Discovering of new rice genotypes for restoration/maintenance ability and their relationship to hybrid rice seed production

The exploitation of hybrid rice technology has been made possible by the identification of restorers and maintainers as parental lines. Four CMS lines of rice viz., E2015A, G46A, CCG5A, and E0034A were crossed with 24 diverse testers during the growing seasons of 2022 in Experimental Farm of RRTC, Sakha, Egypt. Ninety-six hybrid combinations were generated to identify the effective restores and maintainers from elite local and exotic rice genotypes under test cross nursery and determine the best heterotic combinations in terms of yield and its components during 2023 seasons. The F1 hybrids expressed different fertility reactions. Out of 96 test crosses the results of this investigation revealed that sixteen rice genotypes of tested 24 rice parents were identified as effective restorers (R) which can easily restore four different sources of CMS lines (Pollen fertility and spikelet fertility more than 83%) with heterotic morphological attributes. On the contrary, three rice genotypes of 24 rice parents (BN-19, BN-45, and Winixyan) were identified as maintainers (M) for the same aforementioned CMS lines. Among the fourteen F1 hybrids, assessment of standard heterosis based on the standard check (Giza 178) of five effectively restored cross combinations showed higher useful heterosis than the standard check variety. Three hybrid combinations i.e. E0034A/SR-86 (26.41%) and E0034A/GZ10848 (25.51%) recorded more than 25% yield advantage over the check variety Giza 178. Restorers and maintainers identified illustrate the possibility of the development of new rice hybrids and CMS lines in the future.