Abstract
Out of 153 varieties collected from 16 different countries, 54 were effective restorers, 28 were weak restorers, and the remaining 71 were non-restorers. As a rule, the non-restorers were concentrated in Japonica rice zones, while the effective ones were mainly distributed in Indica rice zones. As to the cytoplasm test with 146 varieties, 142 possessed the normal cytoplasm, but the remaining four contained the same male sterility-inducing cytoplasm as that of variety Chinsurah Boro II. The latter four belong to the boro rice group introduced from India and East Pakistan.
