Classification Of Heterotic Groups And Correlation Analysis Of Agronomic Traits In Sweet Corn

Dividing heterotic groups of sweet corn is a theoretical basis for selecting combination of superiority of sweet corn.Study of genetic diversity of sweet corn inbred lines is one of basis of dividing heterotic groups.In the present study,a set of 89 sweet corn inbred lines,which imported and bred by research heterotic groups of sweet corn of South China Agricultural University,is used to analyzing genetic diversity and then assigned sweet maize inbred lines to corresponding heterotic groups.Agronomic trait,as significant expression of genetic composition of sweet corn,has been primary basis of varieties' breeding on breeding process at present.In my study,investigation is used about five agronomically important traits and seven traits of ear respectively,and correlation analysis and genetic analysis are used about correlative traits.To provide academic support for breeding of sweet corn inbred lines.1.Seventeen pairs of SSR markers produced 259 polymorphic amplified fragments in 89 sweet corn inbred lines.The average number of alleles per SSR locus was 15.24 with a range from 4 to 26.The gene diversity average 0.85,ranging from 0.51 to 0.94.The polymorphism information content(PIC)for the SSR loci varied from 0.4 to 0.93 with an average of 0.83.2.Among the whole set of 15 simple sequence repeats,dinucleotide repeat sequence could capture more alleles and genetic diversity than other repeat SSRs.3.89 sweet corn inbred lines were divided into 5 groups by UPGMA(unweighted pair-group method with arithmetic means)according to standard of genetic similarities 0.67.The first group includes 71 inbred lines,most of these lines are second cycle inbred lines from tropic and temperate zone sweet corn varieties.The second group includ es 9 inbred lines,most of these lines are second cycle inbred lines from domestic sweet corn varieties.The third group includes 4 inbred lines are second cycle inbred lines from overseas sweet corn varieties.The forth group includes 4 inbred lines,all o f these lines are temperate zone sweet corn varieties.One inbred lines is second cycle inbred lines from temperate zone sweet corn varieties.4.In the present study,by using a model including additive and dominance effects.5 agronomic traits and 7 traits of ear were analyzed for a diallel design with 25 sweet corn varieties(or breeding lines)and their 33 F1 crosses.It was revealed that all of the correlative parameters of the five traits were positive number and degree of correlation reached 1%.Seven traits of ear: except for thickness,the rest of correlative coefficient of all of traits were positive number and degree of correlation reached 1%.Additive effects were the major genetic component for fresh weight,net weight and thickness.In additio n,heritability(N)of fresh weight was high,so we can use correlative coefficient of fresh weight to choose net weight.Narrow heritability,estimated from big to small: fresh weight ?net weight ?pericarp thickness,besides,all were high,for early generation choice was more reliable.