The Enhancement of Soybean Growth and Yield in a Field Trial through Introduction of Mixtures of Bradyrhizobium japonicum, Bacillus sp. and Pseudomonas chlororaphis

Abstract

The effects of plant growth promoting (PGP) bacteria on soybean growth and yield were tested in field conditions using four treatments: (A) Bradyrhizobium japonicum strain 526, combined with cell-free supernatants (CFS) of Bacillus sp. strain Q10 and Pseudomonas chlororaphis strain Q16; (B) B. japonicum 526 + Bacillus sp. Q10; (C) B. japonicum 526 + P. chlororaphis Q16 and (D) commercial fertilizer containing B. japonicum, which served as a control. The average values of dry weight per nodule and shoot dry weight had the maximum values in the B treatment. In dry shoots collected at the flowering stage, nitrogen and carbon content was similar across all treatments, while that of sulphur decreased in treatment A. Relative to the control (D), all treatments showed positive effects on pods number and grain mass per plant, with the best results yielded by treatment A. Nitrogen and sulphur content in grain were significantly higher in treatment C, whereas maximum carbon content was measured in treatment B. In the control, it was obtained the yield of 4,000 kgha-1, which was in accordance with data reported by the seed producer for the same growing conditions (the maximum value). The yields of 4,229, as well as 4,286 and 4,400 kg ha-1 were measured for variants C, B and A, respectively, which were statistically significant higher (5.73 to 10%) than the commercial fertilizer (D). The improvement in soybean growth and yield in the field trial achieved by addition of PGP strains Bacillus sp. Q10 and P. chlororaphis Q16 to B. japonicum 526 can result in more productive agricultural practices.