Studies On Wild Germplasm Resources Of Sickle Alfalfa In China

Sickle alfalfa widely distributes in temperate grassland, which is of many better traits than other alfalfa species. Sickle alfalfa is an important genetic resource for alfalfa breeding. There are abundant germplasm resources of sickle alfalfa in China. It has important significance to protect and to innovate sickle alfalfa germplasm resource and alfalfa breeding, which for promoting native germplasm resources collection, genetic structure, genetic variation, the main agronomic characters and adverse-resistant characteristics were discussed in this study. The germplasm resource of sickle alfalfa were identified and assessed systematically in morphology, agronomy, cytology and molecular marker.The results showed as follows:1. Taxonomic features of thirty four sickle alfalfa populations were compared, there were rich morphological variations on each organ of Chinese native sickle alfalfa, the variation within population was larger than it between populations.Four root system types, three overwintering bud types, two short underground stem types, three aboveground colors, seven leaf types, four flower colors and four hair coat types in leaf surface. New method of classification on pod morphology of sickle alfalfa was put forward and they were accurately divided into thirteen morphology types and basic shape and variation type of Medicago falcata were identified .The variation types which pod bending level exceed semicircle were hybrid progeny between Medicago falcata and Medicago sativa.2. There were obvious differences on main agronomic traits within population and between populations. The seed germination period was 12～13 days and difference between populations displayed mainly vigor of germination. It was more reasonable for statistics vigor of germination when germinating six days. Hard seed rate of native sickle alfalfa was 74～100%.The germination percentage was even low when hard seeds were mechanical broken. Overall vigor of germination and germination percentage of native sickle alfalfa were lower than Russian population. The variations between populations were larger than Russian populations. The phenophase of different populations had obvious difference. It had obvious difference in growth rate in the period of seedling to branching and maturing to brown. This is the good time for phenotypic selection. The grass yield of native sickle alfalfa were low and aboveground biomass of single plant between populations were low. Thirty four populations were divided into three agronomy trait populations with cluster.3. New Approach for the assessment of drought resistance and salt tolerance on sickle alfalfa was developed with individuals and populations. Forty two materials on drought resistance were used to test the drought resistance of sickle alfalfa both in individuals and populations. Sickle alfalfa was of higher torlorence than other cultivated alfalfa varieties. Nineteen populations had strong drought resistance and eight populations had outstanding individuals on drought resistance, six populations had the strongest drought resistance. Thirty four materials were used to test salt tolerance. Salt tolerance of sickle alfalfa in seed germination period was lower than alfalfa and miscellaneous flower lucerne obviously, only two populations had stronger salt tolerance, its'salt tolerance in seedling period was strong significantly. The results showed that salt tolerance of sixteen sickle alfalfa populations were higher than Medicago sativa L.cv.Zhongmu No.1 which has strong salt tolerance. Outstanding individuals were found in six populations, six materials which had the strongest salt tolerance.The results showed that"synthetic index method"was effective for assessing quantitatively and sorting of drought resistance and salt tolerance of different sickle alfalfa germplasms and it had generality for assessing on drought resistance and salt tolerance of other forage germplasm resources.4. Diploid (2n=2x=16) and traploid (2n=4x=32) were detected by chromosome study. They include four chromosome types (M, m, sm and st). Different numbers of B chromosome and some satellites in partial populations of wild germplasm of Chinese sickle alfalfa were found firstly. According to the Stebbins' karyotypic classification method, thirty two populations were divided into four types (1A, 2A, 2B and 3B). According to the analysis of Romero'karyotypic symmetric parameter rich variations of karyotypic not even among different populations were reflected clearly. Geographical features and microevolution directional rule of thirty two native germplasm of sickle alfalfa on chromosome number and type, karyotypic symmetric were also reflected. Variations of Xinjiang sickle alfalfa were larger than Russian sickle alfalfa for testing.5. SSR analysis showed that one hundred sixty seven SSR locus were obtained from thirteen sickle alfalfa populations using five pairs of primers and poly morphism was up to 98.24%. The average polymorphic loci number and polymorphic loci percentage of Xinjiang populations were higher than Inner Mongolia. Shannon and Nei indexes analysis showed that Chinese sickle alfalfa native population had rich genetic diversity and gene differentiation diversity. Genetic variation within population was larger than between populations'. Genetic variation of Xinjiang sickle alfalfa was larger than Inner Mongolian. Cluster analysis showed population geographical cluster trend and some separate cluster showed their genetic specificity.6. Xinjiang was the origin of Chinese sickle alfalfa where had valuable resources for alfalfa breeding due to its'multilevel and rich genetic variations from morphology to DNA molecular level. Inner Mongolia located in edge zone of sickle alfalfa distribution. It has rich genetic variation of sickle alfalfa and uniqueness of system evolution. So, it has special significance for alfalfa hybrid breeding.