Effect of Nitrogen Doses and Preculture of Plant Species on Watermelon Culture

Aims: The aim of this study was to evaluate the best crop succession strategy and nitrogen dose for irrigated watermelon cultivation in the cerrado of Roraima.

Experimental Design: The experimental design was a randomized complete block design, arranged in a split-plot scheme, with four replications.

Place and Duration of Study: Two experiments were conducted (2014/2015 and 2015/2016 growing seasons), with the ‘Crimsom Sweet’ watermelon cultivar, grown under different N doses in succession to cover crop species, at the experimental field “Água Boa”, belonging to Embrapa Roraima, located in the municipality of Boa Vista, state of Roraima, Brazil.

Methodology: The three plots consisted of cultivating watermelon in succession to: maize intercropped with pigeon pea (Cajanus cajan), Brachiaria (Urochloa ruziziensis) and control with natural vegetation. The subplots consisted of four doses of nitrogen (0, 75, 150 and 225 kg ha-1 of N) applied in the watermelon culture. The following variables were evaluated: average fruit weight, number of fruits per hectare, number of fruits per hectare with a mass between 5 and 10 kg, number of fruits per hectare with mass greater than 10 kg, productivity, soluble solids content, pH and titratable acidity.

Results: The pigeon pea provided an increase in the number of fruits per hectare with mass ≥ 10 kg and in productivity. Nitrogen doses between 118 and 124 kg ha-1 produced the highest number of fruits, number of fruits with mass ≥ 10 kg and higher soluble solids content.

Conclusion: Fruit quality was influenced by the year of cultivation, predecessor cover crop species and the N doses. Pigeon pea and U. ruziziensis favor the availability of nitrogen in the soil for the following crop in succession.