OPTIMIZATION OF SEEDING RATE OF SOYBEAN SEEDS DEPENDING UPON THE GROUP OF VARIETY RIPENESSCONDITIONS FOR THE CENTRAL STEPPES OF UKRAINE

Impact of variety qualities and seeding rates on the level of soybeanyield has been established. Influence of weather conditions on formation of yield of soybean varieties of different ripeness group has been analyzed. It has been determined that during three research years the most favourable weather conditions for yield formation were in 2015. Early-ripening varieties produced higher yield among the groups of variety ripeness. The seeding rate of 900 thousand/ha affected yield formation of varieties of fast-ripening group in the best way. For varieties of early-ripening group optimal conditions for gaining high yield were created in agrophytocenosis with seeding rate of 800 thousand/ha. On average during three research years variety Kuban produced the highest yield at the levelof 2.57 t/ha.According to duration of vegetation periodvariety Kuban belongs to earlyripening group. Variety Vilshanka formed the highest yield at the level of 2.43 t/ha among fast-ripening varieties. Thus, it has been defined that for optimization of conditions of soybean growth and development nutrition area must be corrected according to the group of variety ripeness. That is whystudy of impact of soybean plant density for new varieties is a perspective of further research.