PRODUCTIVITY OF COTTON VARIETIES AND EFFICIENCY OF IRRIGATION

The study was conducted in the period 2018-2020 in the Training and Experimental Base of the Department of Plant Breeding at the Faculty of Agriculture of the Trakia University Stara Zagora on soil type typical meadow cinnamon soil in fertilizer experience in non-irrigated and irrigated conditions. The field experience is by the method of fractional plots in four repetitions with the size of the harvest plot 15 m2 (1.80 x 8.34 m). The research factors are: irrigation (A), variety (B), fertilization rates (C) and meteorological conditions during the marketing year (E). The study was conducted with three varieties of cotton Helius, Darmi and Isabell, with three levels of nitrogen fertilization 80, 160, 240 and 0. The effect of irrigation on cotton productivity has been established. As a result of the conducted Polish research, it was established that the total yield of unginned cotton realized on average for the research was very good - 1,945.2 kg/ha. The average yield under irrigated conditions exceeds the yield without irrigation by 34%. The Darmi variety stands out as the most productive and promising compared to Helius and Isabell. The optimal nitrogen rate of the tested is N160. When fertilizing with N240, the yield shows a downward trend compared to N160 and this fertilization is not effective. On average for the period, at the four levels of nutritional regime, the effect of 100 m3 of irrigation water was established - 89.81 kg/ha. With the naturally coloured variety Isabel, the effect is the highest, on average for 4 levels of fertilization - 100.75 kg/ha.