In many vineyards optimal parcel size exceeds the geospatial complexity that exists in soils and topographic features that influence hydrological properties, sunlight interception and soil depth and texture (available water capacity). A premise of precision management is that such variation can be lessened, but the practices that would be used to achieve this have not been subjected to rigorous scientific evaluation. During 2004-2006 we examined spatial heterogeneity of soils and topographical features and related them to yield, industrial quality (soluble solids content, titratable acidity and pH), vine water status (predawn, ψPD, and midday, ψL, leaf water potential) and vigor (pruning weights), in an extremely complex hillside vineyard that had undergone terraforming as a means of increasing planted hectares and diminishing soils variation. Factor analysis was used to identify latent variables used in a multiple linear regression model with least squares estimation to identify correlations among soil and topographic factors, vine physiology and industrial quality parameters. Our results indicated that overall vine water status (ψPD and ψL) had the largest influence on within vineyard variation on an interannual basis, and that extreme spatial heterogeneity was evident in this vineyard in spite of terraforming efforts.
Authors: David R. SMART (1), Alison BREAZEALE (1), Joshua VIERS (2), Dr. Richard PLANT (3)
(1) Department of Viticulture & Enology, University of California, One Shields Avenue, Davis CA 95616
(2) Department of Environmental Science & Policy, University of California, One Shields Avenue Davis CA 95616
(3) Department of Plant Sciences, University of California, One Shields Avenue, Davis CA 95616
Email: drsmart@ucdavis.edu
Keywords: Complex slopes, ripening uniformity, precision viticulture, water potential, terraforming