Twenty six rice genotypes were selected based on the rice blast disease reaction and yield attributes. Blast disease screening was done for all the entries under natural and artificial conditions to know their disease reaction. Line x tester analysis was carried out from the 20 selected entries with 4 lines having higher to moderate yield and 16 testers which showed blast disease resistance. General combining ability of parents and specific combining ability and heterosis among 64 hybrids for yield and its components were analysed. Under natural conditions and artificial screening conditions, among the 26 genotypes screened, highly significant lower mean disease reaction score and mean Potential Disease Incidence [PDI%] was recorded by a West African land race, Moroberekan. Mean squares due to females were larger in magnitude than male parents for all the characters. The magnitude of SCA variance was higher than GCA variance for all the characters except grain yield where the GCA variance was higher. Among the lines, IR 50 was found to be a good general combiner for six traits. Among the testers, IR 64 recorded high per sec performance along with high gca effects for panicle length, filled grains per panicle, 1000 grain weight and grain yield per plant. Most of the hybrids recorded positive significant standard heterosis values for grain yield per plant. IR 50/IR 64 recorded highest heterosis values for relative heterosis and TN 1/IR 64 recorded high heterobeltiosis and standard heterosis over the standard check ASD 16. Among 26 selected F1s, Most of the combinations were resistant.
C. Immanuel Selvaraj, P. Nagarajan, K. Thiyagarajan, M. Bharathi and R. Rabindran, 2011. Studies on Heterosis and Combining Ability of Well Known Blast Resistant Rice Genotypes with High Yielding Varieties of Rice (Oryza sativa L.). International Journal of Plant Breeding and Genetics, 5: 111-129.