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以目前生产上大面积应用和新育成的16个籼型三系杂交水稻亲本为材料，根据11个主要农艺和经济性状进行主成分分析和聚类分析，以马氏距离为指标，研究了杂交水稻亲本间遗传差异的状况及其与杂种优势的关系。在16个亲本的120个遗传距离中，80％以上小于2；9个恢复系间的平均遗传距离仅为0．4793，7个保持系间，除湘香2号B外，平均遗传距离为0．7723。说明现有杂交稻亲本间遗传差异较小，尤其是保持系内和恢复系内遗传差异更小。对亲本间遗传距离与杂种优势的相关分析表明，现有籼型三系杂交稻亲本间遗传差异与杂种优势关系不密切，而杂交稻产量的高低与双亲产量尤其是双亲产量平均值的高低密切相关。说明亲本改良在提高杂交稻产量中极为重要。此外，还对亲本改良与杂种优势的关系、杂交相亲本改良的方法和途径以及杂交稻组合亲本选配原则进行了讨论。
Based on the principal component analysis and cluster analysis of 16 major indica type three-line hybrid rice parents, which were widely used and newly bred in the present production, the principal component analysis and cluster analysis were conducted on 11 major agronomic and economic traits. Mahalanobis distance was taken as the index to study the hybridization Genetic Differences among Rice Parents and Their Relationship with Heterosis. Among 120 parents of 120 parents, more than 80% were less than 2; the average genetic distance among 9 restorer lines was only 0.4793 and 7 maintainer lines. Except for Xiangxiang 2 B, the average genetic distance was 0.7723. The results showed that there was little genetic difference among existing hybrid rice parents, especially within the maintainer line and restorer line. The correlation analysis of genetic distance and heterosis between parents showed that the genetic differences between the three indica hybrid rice parents and heterosis were not close, but the hybrid rice yield was closely related to the parents’ yield, especially the average parental yield Related. It shows that the improvement of parents is very important in improving the yield of hybrid rice. In addition, the relationship between parental improvement and heterosis, methods and ways to improve parental hybrid parents, and parent matching principles of hybrid rice combinations were also discussed.