Plant and Soil

, Volume 158, Issue 2, pp 151–162 | Cite as

Measurement of nitrogenase activity in legume root nodules: In defense of the acetylene reduction assay

  • J. Kevin Vessey


The closed acetylene reduction assay has been used as a measure of nitrogenase activity and an indicator of N2 fixation in Rhizobium/legume symbioses for 25 years. However, starting 10 years ago this assay has come under harsh criticism as being inaccurate. Currently, confusion exists regarding the conditions under which the acetylene reduction assay can be used accurately, or whether it can be used at all as a measure of nitrogenase activity. This article reviews the circumstance that has lead to this confusion. The author argues that under the proper assay conditions and with the appropriate checks, the closed acetylene reduction assay is still a valuable tool in assessing relative differences in nitrogenase activity in Rhizobium/legume symbioses.

Key words

acetylene reduction gas exchange hydrogen evolution nitrogen fixation oxygen diffusion rhizobia 


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Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • J. Kevin Vessey
    • 1
  1. 1.Department of Plant ScienceUniversity of ManitobaWinnipegCanada

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