Influence of Clonal Variation, Pruning Severity, and Cane Structure on Yield Component Development in `Cabernet Sauvignon' Grapevines

Abstract

Yield components responsible for yield variation within and among three `Cabernet Sauvignon' grape (Vitis vinifera L.) clones in a cane-pruned vineyard were determined over 2 years using a multivariate analysis procedure, two-dimensional partitioning (TDP). TDP analysis indicated that canes were producing at their capacity and yield per vine was limited by the number of canes retained. Yield per cane was limited by the portion of nodes at which shoots developed, and yield per shoot was limited by cluster number and fruit-set. The highest-yielding clone bore more fruit on non-cane shoots and fewer and larger clusters on cane shoots than the moderate-yielding clone. Poor fruit-set exhibited by the lowest-yielding clone resulted from inadequate or inviable pollen. In one year, thicker canes were more productive than thinner canes due to better bud burst and fruit set.