Wheat varieties seeds structural elements depending on the sowing time and sowing rates in the Tyumen region northern forest-steppe

The purpose of research is to study the effect of sowing dates and seeding rates on the structural elements and seed yield of wheat varieties Novosibirskaya 31 and Iren in the northern forest-steppe of the Tyumen Region. The studies were carried out in 2018-2020 on the experimental field of the State Agrarian University of the Northern Trans-Urals. The seedling density in variants with seeding rates at the first sowing term at Novosibirskaya 31 was 87.4; 87.4; 87.1; 85.6, Iren' - 85.7; 82.9; 86.4; 83.6 % respectively. In the second and third sowing terms, the seedling density in both varieties decreased. Preservation of plants for harvesting, depending on the sown seeds for variety Novosibirskaya 31 at the first sowing date, was 72.6; 71.4; 68.3; 59.8 %, with the second - 68.4; 66.9; 64.4; 55.9; at the third - 66.3; 63.5; 61.6; 53.4, for the Iren’ variety at the first sowing date - 63.6; 69.0; 66.5; 47.0, with the second - 63.3; 67.9; 66.1; 58.4, with the third - 60.0; 64.4; 61.2; 55.9 %. Productive tillering in both varieties decreased from 1.32-1.29 at the first sowing period to 1.02-1.01 at the third sowing period, the grain count of the ear decreased from 19-21 to 11-12 pieces, the weight of grain per ear was from 0.69-0.72 to 0.36-0.34 g. On average, over the three years of the study, the maximum seed yield for the variety Novosibirskaya 31 was obtained at the first sowing date with a seeding rate of 6.2 million germinating grains per hectare and amounted to 3.35 t/ha, for the Iren variety, variants with a seeding rate of 5.7 and 6.2 million germinating grains per hectare were distinguished at the first sowing term, as well as a variant with a seeding rate of 6.7 million germinating grains per hectare at the second sowing term from yield 2.70; 2.77; 2.80 t/ha, respectively. Economically more profitable for Novosibirskaya 31 was the variant with a seeding rate of 5.7 million germinating grains per hectare at the first sowing term, the profitability level was 101.5 %. For the Iren’ variety, a variant stood out with a seeding rate of 5.7 million germinating grains per hectare with a profitability level of 97.4 %.