Influence of Trellis-Training System and Rootstocks

The first year’s data from four-year-old Cabernet Sauvignon vines grown at the South Oakville Experimental Vineyard (OEV) comparing in-row vine spacings of 1. 2, and 3 meters showed average crop yields of 4.4, 3.7, and 2.7 tons/acre, respectively, when data of seven trellis systems and two rootstocks were averaged together. Closer vine spacing reduced the number of clusters per vine and slightly reduced the number of berries per cluster and cluster weight but had little effect on berry weight. The greater number of vines and clusters per acre, as a result of closer vine spacing, more than compensated for the fewer clusters per vine and berries set per cluster, accounting for the higher crop yield of closer vine spacing. Decreasing the distance between vines from 3 to 1 m significantly increased the level of titratable acidity and malic acid in fruit at harvest, but °Brix, pH, K, and anthocyanins in berry skins did not differ between vine spacing treatments. With wider vine spacing, there was an increase in the number of shoots, leaf area and pruning weight per vine, but a reduction in leaf area and pruning weight per meter of row length. With an increase in vine spacing from 1 m to 3 m there was a 33%decrease in average shoot length and also a reduction in number of leaves/shoot, internode length, primary and lateral leaf area per shoot and percentage of total leaf area accounted for by lateral leaves, resulting in a reduction in canopy density. The amount of leaf area per gram of fruit was also significantly less at 2 and 3 m vine spacing than at 1 m vine spacing. Data obtained in 1993 comparing the performance of 039-16 and 110R rootstocks grafted to Cabernet Sauvignon at vine spacings of 1, 2, and 3 m showed that 110R rootstock produced significantly more shoot growth, pruning weight, and crop yield than 039-16. UOR stock produced 20%more shoots per vine than 039-16 and shoot length was also about 20%longer on 110R grafted vines compared to 039-16. Pruning weights per vine of 110R stock was more than double that of 039-16. The yield/pruning weight ratio of vines on 110R stock was significantly less than 039-16 for each of the seven trellis systems. Cabernet Sauvignon on 110R stock produced 3.8 tons/ac compared to 2.87 tons/ac on 039-16. Wider vine spacing generally resulted in wines of lower pH and titratable acidity for all trellis systems. However, vine spacing had no significant effect on the level of ethanol and wine color. Duo-trio taste comparisons of wines made from the in-row vine spacings revealed that 1 m vine spaced wines could be distinguished from 3 m vine spaced wines for two of the four trellis systems, namely the GDC and Shoot Positioned Vertical trellises. Wines made from the V-trellis showed that 2 m vine spaced wines differed from 3 m vine spaced wines. In no case was the taste panel able to show significant differences between 1 and 2 m vine spaced wines.