水稻粒重的粒位效应及遗传分析

选用6个粒重差异较大的粳稻亲本,按完全双列杂交方式配制30个杂种F1、2个F2及部分回交组合,研究了同一稻穗不同粒位粒重的变异度和籽粒谷粒性状的遗传,结果表明:上部籽粒粒重的变异度极显著地小于中、下部;不同粒位粒重的变异度随着粒重的增高而增大,这一特征在下部小穗表现明显,而上、中部小穗,粒重在30g以下时,粒重的变异度没有显著差异。不同粒位的小穗结实率存在极显著差异,上、中部明显高于下部。粒重相关性状具有较高的遗传力,环境对这些性状的影响很小,表明粒重的变异主要受遗传控制。在遗传作用中,基因的加性作用是主要的,因而谷粒性状可以在早代进行选择。杂交后代群体随着世代增加、基因纯合度提高,其平均粒重有下降的趋势。

Effect of Grain Position and Genetic Analysis on Grain Weight of Rice

30 F1,2 F2 and some BC1F1 populations from crossing between six japonica rice varieties or lines with great difference in grain weight were used to study the variation of grain weight in different positions and genetics of grain characters.The results showed that grain weight of upper grain in a spike had significantly less variation than that of middle and botton grain,variation of grain weight in different panicle positions was increased along with the increase of grain weight.There was no significant difference in variation of grain weight between upper panicle and middle panicle when 1000-grain weight was below 30g,while the variation was increased obviously when 1000-grain weight was over 30g.Significant difference was observed for seed set rate of spikelet in different positions.Grain characters have higher heritability,the variation of grain weight was mainly controlled by additive gene effects.When the generation advanced and gene homogeneity degree increased,average grain weight decreased in a segregation population.