Object: regularities of recombination processes in intervarietal crossings, effectiveness of breeding by hybridization of soybean of different ecological and geographical origin, peculiarities of variability and inheritance of valuable economic traits in hybrid populations F1 – F4; ecological stability and plasticity of soybean varieties according to the complex of valuable economic traits, and establishment of their manifestation peculiarities. Methods: field, laboratory, breeding, in particular method of intravariety hybridization, morphological analysis, genetic analysis, statistical. Results: eleven soybean varieties have been created in co-authorship (Ametyst, Ahat, Artemida, Vinni, Vezha, Almaz, Antratsyt, Aleksandryt, Adamos, Avantiuryn, Akvamaryn) which are characterized by early ripeness, high content of protein (38–45 %) and fat (20–26 %) in seed. They have been included in the State Register of Plant Varieties Suitable for Dissemination in Ukraine. Hybrid combinations with the increased productivity indicators have been created. They are a source of valuable traits. Newly created forms having no pubescence are evaluated at the different stages of breeding process in order to create varieties of vegetable and stubble production areas. Twelve breeding lines and soybean variety Antratsyt have been submitted to the National Centre for Plant Genetic Resources of Ukraine for being used in the breeding process. The recommendations have been developed how to use newly created soybean varieties in production; their morphological and biological features and economically valuable traits have been described. The breeding and genetic characteristics of soybean varieties have been determined, on the basis of which a model of very early ripening and early ripening soybean varieties has been developed for the Forest-Steppe environment. Taking into account the features of the created varieties and the improvement of their main economic traits, the modern biological preparations and their complexes for each of the varieties have been studied and evaluated on the individual basis. Novelty: Ecological stability and plasticity of modern soybean varieties have been determined for the first time in the Forest-Steppe of Ukraine. The collection samples of different ecological and geographical origin with a sustainable high level of homeostaticity and breeding value have been singled out. The best of them have been involved into hybridization with newly created varieties. The hybrids obtained in topcross crossings have been analyzed, varieties with high effects of general and specific combination ability have been identified, which provide successful combination of genes in the specific combinations of crossings. A high differentiating ability of the Ametyst and Almaz testers has been revealed. The breeding and genetic features of the obtained hybrid material have been determined according to the manifestation of heterosis in F1, variability and inheritance of valuable economic traits. The degree and frequency of positive transgressions in the F2 -F4 hybrid populations have been analyzed. Selected transgressive forms were used as a source material in order to select valuable genotypes. New soybean lines without pubescence have been created, their breeding value has been determined and the areas of usage have been substantiated. High-yielding, resistant to abiotic factors, high-performance and high-quality soybean varieties have been created. The genetic diversity of the source material has been expanded through the use of intravarietal crossings. The varietal peculiarity of the positive interaction of soybean with biocomplexes and its impact on yield has been proved. Yield of standard seed, weight of 1000 seeds and laboratory germination have been determined. The model of very early ripening and early ripening soybean varieties has been improved for the environment of the Forest-Steppe of Ukraine. Branch – Agricultural Sciences and Food.
