Abstract: The growth duration (GD) of hybrid F₁s between indica and japonica rice was studied in 80 indica×japonica combinations between indica CMS restorers or maintainers with different GD and typical japonica or middle type varieties by contrasted with indica×indica or japonica×japonica combinations. It was shown that the GD heterosis of intersubspecific F₁s is the most vigorous, generally, superior to the average of their parent's value, and the GD heterosis of intrasubspecific F₁s is the weakest, approaching the medium value of their parents, and the GD heterosis of indica or japonica crossed with middle-type parents is situated between the preceding two kinds of combinations. The GD heterosis among different intersubspecific combinations greatly varied with their adopted parents, negative heterosis was found in some combinations. The variation in GD heterosis was caused by following points. Firstly, it was influenced by two parents GD, the order of hybrid GD from long to short was in turn medium indica/late japonica>medium indica/early or medium japonica>early indica or early-maturing medium indica/early or medium japonica. Secondly, it was conditioned by the restoring gene in indica parent. The indica×japonica hybrid heterosis was retarded as the indica CMS restorers was used, and it was also found that the greater the genetic distance of their parents was, the stronger the GD heterosis of hybrid was.

Key words: genetic distance, growth duration, indica x japonica hybrid, indica restorer line

摘要： 采用生育期不同的籼型野败恢复系和保持系与典型粳稻和籼粳中间型亲本配制成80份籼粳杂种一代组合，用亚种肉品种间杂交为对照，研究了籼粳稻杂种一代生育期的表现。结果表明，以籼粳亚种间杂种一代生育期优势最强，一般都超过双亲平均值；品种间杂种一代生育期优势最弱，接近中亲值；籼或使型亲本配籼粳中间型亲本，杂种一代生育期优势介于上述两类型组合之间。籼粳杂交由于双亲的不同，组合间F₁生育期优势差异很大，有的组合甚至出现负向优势．这种生育期优势差异既受双亲本身生育期的迟早所支配，如杂种一代生育期长短排列顺序为中籼／晚粳＞中籼／早或中粳＞早籼或早熟中籼／晚粳＞早籼或早熟中籼／早或中粳；又受籼型亲本所含的野败恢、保遗传基因所制约，凡用籼型野败恢复系配制的籼粳杂种一代其生育期优势明显减弱，并与双亲籼、粳遗传距离的大小有关，杂种一代生育期优势随双亲籼、便遗传距离的扩大而增强。

关键词: 遗传距离, 生育期, 籼粳杂种一代