Gibberellic acid bloom sprays reduce fruit set and improve packable yield of Autumn Royal table grapes

• Author(s): Dokoozlian, N.; Ebisuda, N.; Hashim, Jennifer;
• Abstract: A three-year study (1997-1999) examined the effects of gibberellic acid (0, 5, 10, 15 or 20 g . ha(-1) GA(3)) applied at bloom (approximately 80% capfall) on the berry growth, fruit composition and productivity of Autumn Royal table grapes (Vitis vinifera L.). The results indicate that 5 g . ha(-1) GA(3) was the optimum treatment for this cultivar, significantly reducing berry set and cluster compactness, as well as the amount of fruit per vine with bunch rot, compared to the control. This treatment also increased berry length and reduced the number of seed traces per berry, but had no effect on berry weight or diameter. The packable yield of vines treated with 5 g . ha(-1) GA(3) were either similar to or significantly greater than the control, while rates greater than or equal to 10 g . ha(-1) reduced vine productivity and fruit growth, and were therefore unacceptable.
• Publication Date: Jan 2001
• Journal: Journal American Pomological Society