Effect of Various Fertilizer Rates of Water-Soluble NPK on Growth, Photosynthetic Pigments, Yield and Fruit Quality of Watermelon

Commercial watermelon farming in open fields relies on granular fertilizer to increase yield and quality. Nevertheless, granular fertilizer application is inefficient, leads to poor nutrient absorption, and can be hazardous. To address this challenges, the application of water soluble fertilizer through fertigation system is the best solution. Hence, an experiment was conducted to evaluate and select the optimum water soluble NPK rates used on growth, photosynthetic pigments, yield and fruit quality of watermelon. Watermelon seedlings were subjected to four water-soluble NPK fertilizer rates at 75%, 100% (Control – 108 kg N, 247.32 kg P and 153.6 kg K), 125% and 150% based on common practices of NPK granular fertilizer used in watermelon at open field planting system for 65 days. Fertilizer rates induced at 125% significantly increased stem diameter and leaf area index of watermelon as compared to control at 15% and 13.1% respectively. Whereas, application of fertilizer at 150% significantly increased the chlorophyll a and b with the respective increments of 3.71% and 10.22%. In addition, both fertilizer rates of 125% and 150% were significantly increased the fruiting day, fruit weight and total soluble solid (TSS) when compared to control. To sum up, increasing 25% NPK standard fertilizer rate (125%) could be promising for watermelon cultivation. Further trials in commercial scale need to be undertaken to verify the selected rate identified in this study.