Seeding rates and sowing time influence on the spring wheat grain quality in the Tyva forest-steppe zone conditions

The purpose of research is to study the effect of seeding rates and sowing dates on the quality of spring wheat grain in the conditions of the forest-steppe zone of the Tyva Republic. The study was carried out in the forest-steppe zone at the experimental site of the Tuva Research Institute of Agriculture in 2019-2021. The soil of the site is dark chestnut, the mechanical composition is light loam with a neutral soil reaction pH 7.0. The object of the study is the varieties of soft spring wheat Altaiskaya 75 and Novosibirskaya 31. The standard is the local zoned variety Chagytai. We studied two norms (3.5 and 4.5 million germinating grains per 1 ha) and two sowing dates (the first term - May 15 and the second term - May 25) of spring wheat, fourfold repetition, randomized placement of options. Weather conditions in 2019-2021 were distinguished by sufficient moisture, and low temperature regime during the growing season of plants, the sums of active temperatures above 10 °C were low compared to long-term data. The optimal sowing time for the mid-season variety Altaiskaya 75 and the mid-early variety Novosibirskaya 31 is the third decade of May; high vitreousness and the highest content of gluten in the grain of wheat of the Altaiskaya 75 variety - when sown with a seeding rate of 3.5 million germinating grains per 1 ha, of the Novosibirskaya 31 variety - with a seeding rate of 4.5 million. Qualitative indicators of the use of turnover depending on weather conditions, in 2019, the vitreousness of sales for all varieties was above 60 %. In the same year, the variety Novosibirskaya 31 surpassed the control in terms of grain size by 27 g/l at the first sowing date (beginning of May) with a norm of 3.5 million germinating grains. The content of gluten in the grain in most variants for 3 years was less than 28 %, except for the variety Altaiskaya 75, the content of gluten in the grain of which, at a rate of 3.5 million germinating grains, was at the control level of 35 %.