G. Milev
Abstract. During 2010 – 2012 a field trial was carried out with the new cultivar Beslet in the trial field of Dobrudzha Agricultural Institute on slightly leached vertisol. The aim of the investigation was to find out the optimal sowing and nitrogen norms for this cultivar under the conditions of slightly leached vertisol in Dobrudzha region. Five sowing norms were tested: 30, 35, 40, 45 and 50 germinating seeds per m2, as well as four variants of nitrogen fertilization: 0, 40, 80, and 120 kg/ha against phosphorus background of 60 kg/ha. The trial was designed according to the split plot method, with four replications of the variants, the size of the harvest plot being 12 m2. The sowing norm of 45 g.s. / m2 was found the most efficient with regard to yield from cultivar Beslet. Nitrogen fertilization increased seed yield, the rate of increase being the highest with the lowest nitrogen norm – N P . Subsequent increase of the sowing norm did not go together 40 80 with the same rate of yield increase. One thousand seed weight reached a maximum as early as the second sowing norm (35 g.s. /m2) and fertilization norm N P . The effect of the investigated factors on yield structure generally followed the same model of variation as yield itself. The effect of the sowing norm on the 120 80 yield components was better expressed than the effect of nitrogen fertilization. The highest effect on the three investigated indices was determined for the respective year conditions. The highest yield was obtained in the first year of the investigation: 2010, i.e. the year with optimal conditions for expression of the biological potential of cultivar Beslet.