벼의 分蘖別突然變異率에 關한 硏究

Mutation Frequency of Tillers after the Irradiation of Dormant Rice Seeds

X-ray irradiated rice seeds were sown directly on the pots (not transplanted) and all the tillers including lower ones usually liable to perish in transplantation were allowed to grow fully in order to examine the differences in mutation rate among tillers. Mutation rate was considered in two ways: mutation rate based on M₁ panicle and number of mutated M₂ seedling. No definite tendencies were observed in mutation rate among the tillers in any of the doses applied. It has been regarded by some workers that the number of initial cells (in the seed embryo of cereal crops) destined later to form the sporogenous tissue of M₁ spike decreases with the order of tiller emergence, main culm having several and upper tillers having only one cell. Present results, when considered based en the initial cells, are rather contradictory with the above-mentioned hypothesis.