The production of mini shallot bulbs from true seed offers potential advantages for efficient propagation and high-quality seed systems. This study evaluated the responses of shallot growth and bulb miniaturization to planting density and paclobutrazol root-dipping under greenhouse conditions. The experiment was arranged in a split-plot design with three planting densities (100, 200, and 300 plants m-²) as main plots and four paclobutrazol concentrations (0, 150, 300, and 450 mg L-¹) as subplots. Growth traits, yield components, biochemical attributes, and geometric characteristics were analysed using ANOVA, regression, and correlation analyses. Paclobutrazol temporarily reduced plant height and leaf number during early growth but did not significantly affect bulb size, bulb weight, or pigment composition at harvest. In contrast, planting density markedly influenced plant morphology and yield distribution. Increasing density significantly decreased bulb diameter, fresh weight, and biomass per plant, while increasing the proportion of mini bulbs and single-bulb formations. Leaf pigment stability across treatments indicated no evidence of physiological stress associated with either factor. Regression analysis further showed that planting density exhibited stronger predictive relationships with yield parameters than paclobutrazol concentration. Overall, the findings indicate that bulb miniaturization in true-seed shallot is primarily associated with planting density rather than paclobutrazol application, highlighting high-density planting as a practical approach for mini-bulb production systems.
Syam’un et al. (Wed,) studied this question.