The relative merits of the three methods of measuring mutation frequency in barley

Abstract

Mohan Rao P.K. The relative merits of the three methods of measuring mutation frequency in barley . Radiation Botany 12 , 323–329, 1972.-Chlorophyll mutation frequency induced by single treatments with radiation (X- or γ-rays) and diethyl sulfate (dES) and by pre- and postradiation dES-treatments were analysed using M 1 -plant, M 1 -spike and M 2 -seedling methods in order to determine whether the mutagenic effects of radiation and dES combined additively or non-additively in combination treatments. The type and magnitude of the apparent combination effect (the deviation of the mutation frequency shown by combination treatment from the mutation frequency expected on additive basis) depended on the method of mutation analysis and the severity of the combination treatment. This result was considered to be due to the existence of appreciable differences in the ability of the three methods to measure the true mutation frequency induced by mutagens. It was concluded that M 1 -plant and M 1 -spike methods grossly underestimate the induced mutation frequency, especially, in severe mutagenic treatments. This tendency was attributed to the inability of these methods to account for the frequency of mutant initials in each spike primordium which, together with the frequency of spike primordia mutated, determines the total induced mutation frequency. The M 2 -seedling method was considered to be superior to both M 1 -plant and M 1 -spike methods since it measures both the components of induced mutation frequency.