A new approach to assessing interspecific relationships of micromycetes from the genus Fusarium Link. with Bipolaris sorokinana Sacc. Shoem
E. Yu. TOROPOVA1, I. G. VOROB’EVA2,3, O. A. KAZAKOVA1
1Novosibirsk State Agrarian University, Novosibirsk, Russia
2Central Siberian Botanical Garden SB RAS, Novosibirsk, Russia
3Novosibirsk State Pedagogical University, Novosibirsk, Russia
Keywords: micromycetes, interspecific relations, competition, interspecific relations, biological diversity, generative organ, colonization, underground organ, quantification scale
Abstract
The aim of the study was to develop an approach to the quantitative assessment of interspecific relationships nature in soil micromycetes. The studies were carried out in the northern forest-steppe of West Siberia by conventional and author’s methods. It has been established, that during 2020-2022 the phytopathogenic mycocenosis of underground and generative organs of cultivated and wild-growing cereals was characterized by stability: the main phytopathogens were Bipolaris sorokiniana Sacc. Shom. and Fusarium Link. fungi, whose occurrence was close to 100 %. The total number of micromycete species on underground organs was 13, on generative organs - 8. The biological diversity of fungi was maximal in humid conditions, a change in the dominance of the moisture-loving F. poae (Peck.) Wollenw. by drought-resistant F. oxysporum Schltdl. was revealed. The coefficients of the species composition commonality of Fusarium root rot pathogens reflected the degree of the weather factors contrast during vegetation. The succession of Fusarium fungi in the system of plant organs according to the phases of vegetation was revealed, The quantitative parameters of their realized ecological niches overlapping were also determined. The study of pairwise interspecific relationships of micromycetes by the method of counter cultures, thanks to the development of a new original scale for the quantitative assessment of the interaction of species, made it possible to identify the most competitive species. Competition was expressed in a decrease in the rate of radial growth of colonies (up to 2.5 times), significant morphological deviations from pure cultures (up to 7 characters out of 10), in the formation of a lysis zone more than 7 mm wide (maximum 12 mm), and also in a change in the intensity of sporulation both in the direction of stimulation (up to a maximum of 20 times) and oppression (up to a maximum of 30 times). Within the studied combinations, competitive relations were identified in 46.4 % of cases, and neutral - in 53.6 %.
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