Extension of genetic variation including development of high yielding varieties to be applied in hybrid rice technology (A,B and R lines) is very important. Hybrid seed production is not practiced in Iran and is completely dependent upon introduction of cytoplasmic male sterile lines (CMS lines) from other countries. Evaluation and transformation of this phenomena (CMS) to the high yield new well adapted varieties must be followed. For this purpose one of IRRI CMS lines was used as female and crossed with seven high yielding local varieties namely Nemat, Neda, Amol3, Dasht, Champa, Tarom Mahalli and Rashti Sadri. The offspring of all crosses(F1) were tested for pollen grain fertility through staining with %1 IKI solution. The results indicated complete male sterility (> 99 %) of crosses between Nemat, Neda, Amol3 and Champa with IR58025A, sterile in cross between IR58025A / Dasht, (98%) and partial sterile (30 - 60%) in crosses between Tarom Mahalli and Rashti Sadri with IR58025A. All Crosses demonstrated well panicle exertion and good phenotype acceptability (1 from 9 score).The final output of these two years of study indicated that Nemat, Neda, Dasht , Amol3 and Champa contain recessive nucleus genes (rfrf) for controlling sterility of pollen grain with N (Normal) cytoplasm. These varieties can potentially be used as sterility maintainers. So through conventional breeding methods (back crosses) we may produce some new CMS lines, but Tarom Mahalli and Sadri Rashty local varieties in crosses with IR58025A indicated partial sterility thus were eliminated in further study in this project.
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