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Aims: The impact of water deficit stress on vine shoot growth, berry weight, grape composition and overall vintage quality was investigated in Bordeaux vineyards. Methods for assessing water deficit stress were compared.Methods and results: Vine water status was assessed on three soil types during four vintages by means of stem water potential and carbon isotope discrimination measured on grape sugar. Regional water deficit was compared for a range of over 30 vintages by means of water balance modelling. It was shown that water deficit stress anticipated shoot growth slackening, limited berry weight and enhanced berry anthocyanin content. Berry sugar content was greatest when water deficit was mild. It was shown that stem water potential measurements and carbon isotope discrimination are accurate tools for assessing vine water status at plot scale. Seasonal water deficit at a regional scale can be correctly estimated by water balance models. Vintage quality in Bordeaux is determined by the intensity of water deficit stress rather than by the level of the temperatures.Conclusions: Vine phenology and grape ripening are highly dependent on water uptake conditions. Mild water deficit stress enhances grape quality for the production of red wines. Vine water status can accurately be assessed by means of stem water potential or carbon isotope discrimination measured on grape sugars. Quality losses through severe water stress can be avoided through the use of drought-adapted plant material, appropriate canopy management, yield reduction or the implementation of deficit irrigation.Significance and impact of the study: This study shows the key role of water deficits in the production of quality grapes for red wine production. Methods for assessing vine water status are compared and discussed. Among many existing methods, the accuracy of stem water potential, carbon isotope discrimination measured on grape sugar and water balance modelling are emphasized.

Aims: It is well known that vine nitrogen deficiency can negatively impact on aroma in white wines. Soil nitrogen fertilization enhances aroma expression, but it also increases vine vigour and susceptibility to grey rot. The aim of this work was to investigate the impact of foliar nitrogen as well as foliar nitrogen and sulphur applications on aromatic expression, vigour and susceptibility to grey rot of Vitis vinifera L. cv. Sauvignon blanc. Methods and results: The impact of foliar nitrogen (N) and sulphur (S) application on aromatic expression of Vitis vinifera L. cv. Sauvignon blanc has been investigated. On a plot where vine nitrogen status is naturally low and water availability not limiting, foliar nitrogen and sulphur fertilization (10 kg/ha of N and 5 kg/ha of S) increased yeast available nitrogen content. Vine vigour and maturity level of grapes were not modified compared to the control. The wines produced from N+S vines contained more volatile thiols and glutathione. These results were confirmed by a tasting of wines produced with grapes from the experimental plots. Foliar nitrogen fertilization alone (10 kg/ha of N) also increased Sauvignon blanc aromatic expression, but less so than the N + S treatment. Conclusions: Foliar N and foliar N + S applications can enhance aromatic expression in Vitis vinifera L. cv. Sauvignon blanc wines without increasing vine vigour and infestation by grey rot. Significance and impact of the study: Vine nitrogen deficiency can negatively impact on grape aroma potential. Soil nitrogen application can increase vine nitrogen status, but it has several drawbacks: it increases vigour and enhances Botrytis susceptibility. This study shows that foliar N and foliar N + S applications can improve vine nitrogen status and enhance aroma expression in Sauvignon blanc wines without the negative impact on vigour and Botrytis susceptibility. Although this study was carried out on Sauvignon blanc vines, it is likely that foliar N or foliar N + S applications will have similar effects on other grapevine varieties containing volatile thiols (Colombard, Riesling, Petit Manseng and Sémillon).

Carbon isotope discrimination in primary products of photosynthesis varies with plant water uptake conditions. This property was used to show that the 13C/12C ratio (called ΔC13) in grape sugars and tartrate measured at ripeness can be a valuable indicator of vine water deficit. Correlation between ΔC13 in grape sugar and minimum pre-dawn leaf water potential is excellent (R2 = 0,81; n = 36). A statistically significant effect of soil and vintage is pointed out. When measured on a great number of plots of an estate, ΔC13 varies with the soil type. This proves ΔC13 can be a valuable tool in « terroir » studies. ΔC13 measured on phenolic compounds in wine is also significantly correlated to minimum pre-dawn leaf water potential as well as to ΔC13 in grape sugar. ΔC13 is actually the only tool capable to assess global vine water uptake conditions between veraison and harvest at a low cost, without the installation of heavy equipment in the vineyard.

