Dependence of soybean plant survivability on the feeding area on typical chernozems

Topicality. Plant density is one of the key factors in the formation of soybean productivity, given that the most productive crops are formed with the optimal number of plants per unit area and the rational utilisation of actual environmental resources by each plant and the agrophytocenosis in general. Optimal plant spacing reduces the competition of soybean plants and ensures adequate supply of crop to soil nutrients, so both sparseness and thickness of crops significantly affect the yield shortfall. Purpose. To study the effect of row spacing and seeding rate on the survivability of soybean plants of early ripening varieties Vyshyvanka and Zhaklin. Methods In 2021–2022, the research was conducted in scientific laboratories and stationary crop rotation by the Department of Plant Production in the fields of the Separate Subdivision Agronomic Research Station of the National University of Life and Environmental Sciences of Ukraine (Pshenychne village, Vasylkiv district, Kyiv region), in the northeastern part of the Right-Bank Forest-Steppe of Ukraine. Phenological observations and assessment of crops were carried out according to the F. M. Kuperman's method at the main stages of plant growth and development: seedling, flower-bud formation, flowering, and ripening. The main phases of plant growth and development were noted: seedlings, budding, flowering, ripening. The beginning of the stage was considered to be the presence of the controlled trait in at least 10 % of plants, and 75 % of plants were considered as complete stage. The plant density was recorded in the stage of full seedlings and before harvesting according to the Methodology of State Variety Testing of Crops. Results. It was found that plant survivability depends on the feeding area, so the greatest losses (10.3–13.2 %) of plants during the harvesting period were observed when soybeans were sown in a wide-row method (45 cm) with a seeding rate of 750 thousand seeds/ha. The lowest losses (3.4–5.3 %) were observed in the wide-row method of sowing with a seeding rate of 450 thousand seeds/ha. Soybean crops sown in a conventional row method with a row spacing of 15 cm and various seeding rates did not show any particular sparseness during the ripening period, and the death rate did not exceed 5–7 %. The best plant development occurs at the optimal feeding area with an even distribution of plants on the field. Conclusions. On the typical low-humus chernozems of the Forest-Steppe of Ukraine, it is recommended to sow early ripening soybean varieties using the conventional row method of sowing, with a seeding rate of 450 thousand seeds/ha that to ensure even placement of plants, optimal nutrition area and survivability during the growing season.