Abstract- (control), -3, -5, -7, -9, -11 and -13 bars were performed using polyethylene glycol-6000 (PEG-6000). A completely randomized design with three replications was used for this experiment. Germination percentage (GP), germination rate (GR), mean germination time (MGT), root length (RL) and shoot length (SL

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 M 2 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. Keywords: rapeseed / quantitative traits / mutation breeding / EMS treatment / Gamma rays Résumé -Développement et évaluation de divers mutants prometteurs de colza (Brassica napus L.) obtenus par mutagénèse physique et chimique. La variabilité génétique est essentielle pour tout programme d'amélioration de plantes et la mutagénèse s'avère une technique incontestable d'induction de nouvelle variabilité génétique dans les germoplasmes des cultures. Chez le colza, une nouvelle variabilité génétique a été induite après traitement de semences par les rayons gamma, l'EMS et leur combinaison, en utilisant différentes doses et concentrations. L'objectif de cette étude est d'évaluer et comparer les mutants M 2 obtenus pour des caractères quantitatifs, dans deux environnements contrastés. Les paramètres étudiés sont d'ordre phénologique, morphologique et agronomique. Une grande variabilité a été observée et les traitements mutagènes ont eu un effet significatif sur tous les paramètres. Les mutants qui proviennent d'une faible concentration d'EMS, durant une période modérée, sont plus précoces et ont un nombre de siliques plus élevé que la variété témoin (non traitée). Par contre, des mutants dérivés de forte concentration d'EMS, pendant une longue période, et de la combinaison d'EMS avec les rayons gamma, ont montré une réduction significative de la hauteur et de la vigueur des plantes. Par ailleurs, les plantes dérivées de ☆ Contribution to the Topical Issue "Rapeseed / Colza"

Safflower (Carthamus tinctorius) is an oilseed crop with high quality vegetable seed oil. A set of 55 accessions from different geographical origins were introduced to constitute a breeding program germplasm. These materials were characterized by inter-simple sequence repeat (ISSR) as a simple method to reveal polymorphism among them. ISSR analysis was carried out with 13 primers. After agarose gels analysis, ISSR banding patterns were converted into binary data of presence-non presence and matrices were processed. Genetic distances between all pairwise combinations of the accessions were calculated using similarity of simple coefficient matching (SCM). Dendrogram of studied accessions was constructed using the UPGMA (unweighted pair group method arithmetic average) method. A high number of reproducible ISSR bands exhibited a high percentage of polymorphism (69.64%), indicating a high genetic diversity among the material studied. The lowest similarity coefficient was 0.462, observed between accessions 109 and 135, whilst the highest one was 0.962, observed between accessions 68 and 126, with an average of 0.726. Dendrogram similarity relationships revealed some clusters according to different genetic pools. The ISSR markers were very informative and exhibited a high level of polymorphism. The findings of this study would be useful for safflower breeding program in Morocco as well as in other countries of the world.

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In the context of climate change and water scarcity, there is a need to develop and use drought-tolerant sesame cultivars. This study was conducted to evaluate the response of 13 sesame genotypes, including 11 mutants and their wild-types, to drought during germination and early seedling growth. Moderate and severe drought stress was simulated by applying polyethylene glycol (PEG) at two osmotic potentials, −0.6 MPa and −1.2 MPa, respectively, on seeds of two successive mutant generations, M2 and M3. The parameters measured or calculated were germination percentage (GP), germination rate (GR), mean germination time (MGT), root length (RL), shoot length (SL), root to shoot ratio (RSR), and the seedling vigor index (SVI). Results showed the significant effect of genotype, drought, and drought × genotype interaction on all parameters investigated. Under severe drought, seeds of seven genotypes, including wild types, were not able to germinate. There was a drastic decline of all parameters for the rest, except MGT and RSR, which markedly increased. Interestingly, two mutants, “ML2-5” and “ML2-10”, were identified as the most tolerant to severe drought and the most stable over both generations. The present work is the first report of sesame germplasm with such a high level of tolerance to drought during germination and early seedling growth stages.