11. A probable new male sterile line with cytoplasm from a Boro rice of Uttar Pradesh, India

Rejendra Agricultural University, Agric, Research Institute, Mithapur, Patna, India

In search of the alternative sources of sterile cytoplasm, 51 direct and reciprocal crosses were made at IRRI with 16 advanced breeding lines of IRRI and 23 indical/japaonica derivatives from Korean rice breeding program in 1980. Most of the F\1\s were normal but partial sterility was observed in crosses involving IR46, IR10154-23-3-3, FR 43 B and IR13426-19-2. Reciprocal differences for sterility were significant in these cross-combinations.

In the backcross generations, segregation for sterility occurred which ranged from 1.7 to 98.3 percent in the cross UPRB 31/IR46. As a result, this cross was studied further and backcross F\2\ was grown during Kharif, 1982 at Agricultural Research Institute, Patna, India. There were 70 fertile and 170 sterile plants. Few sterile plants with white anthers were detected late in the season so that planned backcrosses could not be made and open pollinated seeds were collected. During Kharif, 1983, 6 plant progeny rows each having 40 plants were grown. Two progenies had as high as 80 percent sterile plants and sterile plants were 100% pollen sterile. Further backcrosses as high as 80 percent ster eri have been made to maintain and multiply these plants. This male sterile line is being named as Patna CMS-1.