Response of Growth and Yield of True Shallot Seed (TSS) to the Application of PSB Liquid Organic Fertilizer and Inorganic Fertilizer

Abstract

True Shallot Seed (TSS) is an alternative source of shallot seeds (Allium cepa L. var. aggregatum) that has the potential to increase production efficiency, but its response to a combination of liquid organic fertilizer Photosynthetic Bacteria (PSB) and inorganic fertilizer still needs to be studied. This study aims to evaluate the effect of the combination of PSB and inorganic fertilizers on the growth and yield of TSS-based shallots and to identify the most effective dose combination. This study was conducted in Rejang Lebong Regency, Bengkulu Province, Indonesia, at coordinates 3.459831° S and 102.615364° E at an altitude of approximately 1,100 m above sea level, from July to October 2025, using a one-factor Complete Randomized Block Design (CRBD) with seven treatment combinations and four replicates The treatments consisted of P0 (100% inorganic fertilizer), P1 (50% P0 + LOF PSB 10 ml/L), P2 (25% P0 + LOF PSB 10 ml/L), P3 (100% LOF PSB 10 ml/L (without inorganic fertilizer)), P4 (50% P0 + LOF PSB 20 ml/L), P5 (25% P0 + LOF PSB 20 ml/L), P6 (100% LOF PSB 20 ml/L (without inorganic fertilizer)). The parameters observed included plant height, number of leaves, number of tillers, number of bulb per clump, fresh and dry bulb weight, bulb diameter and height, and bulb yield per plot. The data were analyzed using Analysis of Variance (ANOVA) at a significance level of 5% and the Least Significant Difference (LSD) test at a significance level of 5% if there were significant differences. The results of the analysis showed that the combination of PSB fertilizer and inorganic fertilizer had no significant effect on all variables of growth and yield of TSS shallot. Descriptively, full inorganic fertilizer treatment produced the highest plant height (21.95 cm) and the highest number of leaves (4.05 leaves), while the combination of 25% inorganic fertilizer + 20 ml/L PSB produced the highest number of tillers and bulbs (2.65 per clump) and the highest bulb yield per plot (4.60 g), which was about 15.6% higher than the single PSB treatment (3.98 g). The percentage of plants that grew was also high in all treatments, ranging from 93–100%, indicating good seed viability. Overall, the combination of PSB fertilizer and inorganic fertilizer did not show a significant increase in yield compared to single inorganic fertilizer under the conditions of this study. These findings indicate that the use of inorganic fertilizer remains important in TSS shallot production, while the integration of PSB liquid organic fertilizer has the potential to be a supporting alternative in sustainable nutrient management strategies.