Abstract
The aim of the study is to evaluate experimentally the predictive effectiveness of the “the degree of phenotypic dominance (Hp) in F1 “parameter for identifying the hybrid populations of spring soft wheat that are most promising for selecting trans-gressive forms based on the “number of grains per ear” and "1000 grain weight" productivity traits. The study of hybrid populations by 64 cross combinations, along with the parental forms, was conducted under field conditions in 2018–2023 across four consecutive generations. The relationship between the index of the degree of phenotypic dominance (Hp) in F1 and the average level of traits in subsequent generations (F2–F4), as well as the percentage relation to the best parent, was determined. It has been established that the Hp indicator based on the "number of grains per ear" has a limited predictive ability (R2 = 23.9 %; r = 0.489, significant at p<0.01). High heterosis in F1 (Hp = +1.0...+44.3) only in half of the cases determined the high potential of the trait in subsequent generations, however, extremely low Hp values (Hp<-10.0) can serve as an indicator of the futility of the combination. For the "1000 grain weight" trait, no linear relationship was found between the level of dominance in F1 and the value of the trait in older generations (R2= 0.85 %; r = 0.092). Genotypes exceeding the best parental form in F2–F4, as a rule, inherited the trait in F1 by the type of intermediate inheritance or moderate overdominance (both positive and negative). The high stability and repeatability of the mass of 1000 grains indicate a strong genetic conditioning of the trait and makes it possible to directly select for grain size in early generations, starting from F2. A comparative analysis of hybrid populations created in different areas of breeding (drought resistance, immunity, productivity) revealed that the max-imum yield of promising material in F2–F4 (up to 61 % of combinations exceeding the best yield standard) is provided by com-binations with a moderate level of phenotypic dominance in both productivity components. As a breeding strategy, it is proposed to increase the volume and intensity of selections from the best combinations to more effectively search for transgressive forms with an optimal combination of additive genetic complexes.