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ORIGINAL RESEARCH article

Front. Sustain. Food Syst.
Sec. Crop Biology and Sustainability
Volume 8 - 2024 | doi: 10.3389/fsufs.2024.1506346

Isolation, Screening and In-vitro Characterization of Plant Growth-Promoting Bradyrhizobium Isolates from the Nodules of Bambara groundnut (Vigna subterranean) for Potential Use as Bioinoculants

Provisionally accepted
Osman Abdulai Seidu Osman Abdulai Seidu 1*Stephen Mwangi Githiri Stephen Mwangi Githiri 2John Mwibanda Wesonga John Mwibanda Wesonga 2Victoria Wambui Ngumi Victoria Wambui Ngumi 3
  • 1 Pan African University Institute of Basic Sciences, Technology and Innovation, Nairobi, Kenya
  • 2 Department of Horticulture and Food Security, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
  • 3 Department of Botany, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya

The final, formatted version of the article will be published soon.

    Bambara groundnut (Vigna subterranean) is a resilient leguminous crop that can withstand drought conditions and is commonly grown in arid regions where soils are degraded and of low fertility status. Although the crop can fix nitrogen, its yields frequently fall short of their maximum potential which can be attributed to association with ineffective rhizobia strains. In the present study, we isolated, screened, and in-vitro characterized Bradyrhizobium isolates from the root nodules of Bambara groundnuts with plant growth promoting properties for potential use as bioinoculant. Root nodules were sampled from JKUAT farm where healthy Bambara groundnut plants were growing. Ten isolates with slow growth rate were isolated. The ten isolates were screened using morphological, biochemical and molecular (16S rRNA gene sequencing) techniques. The sequence analysis established that all isolates were congeneric with Bradyrhizobium. In addition, all the isolates showed Nitrogen-fixing potentials and also had significant (p<0.005) ability to solubilize phosphate in the range of 0.77±0.771 to 3.22±0.368 phosphate solubilizing index. Further, isolates P4A17, P4A18, P4A16, P4A6 and C2 produced IAA concentrations of 54.97±3.21 µg/mL to 108±12.10 µg/mL. However, none of the isolates could produce HCN. The isolates were assessed further on their ability to grow in varied physiological conditions. Among them, P4A6 and P4A18 demonstrated higher growth potential under pH 3, pH 5, pH 9, pH 11, 1% NaCl, 3% NaCl, 5% NaCl and high temperature range of 40°C-50°C than the rest of the isolates. Given the in-vitro results, these isolates are promising bioinoculant (biofertilizer) candidates and, ought to be further tested in greenhouse and field conditions for Bambara groundnut production.

    Keywords: Bradyrhizobium, plant growth promotion, Bambara groundnuts, 16S rRNA, biofertilizer

    Received: 04 Oct 2024; Accepted: 27 Dec 2024.

    Copyright: © 2024 Abdulai Seidu, Githiri, Wesonga and Ngumi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Osman Abdulai Seidu, Pan African University Institute of Basic Sciences, Technology and Innovation, Nairobi, Kenya

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.