Rendimento da cebola em função de doses e parcelamento de nitrogênio

Abstract

The onion is the third vegetable in economic importance for Brazil, being surpassed only by the potato and the tomato. The objective of this study was to evaluate the effect of nitrogen fertilization on the yield and quality of onion bulbs. The work was conducted in the field, in an area belonging to the Center of Agrarian Sciences at the Federal University of Paraíba, in Areia - PB, between June and November 2015. The experimental design was in randomized blocks with treatments 6, 5, with the factors six nitrogen rates (0, 50, 100, 150, 200 and 250 kg ha-1 of N) and five forms of (DAT), all at 40 DAT, at 20 and 40 DAT and at 20, 40, 60 DAT), in three replicates. The following were evaluated: plant height-1 , shoot green and dry mass, average mass, total and commercial productivity, bulb classification and leaf N content. Plant height and fresh and dry shoot mass reached maximum values of 57 cm, 6,3 and 2,1 g plant-1 , respectively at 60 DAT. The mean mass of bulbs increased up to the dose of 132 kg ha-1 of nitrogen with a maximum value of 174 g. The total bulb yield was not altered by the treatments, and the dose of 153 kg ha-1 of nitrogen was responsible for the maximum commercial yield of 25 t ha-1 bulbs. In the classification of the onion the dose of 178 kg ha-1 of nitrogen provided the production of 78% bulbs well accepted in the consumer market and for industry (class 3). Leaf N content was 24 g kg-1 at 250 kg ha-1 of nitrogen. All the evaluated characteristics were superior when nitrogen was applied at 20 and 40 DAT and at 20, 40 and 60 DAT.