Influence of sowing dates and backgrounds of mineral fertilizers on the productivity of sorghum in the conditions of the forest-steppe of the Middle Volga region

Abstract

Relevance. The forest-steppe of the Middle Volga region is most susceptible to the influence of summer droughts. Forage crops in the study area due to lack of moisture in the second half of the growing season often form insufficient yields. Sorghum crops, in particular sugar sorghum, due to their heat and drought resistance, deserve to take a place in the field fodder crop rotations.
Methods. To conduct research in the conditions of the forest-steppe of the Middle Volga region at different sowing dates and norms of mineral nutrition, two-factor experiments were laid. Factor A — sowing dates: I — May 10; II — May 20; III — May 30. Factor B — mineral fertilizers: without fertilizers (control); N₆₀P₆₀К₆₀; N₈₀P₈₀K₈₀.
Results. It was revealed that the timing of sowing and the background of mineral nutrition had an impact on the formation of the leaf surface, plant height, the dynamics of their density, and on the formation of the crop. The leaf surface was from 32.4 to 38.3 thousand m²/ha on an unfertilized background in the booting phase, on an average background — 34–37.0 in the flowering phase, on a high background — 51.9–55.0 thousand m²/ha before harvesting. A similar situation was observed in terms of plant height and tillering of plants. When using N₆₀P₆₀К₆₀ the duration of the growing season averaged 113 days over three years, which is 9 days more than in the control. The variant of the mineral background N₈₀P₈₀K₈₀ increased the vegetation period by 15 days compared to the non-fertilized variant of the experiment. The creation of a background of mineral nutrition N₆₀P₆₀К₆₀ in the second term of sowing sorghum made it possible to obtain an increase in the yield of fodder mass from 6.6 to 8.0 t/ha. The application of mineral fertilizers at a dose of N₈₀P₈₀K₈₀ provided an increase in yield from 10.8 to 15.4 t/ha.