Transgressive variability in the number of ears of the main spike in F2 populations when crossing soft winter wheat varieties of different early maturity.
Authors: Ustinova H. L. 
Published: December 2021

Aim. Determination of the degree and frequency of positive transgressions by the number of ears of the main spike in F2 populations created by crossing varieties of soft winter wheat of different maturity depending on the hydrothermal conditions of the year and selection of economically valuable biotypes for subsequent breeding work. Methods. Field, laboratory, mathematical and statistical. Results. In the majority of F2 populations, created by hybridization of soft winter wheat varieties of different vegetation periods, a significant form-making process took place in terms of the number of spikelets in the main spike. The experimental data obtained indicate a significant effect of matched pairs before hybridization and hydrothermal conditions of the year on the manifestation and formation of the number of spikelet’s in an ear F2. So, under the conditions of 2019, the majority of F2 populations for the number of spikelet’s in the main spike (17.4–21.5 pcs.) Significantly exceeded the parental forms. A positive degree (Td = 5.3–33.3 %) and the frequency of transgression (Tf = 3.3–96.7 %) were found in 85.7 % of the populations. In 2020, the average population number of spikelets in the main spike (15.0–18.6 pcs.) Was significantly less. When used in hybridization of early maturing varieties by the parent form, the decrease in the number of spikelets was 0.5–19.9 %. At the same time, for crossing mid-early, mid-ripening and mid-late varieties, the number of spikelets decreased by 2.8–28.9 %. Thus, it can be argued that populations in which early maturing varieties were the maternal form are less exposed to unfavorable conditions of the year. A positive degree (Td = 5.3–38.9 %) and the frequency of recombinants (Tf = 3.3–46.7 %), under the conditions of 2020, was established in 35 out of 42 F2 populations, which amounted to 83.3 %. Conclusions. The use of winter wheat varieties of different early maturity in hybridization in most cases contributes to the formation of F2 in populations and the selection of positive transgressive biotypes by the number of spikelets in the main spike. Conducted studies have established a significant effect of the parental forms used in hybridization and the hydrothermal conditions of the year on the formation of the number of spikelets in the main spike in F2 populations of soft winter wheat. Populations where the early maturing varieties were the maternal form are characterized by a more stable manifestation of the number of spikelets in the main spike. The decrease in the number of spikelets in 2020 compared to 2019 was 0.5–19.9 % for 2.8–28.9 % in populations obtained by hybridization of mid-early, mid-ripening and mid-late varieties. In years with contrasting hydrothermal conditions, hybrid populations F2 were identified, which formed more than the average F2 number of spikelets in the main spike and had high rates of the degree and frequency of positive transgressions, namely: Mironovskaya early / Kolchuga; Kolchuga / Stolichnaya; Shchedraia niva / Vidrada; Antonovka / Stolichnaya.