Segregation analysis of the mixed genetic model of major gene plus polygene was used to identify the major genes for cotton yield-related traits using six generations P1,P2,F1,B1,B2,and F2 generated from the cross of Baimian 1×TM-1.In addition to boll size and seed index,the major genes for the other five traits were detected:one each for seed yield,lint percentage,boll number,lint index;and two for lint yield.Quantitative trait locus/loci(QTL)mapping was performed in the F2 and F2:3populations of above cross through molecular marker technology,and a total of 50 QTL(26 suggestive and 24 significant)for yield-related traits were detected.Four common QTL were discovered:qLP-3b(F2)/qLP-3(F2:3)and qLP-19b(F2)/qLP-19(F2:3)for lint percentage,qBN-17(F2)/qBN-17(F2:3)for boll number,and qBS-26b(F2)/qBS-26(F2:3)for boll size.Especially,qLP-3b(F2)/qLP-3(F2:3),not only had LOD scores>3 but also exceeded the permutation threshold(5.13 and 5.29,respectively),correspondingly explaining 23.47 and 29.55%of phenotypic variation.This QTL should be considered preferentially in marker assisted selection(MAS).Segregation analysis and QTL mapping could mutually complement and verify,w hich provides a theoretical basis for genetic improvement of cotton yield-related traits by using major genes(QTL).
