EFFECTS OF NUTRIENT SOURCES ON GROWTH AND FRUIT YIELD OF WATERMELON (Citrullus lanatus) IN OGBOMOSO, NIGERIA

Abstract

Watermelon (Citrullus lanatus) is an economically and nutritionally important fruit crop cultivated across tropical and subtropical regions. However, its productivity in smallholder farming systems is often limited by declining soil fertility and the unsustainable use of inorganic fertilizers. This study evaluated the effects of different nutrient sources on the growth and reproductive performance of watermelon under field conditions at the Ladoke Akintola University of Technology (LAUTECH) Teaching and Research Farm, Ogbomoso, Nigeria in years 2022 and 2023. Eight fertilizer treatments (no fertilizer, 100% NPK, 100% compost, Supergrow, poultry manure, 75% NPK + 25% compost, 50% NPK + 50% compost, and 25% NPK + 75% compost) were arranged in a randomized complete block design with three replications. Data were collected on vine length, number of secondary vines, number of leaves, number of flowers, and yield attributes at different growth stages. Results indicated that nutrient sources significantly (P ≤ 0.05) influenced all measured parameters. At 8 weeks after planting, plants treated with 100% compost recorded the longest vines (260.67 cm) and highest number of leaves (139.67), while the no-fertilizer treatment produced the most flowers (12.03). Reproductive performance varied across treatments: 100% compost yielded the highest total fruit set (27.50 per plant), whereas 75% NPK + 25% compost produced the highest fruit number (4.40 per plant) and a high mean fruit weight (2.67 kg). The heaviest individual fruits (2.80 kg) were obtained from 100% NPK. The application of organic and inorganic fertilizers enhanced watermelon growth and yield more effectively than the sole use of either nutrient source. Highest yield was obtained from 100% Compost (34.00 t ha⁻¹) while Lowest yield was observed in Control (21.33 t ha⁻¹). The study demonstrates the synergistic benefits of integrated nutrient management in improving watermelon performance and maintaining soil fertility. Therefore, application of 100% compost is recommended for achieving optimal yield and sustainable production for watermelon under similar agro ecological conditions.