Effects of super absorbent polymer and different fertilizer rates on growth and fruit quality of melon (Cucumis melo L.) Cultivated in Ultisol Soil

Melon (Cucumis melo L.) is a high-value horticultural commodity, yet its productivity on drylands like Ultisols is strictly limited by low water-holding capacity and severe nutrient leaching, particularly during the rainy season. This study evaluated the effects of Super Absorbent Polymer (SAP) application and different macro-nutrient fertilizer rates on soil properties, growth, yield, and fruit quality of melon cultivated on Ultisol soil. The experiment was conducted from September 2025 to April 2026 in Gelumbang, South Sumatra, Indonesia. A Randomized Complete Block Design (RCBD) with two factors was employed: SAPs dosage (A0: SAP 0 g plant⁻¹; A1: SAP 3 g plant⁻¹) and macro essential fertilization rates (B0: 0%, B1: 25%, B2: 50%, B3: 75%, and B4: 100% of recommended dose). The results demonstrated that SAPs application significantly enhanced vegetative growth parameters plant length and stem diameter from 4 to 6 weeks after planting (WAP). A significant interaction was observed regarding fruit weight, the combination of 3 g SAPs and 75% fertilizer dose (A1B3) produced the highest fruit weight and optimal fruit quality of Brix, outperforming the 100% fertilizer application without SAPs. These findings suggest that SAP improves nutrient retention and fertilizer use efficiency by reducing nutrient losses through leaching.