Evaluating Viticulture Manipulations Effects on Glycoside Abundance and Diversity in Vancouver Island Pinot Gris
Date
2023-09-07
Authors
Watts, Andrew
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Abstract
Common techniques to modify growing conditions of wine grapes such as leaf removal, kaolin application and cluster thinning are assumed to improve grape quality. Abundance and diversity of appropriate aroma compounds are key markers of wine grape quality. Grape varietal and location specific responses to these common vineyard management techniques have not been explored on Vancouver Island. To evaluate the response of Pinot gris to common vineyard management techniques a stratified random block design encompassing three management strategies in two Vancouver Island vineyards, both growing Pinot gris over the 2018 and 2019 growing seasons was conducted. Vines were manipulated with seven treatment combinations that included reference, heavy leaf removal, kaolin application on fruit and cluster thinning. Vine physiology metrics were monitored during the growing season, while mature grapes were evaluated at harvest for total soluble solids (TSS), titratable acidity (TA), and (pH). Further, gas chromatography and mass spectrometry were used to quantify glycoside aroma compounds abundance and diversity across the treatments and vineyards.
Results show heavy leaf removal decreased incidence of botrytis bunch rot and affected aroma compound abundance over the two growing seasons. Cluster thinning yielded consistent increased TSS and decreased TA at both vineyards. Kaolin did not significantly affect grape quality metrics. These results suggest heavy leaf removal and/or cluster thinning may yield significant benefit in the form of reduced botrytis pressure and improved grape quality in Vancouver Island grown Pinot Gris.
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Keywords
Viticulture, Pinot gris, Basal leaf removal, Cluster thinning, Kaolin, Vancouver Island, GC/MS