Agrotechnological Potential of Phosphate Mobilizers Isolated from Ordinary Chernozem of the Steppe Zone of the Kabardino-Balkarian Republic

Free-living phosphate-mobilizing microorganisms (FM) were isolated from common chernozem of the Kabardino-Balkarian republic steppe zone and their agrotechnological properties were comprehensively evaluated, in particular, the ability to dissolve strongly bound phosphorus mineral compounds, produce phosphatase and have a growth-stimulating effect on plants. To achieve this goal, 13 strains of free-living phosphate-mobilizing microorganisms were isolated from ordinary chernozem (long-term observation site № 082 Geoset, KBR, Tersky district, village of Opytnoye) by surface seeding on solid elective nutrient media. For a comprehensive assessment, methods for determining tricalcium phosphate dissolution, determination of phosphatase activity, germination, and dry biomass of test plants were used. It was found that the studied strains showed high specificity in creating a microbial-plant symbiosis, the effectiveness of which depended on the type of agricultural crop. One strain of FM-20 had a relatively high agrotechnological potential for the ability to dissolve mineral and organic phosphates and maximize the growth and development of barley plants (315%). For corn culture, the list of promising microorganisms turned out to be broader and was represented by 4 strains: FM-11, FM-18, FM-20 and FM-22, which demonstrated growth stimulation in the range of 21.8–264%. Two strains of FM-18 and FM-19 proved partially effective for sunflower (25–30.8%). The data obtained indicated the presence of high specificity of microbial-plant consortia and the importance of a comprehensive physiological and biochemical assessment of potentially promising strains of soil microorganisms from an agronomic point of view.