Abstract
Experiments are reported in which the meristem of the root of Vicia faba was irradiated while the root was immersed in deoxygenated water. Oxygen was supplied in various N2[long dash]O, and He[long dash]O2 gas mixtures to the cotyledons of the seedlings. The relative radiosensitivity of the meristem was used as an indicator of O2 reaching the meristematic tissue. The supply of O2 to the lower parts of the roots is discussed.