Effects of water stress on dry matter content and partitioning in four grapevine cultivars (Vitis vinifera L.)

Three-year-old grapevines of four cultivars (Garnacha tinta (Grenache noir), Tempranillo, Chardonnay and Airen) were grown on 35 L container under full irrigation and restricted irrigation conditions in order to determine the effect of water stress on carbohydrate allocation. Total grapevine dry matter was measured at pruning, fruitset, veraison and harvest. Roots, wood, shoots, leaves and clusters were dried separately. Shoots were the most affected organs by water stress, while wood was the least affected. Vines under water stress partitioned more dry matter to wood and roots to the detriment of fruits and shoots. The period from fruitset to veraison was the most active for dry matter accumulation under conditions of stress, whereas non-water stressed vines accumulated more dry matter from veraison to harvest. Under both irrigation treatments, fruits competed with roots for dry matter partitioning. Irrigation treatment and cultivar determined fruit size. Fruit size determined dry matter partitioning between organs and the dry matter accumulation pattern.