Parasitic activity of plant pathogens at the underground organs of spring wheat in the West Siberia

Abstract

Abstract The purpose of the research was to determine the factors of soil phytopathogens parasitic activity at the underground organs of spring wheat varieties, to clarify the etiology of root rot during the growing season. The studies were carried out in 2020-2021 in the northern forest-steppe of the Ob region (West Siberia) using generally accepted methods. A high parasitic activity of soil phytopathogens was established during the entire growing season of spring wheat: the zonal threshold of harmfulness was exceeded at seedlings up to 2.8 times, at bloom stage to 5 times, and at ripeness stage up to 4 times. The host plants susceptibility to infection with phytopathogens increased during the growing season due to abiotic (drought) and biotic (cereal flies) stresses, which neutralized varietal differences. The main phytopathogens at the underground organs of 20 spring wheat varieties were Bipolaris sorokiniana Sacc. Shom. and Fusarium Link. fungi, the occurrence of which at all underground plant organs (primary roots, secondary roots, stem bases) during the growing season was 100%. The dominance of Fusarium fungi increased during the growing season of plants. The biological diversity of Fusarium fungi was maximal in the bloom phase (up to 7 species on secondary roots of one variety). The species composition of Fusarium fungi was represented by permanent species-F. poae (Peck.) Wollenw. and F. oxysporum Schltdl., additional species-F. sambucinum Fuck., F. graminearum Schwabe and F. equiseti (Corda) Sacc., rare-F. solani Koord., F. sporotrichioides Sherb., F. culmorum Sacc., F. heterosporum Nees., F. acuminatum Ellis & Verh. The succession of Fusarium fungi in the system of plant organs and in the phases of vegetation was revealed, and the parameters of realized ecological niches overlap of Fusarium fungi species were determined.