Free amino acids in unhardened and cold‐hardened winter wheat crowns

Abstract

Abstract The free amino acids proline and glutamic acid increased in the crown of winter wheat in all treatments when exposed to cold‐hardening. Glutamine also increased except when 90–80 N‐P fertilizer was applied. The increase of proline and glutamic acid was enhanced with the application of P but counteracted by N. This enhancement was smaller with glutamine. The decrease of threonine, tyrosine, phenylalanine, lysine and α‐aminobutyric acid with cold‐hardening was not counteracted by application of N and P. However, isoleucine in cold‐hardened winter wheat increased with the application of 180–0 fertilizer and aspartic acid increased when P was added. The increase in alanine with cold‐hardening was enhanced by P alone but counteracted by N‐P treatments. The marked increase in proline during cold‐hardening could be useful in the detection of cold‐hardiness in winter wheats.