抄録
The frequency of induced mutations in cereals has been denoted mostly in terms of 'the number of mutations per 100 X1-spike strains'. In this case, workers did not consider the number of individuais within one strain. Since a segregation ratio of recessive mutants in a strain was slightly lower than that from the Mendelian expectation, the smallness of the strains produced by the sterile spikes of X1 plant caused a statistical reduction in the frequency of mutations. This shortcoming has been overcome by the develop-ment of an elaborate statistical technique(GAUL, 1958). However, the estimati, on of frequency of mu-tations by GAUL's method was so complicated that it has been rufed out of general use. Therefore, the author has proposed an easier procedure in this pa-per and applied it to estimate the frequencies of chlorophyll mutations in rice induced by γrays and pile radiations.
