放射線에 依한 水稻의 可視的 突然變異의 出現率에 關한 硏究

Studies on Frequency of Visible-Macro Mutations in X-irradiated Rice Seeds

Frequency of macro-visible mutations such as early heading, short culm, leaf and plant type etc. was compared with that of chlorophyll mutions in X-irradiated rice seeds with 25kR. Various morphological mutation types of different M₁ panicles and segregation ratio of mutant types in M₂ generation were investigated. Rate of macro-visible mutation was much higher than that of chlorphyll mutation and the majority of mutation type was early heading and short culmed types among the macro-visible mutations. Since the same types of morphological mutation were found in different panicles of single M₁ plant, one panicle selection per M₁ plant will be enough for raising M₂ progenies in mutation breeding. Consequently, estimation of number of initial cells in the seed embryo by means of M₂ segregation ratio will be reconsidered.