Nitrogen metabolism of Spirodela oligorrhiza : III. Amino acids and the utilization of nitrate.

Wheras ammonium inhibited almost completely utilization of nitrate (NO3) by Spirodela oligorrhiza, asparagine, aspartate, glutamine, and glutamate had only a sparing effect. Asparagine and glutamine were used more rapidly than NO3; aspartate and glutamate at about the same rate. These differences in utilization of NO3 were not determined by differences in the levels of nitrate reductase.