Efficacy of rhizobacteria to enhance the growth of Vigna mungo (L.)

Vigna mungo (L.), commonly known as black gram, is a highly nutritious crop most commonly found in Asia. The present study aimed to evaluate the effect of the Bacillus strains on the growth parameters of the plant. Biochemical characterization of the bacterial strains was carried out. After that, a seed germination assay was carried out in vitro. For this purpose, seeds were treated with the monocultures and mixed cultures (Z-06+Z-43, Z-06+Z-07, Z-02+Z-43, Z-02+Z-07) of bacterial strains for 1 week. Monocultures showed a germination percentage in the range of 14%-50% while the mixed cultures showed a germination percentage in the range of 33%-100%. Auxin bioassay was carried out in which strains were inoculated in the medium containing tryptophan and also without tryptophan. Z-07 and Z-43 gave 83.3% and 62.5% more promising results than Z-02 and Z06. Analysis of auxin-producing strains was done by FTIR (Fourier Transformed Infrared spectroscopy). A pot trial was carried out of the auxin-producing strains in monocultures and mixed cultures. Two harvestings were done after 1 month and 2 months, respectively. In both harvestings, plant parameters were measured including shoot length, fresh weight, dry weight, and number of pods. It was shown that plant growth parameters were improved after treating the seeds with the bacterial cultures. Z-07 and Z-43 gave more promising results in auxin bioassay and increase in plant growth parameters. So, these strains can be used in agricultural applications.