STUDY OF THE HETEROSIS EFFECT BY QUANTITATIVE TRAITS IN HYBRIDS F1 OF TOMATOES WITH THE PRESENCE OF β-CAROTENE IN THE FRUITS

The aim is to determine the patterns of heterosis effect and the degree of phenotypic dominance in terms of structural components of yield and phenological phases of growth of F1 hybrids that are carriers of high β-carotene content in fruits. Methods. Determination of true and hypothetical heterosis, degree of phenotypic dominance, measurement and weighing, variation statistics. Results. As a result of the research, the Aleta tomato variety, bred domestically, was identified as a carrier of high β-carotene content in fruits at the stage of technical ripeness. The use of this variety as a maternal component of crossbreeding made it possible to create three F1 hybrids with a carotenoid content of 7.77–13.85 mg/100 g. Hybridization with this variety confirmed a high heterosis effect in F1 hybrids, with a significant prevalence in most quantitative traits compared to hybridization partners: “Number of fruits on 3 racemes”; “Number of fruits on the main shoot”; “Average fruit weight”, “Productivity of one plant”; “Yield”. In particular, in absolute terms, the yield indicators of the three created β-carotene F1 hybrids varied between 11.60 and 12.70 kg/m2. In the Aleta variety as the maternal partner of hybridization, the yield was 7.80 kg/m2. In the first F1 hybrid, the yield of the parental component, the four-genomic line LMRS-1, was 8.13 kg/m2. The parental partner of the second hybrid F1, mutant line LMS-1, had a yield of 7.77 kg/m2. The Chaika variety, which was used as the parental component of the third hybrid F1, had a yield of 10.86 kg/m2. The hybridization experiments confirmed the experimental possibility of increasing the productive properties of gene carriers with a high content of β-carotene in fruits by expanding their genetic potential using hybrid breeding methods. According to the quantitative characteristic “Yield”, the values of true and hypothetical heterosis in the above-mentioned F1 hybrids varied within the following limits: Ftrue = 7.11...61.80 %; Fhyp = 24.65...62.57 %. In terms of the “Vegetation period duration” trait, all F1 hybrids created showed either early maturity in relation to two hybridization partners or to one: Ftrue = -7.92...0.0 %; Fhyp = -14.29...-5.94 %). As evidenced by the data obtained, the phenotypic dominance index for the trait “Yield” varied in the range hp > +1, which indicates positive superdominance (hp = 1.51…311.15). Conclusions. As a result of many years of research on introgressive, recombination, and mutation breeding of tomatoes, it was possible to obtain selectively valuable lines, the inclusion of which in hybrid selection as a parental component of crossing made it possible to create highly productive heterozygous hybrids F1 with a clear prevalence over hybridization partners in terms of a complex of valuable economic traits. The potentially high genetic ability of the Aleta variety, which is a gene carrier of high β-carotene content in fruits, to create highly productive F1 hybrids with an inherited ability to synthesize this carotenoid has been confirmed: F1(variety Aleta / LMRS-1); F1(variety Aleta / LMS-1); F1(variety Aleta / variety Chaika).