The effect of transient water deficit on berry development of cv. Shiraz (Vitis vinifera L.)

The effects of transient water deficits on berry growth on field-grown grapevines were examined over four consecutive seasons. Varying deficits were achieved by withholding irrigation during four periods of berry development after flowering of Vitis vinifera cv. Shiraz. Water deficit during the period after flowering resulted in the greatest reduction in berry weight compared with that of well-watered vines especially in years with high temperature summation. In contrast, water deficit after veraison had only a minor effect on berry weight at maturity and berries were insensitive to water deficit during the month before harvest. In each of the four seasons, which were climatically diverse, berry growth exhibited a normal double-sigmoid development but with a distinct decline in weight before harvest. The onset of the loss in weight was coincident in all treatments in each year and was not related to the season, the degree of water deficit or to berry size. These findings have implications for yield prediction and for the chemical composition of the crop.