Nitrogen uptake and assimilation by corn roots

In corn roots, 15N-labelled ammonium was rapidly assimilated into glutamine, glutamic acid, and aspartic acid in this order in a short time. 15N-labelled nitrate was assimilated into amino acids in almost the same way with ammonium, but at lower 15N value. The inhibitory effect oflow temperature was more drastic on the nitrate uptake than on the ammonium uptake. Newly absorbed ammonium nitrogen was more utilizable for the growth of root top than nitrate nitrogen.