Effect of GA3 on Fruit Set and Yield of Young Southern Highbush Blueberry Plants

Gibberellic acid is a plant growth regulator that affects plant cell division, expansion, and other processes. Gibberellic acid (GA(3)) applied at flowering to highbush (Vaccinium corymbosum L) and rabbiteye blueberry plants (Vaccinium ashei Reade) increases fruit set and yield under suboptimal pollination conditions, however, this response has been insufficiently tested on southern highbush blueberries. The authors applied GA(3) during 75 to 100% flowering to one-year-old 'Emerald' and 'Meadowlark' southern highbush blueberries, with six replicates of three plant plots per treatment. Treatments were either water, GA(3) at 40 fl oz/acre, or, GA(3) at 20 fl oz/acre applied twice, with the second treatment 14 days later. At harvest, total fruit weight per plant, fruit number, and average fruit weight were measured. Results verified that GA(3) has little to no effect on fruit set in two primary southern highbush blueberry varieties.