Chapter 2 The domestication of cultivated barley

Abstract

This chapter describes genetic diversity in barley. Through evolutionary processes, domestication, migration correlated with adaptation to new environmental conditions, and conscious selection by early farmers a wealth of genetic diversity was created in barley. These dramatic changes developed as a result of human activity over a period of 10,000 years. A large number of essential characters were irreversibly changed when barley became a cultivated crop, due to intense selection in the early phases of domestication. The last step for the development of the present day state of genetic diversity took place due to intensive breeding based on a wide array of new methods. During the time span from the early domestication up to now, particular distribution patterns of genetic diversity have been substantiated, such as the differentiation of oriental and occidental types based on the brittle rachis genes, differentiation of two- and six-rowed types, development of secondary diversity centers outside the centre of origin in the Fertile Crescent. Later breeding, exchange of material, and the use of exotic germplasm have made the genetic diversity pattern even more complicated. This rich genetic variation was the basis for modern plant breeding and a great deal of the genetic variation in landraces is certainly present in the modern varieties.