A Knowledge Base Approach to Site and Variety Selection in Viticulture

Abstract

Regional site suitability for wine grape varieties is generally considered to be closely related to environmental conditions. However, the global spatial distribution of grape varieties is also strongly influenced by socio-economic factors. These factors have shaped and given prominence to the classic wine growing regions of the Old World. New World and other prospective wine growing areas have not benefitted from centuries of trial and error in the selection of appropriate varieties. The goal of this study was to develop a knowledge base for understanding the role of environmental factors in regional selection of wine grape varieties for optimal production. Decision support tools are developed to guide potential and existing growers in selecting appropriate grape varieties for their region. Voluminous environmental data from numerous sources and at varying spatial and temporal resolutions are incorporated in a broad scale spatial analysis of environmental conditions associated with wine grape varieties.

Many of the environmental indices that are widely used throughout the viticulture industry in evaluating regional suitability for grape varieties came into use before the advent of geographic information system (GIS) analysis and are relied upon due to historical precedence. We statistically analyzed the relationship of the most commonly used index of growing degree days (GDD) with regional price as a measure of viticultural success. We also assess the relationship between other commonly used environmental indices and price with several years of comprehensive data collected from the grape crush districts of California. Finally, we propose a general broad scale approach to assessing the environmental similarity of renowned growing regions for selected varieties with prospective regions.

Our results suggest that systematic GIS analysis combined with continued collection of regional performance data of varieties is critical to the continued scientific advance of viticultural site selection. A clear and consistent measure of viticultural success is necessary. Indices such as GDD are useful guides in viticultural site selection, but should be used with caution. Viticultural site and variety selection should focus on the similarity of a broad selection of environmental variables in known Old World regions of success with those of prospective regions.