Vine water status is an important factor in grape quality. High tannin and anthocyanin content in red grape berries are related to moderate vine water deficits. Hence, a simple and sensitive indicator is required to determine vine water status and especially water constraint. Pressure chamber allows a quick and easy to practice determination of water status in the vineyard. Three applications of pressure chamber are known: predawn leaf water potential (ΨB), leaf water potential (ΨF) and stem water potential (ΨT). Only ΨB and ΨF are widely used on vines. In this survey ΨB, ΨF, ΨT and transpiration flow were measured on mature leaves to determine non-irrigated vine water status in field grown vines during the growing season. In California as well as in France, stem Ψ was the most discriminating indicator for both moderate and severe water deficits. In every plot surveyed ΨT was much better correlated to leaf transpiration than ΨF. Moreover, ΨT revealed nascent water deficit earlier than ΨB did. Among the three application of pressure chamber, ΨT was the only one to indicate short term water deficit after a rainfall. Hence, ΨT appears to be a useful indicator for grapevine management in both non-irrigated and irrigated vineyards.

International audience; Aims: To study the impact of soil-type, grapevine variety and rootstock on grape yield and wine quality in prestigious estates located in the Bordeaux area (France). Methods and results: High-resolution soil maps (scale: 1/3000(th)) were created for seven prestigious red wine-producing estates in Bordeaux. covering a total area of approximately 400 ha. Soil-type, rootstocks and grapevine varieties were recorded for each vineyard block. A Quality Index was created by considering the destination of the grapes produced in each block, whether they were integrated in the first, the second or the third quality wine produced by the estate. Quality Index was averaged over five vintages. Yield was also measured for each vineyard block and averaged over live vintages. PEYROSOL (gravelly soil) was the most frequent soil-type in these estates (45% of the total mapped area). Soils with temporary waterlogging (REDOXISOL). heavy clay soils (PLANOSOL) and sandy-gravelly soils (BRUNISOL) covered around 10% of the mapped area each. Highest quality was obtained on PLANOSOLS, ARENOSOLS (sandy soils), BRUNISOLS and PEYROSOLS. Quality was low on COLLUVIOSOLS (deep soils on colluvium). LUVISOLS (leached acidic soils) and REDUCTISOLS (soils with permanent waterlogging). Cabernet-Sauvignon was the dominant grapevine variety (59% of the mapped area). followed by Merlot (32%), Cabernet franc (8%) and Petit Verdot (1%). On average. the Quality Index was higher for Cabernet-Sauvignon and Merlot compared with Cabernet franc and Petit Verdot. Riparia Gloire de Montpellier (RGM) was by far the most used rootstock. It covered 45% of the mapped area. Including 3309C and 420A. these three rootstocks covered 75% of the total acreage planted in these estates. Highest quality wine was produced with 420A. RCM, 3309C and Gravesac. Highest yields were obtained with 161-49C. 101-14MG, RGM, SO4 and 420A. Conclusions: Soil, grapevine variety and rootstock have a major impact on yield and wine quality in prestigious Bordeaux wine producing estates. Significance and impact of the study: Assessment of a Quality Index by soil-type, cultivar and rootstock can indicate which combinations of soil-type, cultivar and rootstock would best optimise quality performance in Bordeaux vineyards.; Objectifs : Étudier l’effet du sol, du cépage et du porte-greffe sur le rendement et la qualité du vin produit dans des domaines prestigieux du vignoble de Bordeaux. Méthodes et résultats : Des cartes de sol à haute résolution (échelle : 1/ 3000e) ont été réalisées pour sept domaines produisant des vins rouges réputés à Bordeaux sur une superficie totale d'environ 400 ha. Le type de sol, le cépage et le porte-greffe ont été identifiés pour chaque parcelle de vigne. Un indice de qualité a été créé en tenant compte de la destination des raisins produits sur chaque parcelle. Une note différente a été attribuée suivant qu'ils furent intégrés dans la première, la deuxième ou la troisième qualité du vin produit sur chaque domaine. L’indice de qualité a été pondéré sur cinq millésimes. Le rendement a également été évalué pour chaque parcelle de vigne sur cinq millésimes. Le PEYROSOL (sol graveleux) est le sol dominant dans ces domaines (45 % de la superficie totale cartographiée). Les sols présentant une hydromorphie temporaire (REDOXISOLS), les sols argileux (PLANOSOLS) et les sols sablograveleux (BRUNISOLS) couvrent chacun environ 10%de la superficie cartographiée. La plus haute qualité a été obtenue sur les PLANOSOLS, les ARENOSOLS (sols sableux), les BRUNISOLS (sols sablo-graveleux) et les PEYROSOLS. La qualité a été faible sur les COLLUVIOSOLS (sols profonds de colluvions), les LUVISOLS (sols lessivés acides) et les REDUCTISOLS (sols à hydromorphie permanente). Le Cabernet-Sauvignon est le cépage dominant (59 % de la superficie cartographiée), suivi par le Merlot (32 %), le Cabernet franc (8 %) et le Petit Verdot (1 %). En moyenne, l'indice de qualité était plus élevé pour le Cabernet-Sauvignon et le Merlot, comparativement au Cabernet franc et au Petit Verdot. Le Riparia Gloire de Montpellier (RGM) est de loin le porte-greffe le plus utilisé. Il couvre 45%de la surface cartographiée. Les trois porte-greffe les plus plantés (RGM, 3309C et 420A) couvrent 75 % de la superficie totale. La meilleure qualité de vin a été produite avec 420A, RGM, 3309C et Gravesac (indice de qualité > 2,5). Les rendements les plus élevés ont été obtenus avec 161-49C, 101-14 mg, RGM, SO4 et 420A. Conclusion : Le sol, le cépage et le porte-greffe ont un effet majeur sur le rendement et la qualité du vin produit dans des domaines prestigieux du vignoble de Bordeaux. Signification et l'impact de l'étude : Ces données quantitatives et qualitatives permettent d’évaluer les performances de différents types de sol et du matériel végétal associé dans le vignoble de Bordeaux. Elles permettent de formuler des recommandations concernant les associations entre le type de sol, le porte-greffe et le cépage qui permettent de valoriser le mieux quelques-uns des principaux types de sol du vignoble de Bordeaux.

