Rootstock Effects on Deficit-Irrigated Winegrapes in a Dry Climate: Grape and Wine Composition

摘要

This study compared own-rooted vines and different scion/rootstock combinations in arid eastern Washington, where vineyards are primarily deficit-irrigated and own-rooted. The performance of Chardonnay, Merlot, and Syrah on five rootstocks (5C, 140Ru, 1103P, 3309C, and 101CU) or on their own roots was evaluated with 10 field replicates over three vintages (2007-2009) in the Yakima Valley AVA. At harvest, two field replicates each were combined to make five winemaking replicates; 45 kg of grapes were made into wine. The grape variables measured were total soluble solids (TSS), titratable acidity (TA), pH, potassium (skin, seeds and pulp), tannins (skin and seeds), and anthocyanins. Wine variables measured were ethanol, TA,,pH, potassium, tannins, total iron reactive phenolics, anthocyanins, and polymeric pigments. Rootstock caused few significant differences in fruit and wine composition and instead the dominant factors were scion and, to a lesser extent, vintage. All fruit and wine variables measured with the exception of TSS varied significantly with scion. Only TSS and berry size were consistently affected by vintage. Rootstock had no effect on grape anthocyanins and tannins. However, significant but small and variable effects were observed for wine anthocyanins and tannins. Wines from own-rooted vines tended to have somewhat higher pH, potassium, and total tannin than did wines from grafted vines. The relationships between fruit and wine for anthocyanins and tannins were not straightforward and warrant further research.