Unravelling Promising Diazotrophic Microbiota of Rauvolfia tetraphylla L.  with Existing Conventional Nitrogen-Fixing Microbial Partners

Manisha Mishra^1*, Sandeep Kumar ²and Arvind Kumar³

¹University Department of Botany, Tilka Manjhi Bhagalpur University, Bhagalpur, Bihar, India

²Department of Soil Science and Agricultural Chemistry, Bihar Agricultural University,  Sabour , Bhagalpur, Bihar, India

³Department of Botany, TNB College, Tilka Manjhi Bhagalpur University, Bhagalpur, Bihar, India

Corresponding Author E-mail: mmishra.tmbu2019@gmail.com

Abstract:

Post green revolution witnessed excessive production of nitrogenous fertilizers and their application in farmers’ fields, which although initially enhanced agricultural production, but later due to indiscriminate use, led to ecological perils including enhanced nitrogen footprint, emission of Green House gases, nitrate run off, eutrophication and several others. To address these concerns and promote sustainable agriculture, microbial inoculants, particularly based on diazotrophs or nitrogen fixing bacteria like Azotobacter, Azospirillum, Rhizobium etc.  were popularized. However,  ecological  incompatibility and sometimes inconsistent performance in stressed soils, necessitates exploring diverse diazotrophs other than the conventional ones for developing microbial inoculants.  Besides, the use of chemical fertilizers have disrupted native soil microbiome and many rhizospheric bacteria with promising PGP traits might be lost even before their novelty is revealed and tapped. Bioprospecting for unconventional diazotrophs from resilient niches of medicinal plants like Rauvolfia must be prioritized to be utilized as microbial inoculants. In our study,  ten diazotrophs with promising PGP traits were isolated from the rhizosphere of Rauvolfia tetraphylla L. The diazotrophs included members of Bacilli, Pseudomonads, Lysobacter, Stenotrophomonas and Rhizobia. Based on PGP traits Stenotrophomonas maltophilia RT2 was the most potent isolate and  it was recommended as a promising contender for the development of bioinoculants.

Keywords:

Diazotrophs; PGPR; PGP traits; Phylogeny; Rauvolfia tetraphylla L

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