The usage of physiological methods in the creation of soybean varieties

The results of a study of the operation of photosystem II in the leaves of nine soybean varieties bred by the All-Russian Research Institute of Soybean are presented in order to identify genotypes with increased photosynthetic activity for inclusion in the breeding process when creating highly productive varieties of a new generation. A comparative assessment of varieties is given in terms of effective quantum yield of photosynthesis (Y) and chlorophyll fluorescence (F₀), relative electron transport rate (ETR) and photochemical energy conversion depending on light saturation. The soybean varieties Gracia, Sonata and Kitrossa had the highest indicators for the studied parameters, significantly exceeding the standard variety Lydia. The effective quantum yield of photosynthesis, which shows the degree of absorption of solar energy, in the Gracia and Sonata varieties during the entire growing season was at the level of 0.80–0.83 rel. units, with this indicator exceeding for the Lydia variety by 0.09–0.13 rel. units depending on the phase of plant growth and development. The quantum yield of fluorescence (F₀) in the leaves of the Lydia variety during the flowering phase exceeded the Gracia, Sonata and Kitrossa varieties by 60, 56 and 63%, respectively, which indicates a reduced activity of photosystem II in this variety. The efficiency of photochemical conversion of photosynthetic energy during the flowering phase was most stable in the leaves of the Sonata variety at light levels from 600 to 1500 µmol quanta/(m²∙s). Using the soybean variety Gratsia as the maternal form (♀) when crossed with the hybrid Am.2146, which was obtained with the inclusion of the Sonata variety in the hybridization, which also has a high degree of absorption of light quanta, the Radiant variety was create. Variety passed testing in 2021–2022, and in 2023 included in the State Register of Breeding Achievements for cultivation in the Far Eastern (12) region.