| Alfalfa is an important high-quality legume forage grass and an excellent forage resource.It’s known as "the king of forage grasses" because of its excellent nutritional value.Alfalfa forage quality traits are quantitative traits,and their genetic background is complex and needs to be studied in depth,so it is necessary to combine phenotypic variation information and genetic information to study the inheritance pattern of related traits.In this study,the F1 generation produced by crossing Medicago sativa with relatively high nutritional value as the male parent and Medicago sativa subsp.falcata with relatively low nutritional value as the female parent were used as the materials,and the forage quality of the above-ground parts of the F1 generation planted in Yu zhong and Hulun buir sites was studied.The main results were as follows:1.Genetic diversity analysis of nutrient indexes in the F1 generationStatistical analysis of six nutrient composition indicators of the F1 generation populations in the Yu zhong(2021 and 2022)and the Hulun buir(2022)showed that all nutrient composition indicators of the F1 generation were characterized by normal distribution and had different ranges of variation(8.102% ～ 51.868%),and the largest coefficient of variation.The indicators with the highest coefficient of variation were all starch.Correlation analysis showed that starch and crude protein had significant positive correlation analysis.Cluster analysis was performed on the six nutrient indicators,and the F1 generation was divided into five categories,mainly including the paternal population,the maternal population and three types of intermediate populations.2.Analysis of the major gene plus polygene model for nutrient indexes of the F1generationCompared with the parents,the F1 generation showed different degrees of promediated dominance for each nutrient,but no heterobeltiosis phenomenon.The results of the major gene plus polygene model analysis showed that all the indicators were controlled by two pairs of master genes,except for the fat content index which was controlled by one pair of master gene in the 2022 Hulunbuir.The heritabilities of the master genes for curde protein,starch and K were more than 50%,indicating that they were more stable and influenced by genes;while the heritabilities of the master genes for ether extract and Ca were lower,indicating that this trait was more influenced by the environment.3.Genetic diversity analysis of digestibility index of F1 generationStatistical analysis of the five digestibility-related indexes of the F1 generation crosses at the Yu zhong(2021 and 2022)and the Hulun buir(2022)showed that the five digestibility related indexes of the F1 generation were characterized by a normal distribution with different degrees of variation(5.322% ～ 24.073%),and the range of variation was smaller than that of The largest coefficient of variation was for lignin.Correlation analysis analysis showed correlation among lignin,ADF(Acid Detergent Fiber),NDF(Neutral Detergent Fibre),DNDF30h(Digestion of Neutral Detergent Fibrer)and relative feeding value,and there were significant negative correlation analysiss between RFV(Relative Feed Value)and the remaining indicators,and negative correlation analysiss between DNDF30 h and lignin.Cluster analysis was performed on the five digestibility-related indexes,which were divided into groups showing parental groups,maternal groups,two types of intermediate groups and one type of superparental dominant groups.4.Analysis of the major gene plus polygene model of the digestibility index of the F1generationAll digestibility indices were controlled by 2 pairs of major genes,but the dominant and additive effects between genes were more influenced by environment.Lignin content all showed high heritability of the master genes(99.752%,98.433%,and 91.567%),indicating a high genetic effect and a low environmental effect on lignin content.The master gene heritability of ADF,NDF,and DNDF30 h was small(< 50%)in the Yu zhong and Hulun buir.In this study,the genetic diversity and the main polygenic model of the F1 generation between Medicago sativa and Medicago sativa subsp.falcata were analyzed to investigate the forage quality traits at the phenotypic and genetic levels,which is not only important for analyzing the genetic pattern of alfalfa forage quality traits,but also provides a theoretical basis for further association analysis and reference for breeding new high-quality alfalfa varieties. |
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