Dose econômica de nitrogênio na produtividade e armazenamento de cultivares de cebola

Abstract

The elements absorbed as a percentage of dry matter in onions are potassium and nitrogen. One trial was carried out to evaluate the influence of nitrogen levels and cultivars on yield and postharvest storage from September 2009 to February 2010. The experimental design was a completely randomized block in a 5×2 factorial scheme, composed of five nitrogen levels (0; 60; 120, 180 and 240 kg ha-1) and two cultivars (Alfa Tropical and Alfa São Francisco) with three replications. Highest commercial yields were obtained at doses of 161.4 kg ha-1 N (Alfa Tropical) and 216.2 kg ha-1 N (Alfa São Francisco) associated with economic doses of 159.6 and 213.8 kg ha-1 of N respectively. With increasing N levels, a gradual reduction in the production of non-commercial bulbs was verified, and a lower production of refuse was obtained when an estimated dose of 185.4 kg ha-1 of N was applied. Commercial bulbs of higher fresh mass and diameter were obtained with the increment of nitrogen. However, after 60 days of curing we detected quadratic effects with maximum fresh loss of bulb at the dose of 149.0 kg ha-1 N (38.4%).