Shading Effects on Dry Matter Partitioning, Remobilization of Stored Reserves and Early Season Vegetative Development of Grapevines in the Year after Treatment

Abstract

Grapevines (Vitis vinifera L.) were covered with an 80% neutral shade cloth from flowering until harvest to investigate effects of shade on early season vegetative development in the year after treatment. Shading reduced root dry weight, the concentration of soluble sugars, and amino nitrogen in xylem sap at budbreak, and leaf area expansion in the following year. Dry weight of roots on both shaded and nonshaded vines declined by more than 50% in the first 3 weeks after budbreak and then began to increase, but still had not recovered to prebudbreak levels, 10 weeks after budbreak. Total leaf area per shoot was reduced in the year after shading due to both fewer and smaller leaves.