Genetic Diversity Of Different Alfalfa Germplasm Materials

Alfalfa because of its high biomass yield and protein content,and so was widely grown in the world,for the development of animal husbandry in our country attaches great importance to and vigorously support,increasing demand for high quality forage grass,and alfalfa as the "king of the grass" by a great number of breeding researchers and molecular biology,the researchers paid great attention both in terms of phenotype,physiology or molecular level are gradually in-depth understanding of alfalfa.In this paper,46 alfalfa germplasm were analyzed from three aspects: agronomic traits,drought and cold resistance,and SSR molecular markers.The results were as follows:Using 44 alfalfa germplasm as material,14 agronomic traits including plant height,stem diameter and number of reproductive branches were determined,and analysis of variance,principal component analysis,correlation analysis and cluster analysis were carried out for 14 agronomic traits.The comprehensive evaluation showed that the 20 materials,such as M1,were outstanding in plant height,seed yield,pod number per inflorescence,pod diameter,pod width and number of seeds per pod.The plant characteristics of this kind of material are high plant,high seed yield,more pods per inflorescence,more pods and more seeds per pod,which is suitable for priority in the process of breeding and promotion.The cold resistance was evaluated with the overwintering rate of 46 materials.The cold resistance of 4 materials was poor,among which M8 and M9 failed to overwintering,and the overwintering rate of M19 and M29 was low.M7 and other 11 materials have low cold resistance.The cold resistance of21 materials,including M1,was above average.Among them,12 materials such as M5 have strong cold resistance.The 36 materials were treated with PEG stress,and the germination rate,relative germination rate,germination potential,relative germination potential,germination index,relative germination index,drought resistance index and chlorophyll content of the seeds during germination were determined.After comprehensive evaluation and analysis,The 36 pieces of materials were divided into 5 grades,and 6 pieces of M2 were divided into 1 grade,with strong drought resistance.Ten materials,such as M4,were divided into grade2 with strong drought resistance.M1 and M8 are grade 3 with moderate drought resistance.Twelve materials,such as M17,were classified into grade4 with weak drought resistance.Six materials,including M21,were grade 5,with poor drought resistance.The chlorophyll content in seedling stage was different from that in germination stage.The SSR molecular markers of 44 alfalfa germplasm were determined,and a total of 120 amplification bands were amplified from 13 pairs of SSR On average,each pair of primers had 7.85 amplification bands,and the percentage of polymorphic sites was 85%.The variation range of Nei genediversity index ranged from 0.1116 to 0.4331,with an average of0.2929.Shannon information diversity index ranged from 0.5714-0.8333,among which,there were 14 pairs of materials between 0.5417-0.5917,accounting for 1.48% of the population.There were 499 pairs of materials with similarity coefficient between 0.6083 and 0.6917,accounting for 52.75%of the total.There were 414 pairs of materials with similarity coefficient between 0.700 and 0.7917,accounting for 43.76% of the population,and 19 pairs of materials with similarity coefficient between 0.800-0.833,accounting for 2.01% of the population.It can be seen that the genetic diversity of the 44 materials is relatively rich,the population differentiation degree is high,and the genetic diversity among the materials is abundant,which provides reference for the future breeding work.In this study,the genetic diversity and genetic differences of 46 alfalfa germplasm materials were revealed through the identification of field phenotype and agronomic traits,and indoor cold and drought resistance.Based on the molecular level of microsatellite markers,the genetic differences and genetic relationships among different alfalfa cultivars were revealed,which laid an important research foundation for selecting excellent alfalfa germplasm and cultivating new alfalfa cultivars.