OPTIMIZATION OF STANDING DENSITY OF SOY PLANTS DEPENDING ON THE SORT’S MATURITY GROUP OF THE VARIETY FOR THE CONDITIONS OF THE NORTH-EASTERN PART OF THE FORESTSTEPPE OF UKRAINE
Authors: Hlupak Z. I. 
Published: February 2021

The aim of the article is to establish the optimal sowing density of soybean plants depending on the maturity group of the variety to obtain consistently high yields. For this purpose, new varieties of soybeans Siverka, Medison and Sihaliia were taken for research, which differ not only in the duration of vegetation, but also in morphological characteristics. The object of the research is the process of forming soybean yield depending on the variety and standing density. The subject of the research is the varieties: early-ripening Siverka from the Institure of Agriculture of the National Academy of Agrarian Sciences of Ukraine (NAAS), year of registration - 2013, plant growth type - intermediate; middle-early Medison from Hyland seeds: it has been in the Register of the varieties of Ukraine from 2008; type of growth - indeterminate; middle-ripening Sihaliia fro Dunai Agro, which was brought in the Register of the varieties of Ukraine in 2014, type of growth - indeterminate; seeding rates of 600, 700 and 800 thousand per ha; soybean grain yield. The forerunner in the experiments was winter wheat. Soil preparation consisted of stubble peeling and fallow plowing. Before sowing cultivation with harrowing was conducted. Sowing was carried out at a time when the soil at thr depth of 10 cm warms up to 100C in the usual row manner with a row spacing of 15 cm to the depth of 4-5 cm. Crops care laid in carring out preemergence and two post-emergence harrowings. Studies have shown that soybean yields depended on the variety and density of plants. Thus, on average over the years of research, the yield in the variety Siverka varied from 2.01 t per ha at a density of 800 thousand pieces per ha and decreased as it thickened to 2.26 t per ha at a density of 600 thousand pieces per ha. In the Medison variety, the yield ranged from 2.18 t per ha at a density of 600 thousand units per ha to 2.41 t per ha at a density of 700 thousand units per ha. In the Sihaliia variety, the yield varied from 2.28 t per ha at a density of 600 thousand pieces per ha to 2.50 t per ha at a density of 800 thousand pieces per ha. The maximum yield for the years of research (2.09-2.39 t per ha) the variety of Siverka formed at a density of 600 thousand pieces per ha. In the Medison variety the highest yield (2.31-2.52 t per ha) was obtained at a standing density of 700 thousand pieces per ha. The yield of the Sihaliia variety depended to a greater extent on the weather and climatic conditions of the year. Thus, under drier conditions in 2017, the highest yield of the variety (2.44 t per ha) was formed at a density of 700 thousand pieces per ha. Under more favorable conditions, the highest yield was obtained at a density of 800 thousand pieces per ha - 2.51-2.69 t per ha. Depending on the weather and climatic conditions of the years of research, the highest yields of all varieties were obtained under favorable conditions in 2019 - 2.27-2.56 t per ha. Under drier and cooler conditions in 2017, the yield of all varieties was lower by 0.13-0.41 t per ha. Thus, in the conditions of the north-eastern part of the forest-steppe of Ukraine, in order to obtain a high soybean yield, it is necessary to take a differentiated approach to the choice of the optimal standing density depending on the maturity group of the variety. Optimal conditions for the formation of maximum productivity of early-ripening soybean variety Siverka were created in the agrophytocenosis at densities of 600 thousand per ha, for medium-early variety Medison - 700 thousand per ha, and for medium-ripening variety Sihaliia - 700-800 thousand pieces per ha.