EFFECT OF NITROGEN FERTILIZATION ON QUALITY AND YIELD OF RED BEET (BETA VULAGARIS VAR. CONDITIVA ALEF.)

This paper describes first year results of an investigation which evaluated the influence of nitrogen (N) fertilization level, cultivar and length of vegetation period on yield and accumulation of dry matter, nitrate, oxalic acid, calcium (Ca), phosphorus (P), potassium (K), ascorbic acid and betanine and vulgoxantine I pigments in red beet roots. Four levels of N were applied (0, 75, 150 and 225 kg N/ha^-1) to two cultivars of red beet (‘Bicores’ and ‘Pablo’) which were harvested 118 and 145 days after sowing. Higher N levels were advantageous for the achievement of high yields. On the other hand, with high N supply the quality of roots was reduced because of higher nitrate content and lower contents of minerals, ascorbic acid and red betanine pigments. A longer vegetation period resulted in higher yield, higher contents of Ca and oxalic acid and lower contents of K, dry matter, ascorbic acid and pigments. Differences between the cultivars were observed in yield and in the content of all substances except P and K. Cultivars responded differently to higher N levels as shown by yield and accumulation of vulgoxantine I. Different responses of cultivars to vegetation periods was found in the accumulation of P and ascorbic acid. When evaluating the influence of nitrogen fertilization on the yield and quality of red beet, the length of the vegetation period and the cultivar must be taken into account.