The Effect of Concord Vineyard Microclimate on Yield. II. The Interrelations between Microclimate and Yield Expression

Abstract

Concord grapevine yields were increased by less severe pruning and divided-canopy training. For high node numbers per vine, the yield components of shoots per node, berry weight and sugar concentration were reduced. The number of berries, especially on the primary shoot, was more important in affecting yield per node than variations in berry size. A very large difference in yield per node was observed and, even for adjacent nodes on four-node bearers, there was no correlation between node yields.

This difference in yield per node was shown to be positively correlated with variation in the radiation microclimate of the subtending leaf in the growing season preceding fruiting. The correlation was highest for leaves well exposed in the pre-bloom period, especially for those with constant illumination.