Influence of Vine Capacity and Crop Load on Canopy Development, Morphology, and Dry Matter Partitioning in Concord Grapevines

Abstract

Mature Concord grapevines were pruned to 20, 40, 80, 120, or 160 nodes in each of three vine capacity classes. Vines were grouped by cane weight, as determined during dormant pruning, into low (0.45 - 0.70 kg), moderate (0.90 - 1.14 kg) and high (1.36 - 1.60 kg) vine capacity classes. Yield, cluster number and berry number increased with node level, but cluster weight, berries per cluster, berry weight, and fruit soluble solids decreased. Yield ranged from 4.0 to 23.7 kg per vine among node levels. Canopy leaf area during the spring growth flush increased with increasing node number up to 120 nodes. Canopy dry weight at harvest increased with increasing node level up to 80 nodes. As node level increased from 80 to 160 nodes per vine, there was no significant increase in canopy dry weight. Fruit soluble solids dropped below acceptable levels between 40 and 80 nodes when averaged across vine capacity classes. Fruit dry weight increased with crop load but the weight of current season canopy vegetative tissues decreased indicating a shift in carbon partitioning from vegetative to reproductive tissues. The data indicate that: (a) very severe pruning can limit dry matter production by vines, but it is not necessary to retain all shoots for maximum dry matter production; (b) increasing the crop load up to the vine's capacity causes greater carbohydrate partitioning to fruit at the expense of vegetative tissues, thus accounting for most of the dry matter in fruit.