Aims: It is well known that vine nitrogen deficiency can negatively impact on aroma in white wines. Soil nitrogen fertilization enhances aroma expression, but it also increases vine vigour and susceptibility to grey rot. The aim of this work was to investigate the impact of foliar nitrogen as well as foliar nitrogen and sulphur applications on aromatic expression, vigour and susceptibility to grey rot of Vitis vinifera L. cv. Sauvignon blanc.Methods and results: The impact of foliar nitrogen (N) and sulphur (S) application on aromatic expression of Vitis vinifera L. cv. Sauvignon blanc has been investigated. On a plot where vine nitrogen status is naturally low and water availability not limiting, foliar nitrogen and sulphur fertilization (10 kg/ha of N and 5 kg/ha of S) increased yeast available nitrogen content. Vine vigour and maturity level of grapes were not modified compared to the control. The wines produced from N+S vines contained more volatile thiols and glutathione. These results were confirmed by a tasting of wines produced with grapes from the experimental plots. Foliar nitrogen fertilization alone (10 kg/ha of N) also increased Sauvignon blanc aromatic expression, but less so than the N + S treatment.Conclusions: Foliar N and foliar N + S applications can enhance aromatic expression in Vitis vinifera L. cv. Sauvignon blanc wines without increasing vine vigour and infestation by grey rot.Significance and impact of the study: Vine nitrogen deficiency can negatively impact on grape aroma potential. Soil nitrogen application can increase vine nitrogen status, but it has several drawbacks: it increases vigour and enhances Botrytis susceptibility. This study shows that foliar N and foliar N + S applications can improve vine nitrogen status and enhance aroma expression in Sauvignon blanc wines without the negative impact on vigour and Botrytis susceptibility. Although this study was carried out on Sauvignon blanc vines, it is likely that foliar N or foliar N + S applications will have similar effects on other grapevine varieties containing volatile thiols (Colombard, Riesling, Petit Manseng and Sémillon).

Carbon isotope discrimination in primary products of photosynthesis varies with plant water uptake conditions. This property was used to show that the 13C/12C ratio (called ΔC13) in grape sugars and tartrate measured at ripeness can be a valuable indicator of vine water deficit. Correlation between ΔC13 in grape sugar and minimum pre-dawn leaf water potential is excellent (R2 = 0,81; n = 36). A statistically significant effect of soil and vintage is pointed out. When measured on a great number of plots of an estate, ΔC13 varies with the soil type. This proves ΔC13 can be a valuable tool in « terroir » studies. ΔC13 measured on phenolic compounds in wine is also significantly correlated to minimum pre-dawn leaf water potential as well as to ΔC13 in grape sugar. ΔC13 is actually the only tool capable to assess global vine water uptake conditions between veraison and harvest at a low cost, without the installation of heavy equipment in the vineyard.

Continuous measurement of micro variations in the diameter of woody organs provides an early detection of mild water deficits in field grown vines. Trunk diameter variations gives more reliable data than cane diameter variations. Water deficit induces trunk shrinkage and increases the Daily Contraction Amplitude / Potential Evapo Transpiration ratio ( DCA / PET). This does not occur on irrigated control vines. Moreover, micromorphometry appears to be an accurate technique for detecting short-term water deficits, because the measurements are continuous. Major constraints in the use of micromorphometry on field grown vines include the positioning of sensor needles on the trunk and the need to maintain fragile equipment permanently in the vineyard. Additionally, this method does not quantify water deficits.