Quality of the sweet potato under different doses and split application of nitrogen fertilizer

Abstract

The sweet potato is a species with socio-economic and cultural importance, participating in supplement for calories, vitamins and minerals in human food. In despite of having studies on nutrition and fertilizer recommendations for sweet-potato cultivation, there is very little research addressing the effects of nitrogen doses and its allocation on sweet-potato postharvest quality. The objective was to evaluate the influence of nitrogen doses with and without allocation in coverage on sweet potato postharvest quality. The experiment was conducted at São Manuel Experimental Farm belonging to the Agricultural Sciences College, São Paulo State University, Botucatu, Brazil and its statistic design was randomized blocks, 2×3+1 factorial, with seven treatments (three nitrogen rates, 30, 60 and 90 kg ha-1 in coverage and two allocations, 30 and 50 days after transplanting and a control, with no application nitrogen in coverage) and five repetitions. Titratable acidity, soluble solids, pH, levels of protein, sugars, starch and moisture have been evaluated. From the physicochemical characteristics of sweet potato roots statistical differences were observed in pH, soluble solids and tritatable acidity, increasing from dose 0 to 90 kg ha-1 N and the pH value increased when doses of N were installed.