Influence on growth and yield of shallot onion (Allium cepa L.) by application of gibberellic acid

The study was conducted to determine the effect of gibberellic acid (GA(3)) at different concentrations (25, 50, 75, 100 and 125 ppm) on the growth and yield of shallot (Allium cepa L., aggregatum group, Batanes variety). The different concentrations were sprayed separately at 36 and 56 days after planting (DAP). Generally, the application of GA(3) improved plant height and number of leaves per hill. Higher than 50 ppm did not increase the number of leaves and plant height of shallots at 45 DAP. Farmers can follow this for the green onion production at this harvesting period and concentration. Higher than 75 ppm resulted in delaying the maturity of the shallots, whereas zero application of GA(3) entailed earlier harvesting. Bulb mass and bulb diameter were higher at 50 ppm and further concentration increase did not significantly increase its weight and diameter. These results suggest that GA(3) at 50 ppm could enhance yield for green and bulb shallots using the application method described.