Prospects for the use of pgpr in the cultivation of agricultural crops in different agrobackgrounds

Abstract

<p>The research was conducted under the conditions of a stationary field experiment on leached chernozem (short rotational crop rotation: potatoes-spring barley-peas-winter wheat). In the experiment, with an area of 2 hectares, different fertilization systems are provided: mineral low (N<sub>30-40</sub>P<sub>30-40</sub>K<sub>30-40</sub>), mineral medium (N<sub>60-80</sub>P<sub>60-80</sub>K<sub>60-80</sub>), mineral intensive (N<sub>90-120</sub>Р<sub>90-120</sub>K<sub>90-120</sub>), organic (separately: 40 t/ha of cattle litter manure, intermediate lupine siderate and their combination). Organic fertilizers were applied from autumn under potatoes, mineral fertilizers – immediately before sowing seeds. The repetition in the experiment is fourfold, the area of a separate plot is 42.4 m<sup>2</sup>.</p> <p>Potatoes and barley were inoculated with <em>Azospirillum brasilense</em> 410, peas with <em>Rhizobium leguminosarum</em> 2051, and winter wheat with <em>Paenibacillus polymyxa</em> KB. The strains are deposited in the Collection of Microorganisms of the Institute of Microbiology and Virology of the National Academy of Sciences of Ukraine. Previously, the active interaction of these bacteria with plants of the corresponding species was shown in laboratory conditions.</p> <p>When conducting field research during 2014-2022, it was established that inoculation has a positive effect on the growth and development of plants, the formation of the crop and its quality when growing crops on low and medium mineral agrobackgrounds.Increased doses of fertilizers reduce the efficiency of inoculation. The high efficiency of PGPR was noted for siderate actions and aftereffects. The effectiveness of inoculation leveled off when growing crops on the background of manure in the first year of its introduction and gradually recovered during the aftereffects (in crop rotation).</p> <p>A version has been put forward regarding the creation of a highly competitive environment of microorganisms in the soil when manure is applied, which prevents the interaction of PGPR with plants. This was confirmed in laboratory experiments when using genetically marked analogues of the corresponding bacterial strains for inoculation. The development of labeled strains in the root spheres was not observed when inoculating plants grown in soil taken from the field experiment plots where manure was applied. At the same time, active interaction of strains with plants was observed when growing plants in soil from areas where mineral fertilizers and sideral biomass were used.</p> <p>Similar results were also obtained in experiments conducted on sod-podzolic soil.</p> <p>In our opinion, the obtained results should be taken into account in the latest technologies for growing agricultural crops, especially under the conditions of organic production.</p>