Manifestation of Heterosis and Degree of Phenotypic Dominance by the Number of Grains from the Main Ear in the Hybridisation of Different Early-Maturing Varieties of Soft Winter Wheat

Winter wheat (Triticum aestivum L.) is the main food crop on a global scale, in the growth and stabilisation of yields, of which varietal resources are a significant factor. In practical breeding work, an essential role is played by a variety of thoroughly investigated source material. The purpose of this study was to determine hypothetical and true heterosis and establish the nature of inheritance of the number of grains from the main ear in hybrids of soft winter wheat. In 2018-2020, 45 combinations of cross-breeding of soft winter wheat varieties obtained from hybridisation of different growing season periods were investigated in the experimental field of the Research and Production Centre of the Belotserkovskyi National Agrarian University. Generally accepted methods were used to determine the hypothetical and true heterosis and the degree of phenotypic dominance by the number of grains in the main ear. Studies indicate that the number of grains in the ear of the main stem of the parent components of hybridisation is determined by genotype and considerably depends on the hydrothermal conditions of the year. The author of this paper established the influence of maternal cytoplasm on the manifestation of the trait under study. Thus, when used in hybridisation of early-maturing varieties with the mother form, the largest average number of grains in the main ear for hybrids (63.3 pcs.) was formed in 2019. At the same time, for the use of medium-early, medium maturing, and medium-late varieties in hybridisation, the maximum number of grains (64.8 pcs.) was marked in 2018. Therewith, all hybrids formed the minimum number of grains in 2020. The obtained experimental data indicate the influence of parental genotypes and year conditions on heterosis indicators and the degree of phenotypic dominance in first-generation hybrids. It is determined that the most common type of inheritance (85.6%) of the number of grains from the main ear is positive overdomination. Practical value for the selection of soft winter wheat are the selected cross-breeding combinations: Myronivska early / Zolotokolosa, Myronivska early / Cherniava, Bilotserkivska semi-dwarf / Cherniava, Bilotserkivska semi-dwarf / Antonivka, Kolchuha / Antonivka, Zolotokolosa / Charniava, Zolotokolosa / Yednist, Cherniava / Vidrada, Cherniava / Stolychna, Shchedra Nyva / Dobirna, Antonivka / Stolychna, Dobirna / Pyvna, which significantly exceeded the average number of grains from the main ear for F1 in the changing fields under hydrothermal conditions the years of researc