Determination of Seedling Sensitivity and Selection of Morphological Mutants by Treatments of Gamma-Ray and EMS in Rapeseed and Leaf Mustard

감마선 및 EMS처리에 의한 유채(Brassica napus L.)와 갓(Brassica juncea L.)의 유묘 감수성 평가 및 형태적 변이체 선발

This study was aimed to select useful mutants of rapeseed (Brassica napus L.) and leaf mustard (Brassica juncea L.), the seeds of three lines S-14, S-27, and S-28 were treated with gamma-ray and EMS. The optimum ranges of gamma-ray dose and EMS concentration to enlarge the characteristic morphological variations were also separately investigated. The survival rates of S-28 only linearly decreased with increasing the gamma-ray dose. The overall growth parameters decreased of gamma-ray dose in all three lines of S-14, S-27, and S-28. The reduction dosage 50 of gamma-ray was identified as 1,200 Gy for S-14 leaf mustard, while those of S-27 and S-28 rapeseed lines were appeared as same 1,000 Gy. The emergence rates of S-14 and S-27 showed no significant differences by EMS treatment, while the growth of all three lines were significantly decreased. The reduction concentration 50 in S-14 could not be determined, demonstrating that this leaf mustard line is presumably insensitive to mutagenic EMS, while those in S-27 and S-28 were identified as 3.0 and 2.5%, respectively, showing that these rapeseed lines possess higher sensitivity to EMS than S-14. Various morphological characteristics of $M_1$ generation obtained from mutagen treatment were elaborately investigated for further maintenance of $M_2$ generation. In $M_2$ generation variants showing short stem, yellow color in seed coat, chlorophyll deficiencies in leaf or pod, abnormal flower color were selected as potentially useful mutants for breeding.