Indexed on: 01 Sep '79Published on: 01 Sep '79Published in: Plant and soil
In the growing season no net H2 evolution is detected when root nodules ofAlnus glutinosa are incubated in air or in argon containing 20% O2. Due to the hydrogenase activity, N2-fixing root nodules consume added H2 at a rate of about 1.4 μmoles H2.g fresh nodule−1.h−1. The uptake of H2 is only found in summer. At the end of the season, in autumn, nodules evolve significant quantities of H2 although the nodules still continue to fix nitrogen.In-vitro studies with fractionated homogenates of summer-harvested nodules show that the recovery of the hydrogenase is high when using methylene-blue or phenazine metasulfate as electron acceptors. No hydrogenase activity is detected in homogenates of autumn-harvested nodules.The hydrogenase is localised in the microsymbiont.