Endive, like another leafy vegetables, as an annual plant with short time vegetation is prone to nitrate accumulation. The aim of research conducted in the years 2007–2009 was the assessment of the effect of diversified nitrogen doses on growth, yielding and nutritive value of two ‘Excel’ and ‘Cigal’ –endive cultivars. There were compared the effects of two kinds of fertilizer: ammonium saltpeter and Entec 26 containing DMPP nitrification inhibitor. On the basis of the results obtained it was possible to prove that ‘Excel’ endive cultivar gave marketable yield higher, average, by 19.4% as compared to Cigal cv. Significantly increased marketable yield of endive, regardless its variety, resulted from a single application of Entec 26 fertilizer, especially in the doses of 90 and 135 kg N·ha^-1. The experiments also pointed to the fact that the method of fertilization, as well as nitrogen doses did considerably affect biological value of the examined endive varieties Excel cultivar characterized higher degree of nitrates accumulation and higher content of carotenoids, while Cigal cultivar featured increased content of vitamin C (average by 8.8%), dry matter and chlorophyll.

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