RT Journal Article SR Electronic T1 Terroir of Winter Hardiness: Bud LT50, Water Metrics, Yield, and Berry Composition in Ontario Riesling JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP 288 OP 307 DO 10.5344/ajev.2020.19084 VO 71 IS 4 A1 Mary K. Jasinski A1 Andrew G. Reynolds A1 Fred Di Profio A1 Audrey Pasquier A1 Maxime Touffet A1 Rea Fellman A1 Hyun-Suk Lee YR 2020 UL http://www.ajevonline.org/content/71/4/288.abstract AB Grapevine winter hardiness is governed by several factors besides extreme weather conditions, such as site-specific soil factors (texture, composition, moisture, drainage), vine water status, and yield. It was hypothesized that winter hardiness would be influenced by specific vineyard terroir-driven factors and that zones in vineyards with low water status (leaf water potential [Ψ]) would likewise be more winter hardy than vines with high water status (less negative leaf Ψ). Six Riesling vineyards were chosen throughout the Niagara region in Ontario. Data were collected at fruit set, lag phase, and veraison (soil water content [SWC], leaf Ψ), at harvest (yield components, berry composition), and three times during the winter (LT50; the temperature at which 50% of buds die) in 2010 to 2012. Interpolation and mapping of variables was completed using kriging, and statistical analyses (linear correlation, k-means clustering, principal components analysis, multilinear regression) were performed. SWC, leaf Ψ, yield components, berry composition, and LT50 were spatially clustered in each vineyard. GIS and multilinear regression revealed that leaf Ψ could predict the LT50 value, with strong correlations observed between LT50 and leaf Ψ values in most of the vineyard blocks in 2010 to 2011 (4/6 and 5/6, respectively). In the extremely dry 2012 season, leaf Ψ (range across sites at veraison 0.9 to 1.4 MPa) was positively correlated to LT50, yield, titratable acidity, pH, and Brix and inversely correlated to SWC and monoterpene concentration. Results suggest that there is a spatial component to winter hardiness, as with other aspects of terroir. This study allows a method to compare winter hardiness to other critical variables to better understand terroir-based factors of the Niagara region.