Abstract
One hundred and fifty lowland-rice varieties recommended by forty-seven prefectural authorities of Japan in 1962 were crossed with two different testers in order to screen male sterility-inducing cytoplasm and fertility-restoring genes.
Nineteen varieties (12.7%) carrying weak fertility-restoring gene(s) and 131 non-carriers (87.3%) were found. Almost all varieties carrying the weak restoring gene(s) were concentrated in southern Japan (Kyushu, Shikoku, Chugoku and Kinki Districts) and were developed by pure-line selection from their native varieties.
As to cytoplasm type, male sterility-inducing cytoplasm such as that found in Chinsurah Boro II was not found. Namely, all varieties tested possessed a normal cytoplasm.
