Five CMS lines were crossed with 49 genotypes as ‘testers’ to get 245 hybrids. The 245 hybrids were subjected to pollen and spikelet fertility analysis. Among the 245 hybrids 21 hybrids were expressed as restorers, 24 as maintainers, and 200 intermediate types. Six tester’s viz., BR6592-4-6-4, BR6839-41-5-1, IR74052-184-3-3, IR72593-B-3-2-2-2, BR7011-37-1-2, and IR72049-B-R-22-3-1-1 were identified as restorers for highest 2 lines out of the five CMS lines, differently. None of them were found to be restorer for all the five CMS lines. BAU581 was found to be maintainer for four lines except for D.ShanA. Purbachi was found to be maintainer for three lines except for D.ShanA and IR73328A out of the five CMS lines. Out of 245 crosses only 45 crosses contributed directly to the identification of maintainer and restorer. Other crosses were more or, less of intermediate types which indicated neither maintainer nor restorer. It is well known that, pollen fertility is controlled by one dominant gene (RfRf). If pollen fertility is governed by only one gene the product would be either restorer or, maintainer where will be no existence of intermediate types. So, there might be modifier genes in different genotypes which interacted with male sterile nuclear genes that resulted in intermediate male sterility in the crosses.

Bacterial blight (BB) disease, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the major bottlenecks of rice (Oryza sativa) production. The present study was undertaken to identify BB‐resistant parental lines of hybrid rice based on pathogenicity tests and molecular screening. Three virulent races of Xoo, i.e. BXo93, BXo822 and BXo887 were used to evaluate the 66 maintainers and 200 elite restorer lines against BB. Based on the pathogenicity test, none of the maintainer lines was found resistant, whereas 16 restorers were resistant against the three races and 15 restorers were resistant to a single race (Bxo93). These 31 restorer lines were selected to detect the presence of major bacterial blight resistance genes, i.e. Xa4, xa5, Xa7, xa13, Xa21 and Xa23 using molecular markers. Thirteen restorer lines carried the Xa4 gene but were not resistant to all three races of BB. Fourteen restorers and one restorer had two (Xa4 + xa5; Xa4 + Xa7; Xa4 + Xa21 and Xa7 + Xa21) and three (Xa4 + xa5 + Xa7) BB resistance genes, respectively. Genotypes having Xa21, Xa7 + Xa21 or Xa4 + Xa21 had reduced lesion lengths that ranged from 1.4 cm (against BXo93)–3.0 cm (against BXo887), 1.6 cm (against BXo93)–2.0 cm (against BXo822 and BXo887) and 2.5 cm (against BXo887)–3 cm (against BXo822), respectively, and were found to be the most effective resistance genes against bacterial blight. The restorer lines having the Xa21, Xa7 + Xa21 or Xa4 + Xa21 could be used as parental lines for the development of bacterial blight‐resistant hybrid varieties.