Sensitivity to gamma rays studies in two Iranian rice (Oryza sativa) genotypes

Determination of effective irradiation dose is prerequisite for mutation breeding and development of genetic variations by induced mutation. In this study, two rice genotypes (cultivar Fajr and landrace Tarom mohalli) were used for effective dose determination and to compare their sensitivity to different doses of gamma rays in a completely random design. It was found that, irradiation reduced significantly adventure and survival percentages of seedlings in higher doses and this reduction was more pronounced in inbred cultivar. With attention to LD50 data, our results indicated that optimum doses for landrace Tarom mohalli and for cultivar Fajr were 220 and 200 Gy, respectively. Although LD(50) was the same in both genotypes, but survival percentage of seedlings was more in landrace Tarom mohalli. We concluded that cultivars are more sensitive to gamma rays than landraces.