Experimental substantiation of the method for assessing the phytotoxicity of micromycetes on wheat seedlings

Relevance. Currently, the relevance of studying to identify the ability of many micromycetes to synthesize phytotoxic substances that reduce seed germination and lead to huge losses in the yield of strategic agricultural crops is increasing. To solve the problem, the development of new methodological approaches is required, which is significant for immunologists and phytopathologists.
The purpose of this work is to determine the phytotoxic activity of micromycete strains from the genera Fusarium, Alternaria, Bipolaris, parasitizing on all agricultural crops cultivated in Russia.
Materials and methods. The strains, the methods of their cultivation, the bioassay method were used, and the statistical processing of the results obtained was carried out. A modification of some methodological approaches for assessing the phytotoxicity of micromycetes has been carried out. The selection of representative concentrations of culture fluid filtrates (FCF) of strains for phytotoxicity evaluation was carried out.
Results. A correlation was established for all variants of the experiment between two independent parameters: the development parameters of wheat seedlings and the concentration of cultural liquid filtrates. New results have been obtained on the study of the phytotoxic activity of 70 strains of hemibiotrophic micromycetes and the optimal concentrations of fungal FAs for classifying fungal strains into toxicity groups have been established. The most variable toxicity values were found when using a 40% solution of FCL. It was shown that, under these conditions, fungal strains can be divided according to the degree of toxicity into significantly different groups. This circumstance is an important reason for including strains of micromycetes with certain toxicity properties in the State Collection of Phytopathogenic Microorganisms. Fungal strains are necessary and appropriate for use in breeding to create resistant and tolerant varieties to phytopathogens from the genera Fusarium, Alternaria, Bipolaris.
Conclusion. New methodological approaches have confirmed that the most variable toxicity values were found with the use of FCF in a ratio of 2:3. This concentration of FCF strains are divided into 4 groups with characteristic differences in the degree of toxicity, which is an important reason for including such strains of micromycetes in the State Collection of Phytopathogenic Microorganisms and will be further used in breeding to create resistant and tolerant varieties of agricultural crops.

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