Combining Ability and Heritability of Major Agronomic Characters in 5 Vietnamese Rice Restorer Lines

5 CMS lines and 5 Vietnamese restorer lines and 1 Chinese restorer line were chosen to analyze the combining ability of 9 agronomic characters by way of incomplete diallele cross(NCⅡ) design.The results were as follows: ① the variance of both general combining ability(GCA) and specific combining ability(SCA) of most major characters were significant or greatly significant,the additive variation was principal for the characters of plant height(PH),spikelets per panicle(SP),filled spikelets per panicle(FSP),seed setting rate(SSR),1000-grain weight(TGW),sowing to heading date(STHD) and grain yield(GY),while the non-additive variation was principal for the characters of panicle length(PL) and effective panicles per plant(EPP);② most characters were influenced by restorer line more greatly than by sterile line;③ the GCA of parents was not significantly related to the SCA of groups.The order of narrow heritability in various characters was: TGWSSRSTHDPHFSPGYSPEPPPL.