Rootstocks Impact Vine Performance and Fruit Composition of Grapes in British Columbia

Nine wine grape cultivars [`Chardonnay', `Gewurztraminer', `Ortega', `Riesling', `De Chaunac', `Marechal Foch', `Okanagan Riesling', `Seyval blanc', and Verdelet'], own rooted or grafted to four rootstocks [`Couderc 3309' ( Vitis riparia × V. rupestris ); `Kober 5BB' (5BB), `Teleki 5C', and `Selektion Oppenheim 4' (SO4) ( V. riparia × V. berlandieri )] were planted into a randomized complete block experiment in 1985. Data were collected on yield components, weight of cane prunings (vine size), and fruit composition between 1989 and 1996. Yield per vine, clusters per vine, cluster weight, and berry weight were not affected by rootstock, but SO4 tended to produce lowest berries per cluster. Lowest vine size was associated with 5BB and own-rooted vines were usually largest; 5BB was also associated with highest crop load (yield to vine size ratio). Own-rooted vines tended to produce berries with lowest percentage soluble solids (%SS) while 5BB led to highest %SS. Titratable acidity was not strongly affected and pH differences between rootstocks were very small. These data suggest that rootstocks may not provide significant advantage over own-rooted vines under conditions found in the arid regions of the Pacific northwestern U.S. and British Columbia.