Study of the ability of cultures of rhizobacteria to colonize the root system of sugar beet

The article discusses the ability of the rhizobacteria Agrobacterium tumefaciens 184 and Streptomyces sp. 3 Colonize the root system of sugar beet. The study was conducted by growing plants in semi-liquid (0.7%) starved agar inoculated with these bacterial strains. It has been shown that these microorganisms can take root and develop in the rhizosphere due to root exudates, which confirms their phytoprotective and growth-stimulating properties. The authors analyze the influence of environmental factors on the colonization process, as well as assess the degree of influence of the studied bacteria on the beneficial soil microflora. It was revealed that the introduced microorganisms do not have an inhibitory effect on the main ecological and trophic groups of the microbiota involved in ensuring soil fertility. It has been established that the colonization process depends on a number of factors, including the composition of root secretions, the ability of bacteria to adhere, the rate of their reproduction and survival in the rhizosphere. The method of assessing the colonizing ability, based on growing plants in semi-liquid starved agar, has shown its effectiveness and allows for rapid primary diagnosis of promising strains of rhizobacteria. It has been experimentally proven that in the presence of root exudates of Agrobacterium tumefaciens 184 and Streptomyces sp. 3 actively form microcolonies on the root surface of sugar beet, starting from 2-5 days after inoculation. The development of bacterial colonies increases by the 14th day, with the highest density observed in the area of the root apex. The results obtained emphasize the prospects of using these strains in agricultural technologies aimed at increasing the resistance of sugar beet to phytopathogens and improving its growth. An important conclusion is the absence of negative effects of rhizobacteria on the natural microflora of the soil, which confirms the possibility of their use as biological products in agriculture.