Determination of lethal dose for gamma rays induced mutagenesis in different cultivars of dahlia

High aesthetic and economic importance of dahlia stimulates breeders for the development of new cultivars. To determine the lethal dose (LD50) of gamma rays in different cultivars of dahlia, an experiment was conducted at MFC, GB Pant University of Agriculture and Technology, Pantnagar. Rooted cuttings of three dahlia cultivars viz., Jyotsana, Agni and Glory of India were exposed to acute (⁶⁰Co) gamma ray irradiation at 0.0 (Control), 1.0, 1.5, 2.0, 2.5 and 3.0kR to determine the lethal doselevel. Probit analysis for extrapolated LD50 in different cultivars of dahlia for mortality was 2.07, 1.91, and 1.87 kR for Jyotsana, Agni and Glory of India, respectively indicating the higher sensitivity for cultivar Glory of India. There was direct correlation between dose of gamma irradiation and mortality of cuttings. Maximum mortality (47.00%) was observed at 3.0 kR while, minimum (10.00%) was observed at 1.0 kR dose of gamma rays treatment. Different cultivars also exhibited significant differences for mortality percentage by gamma rays irradiation. The LD50 values for maximum survival percentage of cuttings can be fixed at 2.07, 1.91 and 1.87 kR of gamma rays irradiation for cvs. Jyotsana, Agni and Glory of India, respectively.