Object: selection of varieties and heterosexual hybrids of F1 cucumber and watermelon. Objective: Theoretical substantiation, development and improvement of methodological bases of creation and selection of starting material for varietal and heterosis breeding of watermelon and cucumber, development of effective methods of selection and seed production process of F1 hybrids and their practical application. Methods: general scientific, special, measuring and weighing, laboratory, vegetation experiment, chemical analyzes, biotechnological; gamete selection, calculated, statistical. Novelty: For the first time in Ukraine, an important scientific problem of establishing ways of optimization, development of new methodological approaches to increase the efficiency of the watermelon and cucumber breeding process, selection of selective-efficient source forms, hybrid combinations of F1 using a systematic approach is theoretically generalized and practically solved. The efficiency of breeding estimates of source material, selection and its identification, determination of patterns of expression of valuable economic features, heterosis, establishment of criteria and directions of selection of parental components of F1 hybrids are improved. Dependences of manifestation of valuable economic characteristics of F1 hybrids on their manifestation in parental forms are determined, methods of mathematical and statistical modeling for breeding and significant correlations (r = –0,59-0,99) between breeding traits are determined. The value of parental lines and their donor properties are determined. Methodological approaches to broadening the genotype variability spectrum have been established. Results: Improved methodological approaches to selection of starting material and pairs for heterosis breeding, determination of value of breeding material with establishment of its factor structure and basic characteristics, which ensures competitiveness of varieties and hybrids of F1 watermelon and cucumber, method of obtaining apomictic seed of hoghorn, watermelon and suitability of samples of cucumber for processing; method of gamete selection for selection of heat-resistant forms of cucumber; cell selection schemes for screening and selection of sources of resistance of the cucumber to fungi of the genus Fusarium; a method of creating and accelerating the reproduction of initial forms of watermelon with different levels of ploidy using methods of culture of isolated tissues in vitro. The scientific provisions on the specificity of inheritance of F1 hybrids of quantitative traits and the peculiarities of variability of its character depending on weather conditions have been further developed; principles for the manifestation of donor properties and the influence of different parental forms on breeding grounds on the yield level of F1 hybrids; features of the parental lines and hybrids of F1 watermelon and cucumber for resistance to bio- and abiotic factors. Degree of production: 3 monographs, 1 study guide, 3 parts of the book, 9 guidelines. 1018 sources of valuable features have been identified, 627 lines of watermelon and 179 lines of cucumber were created, 28 of which are registered in the NCGPRU provided the creation of 7 varieties and hybrids of F1 watermelon and cucumber, proved the efficiency of their introduction in agricultural production.
