Basic and additional ecological niches of soil phytopatogenes on spring wheat varieties in West Siberia

Abstract

The elucidation of hydrothermal and temporal parameters of the realization of the main and additional ecological niches of jointly parasitizing widespread soil phytopathogenic micromycetes has theoretical and applied significance. The aim of the study was to identify the parameters of the implementation of the main and additional ecological niches by the dominant species of soil micromycetes on spring wheat (Bipolaris sorokiniana Sacc. Shoem., Fusarium poae (Peck.) Wollenw., F. oxysporum Schltdl.) in the system of underground and generative organs of spring wheat varieties. The objectives of the study included determining the level of realization of the main ecological niches by three dominant species of soil pathogenic micromycetes in the system of underground organs of spring wheat varieties in different phases of vegetation, as well as identifying the degree of realization by micromycetes of additional ecological niches in generative organs of spring wheat varieties and assessing the strength of the influence of varieties and conditions of the year on the size of ecological niches in underground and generative organs of plants. The study was conducted on 20 varieties of spring wheat in 2020–2022, in the northern forest-steppe of the Ob region according to generally accepted and author’s methods. It is shown that the soil micromycetes B. sorokiniana, Fusarium poae and F. oxysporum, parasitizing together on the underground and generative organs of spring wheat, have different hydrothermal and temporal parameters of the realization of the main and additional ecological niches. B. sorokiniana is a relatively thermophilic species, its parasitic activity is most successful in underground, especially straw organs, is realized in conditions of unstable humidification, F. poae is a moisture-loving micromycete that prefers underground, especially young organs of spring wheat plants, F. oxysporum is a drought-resistant species that tends to more mature plant organs. As for the generative organs of wheat, B. sorokiniana colonizes them by airborne droplets in humid conditions, keeping them confined to straw-like tissues, the correlation coefficient of B. sorokiniana infection of the ear rods and the SCC of August was equal to r = 0.812 ± 0.412. F. poae could reach ears by vessels, the degree of their colonization by this micromycete was small and practically did not depend on the weather conditions of the year and its representation in underground plant organs. F. oxysporum colonized ears of spring wheat by vessels, and the degree of its representation in pathocomplexes of generative organs closely correlated with its share in pathocomplexes of primary and secondary roots: r = 0.923 ± 0.146.