African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6801

Full Length Research Paper

Inoculation with Rhizobium etli enhances organic acid exudation in common bean (Phaseolus vulgaris L.) subjected to phosphorus deficiency

Maureen Fonji Atemkeng1,2*, Roseline Remans2, Jans Michiels2, Appolinaire Tagne1 and Eddy Leonard Mangaptche Ngonkeu1
  1Annual Crop, Institute of Agricultural Research for Development (IRAD), Yaoundé, Cameroon. 2Centre of Microbial and Plant Genetics (CMPG), Katholieke Universiteit Leuven, Kasteelpark, Arenberg, Heverlee, Belgium.  
Email: [email protected], [email protected], [email protected]

  •  Accepted: 14 April 2011
  •  Published: 31 May 2011



Common bean (Phaseolus vulgaris L.) production is severely limited by phosphorus (P) deficiency in tropical and subtropical regions. Plants are known to exudate organic acids in order to survive in low nutrient environment. However, little is documented on the effect of inoculation on organic acids exudation by plants as a strategy to adapt to low P stress. In this study, the organic acids exuded by two bean genotypes (known to have contrasting symbiotic nitrogen fixation capacities) inoculated with Rhizobium etli and subjected to P deficiency were compared. The results showed that, under P deficiency, the P efficient genotype (BAT477) secretes higher amounts of organic acids serving as nutrient for Rhizobacteria or involved in P solubilisation. Furthermore, inoculation with R. etli under P deficiency strongly enhanced the exudation of oxalate and citrate by the P-efficient genotype. These effects of P-level and inoculation on root exudation were much less observed for the P-inefficient genotype (DOR364). This study indicated the difference in organic acid exudation between the two bean genotypes, especially in combination withRhizobium inoculation which may contribute to the contrast in performance under P deficiency.


Key words: Phaseolus vulgarisRhizobia, root exudation, genotypic performance, phosphorus efficiency