New isolates of soybean nodule bacteria in Central Siberia

In a vegetation experiment, the effect of inoculation with new strains of symbiotic nitrogen fixers on the development of soybeans was assessed. The comparison was carried out with the industrial strain 634 b of the All-Russian Research Institute of Agricultural Microbiology and the autochthonous culture discovered in the Krasnoyarsk forest-steppe (Krasnoyarsk Territory). Two soybean samples were used: variety Zaryanitsa (characterized by high nodulation) and line G-23 with low nodulation capacity. Inoculation of five-day-old seedlings was carried out by immersing the roots in an aqueous solution obtained by washing the colonies from a semi-synthetic nutrient medium. The concentration of the microsymbiont is 1 × 10 7 cells/ml. The plants were planted in 5L pots filled with typical agrochernozem taken from soybean crops. The soil contained an average amount of mobile phosphorus, a high amount of potassium, and a low to medium amount of nitrogen. The count was carried out in the R3 phase of soybean development; for each variant, 16 plants in four vessels were analyzed. Significant differences in plant height, wet and dry weight of stem and root, maximum root length were established. In the G-23 line, the advantage was proven for strains 1–4 relative to the native culture (p < 0.003, 0.012, 0.006, 0.033), industrial drug (p < 0.002, 0.009, 0.004, 0.025), respectively. A significant difference in cultivar Zaryanitsa was obtained between strains 1, 2 and autochthonous culture (p < 0.036, 0.036), preparation 634 b and isolates 2, 3 (p < 0.012, 0.011). The maximum ranks were established for the Zaryanitsa variety for strains 1 (5.14), 2 (4.78), line G-23, strains 4 (5.4) and 3 (5.00). Consequently, new isolates of nodule bacteria are sources of increasing soybean productivity in northern agriculture.