DETERMINATION OF HETEROSIS EFFECT BY A COMPLEX OF VALUABLE QUANTITATIVE TRAITS IN HYBRID PROGENY F1 OF EDIBLE TOMATO, CREATED ON A STERILE BASIS

The aim is to determine the patterns of heterosis manifestation and the degree of phenotypic dominance for structural elements of productivity and phenological phases of plant growth in F1 tomato hybrids created on a sterile basis. Methods. Physical mutagenesis, determination of true and hypothetical heterosis, degree of phenotypic dominance, measuring and weighing, variation statistics. Results. Long-term studies on physical mutagenesis of tomatoes allowed for the breeding of mutant forms with monogenically controlled marked genes from individually selected plants within varieties of domestic and foreign breeding, whose air-dried seeds were treated for several years with γ-irradiation at doses of 60 and 130 Gy: pollen sterility (gene ms); vegetative organs at the level of leaf type change (gene c) and its surface coloration (gene m-2, which controls the manifestation of chlorotic mottling); bush shape (genes sp and sp+); external and internal fruit coloration (genes r, r+ and gf), "golden" stripes on the epidermis of a mature fruit (gene gs); yellow cotyledons (gene wv). As a result of physical mutagenesis, two mutant tomato lines were created, derived from the Inhuletskyi-1 variety, with a high level of sterile pollen at 90–100 %. Based on these two lines, F1 tomato hybrids were created on a sterile basis, whose yield in protected ground conditions was 16.38–17.30 kg/m2, which significantly exceeded the corresponding indicators of hybridization partners by 16.83–178.14 %. F1 hybrids were characterized by a vegetation period duration of 105 days, which is 1–10 days less than that of hybridization partners. In F1 hybrids, a positive overdominance effect (hp = 1.67…32.91) was established for the following traits: "Main shoot height", "Number of fruits on 3 trusses", "Number of fruits on the main shoot", "Productivity per plant", "Yield", "Duration of the interphase period 'Emergence-flowering'", "Duration of the growing season". Conclusions. Selected initial tomato varieties of domestic and foreign breeding, whose genetic basis allows for the creation of mutant forms with a high level of sterility at 90–100 % as a result of γ-irradiation of air-dry seeds with doses of 60 and 130 Gy. The research results confirmed the high efficiency of using the created mutant tomato lines with the presence of the recessive ms gene as maternal components in the creation of highly productive F1 hybrids. Hybrids of the F2 generation obtained on a sterile basis continued to maintain high productivity for a complex of quantitative traits, which are structural components of yield.