Potassium and phosphate fertilization in the growth and production of watermelon fruits in the semi-arid piauiense

Abstract

Watermelon is a vegetable, produced throughout Brazil, with emphasis on the Northeast, however the region’s productivity is the lowest in the country. Low productivity is related to management problems such as fertilization. In this sense, the objective was to evaluate the influence of applying doses of potassium associated with the absence and presence of phosphorus in the production and development of fruits. For this, doses of 0, 50, 100 and 200% of the recommended dose were tested, and for P, doses of 0 and 100% of the recommended dose for the culture were used. After harvest, fruit diameter (FD, cm) was evaluated; fruit length (FL, cm); fresh fruit mass (FFM, kg); number of fruits per plant (NFP); pulp thickness (PT, cm), shell thickness (ST, cm); productivity (PD, t ha-1) and soluble solids content (SSC, ºBrix). The application of phosphorus provided increases of 225.74; 68.32; 58.46; 55.35; 32.5; 39.84 and 225.98%, for the variables FFM, FL, FD, PT, ST, SSC and PD, respectively, compared to the control. For potassium, in FFM the optimal dose was 176%, FL and FD obtained maximum values ​​at doses of 138.5 and 138.6%, respectively, for SSC, the optimal dose was 202.5%, corresponding to the ºBrix of 10.38 and the PD corresponded to a dose of 135.42% of the recommended dose. Phosphate fertilization provided greater fruit quality and increased crop productivity. Potassium fertilization had a positive effect on FL, FD and SSC content, with a dose of 135.42% being recommended.