Trends of Cold Resistance and Chemical Changes Over Winter in the Roots and Crowns of Alfalfa and Medium Red Clover. I. Changes in Certain Nitrogen and Carbohydrate Fractions1

Cold resistance increased from late September to mid‐December. A high level was maintained until February or early March. Resistance was lost slowly until early April and rapidly thereafter. In general, each nitrogen and carbohydrate fraction increased in content during the fall, was at its highest level sometime during the fall or winter, and then decreased during the spring. Correlation coefficients of the trends of the chemical fractions with the trend of cold resistance were significant in many cases.