Cold Acclimation of Concord Grapevines. I. Variation in Cold Hardiness Within the Canopy

Abstract

This study was designed to define a sampling protocol for fall acclimation experiments in Concord grapevines. Vineyard parameters which were investigated included vine size, number of clusters per shoot, exposure of shoots to sunlight, and node position on current season9s growth. Primary buds and canes at the canopy exterior, well exposed to sunlight, were 6.5°C and 6.0°C hardier, respectively, than similar tissues from poorly exposed shoots on the canopy interior. Nodes from basal positions on shoots acclimated sooner than those from apical positions, especially early in the acclimation period (late August) and differences in hardiness between basal and apical positions were as great as 5.5°C for primary buds and 4.5°C for canes. Hardiness differences due to both sunlight exposure and node position were closely and inversely related to water content of the tissues. Neither vine size nor the number of clusters per shoot had an important effect on acclimation.