Object: peculiarities of breeding soybean varieties with high yields, adaptability and product quality; patterns of formation of high yields, adaptability and seed quality by establishing features and improving methods of quantitative assessments of the hydrothermal mode effect on the variability of the main economic characteristics of soybean breeding material and varieties. Objective: theoretical justification and solutions of key scientific problems in soybean breeding related to the creation of novel high-yielding starting material with high adaptability and seed quality, resistant to unfavorable bio- and abiotic environmental factors and practical implementation of scientific approaches to creating new varieties in the eastern forest-steppe of Ukraine. Methods: general scientific, breeding, field, laboratory, biochemical, biometric, mathematical/statistical. Novelty: The patterns of formation of yield capacity and seed quality have been established; on their basis, the efficiency of the created soybean breeding material and varieties with high quality of seeds, adapted to environmental conditions, has been evaluated. Based on the regularities of the hydrothermal mode influence on the variability of the main quantitative and qualitative characteristics of plants and seeds of soybean breeding material, the principles of soybean breeding for adaptability, seed yield and seed quality have been theoretically justified, and ways of its optimization have been outlined in practice. Patterns of relationships between the yield capacity and seed quality in soybean varieties have been theoretically justified and developed, and the optimal parameters of a model variety have been determined. The patterns of formation of the yield capacity and seed quality under changing agrometeorological conditions have been established. The peculiarities of soybean seeds under the influence of phytopathogens and environmental factors have been revealed. The genetic diversity of soybeans has been expanded through the selection of breeding accessions and varieties, formation of working collections and selection of plant gene pool specimens in Ukraine. Peculiarities of environmental plasticity and stability of soybean breeding material, creation and assessments of starting material for yield capacity, seed quality and resistance to environmental factors have been described. Results: The breeding process design has been improved due to the use of the established patterns of the formation of yield capacity, adaptability and seed quality. Valuable collection accessions have been identified. Soybean varieties Podiaka, Malvina, Estafeta, Sprytna, Baika, Kobza, Perlyna, Krynytsia, Pysanka, Melodiia, Raiduha, Krasunia, Rizdviana, and Sloboda have been bred. Degree of Implementation: The created varieties have been introduced into the agriculture of Ukraine. The starting breeding material and methodological know-hows have been included in breeding programs of the Plant Production Institute named after VYa Yuriev NAAS and are used in curricula and research at KhNAU named after VV Dokuchaev, SNAU, SI ‘Institute of Grain Crops’ NAAS, and PDAA. Fourteen copyright certificates for soybean varieties have been received. Scope of Implementation: research institutions, higher education institutions, soybean growing farms.
