Using δ13C and hydroscapes for discriminating cultivar specific drought responses

This article is published in cooperation with Terclim 2022 (XIVth International Terroir Congress and 2nd ClimWine Symposium), 3-8 July 2022, Bordeaux, France.Measurement of carbon isotope discrimination in berry juice at maturity (δ13C) provides an integrated assessment of vine water status and water use efficiency (WUE) during the period of berry ripening, and when collected over multiple seasons, can provide an indication of drought stress responses. Berry juice δ13C measurements were carried out on 48 different varieties planted in a common garden experiment in Bordeaux, France from 2014 through 2020 and found important differences across this large panel of varieties. Cluster analysis showed that δ13C values are likely affected by the differing phenology of each variety, resulting in berry ripening of different varieties taking place under different conditions of soil water availability within the same year. Accounting for these phenological differences, the cluster analysis created a classification of varieties that corresponds well to our current empirical understanding of their relative drought tolerance. In addition, using measurements of predawn and midday leaf water potential measurements collected over four seasons on a subset of six varieties, a hydroscape approach was used to develop a list of metrics indicative of the sensitivity of stomatal regulation to water stress (i.e., an/isohydric behaviour). Key hydroscape metrics were also found to be well correlated with some δ13C metrics. A variety’s water potential regulation as characterized by a minimum critical leaf water potential as determined from hydroscapes was strongly correlated to δ13C values under well-watered conditions, suggesting that the latter may be a useful indicator of drought stress response.COntinental To coastal Ecosystems: evolution, adaptability and governanc

Aromatic maturity is a cornerstone of terroir expression in red wine

This article is published in cooperation with Terclim 2022 (XIVth International Terroir Congress and 2nd ClimWine Symposium), 3-8 July 2022, Bordeaux, France.Harvesting grapes at adequate maturity is key to the production of high-quality red wines. Viticulturists, enologists, and wine makers define several types of maturity, including physiological maturity, technological maturity, phenolic maturity, and aromatic maturity. Physiological maturity is a biological concept. Technological maturity and phenolic maturity are relatively well documented in the scientific literature, being linked to quantifiable compounds in grape must. Articles on aromatic maturity are scarcer. This is surprising, because aromatic maturity is, probably, the most important of the four in determining wine quality and typicity, including terroir expression, i.e.  the identifiable taste of wine in relation to its origin. Optimal terroir expression can be obtained when technological, phenolic, and aromatic maturity are reached at the same time, or within a short time frame. This is more likely to occur when the ripening takes place under mild temperatures, neither too cool, nor too hot.Aromatic expression in wine can be driven, in order from low to high maturity, by green, herbal, spicy, floral, fresh fruit, ripe fruit, jammy fruit, dried fruit, candied, or cooked fruit aromas. Green and cooked fruit aromas are not desirable in red wines, while the levels of other aromatic nuances contribute to the typicity of the wine in relation to its place of origin. Wines produced in cool climates, or on cool soils in temperate climates, are likely to express herbal or fresh fruit aromas, while wines produced under warm climates, or on warm soils in temperate climates, may express ripe fruit, jammy fruit, or candied fruit aromas.This article reviews the state of the art of compounds underpinning the aromas of wines obtained from grapes harvested at different stages of maturity. Advances in the understanding of how aromatic maturity shapes terroir expression and how it can be manipulated by variety choices and management practices, under current and future climatic conditions, are shown. Early ripening varieties perform better in cool climates and late ripening varieties in warm climates. Additionally, maturity can be advanced or delayed by different canopy management practices or training systems. Timing of harvest also impacts aromatic expression of the produced wine. Gaps in the literature are highlighted to guide future directions of research

Sur les lois de chaînes de Markov duales sur Z

13 pages, 2 figuresOn établit une formule de correspondance entre les lois de chaînes de Markov \flqq duales\frqq$\$ sur $\Z$. Cette formule apporte une contribution à l'étude des marches aléatoires en milieu aléatoire stationnaire

Réduction des comorbidités après chirurgie de l'obésité morbide

PARIS5-BU Méd.Cochin (751142101) / SudocPARIS-BIUM (751062103) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocSudocFranceF

Sur les lois de chaînes de Markov duales sur Z

13 pages, 2 figuresOn établit une formule de correspondance entre les lois de chaînes de Markov \flqq duales\frqq$\$ sur $\Z$. Cette formule apporte une contribution à l'étude des marches aléatoires en milieu aléatoire stationnaire

Enseigner les mathématiques par leur histoire au cycle 3

International audienc

Carbon isotope discrimination (so-called δ¹³C) measured on grape juice is an accessible tool to monitor vine water status in production conditions

Assessment of vine water status is needed to understand the effect of environmental factors and management practices on dry-farmed and irrigated vineyards. Among plant-based indicators, carbon isotope discrimination (δ13C) is easily accessible, reliable, and inexpensive. As it provides a post-hoc assessment of vine water status during the berry ripening period, it can be useful for assessing the results of vineyard management practices during the season, and to map water status in the vineyard to aid in future precision management. Possible applications and limitations of this technique for practical vineyard management are discussed in this article