The effect of nitrogen fertilization on yield and quality of radicchio

In a field experiment conducted in 2005-2006 the effects of the rate and method of nitrogen fertilization on yield and chemical composition of cv. Indygo radicchio cultivated for summer cropping were studied. Nitrogen was used in a single pre-plant dose or in two rates: as a pre-plant and top dressing application conducted at the start of head formation in the total amounts of 50, 100, 100+100, 150, 100+50, 200; 100+100 kg N.ha(-1). The highest yield and accumulation of nitrates were achieved in the treatment with 100+100 kg N . ha(-1). The content of nitrates in radicchio, leaves varied from 1,070 to 1,0350 mg.kg(-1) f.m. for the nitrogen rate of 200 kg N.ha(-1) supplied in one pre-plant dose, and from 1,160 to 1,380 mg.kg(-1) f.m. when the same rate was applied in two doses. The method of nitrogen fertilization had little effect on P and Mg concentration. Potassium and calcium level in leaves of radicchio decreased at higher nitrogen fertilization rates.