Maiia S. Breeding value of winter soft wheat source material created by hybridisation of different ecotypes

The dissertation provides a theoretical generalization and a new solution to an important problem aimed at expanding the genetic diversity of the source material of winter wheat (Triticum aestivum L.) for hybridization of varieties of forest-steppe, steppe and western european ecotypes for further use in the breeding process. For formation in 2021–2023 varieties of soft winter wheat of the studied indicators are determined depending on the genotype of their coefficients of variation: plant heights from significant to large; productive bushiness, the length of the head spike and the number of spikes from weak to moderate and significant; the number of grains from the spike is weak to moderate, significant and large; masses of spike grains and their masses of 1000 grains from weak to moderate, significant and large; the number of grains from the plant and their mass from moderate to significant and large; the mass of 1000 plant grains is weak to moderate and significant. The reliable excess of average values by grades for 2021–2023 has been established with a weak (Cv ≤ 6 %) variation in the following genotypes: Mulan – western european ecotype by the number of ears in the head spike; Zorepad bilotserkivskyi – forest-steppe, Fidelius, Mulan – western european – the number of grains; Fidelius - weight of grain; Madiarka – forest-steppe – weighing 1000 grains of the head spike; Madiarka and steppe ecotype Lastivka odeska – by mass 1000 grains from the plant. In the section of the studied soft winter wheat ecotypes, the greatest influence of the conditions of the year in varieties of forest-steppe ecotype on the variability of productive bushiness was established – 56.87 %; steppe: the length of the main spike is 64.20 %, the number of spikelets is 56.03 %, the number of grains is 57.11%, the mass of the grain of the main spike is 59.63 %, the mass of grain from the plant is 53.90 %; western european: plant heights – 98.42 %, masses of 1000 grains of the main spike – 67.71 % and plants – 61.54 %, the number of grains from the plant – 60.30 %. The preference of the genotype was determined in the forest-steppe ecotype by: the number of grains of the head spike – 46.82 %, the number of grains from the plant – 38.15 %, the mass of 1000 grains from the plant – 32.27 %, the mass of the plant grain – 29.68 %, the mass of grain – 28.24 % and the mass of 1000 grains of the head spike – 27.98 %, plant height – 8.08 %; steppe: productive bushiness – 28.44 %, the number of ears of the head spike – 27.20 %; western european: the length of the head spike is 34.45 %, the weight of the grain from the plant is 30.11 %, the weight of the grain of the head spike is 28.08 %. A large proportion of the interaction «grade–conditions of the year» was determined by: the number of grains of the main spike – 45.81 % and the mass of grain in it – 43.61 %, the number of spikes – 42.04 % and its length – 28.60 %, the mass of grain from the plant – 34.81 % in the forest-steppe ecotype; with a mass of 1000 grains of the main spike – 41.68 % and plants – 38.31 % in the steppe and productive bushiness – 49.05 %, the number of grains from the plant – 29.07 % – western european ecotypes. In the vast majority, the inheritance of the studied features during the hybridization of forest-steppe, steppe and western european ecotypes in F1 occurred by positive overdomination, namely: plant heights in 50.9 % by the degree of phenotypic dominance (hp = 1.4–22.2); productive bushiness in all studied hybrids – hp = 1.6–184.0; head spike: length 68.4 % – hp = 1.1–40.0; 84.4 % of spikelets – hp = 1.1–19.0; grain amounts 82.5 % – hp = 1.2–75.0; grain weight 91.2 % – hp = 2.1–83.0. By partial positive dominance, the determination of plant height occurred in 14 % of hybrids, the length of the main spike – 8.8 %, the number of spikes in the spike – 7.0 %, the number of grains in the spike – 5.3 %; according to the intermediate type: plant heights of 26.3 %, the length of the main spike – 14.0 %, the number of spikes – 2.3 %, the number of grains – 3.5 %, grain weight – 1.8 % hybrids; partial negative inheritance: in hybrids, plant heights – 5.3 %, ear lengths – 5.3 %, the number of grains of the head spike – 1.8 %; negative superdomination: plant heights – 3.5 %, spike length – 3.5 %, number of spikes – 3.5 %, number of grains – 7.0 %, grain weight of the head spike – 7.0 %. The involvement of soft winter forest-steppe, steppe and western european ecotypes in the hybridization of wheat varieties contributes to the formation of the studied characteristics in F2 populations with the possibility of selecting valuable recombinants by plant height and productivity elements of the head ear for further breeding work. Of the 27 studied F2 populations obtained by crossing forest-steppe, steppe and western european ecotypes, a positive degree of transgression was found in 16, and negative in 14 combinations of crossing.