Heritability Estimates of Winter Hardiness in Winter Barley Determined by the Standard Unit Method of Regression Analysis 1

L\CK of winter hardiness in winter barley is the major deterrent toward more extensive growth of this crop. This character, although extremely important in most winter barley breeding'programs, has not been studied genetically in much detail. Winter hardiness in winter barley, like -winter hardiness in most other crops is conditioned by a complex group of interrelated factors involving both the physiological condition of the plant and the plant environment. The complex nature of winter hardiness has made genetic studies of this character very difficult. This deficiency of genetic information prompted G. A. Wiebe, Agronomist, U. S. Department of Agriculture, to initiate a study from which it might be possible to obtain information as to the nature of /the inheritance of the winter hardiness of winter barley. He assembled a group of 18 varieties which represented the most winter-hardy varieties in the important winter barley growing areas of the world. Initial reports of the results obtained from studies of these varieties and all possible single cross hybrids among them were presented by Pulham and Rohde and Pulham. This paper gives a summary of additional results obtained from these studies.