中文摘要：

【目的】探索水稻抽穗期的遗传机制．【方法】以华粳籼74的8个单片段代换系为材料，构建了7个聚合了双QTL的次级F2作图群体，并通过分子标记的选择区分出每个群体的9种基因型以估算水稻抽穗期QTL的各类上位性分量．【结果和结论】除QTL HD3／HD8间的上位性互作不显著外，其他QTL对均存在显著的上位性效应，占85.7％；在检测的28个不同类型的上位性效应中，有60.7％的估计值达到5％或1％的显著水平，其中加加、加显或显加、显显上位性分别占71.3％、42.8％、85.6％．研究结果进一步证实了上位性作用在数量性状遗传体系中的普遍性和重要性，并为水稻抽穗期的分子聚合育种提供了依据和材料．

英文摘要：

[Objective] To explore the genetic basis on heading date in rice .[Method] Eight single seg-ment substitution lines of Huajingxian 74 were applied as experimental materials to construct seven sec-ondary F 2 populations pyramiding dual QTL , in each of which nine marker genotypes were distinguished to allow estimations of epistatic components for the QTL pairs .[Result and conclusion] All QTL pairs tested, except for QTL HD3 and HD8, exhibited significantly epistatic effects , accounting for 85.7%. There were 60.7%of 28 epistatic components to be detected with significant estimations at the probability levels of 5%or 1%, where three types of epistatic interactions , e.g.additive-additive, additive-domi-nance or dominance-additive , and dominance-dominance epistatic effects accounting for 71.3%, 42.8%and 85.6%, respectively .These results further confirmed that the universality and the importance of e-pistasis existed in genetic systems of quantitative traits , providing useful frames and materials for molecu-lar marker assisted pyramiding breeding on heading date in rice .