The effect of gamma ray treatment on seed germination and seedling growth traits Arnica chamissonis Less. ssp. foliosa and suitable gamma ray dose determination in order to induce genetic variation

Arnica chamissonis Less. ssp. foliosa is a herbaceous perennial belonging to the Asteraceae family and endemic to north America and Canada. Inducing genetic mutation is a practical approach to increase genetic diversity for breeding purposes. Effect of different gamma radiation doses (0, 100, 200, 300, 400 and 500 gray) on seed germination and seedling growth of A chamissonis (e. g. plumule and rootlet length, germination percentage, speed and mean, seedling vigor, plumule fresh and dry weight, rootlet fresh and dry weight was measured and the proper dose for mutation induction was assessed. Gamma radiation caused significant effect on parameters such as plumule and rootlet length, germination percentage, germination rate, seedling vigor, rootlet fresh weight, plumule fresh and dry weight (P≤0.01) and also rootlet dry weight (P≤0.05). Radiation with 200 gray showed the most promising effects on germination parameters of this species. Compared to the control treatment, radiation with 300 gray and higher caused adverse effects on all mentioned parameters which may be caused by producing free radicals. An LD50 of 226.275 gray was estimated for this species and the best estimated dose to induce highest genetic mutation was 181.02 gray.