放射線에 依한 水稻 可視的 突然變異의 M₃ 世代의 分離 및 劣性不足

Segregation and Recessive Deficit of Visible-Macro Mutation in M₃ Generation of X-Irradiated Rice

In order to obtain fundamental information for mutation breeding of cereal crops, segregation and recessive deficit in M₃ generation of short culm, early and late heading mutant lines were investigated in rice. About 32% of the total mutant lines selected from M₂ generation was segregated in M₃ generation, and among them segregated lines of short culm, early and late heading mutant lines were 31, 22, and 43%, respectively. Average segregation ratio in M₃ segregating lines of short culm mutants was 0.17, indicating considerable recessive deficit of mutant from. the expected ratio of 0.25, and the tendency of segregation ratio of M₃ was not in confirmity with the trend of M₂ generation. The ratio of fixed lines vs segregating lines in, M₂ basis was deviated frori the expected ratio of 1 : 2 with the deficit or excessive.