Effect of uracil, thiouracil, & guanine on cold resistance & nitrogen metabolism of alfalfa

Abstract

Cold resistance and N metabolism of Medicago sativa roots and crowns were stimulated or inhibited by certain foliar applications of uracil, thiouracil, or guanine. Uracil treated Vernal plants generally contained greater amounts of non-soluble, soluble non-protein, and soluble protein N and were more cold resistant than the thiouracil treated plants following the colder periods while the reverse was true following a warm period. This relationship generally did not exist in the non-hardy Arizona Common plants. Increasing the concentrations of uracil and thiouracil generally caused decreases in the content of soluble protein N in Arizona Common with increases in cold resistance and the reverse was true during the loss of cold resistance.