Development and evaluation of diverse promising rapeseed (Brassica napus L.) mutants using physical and chemical mutagens☆

Genetic variability is a prerequisite for any plant breeding program, and mutagenesis is a proven way of creating new variation within a crop germplasm. Novel genetic variability in rapeseed was induced by gamma rays, Ethyl Methane Sulphonate (EMS) and combined mutagen treatment, using various doses and concentrations. The objective was to evaluate and compare the obtained M2 mutants for important quantitative traits in two contrasted environments. Data on phenological, morphological and agronomic parameters were recorded. A large variability was observed and mutagenic treatments had a significant effect on all traits studied. Compared to control plants, mutant genotypes derived from seeds treated with low EMS concentrations during moderate time were earlier and characterized by a higher number of pods per plant. For high concentration of EMS during long time and for combinations of physical and chemical mutagens, a significant decrease in plant height and stature was noticed, as compared to control. Besides, plants derived from gamma rays-treated seeds exhibited the highest 1000-seed weight. The novel induced variability may be integrated in rapeseed breeding program as a new germplasm with improved agronomic traits. Particularly, EMS1-7-stable mutant may be exploited to develop efficiently and quickly a new rapeseed cultivar with some desirable traits. The present study highlights once more the possibility to bring novel genetic diversity for rapeseed desirable traits improvement through mutation breeding.