In order to select useful mutants, dormant seeds of a Welsh onion variety ´Baekeunju´ were treated with different levels of X-ray and diethyl sulfate (DES). For this study, the sensitivities on germination, emergence, seedling height, and chromosome aberrations in root tip cells were investigated in M₁ seedling stage.
The results obtained were summarized as follows;
1. The germination rate was not influenced by X-ray irradiation but in plots of DES treatment it was significantly decreased according to increasing of the DES concentration.
2. A significant reduction to emergence rate and seedling height measured on 30th day after sowing was in direct proportion to increasing of the X-ray dose and the DES concentration. Fifty per cent growth reduction dose and concentration was determined to about 33kR for X-ray, and about 0.12% for EES.
3. The chromosome aberration, such as chromosome fragment, chromosome bridge and chromosome ring, was shown much frequently in plants treated with high dose or concentration of the both mutagens. However, the DES made less aberration of chromosome than the X-ray in average of all the treated concentrations. A trend was also observed that the X-ray irradiation made more chromosome fragments than chromosome bridges and the DES treatment more chromosome bridges than chromosome fragments.
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