Plant and Soil

, Volume 63, Issue 3, pp 415–426 | Cite as

Microbial responses to salt-induced osmotic stress

II. Population changes in the rhizoplane and rhizosphere
  • D. R. Polonenko
  • E. B. Dumbroff
  • C. I. Mayfield


Balanced and unbalanced high-salt solutions were used to investigate the effects of osmotic stress on microbial activity in the rhizoplane and rhizosphere of barley. Bacteria in the root regions proved sensitive to both high (−1500 kPa) and low (−500 kPa) levels of each type of stress, but bacterial growth was most severely inhibited in the unbalanced treatments both of which contained high levels of sodium. Similar effects of stress were noted with barley. Distinct qualitative changes in microbial populations in the root zones were observed in the balanced stress treatments, but an increase in species diversity did not occur in the rhizoplane or rhizosphere following exposure to the unbalanced, high-sodium solutions. After five weeks of stress, a marked but transitory rise in rhizoplane counts accompanied death of the seedlings in the −1500 kPa, high-sodium treatment indicating that at least some of the soil bacteria retain the potential for rapid growth at high salt concentrations.

Key Words

Bacteria Direct observation Rhizoplane Rhizospher Root region Salinity Salt stress 


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Copyright information

© Martinus Nijhoff/Dr W. Junk Publishers 1981

Authors and Affiliations

  • D. R. Polonenko
    • 1
  • E. B. Dumbroff
    • 1
  • C. I. Mayfield
    • 1
  1. 1.Department of BiologyUniversity of WaterlooWaterlooCanada

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