Probit Analysis to Determine of the Most Appropriate Dose of Gamma Irradiation in Wheat Mutation Breeding

Identification of the appropriate dose for mutagen material is the most important step in setting experiment and creating mutant genetic material. According to a definition the most appropriate dose of mutagen is a dose that causing a reduction of 50% survival or 30% growth, compared to control. The aim of this study was to evaluate the effect of different doses of gamma radiation (0 as a control, 100, 200, 300 and 400 Gary) on the early growth characteristics for determining the appropriate dose of gamma irradiation in wheat cultivar Sardari. Therefore, an experiment was conducted based on completely randomized design with three replications at the laboratory and greenhouse. Data analysis of seed germination experiment showed significant difference in all traits including rootlet length, stemlet length, fresh weight of rootlet, fresh weight of stemlet, dry weight of rootlet and dry weight of stemlet, the exception of germination rate. Analysis of data obtained from a greenhouse, also showed significant difference in plant height and survival percentage. Based on the best fitted regression model and probit analysis determined a dose causing reduction of 50% survival or 30% growth, compared to control. It was in the range between 200 to 300 Gary, for Sardari cultivar. It could help to create adequate genetic diversity by applying this range of gamma radiation, for using in the wheat mutation breeding programs.