Mycobiome of sunflower rhizosphere in organic farming
Physiologically active substances released from the roots of cultivated plants can significantly affect the structure and functioning of the fungal coenosis in the rhizosphere soil. Rhizosphere soil is one of the essential participants in the allelopathic interaction of plants and soil biota, especially in the agrocenosis of sunflower plants, which is characterized by significant allelopathic potential. Studies to determine the number of micromycetes in the rhizosphere soil of sunflower plants hybrids Dushko and Oliver were conducted during 2018-2020, using generally accepted methods prescribed in DSTU 4287:2004 (National Standard of Ukraine). The impact assessment of sunflower hybrid plants and their cultivation technologies on the number and species composition of micromycetes in the rhizosphere soil is presented. It is established that in the conditions of both organic and traditional technologies of sunflower cultivation, the number of micromycetes differs depending on the hybrid, which indicates a significant effect of root secretions on the micromycetes population in the rhizosphere soil. In the conditions of traditional technology, the number of micromycetes in rhizosphere soil ranged from 5.1 to 6.3 thousand CFU/g of dry soil, and in the conditions of organic technology - from 5.4 to 6.7 thousand CFU/g of dry soil. It is noted that the sunflower hybrid root exometabolites and technologies of their cultivation put significant pressure on the number and species of micromycetes biodiversity in the rhizosphere soil. The species composition of micromycetes in the rhizosphere soil of sunflower plants was determined, and it was found that fungi of the genera Aspergillus spp., Alternaria spp., Penicillium spp., and Fusarium spp., are dominant, which are characterized by the different frequency of occurrence, which ranged from 25 to 80%. These micromycetes cause significant damage to sunflower crops and increase the level of biological contamination of agrocenoses during plants' growing season. We suggested that under organic and traditional technologies of sunflower cultivation, the number and species composition of micromycetes depended on the hybrids and technology of their cultivation.