Effect of Gibberellic Acid (GA3) and Humic Acid on Growth and Yield of Tajuk Shallot (Allium ascalonicum L.) in Pasuruan Regency

Abstract

Shallot production declined due to suboptimal cultivation and fertilization practices. The Tajuk variety had high yield potential but wass prone to premature flowering. GA₃ and humic acid played a role in enhancing growth and productivity. This study aimed to evaluate the effect of GA₃, humic acid, and their combination on shallot growth and yield to determine the optimal concentration. The study was conducted from May to August 2025 in Jeruk Purut Village, Pasuruan (±350 m above sea level). The split-plot design consisted of 16 treatment combinations and three replicates. The treatments consisted of GA₃ (0, 200, 300, and 400 ppm) and humic acid (0, 200, 300, and 400 ml/L). Growth and yield parameters were analyzed using ANOVA and the 5% HSD test when significant effect were observed. The combination of 300 ppm GA₃ + 300 ml/L humic acid provided the best growth and yield. Individually, 300 ppm GA₃ and 300 ml/L humic acid were the most effective in increasing plant height, tuber weight, and biomass. Regression analysis showed a weak relationship, with GA₃ being negatively correlated and humic acid being positively correlated with fresh tuber weight.