CHANGES IN COLD HARDINESS ACCOMPANYING DEVELOPMENT IN WINTER WHEAT

Abstract

The cold resistance of 18 varieties of winter wheat hardened in a growth chamber was studied at various stages of development and the results were compared with the field survival of these varieties.In the growth chamber two maxima of cold resistance were found, the first for the dry or freshly moistened seed and the second when plants had approximately 4 to 6 leaves. Varietal differences were found in the exact timing of this second maximum and in its duration. As a result, some varieties changed their rank for cold resistance as they developed.Partial agreement was observed between the field survival of varieties sown at different dates and the changes in cold resistance of these varieties as they developed in the growth chamber.From these tests, a procedure has been developed that should enable fairly reliable predictions to be made of field survival of winter wheat in any area where low-temperature resistance is the major factor in winter survival.