Plant breeding deals with materials that have already undergone evolutionary change. These changes have sometimes been profound and have occurred over long periods of time (Simmonds and Smartt, 1999). Among these, a prominent position should be assigned to cold adaptation. Strictly speaking, a domesticated plant is not the same as a cultivated plant (Harlan, 1992), although the terms are usually regarded as synonymous. According to Harlan (1992), a domesticated plant or animal is one that has been brought into the household to serve those who live there. Domestication is the process through which this plant or animal is so altered from its wild state that it is no longer able to survive if not cultivated by humans. The information available on domestication is mainly historical, and many conclusions must remain speculative.