Heterosis and combining ability in rice as influenced by introgressions from wild species Oryza rufipogon including qyld2.1 sub-QTL into the restorer line KMR3

Parental line improvement is a prerequisite for developing high yielding rice hybrids. Wild rice are reservoirs of useful genes for yield traits and introgression lines (ILs) with higher yield have been reported. The present experiment was carried out according to line × tester mating design. 36 hybrids were phenotyped for yield and its components along with parental lines [6 cytoplasmic male sterile (CMS) lines, 5 KMR3/Oryza rufipogon derived ILs and KMR3 as control]. The performance of hybrids was estimated based on relative heterosis, heterobeltiosis and standard heterosis for yield and its contributing characters along with analysis of variance for combining ability. We identified a set of good general combiners for yield traits (testers: IL50-7, IL86-18, IL50-12 and CMS lines: IR79156A, APMS6A). Of the 36 hybrids tested, four hybrids IR79156A/IL50-13, IR58025A/IL50-12, APMS6A/IL86-18 and APMS10A/IL363-5 showed significantly high specific combining ability and standard heterosis and APMS6A/IL86-18 showed highest yield. Heterosis for yield/plant ranged from 17.6 to 84.9 % and heterobeltiosis from 18.5 to 77.4 % at P < 0.05. Standard heterosis ranged from 20 to 63 % in hybrids derived from ILs compared to hybrid check Karnataka Rice Hybrid-2. Only 7 out of 36 hybrids showed significantly higher yield than their respective controls. O. rufipogon allele of QS15 within sub-QTL3 of qyld2.1 was common in these seven hybrids. These results demonstrate that introgressions from wild species have the potential to enhance yield significantly in popular rice hybrids.