| Alfalfa（Medicago sativa L.）is one of the most important forage legume,for its high nutritious value,good resistance,and wide adaptability.Yield and quality are the most important traits for alfalfa breeding.Studying yield related traits and early-maturing traits is helpful for us to understand the genetic rules of yield quality and the relationship between yield and quality.However,yield and early maturity traits are quantitative traits,affected by environmental and genetic factors.In addition,alfalfa is cross pollinated tetraploid plant.To reveal the genetic rules,both phenotypic information and genetic information need to be analysed.It is easy to analysis genetic rules using hybrid population in alfalfa.Studying the genetic variation rules of phenotype between different hybrid individuals will provide reference information for molecular breeding and theoretical guidance for field breeding.In this experiment,paternal parent exhibits good phenotypic performance for early-flowering but poor forage production.Maternal parent exhibits good performance for forage yield but late-flowering.Crossing paternal parent and maternal parent,resulted in a segregating,full sib F1 population consisting of 152 genotypes.Phenotypic data was measured in two years.Multiple regression analysis was used to analyze the relationship between different indexes.What’s more,the major gene plus ploygenes genetic model analysis would provide reference basis for further association analysis and can be applied to accelerate breeding of alfalfa varieties.The results are as follows:1.The statistical analysis of different agronomic traits of alfalfa F1 individuals showed that the top three traits with high variation coefficients were dry weight,branch number and stem/leaf ratio.The correlation analysis showed that dry weight was significantly correlated with plant height,branch number,diameter and stem/leaf ratio.Path analysis and stepwise regression analysis showed that plant height and branch number were main factors affecting dry weight.2.The experimental results of early flowering were consistent between 2015 and 2016.A double-normal distribution for early flowering was observed in each year.Major-multi genetic model analysis showed that the best candidate genetic model was 2MG-AD.The heritability of major genes was 99%in 2015.The heritability of major genes was 98.5%in 2016.Therefore,flowering time was controlled mainly by two pairs of major gene with additive effects.3.The phenotypic variation information of dry weight was consistent in two years’experimental results.F1 plants had a wide range of variation.Z-test showed that dry weight distribution was normal distribution.Major-multi genetic model analysis showed that the best candidate genetic model was2MG-A and the heritability of major genes was 88.8%in 2015.The best candidate genetic model was2MG-AD and the heritability of major genes was 91.5%in 2016.Therefore,the optimal genetic model was different between two years results.Dry weight was controlled mainly by two pairs of major gene in both years. |
