Study On Genetic Diversity,Evaluation And Selection Of Germplasm In Barley

Barley is one of the earliest domesticated crops used as food,feed,brewing material and health product in the world,and is also a model crop of genetics and molecular biology research with diverse functions.Barley germplasm resources are the foundation of barley breeding.According to row-type,hull/hulless and utility,the barley germplasm aredevided into two-rowed hulled barley(mainly used for beer),two-rowed hullessed barley(mainly used for fodder and health product),six-rowed hulled barley(mainly used for fodder),six-rowed hullessed barley(mainly used for fodder and health product).As differences in the breeding goals with diverse row-types and utilities as well as in the selection and utilization principles for diverse germplasm resources,the study of genetic diversity and reasonable evaluation of different types of barley germplasm resources can contribute to the exploitation of potential gene resources and innovative utilization of germplasm.A total of 186 barley varieties were used in the present study,including domestic and foreign cultivars.Eight major agronomic traits(plant height,internode length below spike,spike length,grain number per spike,spike number per plant,thousand-kernel weight,grain weight per plant,and biological weight per plant)were collected in three locations of two years.Genetic diversity study was carried out with correlation analysis,principal component analysis and cluster analysis.Firstly,all the germplasm were evaluated and classified,and then barley germplasm were classified by row-type.The barley yellow mosaic resistant germplasm were screened out with the identification of resistance across two years.Further more,the selected specific germplasm were evaluated comprehensively.The main results were as follows:1.The major agronomic traits of barley germplasm displayed rich genetic variation and diversity among different types and different locations.The variation coefficient of yield elements was larger,and the variation coefficient of plant type elements was inverse.The genetic diversity index of the the whole germplasm ranged from 1.51 to 2.08,among which diversity index of internode length below spike was highest,and the diversity index of grain number per spike was lowest.The diversity index of two-rowed germplasm ranged from 1.87 to 2.07,while six-rowed germplasm ranged from 1.86 to 2.09.The diversity index of two-rowed germplasm was consistent with six-rowed germplasm.The diversity index of six-rowed hulled germplasms ranged from 1.88 to 2.03,while six-rowed hullessed germplasm ranged from 1.34 to 1.98.The diversity index of six-rowed hulled germplasm was higher than that of six-rowed hullessed germplasm.The genetic diversity index of AUDPS(barley yellow mosaic resistance index)evaluated in the whole germplasm across two years were 1.84 and 1.74,respectively.2.Principal component analysis showed that the reasons of morphological variation in different types of barley germplasm were not completely consistent.In spite of acquiring the same major components related to plant type,panicle traits,yield traits,there were some differences in the importance of selected components.The first four major components of whole germplasm were yield components factor,plant type factor,spike length factor,internode length below spike factor,respectively;the first four major components of two-rowed germmplasm were grain weight factor,spike factor,spike length factor,plant type factor,respectively;the first five major components of six-rowed germplasm were yield factor,plant height and kernel weight factor,spike length and tiller factor,thousand-kernel weight factor,plant type and biological weight factor,respectively.3.Based on Mahalanobis distance of eight agronomic traits,the cluster analysis showed that row-type was the most significant classification character among barley germplasm.There were significant differences in eight agronomic traits between two-rowed and six-rowed germplasm,while it was thousand-kernel weight that behaved significant difference between six-rowed hulled germplasm and six-rowed hullessed germplasm.By clustering,five types of specific germplasm from two-rowed barley germplasm and six types of specific germplasm from six-rowed barley germplasm were obtained.Meanwhile it was found that the clustering results of different types of barley germplasm were not consistent with their geographical distribution.Combining with scatter plots and comprehensive principal component value,the top ten germplasm of general performance,selected from two-rowed barley,six-rowed barley respectively,were varieties that mostly used or being used in field production.4.Forty stable resistant germplasm were selected by the resistance identification of barley yellow mosaic disease across two years,among which thirty and ten barley germplasm belong to two-rowed and six-rowed barley,respectively.It's worth noting that one two-rowed and three six-rowed barley varieties were identified as immune to barley yellow mosaic.TOPSIS analysis based on eight agronomic traits was carried out by using thirty two-rowed germplasm and ten six-rowed germplasm,respectively.The comprehensive performance of eight two-rowed resistant germplasm displayed the top ten,and four six-rowed resistant germplasm displayed the top five across two years.Thus,these germplasm,in terms of stability of resistance and better comprehensive performance,can be used in different types of variety breeding.