ASSOCIATIVE NITROGEN FIXATION IN THE RHIZOSPHERE OF CEREALS DURING SEED INOCULATION BY BACTERIA ARTHROBACTER MYSORENS 7 AND FLAVOBACTERIUM SP.

The general lack of knowledge in the conditions of Western Siberia (Omsk region), the nitrogen fixation process and quantitative data on its activity in agroecosystems do not allow us to establish the true role of nitrogen fixing microorganisms in the nitrogen balance of soils and plant nutrition, to estimate the proportion of biological nitrogen (due to associative nitrogen fixation). The relevance of the research lies in the biological assessment of the reception of inoculation of agricultural seeds with biological preparations of fungicidal-stimulating action of Russian production (ARRIAM, Pushkin). The research were study the infiuence of biological products of associative diazotrophs on the activity of the associative nitrogen fixation process in the rhizosphere of cereals, the survivability of introduced bacteria, and crop productivity in the conditions of the southern forest-steppe abd subtaiga of Western Siberia. The work was carried out in field experiments on varieties of Omsk breeding of spring wheat Omsk 42, Omsk 44, Tarskaya 12, Omsk Coral, barley Omsk 101, oats Siberian Hercules. Pre-sowing bacterization of seeds was carried out with an inoculant of diazotrophic bacteria of the genus Arthrobacter mysorens 7 and an inoculant of fungicidal-stimulating bacteria of the genus Flavobacterium sp. L-30. Rhizosphere sampling was leaded out in tillering (June), earing (July), grain filling (August). The activity of the associative nitrogen fixation process in the rhizosphere of cereals varied significantly depending on the use of biological products, the type of crop and the zone of their cultivation. Under the cultivation of cereals during the growing seasons with the introduction of Flavobacterium sp. bacteria. and Arthrobacter mysorens 7, an increase in nitrogen-fixing activity in the rhizosphere and dinamic survivability of introduced bacteria were found. On gray forest soil, for all crops of the experiment, the absolute sizes of nitrogen fixation were lower than on meadow-chernozem soil. In the conditions of the southern forest-steppe zone, the highest level of nitrogen-fixing activity was in the rhizosphere of soft wheat variety Omsk 42 and durum wheat Omsk Coral variety, amounting to 150.7-322.0 and 140.0-393.0 nM C2H2/100 g of soil with the introduction of bacteria of the genus Arthrobacter mysorens 7, 149.0-281.0 and 86.2-554.5 nM C2H2/100 g of soil with introduction of Flavobacterium sp. accordingly. In parallel, an increase in the number of CFU introduced bacteria was observed, as a result of which the nitrogen fixation process was activated. In the subtaiga zone of the Omsk region, the largest sizes of associative nitrogen fixation were found in the rhizosphere of soft wheat varieties Omsk 44 and Tarskaya 12, amounting to 46.3-230.7 and 24.0-130.0 nM C2H2/100 g of soil with the introduction of bacteria of the genus Arthrobacter mysorens 7, 62.0-208.3 and 52.0-178.7 nM C2H2/100 g of soil with the introduction of Flavobacterium sp. accordingly. Simultaneously with the increase in the size of nitrogen fixation, the number of bacterial cells of diazotrophs of the genus Arthrobacter mysorens 7 in the rhizosphere of these wheat varieties was also significant, during the growing season it varied between 1.28-5.23 × 106 CFU/g and 0.28-7.45 × 106 CFU/g. Barley was isolated from grain crops, the activity of the process in the rhizosphere of this crop was up to 164.3 nM C2H2/100 g of soil when Flavobacterin was used. A statistically significant (p<0.05) positive correlation between the process of associative nitrogen fixation and the yield of agricultural crops was revealed, in the southern forest-steppe zone r=0.927, r=0.986, r=0.897 (Omsk wheat 42, Omsk Coral, Siberian oats Hercules), in the subtaiga zone r=0.998, r=0.991, r=0.916, r=0.990 (Omsk wheat 42, Omsk 44, Omsk barley 101). EDN: NILFDX