Field versus Controlled Freezing as a Measure of Cold Resistance of Winter Wheat Varieties 1

OLD resistance of winter wheat varieties is best measured in C field tests, provided the conditions are suitable for differential killing. In field tests the investigator either must wait for a winter of desired severity or go to much effort in distributing the material over a wide area in hopes of getting the desired degree of killing at one or more places. The development of a rapid and efficient laboratory method for testing the cold resistance of wheat varieties has been the object of much investigation and study. No chemical test for measuring cold resistance yet devised has been consistent enough to be used as a substitute for actual freezing. The objects of the experiments reported here were (a) to secure additional data concerning the correlation between the reaction of some winter wheat varieties to artificial freezing and winter survival in the field, (b) to determine the extent of agreement between replicated freezing tests made at different periods, and (c) to determine the number of freezing tests necessary to evaluate the hardiness of varieties with an accuracy approaching that obtained in the field.