Effect of Induced Nodule Senescence on Parameters Related to Dinitrogen Fixation, Bacteroid Size and Nucleic Acid Content

Abstract

Darkness and treatment with combined nitrogen (NH4Cl or KNO3) were used to induce nodule senescence in alfalfa and soybeans. Nodule senescence was assessed by determinations of the acetylene-reducing activity and leghemoglobin and sugar contents of the nodules. Bacteroids from nodules of the treated plants were compared using flow microfluorimetry. Upon induced nodule senescence, alfalfa bacteroids decreased both in nucleic acid content and cell size while the soybean bacteroids were essentially unaffected.