Rootstock-Scion Interactions Concerning Wine Making. II. Wine Compositional and Sensory Changes Attributed to Rootstock and Fertilizer Level Differences

Large and easily detected differences in wine composition and quality were related to rootstock-scion combinations. As indicated by measurable wine quality differences, most of the 10 varieties responded much more favorably to the `St. George9 than to the `99-R9 rootstock, some did not differ greatly, and several tended to respond more favorably to the 99-R rootstock. The composition effects were increased total nitrogen and decreased amyl alcohols by both the rootstock and fertilizer treatments. Total volatile esters were affected both by year and by root-stock. Total free amino acids, 2,3-butanediols, pH, and extract were greater with the St. George rootstock. Total acid was greater with the 99-R. The treatments did not affect color, tannin, acetaldehyde, isobutyl alcohol, or acetic acid. The residual total nitrogen correlated negatively with the amyl alcohol, and positively with the amino acids and the 2,3-butanediols.