EFFECTS OF 14 MEV NEUTRONS AND 300 KVP X-RAYS ON GEOTROPIC RESPONSE AND SEDIMENTATION VELOCITY OF STATOLITHS IN BARLEY ROOTS

The effects of 300 kVp x-rays and 14 MeV neutrons on the geotropic response and the sedimentation of statoliths in the statocytes of barley roots have been studied. 24 hours after irradiation with 100 rads of x-rays or 60 rads of 14 MeV neutrons in air, the geotropic response was inhibited by 25 and 15 per cent, respectively. Higher doses up to 800 rads of x-rays or 220 rads of neutrons had no greater effect. Irradiation in the absence of oxygen did not affect the geotropic response, and a slight enhancement was observed. Sedimentation of statoliths was slowed down after irradiation in air and speeded up after irradiation in the absence of oxygen. The hypothesis is put forward that the effects of radiation on geotropic response are due to the changes in the viscosity of the protoplasm; irradiation in air increases the viscosity; whereas irradiation in the absence of oxygen decreases it. Mechanisms for the effects of radiation on the viscosity of the protoplasm are suggested. © 1969 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.