Amino acid changes associated with the development of cold hardiness in perennial ryegrass

During the development of cold hardiness in Lolium perenne there is a progressive increase in the free amino acid content of leaves, mainly due to an accumulation of glutamine and proline. These changes are largely reversed within 8 days if plants are transferred to higher temperatures which allow dehardening to occur. It is suggested that amino acid analysis could be used as a means of comparing the response of grass varieties to changing temperature regimes.