E.Yu.Toropova1, M.P. Selyuck1, L.V. Yushkevich2
1Novosibirsk State Agrarian University
2Siberian Scientific Research Institute of Agriculture
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Summary. Purpose of the research was to study the influence of preceding crops and land tillage techniqueson Bipolarissorokiniana population sizein the soil, the development of root rot on spring wheat and suppressive soil level. Studies were conducted in the Omsk region in 2011-2013 years according to standard procedures. The flotation method was used to determine the plant pathogens soil populations, root rot level registration was carried out on different under-land spring wheat organs. Tillage systems affected the B. sorokiniana population in the soil and the common root rot development depending on the distribution of plant residues in the soil layers and the suppressiveness soil level. When moldboardless and minimal-zero tillage phytopathogen propagules were accumulated in the upper layer - 66%. When dealing with a moldboard conidia occurred mainly in the lower soil layer. Maximal number of phytopathogen conidia - 945 in 1g air-dry soil was observed after grain predecessor, the minimum (215) - after the fallow. The conidia degradation occurred to a greater extent after the fallow, rather than after the spring wheat at 26%. The fallow phytosanitary precursor reduced the development of spring wheat common root rot on average 1.2 times. Maximally affected spring wheat organs were the primary roots, especially on moldboardless and minimal-zero tillage after wheat - 53.5% and 45% respectively, or 3.3 times above the threshold, which is a consequence of the conidia concentration in the upper soil layer (0-10cm). When moldboardless and moldboard tillage the phytosanitary precursor (fallow) biological effectiveness was 24% on average in the plant organs. All of the soil samples were attributed to highly suppressive after the fallow. After grain (spring wheat) precursor soil suppressiveness was decreased, due to reduced soil microbial activity.
Keywords: сonidia, root rot, spring wheat, soil, suppressive level, tillage system, precursor.