Davydenko S. Management of grain productivity and qualiti of sorghum grain in the Northeast Steppe

The dissertation provides a theoretical justification and the results of three-year research on determining the impact of various combinations of seed sowing rate and row width, as well as use of the modern growth stimulator Vegestim on the growth, development and productivity of plants, yield and grain qualiti of grain sorghum hybrids of different maturity groups – Swat, Yuki, Iggor and Flagg on the condition of the North-Eastern Steppe of Ukraine. An analysis of the current state of sorghum grain production in Ukraine indicates an insufficient level of realization of the genetic potential of this crop. The reason for this is significant violations of the technological regulations of cultivation, including those that determine the area of plants in agrophytocenoses. In addition, a significant untapped source of increasing plant productivity and yield of sorghum crops is the use of highly effective growth stimulants. Different combination of seeding rate and row width affected the duration of individual phenophases of growth and development of grain sorghum plants. The general regularity was a reduction in the duration of the interfase period of seedlingtrubbing, flowering-milk ripeness and the phase of emergence into the tube (by one to two days) and the extension of the panicle ejection phase under the condition of increasing the sowing rate and widening the rows. The duration of these interphase periods was actually the same within the options for combining seed sowing rates of 100 and 140 th. seeds/ha with 35 and 45 cm row spacing. The preservation of sorghum plants underwent significant changes under the inftuence of seeding rate and row spacing. The thickening of crops and the expansion of row spacing led to its decrease. Thus, in the variants for combining the seed sowing rate of 100 th. seeds/ha with 35 cm row spacing, the sutvival of plants of Swat and Flagg hybrids was 65,7 and 65,8 %, respectively, and in the variants of the combination of the seed sowing rate of 220 th. seeds/ha with row spacings of 70 cm – 63,5 and 62,7 %. The was actually no difference between the preservation of plants on the variants with 35 and 45 cm row spacing. In all phases of growth the air-dry mass of one sorghum plant of Swat and Flagg hybrids did not undergo significant changes within the combination of seed sowing rates from 100 to 180 th. seeds/ha with 35 cm row spacing and seed sowing rates of 100 and 140 th. seeds/ha with row spacing of 45 cm. The index of the leaf surface of sorghum crops was the highest on variants with 35 cm row spacing. With their expansion to 70 cm, it decreased by an average of 10 %. The leaf area of one plant in all phases was the largest in the variants of combining the seed sowing rate of 100 th. seeds/ha with row spacing of 35 and 45 cm. The influence of the sowing rate on the variability of the area of one plant from the tillering phase to the ripening phase increased. Thus, during tillering, with its increase from 100 to 220 seeds/ha, the leaf area of one plant decreased on by 20 %, during tube emergence by 29 % and during grain ripening by almost 39 %.