Three crop levels were induced by cluster thinning in a high yielding Carignane vineyard. Reduction of cluster number from about 60 to 40 per vine did not result in reduction of yield, since berry size and number per cluster were increased. Pruning weight of the thinned treatment was increased and so was the capacity of the vines. Further thinning to 20 clusters per vine reduced the yields since the increase in berry size and number was not sufficient to compensate for the reduced number of clusters. The yield to pruning weight ratio was found to be a good measure for crop load. Crop load reduction from 19.6 to 12.0 kg fruit per kg prunings increased wine quality and a further reduction to 8 did not. It was concluded that crop loads above 12 have conspicious effects of overcropping, i.e., reduced wine quality, color quality and intensity and total ash, delayed maturation, reduced rate of sugar accumulation, must acid concentration at comparable sugar content, proline and amino acids content, bud fertility, and pruning weight. In high yielding cultivars, the crop load ratio has a more relevant effect on wine quality than the crop level as such.
- Copyright 1984 by the American Society for Enology and Viticulture