Hydraulics of the soil-vine system in Walloon terroirs and influence on berry quality

Grapevine (Vitis vinifera) is one of the most economically important fruit crops worldwide and is cultivated in more than 90 countries nowadays. In ten years, the Belgian wine-growing area has more than quadrupled and this continues to increase. A reason is that drought events will be more frequent in Belgium, resulting from climate change. Grapevine has emerged as a model perennial fruit crop for the study of drought effects, as it affects hydraulics of the plant and fruit composition. There are numerous hydraulic traits that determine a vine’s response to water availability: stomatal regulation, root characteristics, xylem architecture, aquaporin regulation, ABA dynamics and osmotic adjustment. All these traits can also be influenced by the grape variety, the rootstock, the soil, other environmental variables such as VPD and light, and their interactions, which also play important roles in the composition and quality of grapes. How different couples variety-rootstock respond to drought, in terms of hydraulics and fruit quality, remains an open and critical question. It is also unclear to what extent regulations of vine hydraulics result from innate genotypic traits or environmental factors. Numerous gaps remain in our understanding of the vine’s behavior in oceanic temperate climate and how climate change could affect Belgian viticulture