Free Amino Acids in Alfalfa as Related to Cold Hardiness.

Alfalfa Mlledicago sativa L., is one of the most widely grown legumes in the northern areas of the United States and Canada. It provides an economical source of protein and other nutrients to all classes of livestock. TMany of the highly productive varieties are either killed or severely weakenedl by winter con(litionis in the northern areas. A better understandiIlg of the physiology and biochemistry of cold resistance would aid in the improvement and maintenance of this crop in the north. M-any investigations have been mla(le in an atteml)t to correlate or associate somle comlponent of the alfalfa plaint with the development of winter hardiness. Although no direct correlations have been established, somle investigators (1. 11. 12, 13) have suggested that protein an(l other nitrogenous components of the planit miav be responsible in part for 'winter hardiness. In early wvork Rosa (8) reported that the hardening process in plaints is acconmpanied by a nmarked increase in water-retaining power of the cell colloids of the plant. In more recent investigations a higher soluble nitrogen content was reported in hardy alfalfa roots comlpared to non-lhardy roots (3. 6. 18). Inivestigations onl the biochenmistry of frost resistance have been hindered because it has been established only recently that frost resistanice is largely a property of the protoplasm of living cells. These advances have come about largely through the work of Scarth and coworkers (4, 5, 10. 14. 15). Scarth (9 ) points out that it seems to be the rule that extreme resistanlce to cold, whether in plant or animal, is associate(l with the ability of cells to endlure (lesiccation. His studies suggest a greater wXater binding capacity of hardy cell colloidls. The intimate associatioIn of