Nitrogenase Activity, Nodule Respiration, and O2 Permeability Following Detopping of Alfalfa and Birdsfoot Trefoil

Abstract
Gas exchange measurements and noninvasive leghemoglobin (Lb) spectrophotometry (nodule oximetry) were used to monitor nodule responses to shoot removal in alfalfa (Medicago sativa L. cv Weevlchek) and birdsfoot trefoil (Lotus corniculatus L. cv Fergus). In each species, total nitrogenase activity, measured as H(2) evolution in Ar:O(2) (80:20), decreased to 0.65 for a majority of nodules of each species. This increase could lead to O(2) inactivation of nitrogenase.