Abstract: Five crosses were obtained by crossing 4 japonica wide compatibility varieties with 4 ordinary indica ones. The grain plumpness for these materials was analysed with additive-dominance genetic models of plant and endosperm genotypes. The main results are as follows: 1 )The differences of grain plumpness among crosses were obvious. Those from crosses as Ce 03×Yangdao 4 and Lunhui 422×3037, both parents and progenies were high, poor grain plumpness of F₁ generations was not a problem. The generations from 02428×Minghui 63 had high values despite their parents' low expression. This shows that under certain genetic backgrounds, the plumpness of grain could be improved by some external supplementary genes, indicating that there are other methods of improving grain plumpness of the hybrids besides 'getting high with high'. Two parents of low grain plumpness could get possible high plump hybrids. The grain plumpness for generations of low parent PC311 with high parent Yangdao 4 tallied well with additive genetic model. The grain plumpness of the descendants from low parents PC311×IR36 was low with few exceptions. 2)Single and joint genetic analysis of grain plumpness of several crosses showed that the increasing effect of Yangdao 4 and Ce 03 and decreasing effect of IR36 and PC311 were obvious. The effects could be explained by joint additive-dominance models of plant and endosperm genotypes. Yangdao 4 and PC311 had the strongest increasing and decreasing genes, respectively. But the grain plumpness of descendants of 02428 and Minghui 63 was mainly caused by positive dominant effect. In the cross PC311×IR36, non-genetic variation played a big role. The genetic analysis for two crosses with Yangdao 4 had high determination coefficient. Over half of variation among generations could be explained by the additive model. Genetic analysis was reliable. In other crosses, the genetic determination coefficient was very low(0.17). The goodness of fit test of genetic model was significant, indicated that besides additive-dominance, other factors, such as epistasis, might affect grain plumpness.

Key words: gene effect, genetic model, grain plumpness, indica and japonica hybrids

摘要： 利用PC311等粳型广亲和品种与扬稻4号等常规籼稻品种配组得到5个组合各18个世代的材料。测定其谷粒充实度并进行母体植株基因型和胚乳基因型联合加性-显性遗传模型分析。结果表明：1)组合之间的充实度差异明显。组合测03×扬稻4号和轮回422×3037亲本的充实度较高(平均为96.17)，杂交、回交后代的充实度也较高(平均数为95.93)，F1等世代充实不良的问题并不严重。组合02428×明恢63两亲本的充实度很低，但杂交、回交等世代的充实度很高，这表明在一定的遗传背景下，导入外源互补基因可提高充实度。两个充实度不高的亲本也可能获得充实度很高的杂种材料，这也说明除了“以饱攻饱”外，也存在其它提高亚种间杂种充实度的育种途径。低亲(PC311)和高亲(扬稻4号) 组合，F1代的充实度较低，其它世代的高低程度与遗传的加性模型较为吻合。低亲(PC311)×低亲(IR36)后代充实度大多数世代均较低。2)对各组合的谷粒充实度进行单个和联合的遗传分析表明，扬稻4号和测03的增效作用、IR36和PC311的减效作用比较明显，这种效应在较大程度上能为母体植株和胚乳基因型联合的加性-显性-细胞质效应模型所说明，遗传表达有较高的可信度。扬稻4号和PC311分别具有最强的增、减效基因。02428×明恢63后代的充实度表现主要由正向显性作用所致。组合PC311×IR36各世代谷粒充实度表现比较复杂，遗传决定系数较低(0.17)，非遗传的变异占有较大的成份。一些组合的遗传模型的离回归测验显著，表明除了基因的加性-显性作用外，还有一些因子对充实度有影响。

关键词: 充实度, 遗传模型, 基因效应, 亚种间杂交稻