African Journal of
Environmental Science and Technology

  • Abbreviation: Afr. J. Environ. Sci. Technol.
  • Language: English
  • ISSN: 1996-0786
  • DOI: 10.5897/AJEST
  • Start Year: 2007
  • Published Articles: 1047

Full Length Research Paper

Nutritional, eco-physiological and symbiotic characteristics of rhizobia nodulating faba bean (Vicia faba L.) collected from acidic soils of Ethiopia

Dereje Tsegaye
  • Dereje Tsegaye
  • Arba Minch University, Soil Science Program, College of Agriculture and Environmental Sciences, P. O. Box 21, Arba Minch, Ethiopia.
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Fasil Assefa
  • Fasil Assefa
  • Addis Ababa University, Microbial, Cellular and Mollecular Biology Program, College of Life Science, P. O. Box 1176 Addis Ababa, Ethiopia.
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Heluf Gebrekidan
  • Heluf Gebrekidan
  • Haramaya University Soil Science Program, College of Agriculture and Environmental Sciences, P. O. Box 138, Dire Dawa, Ethiopia.
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Gemechu Keneni
  • Gemechu Keneni
  • Holeta Agricultural Research Center, P. O. Box 2003 Holleta, Ethiopia.
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  •  Received: 28 May 2015
  •  Accepted: 14 July 2015
  •  Published: 30 July 2015

Abstract

Characterization of root nodule bacteria is used for selecting and using them as inoculants to improve legume production. To this end, faba bean (Vicia faba L.) rhizobia were isolated from nodules collected from acidic soils of Central and Southern-Western parts of Ethiopia. A total of hundred rhizobial isolates were collected and characterized based upon their nutritional, ecophysiological and symbiotic characteristics. The isolates produced low to copious amount of extracellular polysaccharides (EPS) and attain colony sizes ranging from 2 to 7 mm with generation time ranging 0.75 to 3.9 h. Most of the isolates were grown at different pH levels ranging 4.5 to 7.0 and temperatures between 4 and 45°C. They were also capable of growing on many carbon sources and most of the nitrogen sources, and showed significant variations in resisting different types of antibiotics and heavy metals. Based on symbiotic efficiency (SE), 56% of the isolates were found to be very effective when applied with both Degaga and Dosha varieties. All taken together, two isolates, HUGAVf1 and HUCDVf5 were nutritionally versatile, showed a wide range of tolerance to the stress in many of the ecophysiological characters and very effective symbiotic performance should be utilized in future faba bean inoculants production.
 
Key words: Rhizobium leguminosarum biovar. viceae, antibiotic tolerance, carbon utilization, fast growing, heavy metals, temperature tolerance.