A vine physiology-based terroir study in the AOC-Lavaux region in Switzerland

Abstract

Understanding how different pedoclimatic conditions interact with vine and berry physiology, and subsequently impact wine quality, is paramount for an good valorization of viticultural terroirs and can help to optimize mitigation strategies in the face of global warming.The aim of the present study was to establish terroir zones in a steep slope region in Switzerland based on vine and berry physiology. The study area, Villette in the AOC Lavaux, was a unique experimental site due to the homogeneity of plant material in a relatively small microclimate (140 ha) and a multiplicity of different expositions, soil types and altitudes. Vine and berry physiology as well as temperature of twenty-two plots were monitored during three consecutive seasons to investigate whether a link with pedoclimatic parameters can be established.The annual temporal variation of the average temperature was 142 growing degree days (GDD) over all years. Remarkably, spatial temperature variability was twice as high, with a variation between most extreme plots of 395 GDDs on average over all years. PCA and hierarchical clustering of assessed vine and berry physiological parameters resulted in a vintage dependent grouping of plots differing between years, which was not congruent with geological entities. This highlights the importance of the vintage effect, which had a large influence on vine and berry physiology and impacted terroir zones more than soil groups. Important differences in budburst and flowering were observed between plots, whereas altitude was the main driver of precocity in all years, being relatively independent of the vintage, which confirms the importance of topography in viticultural terroirs.