Effect of gibberellic acid application on plant growth attributes, return bloom, and fruit quality of rabbiteye blueberry

• GA3 applied to postharvested whole plants at a concentration of 500 mg/L significantly enhanced return bloom in rabbiteye blueberry plants.
• GA3 increased vegetative growth including leaf area, fresh weight, dry weight, chlorophyll content, the level of chlorophyll a and b.
• GA3 increased individual fruit weight, number of fertile seeds, and antioxidant SOD activity without impact on fruit shape of rabbiteye blueberry fruit.
• GA3 delayed fruit ripening time for all three cultivars.

Gibberellic acid (GA3) plays an important role in many plant growth and development processes. In order to evaluate the effect of GA3 on plant growth, return bloom, and fruit quality of rabbiteye blueberry, three representative cultivars (Powder blue, Garden blue, Climax) were treated by 500 mg/L GA3. Foliar application of GA3 dramatically increased return bloom for three cultivars. Compared to the untreated control plants, ‘Powder blue’, ‘Garden blue’, and ‘Climax’ treated with GA3 increased inflorescences number by 54.3%, 69.7%, and 60.0% in the next year, respectively (p < 0.05). Foliar GA3 application also increased leaf area, leaf fresh weight, leaf dry weight, chlorophyll content, the level of chlorophyll a and b, individual fruit weight, and number of fertile seeds. However fruit ripening and the harvest date of all three cultivars were delayed in the following year. GA3 application did not significantly change length/diameter ratio of rabbiteye blueberry fruits. All the results suggest that GA3 application is potentially promising for enhancing plant growth and fruit quality of rabbiteye blueberry with delayed ripening time.