Efficiency of complex application of bacterial preparations and plant growth regulators in soybean cultivation technology

Goal. To determine the patterns of formation of the soybean production process with the complex use of a bacterial preparation and a retardant, taking into account its variability and the variability of the hydrothermal conditions of the region. Methods. A complex of general scientific and special in agronomy methods was used, in particular: systemic — for generalization and elaboration of scientific sources; field (experimental) — for conducting experiments and fixing indicators of growth, development and productivity of soybeans; calculation-comparative — for processing, comparing and interpreting experimental data; mathematical statistical — for assessing the variability of indicators and establishing the reliability of the identified differences. Results. The study was conducted in 2018 – 2022 on gray forest soils on the experimental field of the research farm “Ahronomichne” of the Vinnytsia National University, located in the Right-Bank Forest-Steppe, according to the 3-factor scheme: factor A — soybean varieties Azymut and Holubka; factor B — pre-sowing treatment of seeds with the bacterial preparation Ryzohumin; factor C — solution of retardant chlormequat-chloride in concentration of 0.5, 0.75 and 1.0%. The retardant was used twice — in the phases of the 3rd trifoliate leaf and budding. It was determined that the efficiency of the studied technological elements depended on the variety and hydrothermal conditions of the region. Pre-sowing treatment of seeds with the bacterial preparation Ryzohumin contributed to the activation of growth processes and increased plant productivity, while the use of the retardant chlormequat-chloride regulated the intensity of linear growth and the formation of a leaf apparatus. The highest yield of the varieties was obtained with the complex use of Rhyzohumin and 0.75% chlormequat-chloride solution: Azymut — 2.43 t/ha, Holubka — 2.67 t/ha, which exceeded the control indicators by 15.23 and 16.85%, respectively. Conclusions. The combination of bacterial inoculation of seeds with the regulation of growth processes with chlormequat-chloride was an effective technological element for increasing soybean productivity. Optimal in the studied conditions was the use of the bacterial preparation Rhyzohumin in combination with a 0.75% solution of the retardant chlormequat-chloride in the phases of the 3rd trifoliate leaf and budding. The obtained results confirmed the prospects of complex biologization and growth regulation in soybean cultivation technology.