<![CDATA[Background. The application of environmentally friendly fertilizers has become an important strategy for improving melon productivity and fruit quality while reducing dependence on synthetic fertilizers. Aims. This study evaluated the effects of humic acid and liquid organic fertilizer (LOF) concentrations on the growth, yield, and fruit quality of Alisha F1 melon (Cucumis melo L.). Methods. The experiment was conducted in a greenhouse at SMKN 1 Cikaum, Subang, Indonesia, from March to May 2026 using a factorial Randomized Block Design. The first factor was humic acid concentration (0, 20, 40, and 60 mL L⁻¹), while the second factor was liquid organic fertilizer concentration (0, 5, 10, and 15 mL L⁻¹). Each treatment combination was replicated twice. Data were analyzed using analysis of variance (ANOVA) at the 5% significance level, followed by response surface regression to determine optimum fertilizer concentrations. Result. The results indicated that the interaction between humic acid and liquid organic fertilizer significantly affected fruit diameter and soluble solids content (°Brix), whereas most vegetative growth parameters showed no significant interaction. The combination of 60 mL L⁻¹ humic acid and 5 mL L⁻¹ liquid organic fertilizer produced the largest fruit diameter (12.10 cm), while 20 mL L⁻¹ humic acid combined with 10 mL L⁻¹ liquid organic fertilizer resulted in the highest fruit sweetness (14.40 °Brix). Response surface analysis predicted that the optimum concentrations for maximizing fruit diameter and quality were 29.04 mL L⁻¹ humic acid and 9.09 mL L⁻¹ liquid organic fertilizer, yielding a predicted maximum fruit diameter of 11.69 cm and soluble solids content of 11.91 °Brix. Conclusion. These findings demonstrate that the combined application of humic acid and liquid organic fertilizer enhances melon fruit quality through synergistic effects on nutrient availability and uptake, providing an environmentally sustainable fertilization strategy for Alisha F1 melon cultivation.]]>
