THE EVALUATION OF THE LEVEL OF BIOLOGICAL NITROGEN FIXATION BY NEW INTRODUCED SOYBEAN VARIETIES, THEIR YIELD AND QUALITY OF SEEDS IN THE MINSK REGION OF BELARUS

Investigation of the efficacy of nitrogen fixation by soybean in symbiosis with Bradyrhizobium bacteria is an essential part of a problem in achieving intensification agricultural production. According to environmental conditions the rate of biological nitrogen fixation significantly depends on host plants and ecological factors. During the field experiment, four soybean varieties were tested with "rizotorfin" and without inoculation. The experiment was carried out on the territory of Nesvizhskaya State crop testing station in Minsk region. Varieties were assessed in terms of biological fixation, yield, quality of seeds: the content of protein and fat. The content of nitrogen and phosphorus in the leaves was also recorded by chemical analysis. In all soybean varieties, inoculated seeds produce the yield average of 40% higher, the protein content increased by 20% in comparing to those on controls plots without inoculation. The fat content, on the contrary, decreased. A negative moderate correlation between oil and protein content in seeds was found. There were no differences in the content of phosphorus in soybean leaves. Accumulation of nitrogen in the yield of seeds depended on the variety and inoculation of seeds by bacterial preparation. The variety Slavyanka was found to be the most responsive variety to such treatment. The level of biological nitrogen fixation depending on soybean cultivar in Minsk region of Belarus may vary from 44 up to 133 kg/ha.