Spatial Variability in Ontario Pinot noir Vineyards: Use of Geomatics and Implications for Precision Viticulture

Abstract

Relationships among vine water status, soil texture, and vine size were observed in four Ontario Pinot noir vineyards in 2008 and 2009. The vineyards were divided into water status zones using geographic information systems to map the seasonal mean leaf water potential (Ψ) and cane pruning weight (vine size). Leaf Ψ zones were confirmed using k-means clustering. Both seasons were cooler and wetter than average and the range of leaf Ψ defining the water status zones was narrow (−0.59 to −0.95 MPa across all vineyards). Yield, vine size, crop load, anthocyanins, and phenols had the highest coefficients of variability. Higher yields, berry weights, titratable acidity, anthocyanins, and color were occasionally associated with low water status zones. There were no berry composition variables with differences between vine size zones in all four vineyards. Higher yields, cluster numbers, and berry weights were frequently associated with high vine size zones. Principal components analysis separated the vineyards but did not create clusters based on leaf Ψ or vine size. There were notable correlations between vineyard and grape composition variables, and spatial trends were qualitatively related for many of the variables. Significant r² values that suggested inverse relationships were found in 2008 for leaf Ψ versus anthocyanins, color intensity, and phenols and for vine size versus anthocyanins, while in 2009 there were significant r² values for soil moisture versus anthocyanins and color intensity that likewise suggested inverse relationships. This study showed that there is potential for using geomatic techniques to understand variability in vineyards, but that erratic weather in eastern North America presents a challenge for understanding the driving forces of such variability.