Exploiting heterosis and combining ability in two-line hybrid rice

Twenty hybrids were developed from crossing four environmental genic male sterile (EGMS) lines with five testers in line × tester mating design to magnitude of heterosis over better parent for grain yield and contributing traits in rice ( Oryza sativa L.). Five hybrids ‘WTSC9059’ × ‘Sakha101’, ‘WTSC9039’ × ‘Sakha102’, ‘WTSC9059’ × ‘Sakha108’, ‘WTSC9039’ × ‘Sakha108’ and ‘WTSC9039’ × ‘Sakha101’ express superior value for number of panicles, fertility percentage, 100-grain mass, grain yield, apparent heterosis and phenotypic acceptance. The top three heterotic combinations identified for grain yield/ha were ‘WTSC9059’ × ‘Sakha101’, ‘WTSC9039’ × ‘Sakha102’ and ‘Longping’ × ‘Sakha105’ which exhibited 100.00, 71.51 and 66.61 % heterobeltiosis, respectively. The lines ‘WTSC9059’ and ‘‘Longping’’ and testers ‘Sakha101’, ‘Sakha102’ and ‘Sakha108’ was found to be good general combiner for most of the characteristics and could be extensively used in future hybrid rice breeding program. The grain yield was correlated highly significant and positive with panicle exertion, panicle mass, fertility percentage and appearance of heterosis, otherwise the negative correlation and significant was found with flag leaf area.