ISSN 0258-7122 Bangladesh J. Agril. Res. 36(2) : 263-270, June 2011 GENETIC VARIABILITY OF SOME CYTOPLASMIC MALE STERILE LINES (CMS) OF RICE (Oryza sativa L.) GENOTYPES M. J. HASAN 1 , UMMA KULSUM 2 , M. H. RAHMAN 3 M. HAZRAT ALI 4 AND A. W. JULFIQUAR 5 Abstract The desirable characteristics of fourteen genetically diverse CMS lines were assessed for their phenotypic acceptability, plant height (cm), days to 50% flowering. panicles per plant, stability for pollen sterility, panicle exertion rate and out crossing rate. The CMS lines viz. BRRI1A. IR 58025A. BRRI10A. BRRI9A. BRRI3A, IR 75608A, and 1132A have been found to be usable female parents for hybrid rice breeding due to their appreciable phenotypic acceptability, stable pollen sterility, panicle exertion rate and good out crossing rate. Panicle exertion rate of CMS lines had moderate heritability (38.34%) coupled with low genetic advance (2.34%) expected in the subsequent generations, that proved to be vulnerable to environmental fluctuation. The genotypic and phenotypic coefficient of variation was not remarkably varied from each other for most of the characters studied, indicated negligible environmental influence on these traits. Overall genetic correlation coefficients were higher than corresponding phenotypic correlation coefficients indicated strong relation present among the studied characters. Keywords: Genetic variability, CMS lines, rice. Introduction Bangladesh is the fourth largest producer and consumer of rice in the world with an annual production ranging from 21 to 22 million tons (Bhuiyan et al., 2002). Rice occupies 77% of total cropped area. At present, rice alone constitutes about 92% of the total food grain produced annually in the country. It provides 75% of the calories and 55% of the proteins in the average daily diet of the people (Bhuiyan et al., 2002). A modest estimate suggests that the demand for rice in Bangladesh will increase by over 80% in the next 20 years to feed the growing population (Zaman, 1996). It is growing concern among the scientists and planners about how to feed the extra millions in future when the productivity of modern rice varieties (MVs) is stagnated and the land and water resources are shrinking. To produce the required quantity, the only option remains open is to increase production per unit area, as there is scarcity of land. 1 Senior Scientific Officer, 2&3 Scientific Officer, 4 Principal Scientific Officer, 5 Project Director, Hybrid Rice Project, Bangladesh Rice Research Institute (BRRI), Gazipur 1701, Bangladesh.