关键词: 野生苜蓿, 群落特征, 来源

Abstract: Deqin wild alfalfa(Medicago sativa L.)was found in Deqin County of Diqing Tibetan Autonomous Prefecture in Yunnan Province.The wild alfalfa populations distribute mainly in xerothermic valleys or the verge of forests at the altitude of 2000-3000 m in drainage area of Lancang River and the Jinsha River.Being a component of shrubbery layer of Sophora viciifolia Hance,they can flourish in farmland areas.Investigation show that rainfall was the most influential ecological factor for their distribution.They grew normally in locations close to water sources in xerothermic valleys.They grew poor in natural communities;if other species dominated,their phenophase would be retarded.They showed an abundaot root system which could be beneficial for soil and water conservation.They gave a tremendous growth density as more than 800 ramifications/m² with ample water supply and favorable management;they produced more than 5 kg/m² in natural condition.Karyotype analysis indicated that Deqin alfalfa is tetraploid,2n=32.The investigation of their origin showed: the first,it must had been dispersed to Tibet from Qinghai Province and Gansu Province in ancient times,then survived in southern canyon of transect mountains where fine living conditions offered; then gradually passed down along rivers’ downstream reaches;the second,alfalfa’s distribution in Deqin areas might had some relations with Buddhism(Buddhism prevalent in Tibet) dissemination. Deqin wild alfalfa populations are the unique alfalfa germplasm distributing as communities found in Yunnan Province.With the diversity of geographical distribution and morphological characteristics it may contain rich genetic foundations, especially ones growing normally in xerothermic valleys may contain unique germlasm.

Key words: Wild alfalfa, Population characteristics, Origin