Spatial variability in Ontario Cabernet franc vineyards III. Relationships among berry composition variables and soil and vine water status

Abstract: The possible influence of vine water status upon berry composition was studied in ten commercial vineyard blocks of Vitis vinifera L. cv. Cabernet franc in the Niagara Peninsula, Ontario from 2005 to 2007. Soil texture, soil chemical composition, soil moisture and leaf water potential (?), as an indicator of vine water status, were determined on ? 80 sentinel vines in each vineyard. In each block, water status zones were identified in GIS-generated maps using leaf ? and soil moisture measurements. Areas of low soil and vine water status were positively correlated linearly and spatially with areas of high Brix, color intensity, anthocyanins and phenols, and were negatively correlated with titratable acidity. In most vineyards, areas of high and low color intensity were positively correlated linearly and spatially with areas of high and low anthocyanins and phenols. Temporal stability was also noticeable for several variables including soil moisture, yield, berry weight, Brix, anthocyanins, and phenols. These data suggest that low soil moisture and low vine water status zones in vineyards are related to corresponding areas of superior berry composition. These data further suggest that precision viticulture techniques may be utilized in this region to delineate vineyard sub-zones of differing quality levels.