O.A. Kazakova, E.Yu. Toropova, I.G. Vorobyova
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Summary. In order to identify the composition and significance of environmental factors that determined the long-term and seasonal population dynamics of the major barley seeds pathogenic micromycetes, the major pathogenic fungi taxonomic groups was monitored for 7 years in Western Siberia and Eastern Zauralie. The investigations were carried out on 59 barley varieties in the steppe zone of Western Siberia and Eastern Trans-Urals. Years of research (2006 - 2012) were characterized by different weather conditions - from dry to moist ones. For plant pathogen monitoring the conventional mycological methods were used. The study of the seasonal dynamics of ears pathogen populations was performed using paper insulators. In dry years, fungi of the genus Alternaria dominated (68,7-71,9%) on the barley seeds, in wet years in Western Siberia - fungi of the genus Fusarium (55,4%), in East Zauralie - Bipolaris sorokiniana (84,3%). Effect of hydrothermal conditions to fungal populations was 84-97 %. The seasonal B. sorokiniana dynamics character was determined by rainfall for August and was predominantly «moisture-dependent» (r = 0,73), fungi population of the genus Fusarium was determined by precipitation (r = 0,86) and was a «moisture-and temperature-dependent» with the earlier (5-7 days) grains infection in warm years. Seasonal dynamics of the Alternaria genus was much less dependent on the hydrothermal conditions (r = 0,40). The predominant (50% and more of isolates combinations) biotic relations between the studied fungi taxonomic groups, influenced mycological composition on barley seeds, was antagonism and competition. Within the Fusarium genus the whole range of ecological interactions from neutralism to antagonism was revealed, indicating varying degrees of fungi ecological niches divergence.
Keywords: pathogenic fungi, barley, seeds, long-term dynamics, seasonal dynamics, natural abiotic factors, biotic relationships.