Yield response of watermelon (Citrullus lanatus Thunb.) cultivars to varied fertilizer rates in Rwanda

Abstract: The choice of cultivar and adequate nutrition are vital for good watermelon (Citrullus lanatus) production. This study evaluated the yield performance of four watermelon cultivars: ‘Sugar Baby’, ‘Crimson Sweet’, ‘Sukari F1’ and ‘Julie F1’ under four different NPK fertilizer rates: 50, 75, 100 and 125 % of the recommended dose (RD) (90:60:60 kg ha^-1 of Nitrogen (N): Phosphorus (P): Potassium (K). The experiment was laid out in a split-plot design, with cultivars in the main plots, fertilizer in the subplots and three replications. The experiment was conducted in two seasons: 2017A and 2017B at two sites; Karama and Rubona. A higher number of fruits per plant (5.1-5.8) was obtained with ‘Julie F1’ + 75 or 100 % of RD at both sites and in both seasons, followed by ‘Sukari F1’ + 100 % of RD and the open-pollinated cultivar A higher fruit weight (4.4-5 kg) was obtained with ‘Julie F1’ and ‘Sukari F1’ under 125 % of the RD. Plots planted with ‘Julie F1’ and treated with 75 % or 100 % of RD recorded higher fruit yield per plant (20.9-27.5 kg) and higher fruit yield per ha (104.2-137.3 t). From these results, it can be concluded that the high yield performance of watermelon in the study area can be obtained with ‘Julie F1’ using 75 % (67.5: 45: 45 kg ha^-1) of the recommended dose of NPK fertilizer.