Soils, rootstocks and grapevine varieties in prestigious Bordeaux vineyards and their impact on yield and quality

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: 1/3000th) 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 five 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, RGM, 3309C and Gravesac. Highest yields were obtained with 161-49C, 101-14 MG, 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 soiltype, cultivar and rootstock would best optimise quality performance in Bordeaux vineyards