Inhibition of Nitrogen Fixation in Non-Legume Root Nodules by Hydrogen and Carbon Monoxide

The effect of the presence of hydrogen and of carbon monoxideon the fixation of nitrogen in detached root nodules of non-legumeshas been studied, fixation being measured by the use of ¹⁵N.Parallel tests on legumes (pea and soya bean) have been included.Fixation in the nodules of Casuarina, Alnus, and Myrica is inhibitedin the presence of substantial proportions of hydrogen, to adegree resembling that shown in legumes. Fixation in Alnus andMyrica is arrested in the presence of small proportions of carbonmonoxide, and here again the sensitiveness is of the same orderas in legumes.