and overcomes several methodological problems, like the visual evaluation of the veraison point and the multi-annual and multi-varieties data processing. It is based on a statistical and mathematical processing of the sugar ripening curves.

As the frequency and intensity of drought events increase, understanding the mechanisms of plant resilience to water deficit is crucial. To maintain an appropriate plant yield, a common practice is the application of high amounts of fertilizers with negative environmental impacts. The single and combined effect of water deficit and nutrient availability, namely nitrogen (N) and potassium (K), in Vitis Vinifera L. cv. Cabernet Sauvignon and Grenache was evaluated. Two-year-old grapevine plants grafted on SO4 rootstock were transferred in pots under semi-environmental conditions. During the growing season, plants were either maintained well-watered (100% ETc) or subjected to a controlled water deficit irrigation (33% ETc).

The influence of climatic conditions on the development of the vine and on the quality of the wines no longer needs to be demonstrated at the scale of the vineyard, by the regional climatic characteristics, determining on this scale the viticultural potentialities (Huglin, 1978; Branas, 1946; Riou et al ., 1994); but also on a local scale, at the level of the basic terroir unit (Morlat, 1989), by the landscape differentiation of the natural environment inducing climatic variability within the same vineyard, and partly explaining differences in functioning of the vine, in connection with the processes of maturation and the quality of the wine (Becker, 1977 and 1984; Morlat, 1989 and Lebon, 1993a). According to these authors, the climatic diversity in a wine region constitutes in addition to the edaphic component, an important component of characterization of the Basic Terroir Units (UTB).

In the Cognac region in France, Ugni blanc is the most planted grape variety (98% of the 80 500 ha). This vine region is in expansion due to the success of the associated well-known brandy and the need of high grape yield to guarrantee the production of base wine for distillation. About 2 to 3000 ha are newly planted each year and rootstocks are one powerfull tool for vineyard adaptation to soil or climate change. As rootstocks ensure water and mineral nutrient supplies to the scion, it is important to better understand their effect on berry compostionnal parameters such as sugars and nitrogen compounds, which are the main precursors for fermentary aroma metabolites, the latter being quality markers for Cognac after distillation.