| Sumario: | Hybrid rice technology is very useful to increase rice production to feed the growing population of the world. Identification of hybrid rice parental lines with high general combining ability (GCA) is crucial for developing specific hybrids with more fertility restoration ability and higher yield. We screened a total of 97 genotypes, which include stress-tolerant (abiotic/biotic) advanced breeding lines, a few popular released rice varieties, known restorer KMR3 (presence of Rf3 and Rf4 genes), and known maintainer IR58025B (absence of Rf3 and Rf4 genes), using the reported functional markers RMS-SF21-5 and RMS-PPR9-1 to Rf3 and Rf4, respectively. Among these genotypes, 21 (21.65%) carried Rf3Rf3/Rf4Rf4, 38 (39.18%) carried rf3rf3/Rf4Rf4, 13 (13.40%) carried Rf3Rf3/rf4rf4, and the remaining 25 (25.77%) carried rf3rf3/rf4rf4 allelic combinations. The identified 21 lines possessing Rf3Rf3/Rf4Rf4, 25 lines carried rf3rf3/rf4rf4, six lines carried Rf3Rf3/rf4rf4, and four lines carried Rf4Rf4/rf3rf3 gene combinations were crossed with two CMS lines IR 58025A and APMS 6A to estimate high fertility and maintainer ability. All the 112 F1s were evaluated for spikelet fertility. Rf3Rf3/rf4rf4 genotypes mostly behaved as partial restorers. In contrast, rf3rf3/Rf4Rf4 genotypes were partial or effective restorers. However, Rf3Rf3/Rf4Rf4 genotypes showed better fertility restoration than the genotypes containing Rf3Rf3/rf4rf4 or rf3rf3/Rf4Rf4 individually, whereas rf3rf3/rf4rf4 genotypes were found to be partial maintainers. Eleven restorer lines were found to have good GCA, and crossing these lines with CMS lines showed significant positive heterosis over mid parent and better parent for grain yield. Twelve crosses/hybrids were also observed that showed significant positive standard heterosis over KRH2 for grain yield. The identified stress-tolerant parental lines with high GCA and fertility restoration alleles will be used for the development of abiotic (submergence and/or drought) stress-tolerant high-yielding hybrids.
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