Phenological stage dependency of Cabernet Sauvignon and Grenache response to water and nutrient limitation 

Grapes composition is a factor well known to affect wines composition and sensory expression. The goal of this study was to evaluate how grapes composition modifications linked to maturity level could affect wines aromatic expression and esters composition.

Context and purpose of the study. Climate change is a major challenge in wine production. It results in erratic weather conditions which may lead to a reduction in grape yield and the subsequent grape and wine quality.

Measurement of carbon isotope discrimination in berry juice sugars at maturity (δ13C) provides an integrated assessment of water use efficiency (WUE) during the period of berry ripening, and when collected over multiple seasons can be used as an indication of drought stress response. Berry juice δ13C measurements were carried out on 48 different varieties planted in a common garden experiment in Bordeaux, France from 2014 through 2021 and were paired with midday and predawn leaf water potential measurements on the same vines in a subset of six varieties. The aim was to discriminate a large panel of varieties based on their stomatal behaviour and potentially identify hydraulic traits characterizing drought tolerance by comparing δ13C and hydroscapes (the visualisation of plant stomatal behaviour as a response to predawn water potential). Cluster analysis found that δ13C values are likely affected by the differing phenology of each variety, resulting in berry ripening of different varieties taking place under different stress conditions within the same year. We accounted for these phenological differences and found that cluster analysis based on specific δ13C metrics created a classification of varieties that corresponds well to our current empirical understanding of their relative drought tolerances. In addition, we analysed the water potential regulation of the subset of six varieties (using the hydroscape approach) and found that it was well correlated with some δ13C metrics. Surprisingly, a variety’s water potential regulation (specifically its minimum critical leaf water potential under water deficit) was strongly correlated to δ13C values under well-watered conditions, suggesting that base WUE may have a stronger impact on drought tolerance than WUE under water deficit. These results give strong insights on the innate WUE of a very large panel of varieties and suggest that studies of drought tolerance should include traits expressed under non-limiting conditions.

Dead or dying vines must be replaced regularly in order to ensure the sustainability of a vineyard. Successful plant replacement is crucial to maintain yield and quality by encouraging balanced root and leaf development in vines. However, young vines planted within an established vineyard encounter several problems, ranging from poor soil conditions to competition with older vines with well-established root systems.  

The effects of temperature on cv Piedirosso, indigenous of the Campania region (South of Italy), were tested in order to study its possible influence on grapevine and to discover how to optimize the qualitative expression