Influence of Nitrogen Source on Nitrogen Metabolism in Detached Wheat Heads

Abstract

Detached wheat heads growing in liquid culture, with either ammonium nitrate or amino acids as the nitrogen source, were exposed to ₁₄CO₂ for 1, 2 or 3 h. Examination of the free amino acids in different parts of the heads showed the highest specific activities in glumes. Specific activities were higher in heads cultured on ammonium nitrate than in those cultured on a complete mixture of amino acids. Of the nine amino acids examined, serine had the highest specific activity in grain, glumes and rachis. Proline was present in glumes and rachis at relatively high concentrations but its specific activity was low. Results suggest that the glumes are a significant site of synthesis of carbon skeletons for amino acids in the grain in detached wheat heads.