Studies on the utility of artificial mutations in plant breeding. : V. Mutagenic effects of several chemicals on rice.

Abstract

The mutagenic effects of six chemical cornpounds, ethyleneimine (EI), ethyleneoxide (EO), diethylsulfate (DS), methyl methanesulphonate (MMS), ethyl methanesulphonate (EMS), and propyl methanesulphonate(PMS), were studied in rice. Dry seeds of the rice variety "Gimbozu" were treated with solutions of these chemicals at various concentrations (0.01-1%), or with X-rays (5-50kr) for comparison. In the treated generation(X1), the chemical agents reduced both the germination rate and the survival rate (lOOXno. of surviving plants/no. of seeds sown) and also delayed the speed of germination, whereas X-rays had no apparent effect on the germination behavior even at the high doses when no plants survived (Fig. 1). The chemical agents as well as X-rays induced chimerical sterility. The fertility of the X1 plants linearly decreased as the dosage of each agent was increased (Fig. 2). Chlorophyll mutations were induced by all of the chemical agents except MMS. Within the limit of the dosage used in the present experiment, the maximum rates of chlorophyll mutation, 33. 3% per X1-panicle progeny and 4. 83% per X2 Seedlings respectively, were obtained at about the LD50- dosage of EI. Although the most effective dosages for the other chemical agents could not be determined, the mutagenic effccts of EMS and PMS seemed to surpass those of X-rays. (Table 3, Fig. 4) These results suggest that a higher mutation rate may be obtained from a more proper application of the chemical agents and that at least EI, EMS and PMS are more effective mutagens than X-rays in rice.