A comparative study of the differential radiosensitivity of seeds, seedlings and tissue cultures of the Japanese morning glory (Pharbitis nil)

Radiobiological effects of gamma rays on seeds, seedlings andcallus tissues of Pharbitis nil were investigated. Strikingdifferences in radiosensitivity were observed among the threetypes. Seedlings treated with doses between 2 and 12 Kr showedsuch morphological effects as stunted growth of the hypocotyl,severe inhibition of root formation and of the development oftrue leaves. Low dose irradiation of seeds resulted in a positivestimulation in seedling height. Higher doses, however, provedlethal; seed germination was inhibited and in seedlings theleaves became chlorotic and development was arrested. Callustissues were more resistant to radiation and could withstanddoses up to 30 Kr. ¹Present address: Bio-Organic Division, Bhabha Atomic ResearchCentre, Bombay 400 085, India. ²Present address: Department of Biological Sciences, Universityof Tsukuba, Ibaraki, 300-31, Japan. (Received September 22, 1975; )