| Understanding the genetic diversity and population structure is a prerequisite for association mapping of complex traits in a target population. Yield traits、genetic diversity and population structure of82alfalfa materials were evaluated using16polymorphic SSR markers screened from a total of140SSR primer pairs. The main results show as follow:1. The alfalfa materials can be cut3times in Yangzhou, the growth days were65days,40days and35days. All alfalfa materials can grow regularly. The alfalfa germplasm resources not withered in winter, but stopped growing.The early flowering stage differ1to10days of different alfalfa materials.2. The average height of different alfalfa cutting times showed height of3rd cutting> height of1st cutting> height of2nd cutting, the highest is Creno, the shortest is CUF101of total height. The hay yield of different alfalfa cutting times indicated that1st cutting> hay yield of3rd cutting> hay yield of2nd cutting, the total yield most is Duolun, the least is Caoyuan No.2.3. Yield traits characteristics analysis of alfalfa materials showed that the genetic variation among the tested alfalfa varieties (lines) is extremely diversity.8yield traits showed ample variations. The coefficient of variation ranked as hay yield of3rd cutting>branch number> hay yield of1st cutting> hay yield of2nd cutting> height of3nd cutting> height of2rd cutting> height of1st cutting> fresh/dry ratio. In82alfalfa materials, the maximum coefficient of variation is Duolun, the value is23.46, the minimum coefficient of variation is1075, the value is6.05.4. A total of190alleles were amplified by using16SSR primer pairs, with an average of11.88alleles per primer pair, the polymorphic rate averaged83.05%, ranging from66.67-100%. The genetic diversity averaged0.2577,0.1477-0.3637, and the PIC averaged0.5501, ranging from0.0079-0.9432.5. Population structure of82alfalfa materials indicated that the likelihood value has maximum when K=5, namely, these alfalfa materials could be divided into5groups. Use Q=0.5 as a standard,62(75.61%) Medicago germplasm Q value is greater than or equal to0.5, were with single genetic components, were divided into specific group. The rest20(24.39%) Medicago germplasm Q value smaller than0.5, were with mixed genetic components, were divided into mix group. The62materials which were assigned to specific groups, the proportion of those groups were15.85%,8.54%,9.76%,26.27%and12.20%. Two-dimension principal components and population structure analysis were basically consistent. The genetic diversities level of five groups comparison results presented that group1is the highest, followed by group2、group3, the genetic diversity level of group4and groups5are relatively low.6. Different groups of alfalfa germplasm resources growth differences are obvious. Group1: hay yield is the highest, branch number is the most; Group2:height is shorter, hay yield is lower; Group3:the height is the shortest; Group4:the height is the highest; branch number is the least, fresh/dry ratio is the largest, hay yield is the lowest; Groups5branch number is lesser, fresh/dry ratio is smaller. The fall dormancy grade of different groups is Group5>Group4>Group3>Group1>Group2. |
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