Ear traits are closely correlated with the yield in maize. The understanding of the genetic basis of heterosis for ear traits could facilitate maize breeding program. In this study, the triple testcross( TTC) populations consisting of 121 testcross progenies were constructed based on the TTC genetic mating design. In total, thirteen different QTLs for five ear traits were mapped on chromosomes 1, 2, 3, 4, 5 and 10 using inclusive composite interval mapping ( ICIM) method. Of these, 2, 4, 1, 2 and 4 QTLs were detected for ear length ( EL) , ear diameter ( ED) , rows per ear ( RPE) , kernels per row ( KPR) and hundred kernel weight ( HKW) , respectively. According to the action mode of QTLs, these QTLs for five ear traits were classified as overdominant (10) and additive (2), with single locus accounting for 8.2%-23. 3% of the to-tal variation. In addition, nine marker pairs with digenic epistatic effects were scaned for the ED, RPE and HKW, and the total variation explained by single digenic interaction was 20.4%-35. 3%. These findings suggest that additive, dominant and degenic epistasis contribute to genetic basis of heterosis for maize ear traits together.%玉米穗部性状与产量密切相关,剖析控制穗部性状杂种优势数量性状位点(QTL)有助于加深杂种优势作用机制的理解,为杂种优势的应用提供理论指导.本研究根据三重测交交配设计方法组配了121个测交后代的三重测交(TTC)群体,并利用完备区间作图法(ICIM)对穗部性状杂种优势进行了QTL分析.经检测,共发现13个主效QTLs.其中,穗长检测到2个QTL,穗粗检测到4个QTL,穗行数检测到1个QTL,行粒数检测到2个QTL,百粒质量检测到4个QTL.这些QTL分别分布于第1、第2、第3、第4、第5和第10染色体上.QTL位点作用模式分析结果表明,超显性位点最多(10个),加性位点最少(2个),单位点可解释8.2%~23.3%的表型变异.对QTL位点上位性互作进一步剖分发现,穗粗、穗行数和百粒质量性状中存在9对不同位点的上位性互作,单位点可解释20.4%~35.3%的表型变异.研究结果表明,加性、显性及两位点上位性互作是玉米穗部性状杂种优势形成的主要遗传学基础.
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