Effect of Gamma Radiation on Onion Seed Viability, Germination Potential, Seedling Growth and Morphology

Seed of onion (Allium cepa L.) cv. Ailsa Craig were exposed to various doses of gamma radiation, i.e. 10,20.40.80. and 100 krad. Irradiation doses have no significant effect on seed viability, except the highest dose (100 krad) which resulted in reduced viabi lity. However, electrical conductivities of the leachates of seeds exposed to gamma radiation were higher than that of un irradiated seeds (control). Seed germination percentage was improved at lower doses of irradiation ( 10 and 20 krad) and was unaffected at higher doses. Number of abnormal seedlings increased with increasing irradiation dose. However. types of abnormalities could not be linked with a particular irradiation dose. Seedling growth was reduced severely with an increase in irradiation dose up to 40 krad. Root growth was more sensitive to gamma radiation than shoot growth.