VARIABILITY OF PROTEIN CONTENT IN SOYBEAN GRAINS IN THE DRY STEPPE OF THE SOUTH PART OF CENTRAL SIBERIA
The results of the study of the influence of the “year” factor on the variability of the protein content in soybean grain and its yield from the seeding unit in Siberian varieties are presented. The main contribution to the formation of the protein content in the grain was made by the "year" factor - 82 %. In 2019, the protein content of soybean grains was 6% higher than in 2018 and 2020, respectively. Varietal differences determined the protein content by only 16%. According to the results of three year environmental testing, the highest protein content was observed in the varieties SibNIIK 315 and Sibiriada. The protein content in the grain of these varieties was 36.07% and 35.73%, respectively. There were differences in the protein content in the grain of the varieties in the range of about 6%. In general, according to the experience, the varieties of Siberian breeding (7 varieties and 3 years) had an average protein content of 32.70% in grain, which can serve as a basic level for potential assessment of the indicator content in the dry steppe on chestnut soils of the south of Central Siberia. The results of protein yield from one ha of seeding are of practical interest. The indicator “protein yield” depends on the percentage of protein in the grain yield of the variety. In 2018, the average yield of protein per ha of seeding of 7 varieties was 0.41 t / ha, which is 0.05 and 0.06 t / ha more than in 2019 and 2020, respectively. The contribution of the “year” factor to the general variability was 40%, which indicates a high dependence of the indicator on weather condition. There were no significant differences in protein yield between the varieties (Fф< F<sub>05</sub>). The contribution of the interaction of factors “year x variety” was 46%, which allows to determine the specific reaction of the variety in protein yield during the study years. The highest protein content in the grain during three years of the study was observed in the varieties SibNIIK 315 and Sibiriada. There were no significant differences in protein yield between the varieties. Soybean cultivation in the south of Central Siberia allows to get from 0.32 to 0.40 t / ha of protein.