Object: formation patterns of major economically valuable traits, genetic value of winter rye lines with systemic properties, influence of weather conditions and agrotechnological techniques on the productivity of parent components and the first generation rye hybrids, creation of new competitive adapted to the agro-ecological conditions of the Forest-Steppe of Ukraine winter rye hybrids. Objective: Development of methodological bases of winter rye breeding and seed production using heterosis effect, development of theoretical bases of winter rye heterosis breeding and seed production, rationale of methodological approaches to breeding and seed production of the crop hybrids, definition of formation peculiarities and variability of traits in parent component of hybrids and their practical application in seed production, creation of new high-yielding winter rye hybrids. Methods: General scientific, field, measuring and weighing, laboratory, statistical. Novelty: For the first time in Ukraine, the important scientific problem devoted to the development of methodological bases of winter rye breeding and seed production using heterosis effect was solved by theoretical rationalizing ways of the creation of high-yielding hybrids of the crop with high adaptive potential. The method estimating the value of parent lines and promising hybrid combinations in terms of GCC and SCC was improved; variability peculiarities of productivity elements of rye winter parent components was determined in hybridization plots, depending on weather conditions and different agrotechnological methods of cultivation; a technology model of obtaining high-yielding hybrid seeds was rationalized; the economic effectiveness of methodic products in seed production was determined. Results: Winter rye hybrids with the grain yield of 9.2 - 10.8 t/ha were created. The developed technology for producing hybrid seeds enables obtaining high yields in hybridization plots. The methods of evaluation and selection of lines - parent component of hybrids were improved. Four winter rye hybrids, 2 female forms of hybrids, 5 lines of parent components of hybrids, which are listed in the Register of Plant Varieties Suitable for Dissemination in Ukraine, were created; a collection containing 15 lines - sterility fixers was registered in the NCPGRU. Degree of Implementation: The research results were used in winter rye breeding programs and seed production, in particular, in the Plant Production Institute nd. a VYa Yuriev of NAAS, Verkhnyachka Experimental Breeding Station Institute of the Institute of Bioenergy Crops and Sugar Beet of NAAS as well as in the educational process at Kharkiv National Agrarian Univeersity nd. a VV Dokuchaev, and the hybrids created are used on farms, in particular in Kharkiv, Poltava, Sumy and Dnipropetrovsk regions on the area of over 40,000 ha. The work resulted in 13 copyright certificates on winter rye hybrids, varieties, and parent components. Scope of Implementation: Scientific institutions of NAAS and the Ministry of Agrarian Policy and Food of Ukraine, higher educational establishments, agrarian enterprises of Ukraine
