Effects of nitrogen, phosphorus and potassium on amino acid composition and on relationships between nitrogen and amino acids in wheat and oat grain

Abstract

AbstractDuring two seasons, pot experiments in which increasing applications of nitrogen, phosphorus and potassium were given to wheat and oats produced grain with widely varying N contents. The total amino acid composition of the grain was mainly dependent on N content of grain. Phosphorus and potassium affected the amino acid composition of wheat and oat grain only indirectly through their effects on nitrogen concentration. In wheat increasing grain N% was accompanied by a decrease in the amount (as g per 16 g N) of lysine, threonine, methionine, cystine and an increase in glutamic acid, proline, phenylalanine, and serine contents. Lysine, methionine, and cystine in oats decreased with increasing grain N content, but arginine, aspartic acid, glutamic acid and phenylalanine increased. Changes were less pronounced with oats than with wheat, and concentrations of most essential amino acids were higher in oats. When expressed as % dry matter all amino acids increased with increasing N concentration. Linear regression equations were calculated and significant correlations were found in both crops between concentrations of most amino acids and N content in grain. Some correlations between amino acids in the grain are also given. Correlations between amino acids and nitrogen within a variety were similar despite widely differing yields.