ISSN: 0041-3216

ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 89 Number 1
Research Papers
Commercial heterosis and combining ability in rice (Oryza sativa L.) hybrids involving bacterial blight resistant and susceptible cytoplasmic male sterile lines. (29)
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Rice hybrids are increasingly occupying more rice growing areas in many countries. Development of high yielding hybrids with resistance to bacterial blight disease is an attractive option for disease management. Through a line x tester mating design involving four cytoplasmic male sterile lines (BB resistant and susceptible) as female parents and 13 fertility restorers as male parents, 52 hybrid combination were generated and evaluated for combining ability and heterosis. Detailed analysis of variance showed significant variation for 7 out of 8 characters studied. Inheritance was predominately under the control of non-additive gene action for 5 important traits viz. productive tillers no., panicle weight, spikelets no./panicle, spikelet fertility and grain yield thus showing the suitability of heterosis breeding for genetic improvement. Two CMS lines PMS11A and PMS12A were found promising for generating better hybrids. Six restorers viz. IR 32841, PAU1106-5-4, PAU1226-1-4, PAU1106-6-2, PAU2024 and IR59566 were identified as good general combiners for exploiting heterosis. For all the studied traits, significant correlation coefficients (‘r’ from 0.16 to 0.37) were observed between specific combining ability effects and per se performance of the hybrids. Based on the studied parameters, importance of higher panicle weight and spikelet fertility is underlined in an effective hybrid rice programme. Incorporation of dominant gene controlled disease resistance in the hybrids did not adversely affect their high yielding potential. The findings can be utilized in designing a hybrid rice breeding program aimed at developing heterotic and disease resistant rice hybrids.
Keywords: Combining ability, heterosis, cytoplasmic male sterile lines, bacterial blight, gene action