Soil microorganisms are an important component of agrocenoses, which due to physiological and genetic features respond quickly to changes in the quality of the soil environment. Each plant in the rhizosphere forms a specific composition of the microflora which depends on the phase of plant development and soil-climatic conditions. The objective of our study was the quantitative composition of ecological and trophic groups of rhizosphere soil micromycetes of different crops in chernozem soils in the Left-Bank Forest Steppe of Ukraine. According to the results of research, it was determined that the rhizosphere soil under different crops – winter wheat, rye and oats in Chernihiv region – is characterized by the largest number of pedotrophic micromycetes. This indicates that the soil contains a sufficient amount of organic matter. The rhizosphere soils under winter wheat and spring barley in Kiev region were characterized by a larger number of pathogenic micromycetes and amylolytic and cellulolytic ecological-trophic groups. This indicates the intensive use of plant protection products. The rhizosphere soil under onions in experimental fields in Kharkiv region was characterized by a high number of the cellulolytic group. This indicates the presence of cellulose-destroying microorganisms. According to the results of statistical analysis, it was found that the number of micromycetes in the rhizosphere soil of the studied varieties of crops was in direct correlation with the value of the hydrothermal coefficient (НTC) in the vegetation period. Weather conditions during the research vegetation period differed by agrometeorological indicators. The characteristic feature was a contrast of differences in air temperature and unequal distribution of rainfall, which affected the composition of the soil mycobiocenosis. The vegetation period of 2021 in Kyiv region was characterized by a sufficiently moist hydrothermal coefficient which increased to1.81 while in Chernihiv, Kharkiv regions drought prevailed, but in some months the HTC increased to 1.32–1.54. It has been shown that the higher the HTC, the greater the number of micromycetes in all study regions.

The article presents the results of analysis of biodiversity and spatial-functional structure of the microbial complex in the soil rhizosphere, and development of ways to regulate the number of phytopathogenic micromycetes in the rhizosphere of soybean plants in organic production. Varieties of plants of soy were grown using the biopreparation "Philazonit", which was developed in the company "Philazonit of Ukraine". The study determined the effect of phylazonite biopreparation on the mycobiome of the rhizosphere of soybean plants. The interaction of plants of soy varieties Kent and Suzir’ja with phytopathogenic micromycetes in conditions of the organic production in the Central Forest-Steppe of Ukraine (Research farm “Skvyrske” of Institute of Agroecology and Nature Management of the National Academy of Agrarian Sciences of Ukraine (IANM of the NAAS) was investigated. The number of phytopathogenic micromycetes in the rhizosphere of plants of different varieties of soy is determined depending on the variety and technology of its cultivation. It was established that the biopreparation Philazonit inhibits the formation of the number of phytopathogenic micromycetes in the rhizosphere of plants of the soy variety Suzir’ja and Kent during the growing season. It is proved that the representatives of genera: Alternaria, Fusarium, Penicillium, Aspergillus are dominated in the rhizosphere of plants of soy of both varieties. In the rhizospheres of plants of the soy Suzir’ja variety the representatives of genus Penicillium (32.8%) most often occurred. The smallest number of micromycetes were members of the genus Aspergillus (9.5%). In the rhizosphere of plants of the Kent variety dominated by representatives of the genera Alternaria and Fusarium (35.6% and 34.1% respectively). Representatives of the genus Penicillium were 15% and Aspergillus – 15.3% It is proved noted that during the studies there was a correlation between the development of micromycetes and the hydrothermal coefficient – in the flowering phase (r=0.8) and in the ripening phase (r =0.9) except for the germination phase

Objective. To establish the influence of exometabolites of winter wheat plants of Podolianka, Natalka, Skagen, Mulan varieties and oats of Skarb Ukrainy, Svitanok, Tembr varieties on the growth and development of Bipolaris sorokiniana micromycete, as well as the influence of onion of Tkachenkivska, Mavka, Veselka, Liubchyk, Variah, Harmonia varieties on the growth and development of the micromycete Alternaria alternata. Methods. Mycological, phytopathological, phytoimmunological. Results. Two hundred isolates of pathogenic micromycetes were isolated from the seeds of the studied crops of different varieties. The most common microbiota were: Bipolaris sorokiniana, Alternaria alternata, Alternaria tenuissima, Alternaria infectoria, Stemphylium vesicarium, Curvularia inaequalis. The highest incidence on wheat and oat seeds (over 80 %) was reported for B. sorokiniana, on onion seeds — for A. alternata. It was found that exometabolites of plants of different varieties can both inhibit and stimulate the rate of radial growth of mycelium of B. sorokiniana and A. alternata. It was proved that exometabolites of plants of wheat, oats, onion can significantly affect the reproductive capacity of the studied micromycetes, which reduced the number of spores per 1 cm2 of colony area almost 1.2–2.5 times compared to the control. This indicates that exometabolites of plants are characterized by fungicidal properties, which are due to a complex of biologically active substances that can inhibit the intensity of sporulation of B. sorokiniana and A. alternate. Conclusion. The antifungal property of root exometabolites of plants of the studied varieties significantly depends on the genotype of the variety. Therefore, an important timely task is to identify environmentally stable and flexible varieties that are characterized by group resistance to pathogens of fungal origin, as well as the search for mechanisms of action of fungicidal natural origin.