Relationship of Cold‐Hardiness to Soluble‐Protein‐Nitrogen Content and Epicotyl Growth Rates in Winter Wheat 1

ASSOCIATIONS between cold-hardiness and soluble•**• protein-nitrogen content have been reported in alfalfa by Bula et al. (1) and in sweetclover by Hodgson and Bula (4). Zech and Pauli (9) found that soluble-proteinnitrogen content in winter wheat was associated with coldhardiness to different degrees, depending on the variety and/or part of the plant analyzed. Published information also indicates that germination of seeds decreased with increased osmotic pressure of the solution used, and that seed germination and subsequent seedling growth in varying osmotic pressures obtained by use of mannitol, sucrose, or sodium chloride may be related to coldor drouth-hardiness. Powell and Pfeifer (6) on the basis of epicotyl growth in solutions of d-mannitol varying in osmotic tension made selections from Cheyenne winter wheat that differed in growth rate. Rodger et al. (7) found that seed germination of winter-hardy alfalfa types was lower than of nonhardy types in solutions of sodium chloride and sucrose. Dotzenko and Dean (2) reported that differences in ability of alfalfa varieties to germinate at different osmotic pressures were heritable. Schwer et al. (8) made selections from Kenland red clover, Ladino white clover, and Empire birdsfoot trefoil seeds germinated in mannitol. Selected and check plants were intrapollinated under isolated conditions. Seeds harvested from the selected plants germinated more rapidly under osmotic stress than those from check plants. The heat, cold, and drouth tolerance of progenies of the selected plants did not differ from that of the check, however. In view of experimental results indicating an association of cold-hardiness with soluble-protein-nitrogen and with response of plants to varying osmotic tension, a direct comparison of these factors was undertaken.