Abstract:

Tibet is a most beautiful place, located in southwestern China. She has been called “the roof of the world” and “the third pole of the earth”. A combination of unique geological history, complex land surface and climatic zones, various soil types, and different wild vegetation makes Tibet a very typical area of vertical agricultural ecosystem. The ecosystem in Tibet may be the most complex and variable in the world. Unique and complex environments, long agricultural history, different cropping systems, and natural and artificial selection endow Tibetan barely with the richest genetic diversity, which makes Tibet one of the first barley gene centers in the world. Today, whenever and wherever scientists talk about the origin of barley, they always mention Tibet. Since the beginning of this century, Tibet has been drawing attention of scientists from all over the world. Before 1950, because of the known political reasons, some foreign scientists entered and exploited in some collections of Tibetan barley, but they could not capture the whole range of Tibetan barley resources. After the establishment of P. R. China, the Tibetan social system was changed peacefully, and great progress has been made on research of Tibetan barley germplasms. 3 502 accessions of barley germplasm have been collected from Tibet. All of the collections have been cataloged and reserved in the long-term national gene bank. All of these collections have been evaluated and verified on agronomy traits, disease resistance, abiotic stress tolerance, and nutrient content and quality. They were also grouped based on their living habits, botanical and genetic characters. Some elite germplasms were screened out and used in cross breeding programs. Good achievement has been obtained and many high quality papers published. However, the genetic diversity centers and its mode of spread were not studied yet. The author focused on barley genetic diversity centers and its spread mode. The genetic diversity, comprehensive collection of variability of 12 traits and the distribution of 3 204 accessions collected from Tibet and quantitative genetic method are presented in this paper. The results show that: 1) cultivated barley in 28°-30° N × 88°-94° E was highest in accessions, genetic diversity and comprehensive collection of variability; 2) cultivated barley in 30°-31°N×96°-98° E of Hengduan Mountains takes second place. The genetic diversity centers and spread modes of genetic diversity were put forward according to the distribution centers, genetic diversity and comprehensive collection of variability.