Variation in leaf and bud soluble sugar concentration among Vitis genotypes grown under two temperature regimes

Abstract

Soluble sugar accumulation was determined in the grape (Vitis spp.) cultivars Frontenac, Couderc 3309, Concord, Cabernet Franc, Traminette and Seyval grown under two temperature regimes. Shoot growth slowed under cold temperature regimes in all cultivars except Concord, which was the least responsive. Among all sugars, raffinose showed distinctive responses associated with the two temperature regimes. Under a non-acclimating temperature regime, raffinose concentrations were low and similar among cultivars, whereas under cold acclimating temperature regimes raffinose accumulation was generally higher, and cold-hardy cultivars accumulated higher concentrations than did cold-sensitive cultivars. Basal leaves and buds accumulated the most raffinose. Cabernet Franc vines exhibited no differences in sugar accumulation at different stages of development. The results suggest that raffinose accumulation might be an early step in the process of cold acclimation that coincides with slowed shoot growth, and may precede the onset of dormancy and freezing tolerance. Leaf raffinose concentration might be useful as a detection tool to distinguish various Vitis genotypes with contrasting freezing tolerance. Key words: Bud, cold acclimation, leaf, raffinose, Vitis