The dissertation presents a theoretical generalisation and a new solution to the urgent task of increasing the genetic diversity of the source material when using short, medium and tall winter wheat varieties in hybridisation, as well as identifying genetic sources of economically valuable traits for further inclusion in the breeding process.
It was found that the studied parental forms in 2019– 2022 were characterised by differences in individual phenotypic variability in the following productivity elements: length of the main ear, number of spikelets, weight of 1000 grains per ear and plant at the level of insignificant; number of grains and weight of grains per ear from insignificant to medium; productive bushiness, number of grains and weight of grains per plant from insignificant to significant.
The varieties Bilotserkivska semi-dwarf, Donska semi-dwarf and Lastivka Odeska were identified, which showed insignificant variability in most of the studied traits.
Genotypic variability in years with contrasting hydrothermal conditions in the wheat maturity groups studied by height showed some differentiation in quantitative traits, main spike length, number of spikelets, number of grains per ear, weight of 1000 grains per ear and plant – at the level of insignificance; productive bushiness – at the average level; number of grains per plant – insignificant in tall and average in medium-sized groups I–II, low-growing varieties; grain weight of the main ear – insignificant in low-growing varieties and average in other groups; grain weight per plant – from insignificant in medium-sized group I to average in low-growing, medium-sized group II and tall varieties.
The analysis of variance showed that year conditions had the greatest influence on the formation of productive bushiness (56,99 %), main spike length (42,76 %), number of spikelets per ear (41,59 %), number of grains per ear (41,45 %) and plant (46,31 %), grain weight of the main ear (55,84 %) and plant (43,96 %). The modification by genotype ranged from 12,92 % (number of grains per plant) to 35,07 % (number of ears per spike) and the interaction «year conditions-variety» – from 17,91 % (grain weight of the main ear) to 36,52 % – number of grains per plant. Other factors ranged from 0,72 % to 4,97 %. In the formation of the weight of 1000 grains per main spike (55,74 %) and plant (58,47 %), there was a significant modification of the characteristic by the variety, under the influence of the annual conditions, at the level of 18,48–20,48 %. In the context of the studied groups, certain differences in the influence of factors on the elements of soft winter wheat productivity were determined.
The following varieties were characterised by insignificant variability of stem length and coefficient of variation in years with contrasting meteorological conditions: Stolychna, Sonechko, Odeska 267, Lastivka Odeska, Kolos Myronivshchyny, Pysanka, Pylypivka. The genotypic variability of the groups studied by height was insignificant – 7,6–8,2 %.
It was found that in 2019–2022 the length of the main stem of all studied varieties of soft winter wheat was determined by the conditions of the year in 51,07 %, while the variety formed this indicator only in 25,11 %, and the influence of the interaction «conditions of the year – variety» was 23,48 %, and the share of other factors was 0,33 %. In the context of the studied groups, the greatest influence of the genotype on the formation of the length of the main stem (22,93 %) was found in the tall varieties.
The degree of phenotypic dominance in main stem length and productivity elements in soft winter wheat depends on the selection of hybridisation pairs and the conditions of the year.
The most common type of inheritance of the main spike productivity elements when using short, medium and tall varieties in hybridisation in F1 hybrids in 2020–2022 was positive superdominance, namely: productive bushiness – 58,7 %, main spike length – 80,8 %; number of spikelets – 50,0 %; number of grains – 81,7 %; grain weight – 86,5 %, weight of 1000 grains – 59,6 %.
Inheritance of main stem length was negative dominant in most cases: from 74,3 % (medium group I) to 100,0 % (medium group II, tall).
In years contrasted by meteorological conditions, the following cross combinations were identified Lisova Pisnia/Smuglyanka, Lisova Pisnia/Odeska 267, Lisova Pisnia/Pylypivka, in which the inheritance of spike length, number of spikelets and grains, grain weight per spike and weight of 1000 grains was positive dominant, as well as Bilotserkivska semi-dwarf/Vidrada with stable inheritance of productive bushiness, length of the main spike, number of grains, grain weight per spike and weight of 1000 grains by the type of positive dominance.
