GIBBERELLIC ACID ENHANCES FRUIT SET OF PHYSICALLY DAMAGED BLUEBERRY FLOWERS

Abstract

Rabbiteye blueberry (Vaccinium ashei R.) flowers often suffer slight freeze damage that prevents fertilization and fruit development. To determine if gibberellic acid (GA3) might be useful in rescuing freeze-damaged flowers the following treatments were applied before anthesis to two cultivars at different locations: 1) undamaged control, 2) approximately two-thirds of the corolla and most of the style removed, 3) approximately half of the style removed, and 4) ovules lanced with an insect pin by driving it through the equator of the undeveloped berry until the point came out the other side. Half the bushes were not sprayed, and half were sprayed with GA3 (312 ppm, v/v) the night following treatment. `Climax' at Chula, Ga., had good fruit set for treatment 1 with and without GA3 (70% to 85%). Good fruit set also occurred for treatment 2, 3, and 4 where GA3 was applied (47% to 54%), but poor fruit set without GA3 (4% to 16%). `Tifblue' at Chula had significantly better fruit set for treatment 1 with GA3 (54% vs. 27%). Excellent fruit set occurred for treatment 2, 3, and 4 where GA3 was applied (81% to 96%), and poor fruit set without GA3 (6% to 7%). `Tifblue' fruit set by GA3 sized better than `Climax' fruit set by GA3. The experiments provide corroborative evidence that flowers that have suffered freeze damage to the stigma, style, corolla, and perhaps ovules can be set with GA3.