| Elymus sibiricus L.is an excellent perennial forage of Elymus in Gramineae,widely distributed in Eurasia,characterized with high forage yield,rich leaf quantity,soft grass quality and good palatability,etc.It also has the characteristics of drought resistance,cold resistance,salt and alkali resistance,etc.and was widely planted and used in artificial grassland construction and natural grassland reseeding improvement in Northwest,Southwest,Northeast,Inner Mongolia and other places in China.In this study,the basic breeding materials with abundant leaves and high forage yield were selected by identification and evaluation of related traits in 34 Elymus sibiricus L.germplasms and the systematic breeding method was further used to develop new germplasm creation,new strains breeding and multi-pilot testing and identification.Combined with SSR molecular marker technology,the genetic structure,genetic diversity,related phenotypes and agronomic traits performance of the germplasm resources in Elymus sibiricus L.were systematically studied and the marker sites associated with forage yield and other related traits were found by using principal component analysis,grey relational analysis,cluster analysis,association analysis,etc.The results can provide a basis or reference for the genetic improvement,breeding,planting and utilization of Elymus sibiricus L.and other gramineous forages.The results are as follows:（1）Based on the results of the principal component analysis involving plant height,stems and leaves,and agronomic traits,ten germplasm materials with excellent performance were initially screened out,among which 6 were registered Elymus sibiricus L.varieties and 4 were wild Elymus sibiricu L.germplasm materials.A new germplasm with tall plant type and rich leaf quantity was created by the systematic breeding method,and a new strain of Nei-nong Elymus sibiricus L.was obtained after further breeding.The new strain has passed the evaluation of National Grass Variety Approval Committee and entered regional test stage.（2）After a three-year character identification and variety comparison test,the new strain has excellent performance in phenology and main agronomic characters.The three-year average fresh grass yield is 22563.6 kg·hm-2,and the hay yield is 7695.7kg·hm-2,both significantly higher than the control variety（P<0.05）.Reaches the maximum in the second year of growth.At the Wuchuan Experiment Site in Inner Mongolia in the northern foot of Yinshan Mountains,the average of fresh grass yield and hey yield of the new strain for two years reached 20500.1kg·hm-2 and 7613.5kg·hm-2,respectively,which were significantly higher than that of the control variety（P<0.05）.Compared with Elymus sibiricus L.and Tongde Elymus sibiricus L.,the hey yield of the new strain increased by 11.25%and 12.28%,respectively.The average of fresh grass yield and hey yield at the Shaerqin Experiment Site in the southern foot of Yinshan Mountains were 22602.81kg·hm-2 and 7796.41kg·hm-2,respectively,which were significantly higher than that of the control variety（P<0.05）.The high yield trait of the new strain showed good stability.（3）A total of 107 loci were obtained by SSR markers,and the number of polymorphic loci was 100,and the percentage of polymorphism was 93.46%;the genetic similarity coefficient between individual plants was between 0.2683 and 0.9505,with an average of0.619.The analysis of population structure divides 96 individual plants into 3 groups,among which the number of samples of group I is the least,the spatial distribution of group II is more concentrated,and the spatial distribution of group III is more scattered.The genetic diversity of cultivated and domesticated varieties was higher than that of bred varieties.The specific order of genetic diversity is:Tongde Elymus sibiricus L.>Aba Elymus sibiricus L.>Kangba Elymus sibiricus L.>Maiwa Elymus sibiricus L.>Chuancao No.2 Elymus sibiricus L.>Neinong Elymus sibiricus L.（4）In the association analysis of SSR molecular marker,a total of 35 SSR loci were detected to be related to traits of Elymus sibiricus L.,of which 8 loci were associated with2 or more agronomic traits.Most of the quantitative traits are associated with multiple loci,which should be a polygenic effect.The ES53 locus has the highest interpretation rate for trait variation,which is 9.2%.It is extremely significantly related to leaf width（P<0.01）.There are at most 19 sites related to leaf length,and the interpretation rate for trait variation is 2.4%～7.8%.Among the remaining sites,7 sites were related to plant height,10 sites were related to the number of leaves,and 3 sites were related to internode length.Through association analysis,the markers associated with yield traits such as leaf quantitative traits and plant height can be effectively found,which can provide a basis for the germplasm identification,purity identification and molecular breeding of Elymus sibiricus L. |
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