Abstract: The reactions of barley agrophytocenosis components on coenotic stress in the conditions of forest-steppe in Kemerovo region are revealed. The studies were conducted at the experimental test site of the Department of Agriculture and Plant at Kemerovo State Agricultural Institute. The different situations of barley plants (variety Odessa -100, Luka), weeds and pathogens of root rot influence on each other due to the density of the cultural component: 4.5, 6.5, 8.5 million of grains germinating per unit area were simulated. Hydrothermal coefficient was 0.1 in 2012 and 0.7 in 2011 during the growing season, that had an impact on the growth reaction of the components and the development of root rot - Bipolaris sorokiniana. The study of weeds in barley agrophytocenosis showed that their community comprises 14 species belonging to 9 families. The share of anthropochore and apophytes in weed component is 50%. The abundance of weeds in cenosis of variety Odessa 100 depending on the density is 4.5 – 6.91%, 6.5 – 4.35% 8.5 – 7.36%. The variety Luka has an inverse relationship in the proportion of weeds. When planting density is 8.5, the share of weeds is 4.26% of the total number of plants per square meter. Thus, the sort of Luka confirms the competitive ability in relation to biotic factors. It was revealed that the cenosis density had almost no effect on diversity of weeds. There was the formation of a minor type of debris with the dominance of spring weeds (pikulnik beautiful - Galeopsis speciosa MILL. bedstraw Galium aparine L., pigweed white - Chenopodium album L). In Western Siberia the most common diseases in cereals cenoses are root rot, caused by fungi of the genera Fusarium, Helminthosporium, Alternaria. Under the conditions of the provocative background, those are the cenoses with high density, where the development of root rot increases significantly. The disease incidence of barley increases from the early stages of development to mature. The primary roots and stem base are infected the most. In terms of prevalence of the disease, different kinds of reactions and their dependence on the density of the cultural component were determined. Seeding density and stages of ontogeny affect the morphological parameters of the components (plant height, diameter of internodes). Weeds occupy presoil and medium tier at tillering and earing. Higher grade of competitiveness has the sort Luka with productivity of 640h/m2. Productivity analysis let determine that an increase in the density of seeding reduces the productive tillering and grain size. A clear correlation of changes in the number of grains and the number of surviving plants per area unit under coenosis stress was not revealed. The two varieties of barley formed the maximum efficiency in the thickened seeding density such as 6.5 mln. of germinating seeds.

Key words: Agrophytocenosis, growth reactions, barley, productivity

Presentation: oral