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Objectives of this study were to quantify starch and soluble sugar concentrations in wine grape (Vitis sp.) scionwood and rootstock material, and to examine relationships between carbohydrate (CHO) metrics and both grafting success and shoot growth. CHOs of three wine grape scionwood cultivars [Merlot and Riesling (Vitis vinifera) and Vidal blanc (Vitis sp.)] harvested from four separate vineyards in the Niagara Peninsula in Ontario were analyzed for starch, total CHOs, total sugars, sucrose, monosaccharides (glucose, fructose), and oligosaccharides (raffinose, stachyose) to determine if CHO differences existed between scionwood cultivar and site, and whether these impacted propagation success when grafted to two different rootstocks [‘3309 Couderc’ (3309) and ‘101-14 Millardet et de Grasset’ (101-14) (V. riparia × V. rupestris)]. Differences in CHOs existed between vineyards for all cultivars, and their relationship with propagation success was most evident with ‘Vidal blanc’. Differences were also observed between sites for some cultivars in terms of grafting success and shoot length of grafted vines. Hot water treatment (HWT) of rootstock increased total sugars, glucose, fructose, and stachyose in 3309, and led to lower starch, total CHOs, and higher sucrose in 101-14 when measured immediately following HWT. At time of grafting, HWT 3309 had lower starch sucrose and raffinose, and higher glucose, fructose, and total sugars compared with non-HWT material, whereas HWT 101-14 contained lower total sugars, raffinose, and sucrose and higher stachyose and glucose. Stachyose, raffinose, sucrose, glucose, fructose, and total sugars in scionwood at time of grafting were correlated with propagation success. However, CHOs at time of scionwood collection in February did not correlate to successful propagation. Relationships between scion viability of all cultivars vs. stachyose and total sugars for both rootstocks suggested a possible relationship between these CHO metrics and propagation success. Differences likewise existed between propagation success on rootstocks 3309 and 101-14 on most occasions with 3309 displaying higher percent scion viability and shoot growth. This may be of particular importance in grafting difficult-to-propagate rootstock cultivars.

Cabernet Sauvignon (CS) and Cabernet franc (CF) vines were subjected to two crop levels (full, half) and three harvest dates (earliest to latest; T0, T1, T2) over two vintages. Wines were analyzed for anthocyanins, phenolics, and proanthocyanidins. Crop level increased CS hue (2011-2012), increased CS pH and reduced CS color intensity (2012), and reduced CF hue (2012). Harvest date had a greater effect than crop level, with many treatment interactions. Half crop (2011) increased three CS anthocyanins plus procyanidin B. Extended harvest increased eight compounds. Quercetin and (+)-catechin decreased in T1. Crop reduction (2012) increased malvidin-3coumarylglucoside and (+)-catechin, but decreased petunidin and delphinidin-3-coumarylglucoside. Harvest date (2012) impacted all but two compounds, with the highest anthocyanin concentrations in T1 wines. Gallic acid, (+)-catechin and resveratrol increased with harvest date, while three phenols decreased. Half crop (2011) increased CF peonidin. Extended harvest increased four phenols while three others decreased. Crop reduction (2012) increased delphinidin-3-acetylglucoside, cyanidin-3-coumarylglucoside and caffeic acid; (−)-epicatechin and p-coumaric acid decreased. Several anthocyanins and phenols decreased between T0 and T2, nine of 13 anthocyanins decreased between T0 and T1, while others decreased from T1 to T2. Gallic acid and (+)-catechin increased with harvest date; (−)-epicatechin, p-coumaric acid, quercetin, and resveratrol decreased.