A half-embryo test for identification of gamma-irradiated grapefruit

Whole grapefruit were exposed to 5, 15, 30, 50, and 100 krad doses of gamma-radiation. Seeds were removed and half-embryos, consisting of one cotyledon and embryo axis dissected from the surrounding tissue. Nonirradiated half-embryos germinated faster than intact or partially dissected (outer seed coat removed) seeds. Shoot elongation was also quicker, occurring within 6 days. Irradiated half-embryos over 15 krad doses showed markedly reduced root growth and shoot elongation was almost totally retarded. Differences between irradiated and nonirradiated half-embryo were not affected when variety, harvest date, and fruit storage conditions were varied. This test could thus discriminate between irradiated and non irradiated grapefruit