Plant growth-promoting rhizobacteria do not pose any deleterious effect on cowpea and detectable amounts of ethylene are produced

  • Olubukola O. BabalolaEmail author
  • Abiodun I. Sanni
  • George D. Odhiambo
  • Baldwyn Torto
Original Paper


The use of trap crops such as cowpea could reduce the effects of the root parasitic weed, Striga hermonthica and its subsequent constraints on the growth of cereals. Certain bacteria could augment the trap crop stimulatory effect. We studied the effect of three bacteria introduced to the rhizosphere of three cowpea varieties at planting. Number of days to cowpea flowering was noted and at harvest, data were collected on pod characteristics and biomass. Means of data subjected to ANOVA were compared using Tukey’s Studentized Range Test. We analysed bacterial headspace volatiles for ethylene by gas chromatography and gas chromatography–mass spectrometry. Bacterial type significantly influenced the cowpea varieties with better performance over the non-inoculated control. Average pod weight (g) with bacterial treatment was 37.97 for Enterobacter sakazakii 8MR5, 34.38 for Pseudomonas 44MS8 and 27.46 for Pseudomonas 10M3. Non-inoculated control had an average weight of 20.98 g. Bacteria promoted a significant increase in pod weight (≥30.89%), fresh biomass (≥24.22%), and improved pod number (≥20.54%) and pod wall thickness (≥7.33%) with no deleterious effect on plant health. Ethylene released by the bacteria ranged from trace concentrations in Pseudomonas sp. to 210 nmoles/108 c. f. u./ml in Ent. sakazakii 8MR5.


Bacteria Biological control Cowpea Ethylene Gas chromatography Striga hermonthica 



We are grateful to Dr Peter Njagi, and Mr Manyama Onesmas for active technical help and Dr A. Odulaja for statistical analysis. We also acknowledge the assistance of KARI-CIMMYT Striga project for pure ethylene gas. Third World Organization for Women in Science supported this research.


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Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Olubukola O. Babalola
    • 1
    Email author
  • Abiodun I. Sanni
    • 2
  • George D. Odhiambo
    • 3
  • Baldwyn Torto
    • 4
    • 5
  1. 1.Department of MicrobiologyOlabisi Onabanjo UniversityIbadanNigeria
  2. 2.Department of Botany and MicrobiologyUniversity of Ibadan IbadanNigeria
  3. 3.Kenya Sugar Research FoundationKisumuKenya
  4. 4.International Centre of Insect Physiology and EcologyNairobiKenya
  5. 5.USDA/ARS-CMAVEGainesvilleUSA

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