Boron and nitrogen on hollow stem and yield of broccoli

The incidence of hollow stem in broccoli (Brassica oleracea L. var. italica Plenck) depends on several factors that affect the absorption and transport of boron, which is the element responsible for the appearance of this physiological disorder. This study evaluated the effects of four levels of nitrogen and two levels of boron and the interaction between them in the incidence of hollow stem and yield of broccoli. The levels of N (100, 150, 200 and 250 kg ha(-1)) were divided into four applications equal to 15, 30, 45, and 60 days after transplant. Half of the boron (0, 4 and 8 kg ha(-1)) was applied at planting and half in coverage at 45 days after transplanting. Average mass and total yield were reduced with B application, as a result of the slower growth of plants, having been caused by the onset of symptoms of toxicity of this element. However, in areas not fertilized with B, the percentage of plants with hollow stems was on average 44.14%, while the incidence of this anomaly suffered drastic reduction in B application, where the highest level (8 kg ha(-1)) resulted in only 4.52% of affected inflorescences. Levels of more than 215.4 kg ha(-1) of N have increased the number of plants with hollow stems only in areas that did not receive B.