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Dry matter production, dinitrogen fixation activity (ARA), and the release of nitrogenous compounds from the roots of soybean (Glycine max (L.) Merr.) cv. Bragg, nts1116 and nts1007 were studied under nitrogen-free culture conditions. Plants were sampled at the vegetative (54 d after sowing, DAS) and flowering (88 DAS) stages. Nts1116 accumulated the largest and nts1007 the smallest amount of dry matter at both sampling times. Nodule number in nts1007 which was the largest was significantly different times. Nodule number in nts1007 which was the largest was significantly different from that of nts1116 and Bragg. Dinitrogen fixation was greater at the flowing stage and was higher in the mutants than in Bragg. Except for Bragg leaf at the flowering stage, N and ureide concentrations in the nts1007 plant parts, were higher than those of nts1116 and Bragg. Nts1116 and nts1007 accumulated thee largest amount of N at the vegetative and following stages, respectively. The release of nitrogenous compounds from the roots of all the genotypes was higher at the following stage. Nts1116 and Bragg released the largest amount of nitrogenous compounds at he vegetative and flowering stages, respectively. The amount of nitrogenous compounds released that was expressed as a percentage of the amount of total N fixed was largest in Bragg and smallest in nts1007. There was a highly positive correlation between the amount of released nitrogenous compounds and the root size (r=0.93**).