Implications of competitive inhibition in the acetylene reduction assay for dinitrogen fixation

An earlier paper which analysed the implications of diffusion limitation for acetylene reduction by intact legume nodules has recently been criticized for ignoring competitive inhibition of acetylene reduction by dinitrogen. Mathematical analyses of competitive inhibition show that the dependence of acetylene reduction rate on acetylene concentration under atmospheric N₂ is described adequately by an equation functionally equivalent to the Michaelis-Menten equation, despite competitive inhibition. Therefore, no modification of the original analysis is required. However, competitive inhibition is shown to be a significant factor when experiments under atmospheric N₂ and under argon are compared.