Peculiarities of formation of symbiotic apparatus of middle maturing soybean cultivars on leached chernozem of the Krasnodar region

When planting on leached chernozem of the Krasnodar region, in most cases soybean forms actively tubercles. Presnce of soybean rhizobia in studied soils is connected with long-year introduction of these microorganisms from the other soybean-planting regions. The aim of the research was to determine intensiveness of a symbiotic apparatus formation effected by standard (Nitrofix-Zh) and strains of rhizobia allocated from the local soils and two ones of the far-east origins. The object of the research was a soybean cultivar of middle maturity Vilana, the study was conducted in 2015-2016. At strains selection there were studied their morphological and cultural traits. The previous testing was done in laboratory conditions and in 2016 - in small-plots field experiment, which data are considered as preliminary. The yield in control exceeded 2.8 t per ha in 2016, under favorable for soybean hydrothermal regimen during the vegetative period. In the second half of the vegetative period, the tested soybean rhizobia caused increase of the tubercle quantity by 10-31%. Proved increase of tubercles quantity was observed on plots with a standard - 31% and in variants with strains 5-1 and 6-1 - by 29-30%. Authentic rise of yield was effected by strain of rhizobia 5-1 and 6-1 - 0.38-0.39 t per ha, respectively (at LSD05 - 0.37). Soybean yield increased by 0.36 t per ha under standard effect. The current data are obtained at activity of native soybean rhizobia.