Analysis of the results of studying the soft winter wheat collection by tolerance to powdery mildew

Topicality. Thanks to analysis and systematization of wheat collection, we will be able to obtain new sources of tolerance and create a trait collection for the developing tolerant varieties suitable for cultivation in different ecozones of Ukraine. Yield losses from pathogens can be reduced by introducing new varieties with a wide genetic base of group tolerance. Purpose. To characterize the soft winter wheat collection in terms of tolerance to powdery mildew in the conditions of the Southern Forest Steppe of Ukraine. Materials and Methods. During 2011–2019, the research was conducted at the Ustymivka Research Station of Plant Production Institute named after V. Ya. Yuriev NAAS of Ukraine. We studied 1406 samples of soft winter wheat (Triticum aestivum L.) from 33 countries, including 53.1 % – Ukrainian origin, 10.1 % – from Turkey, 8.6 % – from the United States, 6.9 % – from Russia, 17.0 % – from Europe. Research methods: field, dialectical, hypothesis, synthesis, induction, statistical, observation. Results. The manifestation of the main foliar diseases on collection samples of soft winter wheat was observed to determine field tolerance to diseases in the following organogenesis stages: autumn tillering, spring budding, stem elongation, beginning of heading, milk-dough maturity. In the early growth and development stages of wheat plants (seedlings – heading), plants were insignificantly damaged by powdery mildew. In the autumn tillering stage, 5 samples out of 234 were not affected by powdery mildew: 831/10, 853/10 (UKR), Pesma (YUG), Gruia, Gloria (ROU). During the period of stem elongation, there are 12 samples of soft winter wheat susceptible to this disease in this stage of organogenesis. Arid conditions in 2012 and 2013 were more favorable for distribution of the wheat collection for disease tolerance at the heading stage, in which the susceptible and weakly susceptible samples under study accounted for approximately 14 %. The maximum damage by this pathogen occurs in milky-wax ripeness of wheat. Distribution by the level of tolerance significantly depends on the conditions of a particular year. Thus, in 2011 (excessively humid conditions), the percentage of susceptible samples of wheat to the pathogen was 57.5 %; in 2012 and 2013, a larger group of samples was noted as weakly susceptible. The significant influence of the amount of precipitation and the level of hydrothermal coefficient (HTC) on the number of susceptible wheat samples to powdery mildew during heading (r = 0,83 and r = 0,91, respectively) was established. The average level of correlation between the indicators of the number of highly susceptible wheat samples to this disease and the level of HTC (r = 0,33) was noted. The method of distant hybridization using foreign genes helps to obtain lines more resistant to specific pathogens of soft winter wheat. Conclusions. Distribution of winter wheat samples by the level of tolerance to powdery mildew depended significantly on the conditions of a particular year. The special collection of samples resistant to the most common diseases of soft winter wheat allows you to systematize the selection of parental lines on specific traits, which will create more resistant lines. Key words: soft winter wheat, tolerance, powdery mildew, stage of organogenesis, hydrothermal coefficient, distant hybridization method