Nonstructural Carbohydrate Concentrations in Dormant Grapevine Scionwood and Rootstock Impact Propagation Success and Vine Growth

Abstract

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.