A general phenological model for characterising grape vine flowering and véraison

Dans les études des terroirs, il est souvent délicat d’établir des zonages et de mesurer les effets de l’environnement sur les vins. Avec plus d’un million d’hectares dans l’aire d’appellation délimitée, le terroir du célèbre vignoble de Cognac est bien connu pour ces eaux-de-vie et ainsi divisé en 6 crus.

Water stress triggers functional compartmentalization in grapevines, influencing how resources are allocated to different plant organs.

Stomatal traits determine grapevine water use, carbon supply, and water stress, which directly impact yield and berry chemistry. Breeding for stomatal traits has the strong potential to improve grapevine performance under future, drier conditions, but the trait values that breeders should target are unknown. We used a functional-structural plant model developed for grapevine (HydroShoot) to determine how stomatal traits impact canopy gas exchange, water potential, and temperature under historical and future conditions in high-quality and hot-climate California wine regions (Napa and the Central Valley). Historical climate (1990-2010) was collected from weather stations and future climate (2079-99) was projected from 4 representative climate models for California, assuming medium- and high-emissions (RCP 4.5 and 8.5). Five trait parameterizations, representing mean and extreme values for the maximum stomatal conductance (gmax) and leaf water potential threshold for stomatal closure (Ψsc), were defined from meta-analyses. Compared to mean trait values, the water-spending extremes (highest gmax or most negative Ysc) had negligible benefits for carbon gain and canopy cooling, but exacerbated vine water use and stress, for both sites and climate scenarios. These traits increased cumulative transpiration by 8 – 17%, changed cumulative carbon gain by -4 – 3%, and reduced minimum water potentials by 10 – 18%. Conversely, the water-saving extremes (lowest gmax or least negative Ψsc) strongly reduced water use and stress, but potentially compromised the carbon supply for ripening. Under RCP 8.5 conditions, these traits reduced transpiration by 22 – 35% and carbon gain by 9 – 16% and increased minimum water potentials by 20 – 28%, compared to mean values. Overall, selecting for more water-saving stomatal traits could improve water-use efficiency and avoid the detrimental effects of highly negative canopy water potentials on yield and quality, but more work is needed to evaluate whether these benefits outweigh the consequences of minor declines in carbon gain for fruit production.

La région viticole de Mendoza est la principale zone vitivinicole d’Argentine qui se compose de 3 oasis (Nord, Valle de Uco, Sud). La première zone vitivinicole, située dans l’oasis Nord, est composée par les département de Luján de Cuyo et Maipu. C’est la zone de production la plus ancienne et la plus reconnue pour la qualité de sa production. Ce travail se porte plus particulièrement sur le département de Luján de Cuyo qui constitue le lieu traditionnel de production du Malbec argertin. Ce travail propose de caractériser les terroirs et de mettre en avant leurs typicités.

Double cropping is a novel technique, driven by the extension of the growing season caused by global warming.