Radioactive Oxygen in the Study of Gas Transport down the Root ofVicia faba

Abstract

The movement of labelled oxygen down the main root of Vicia faba seedlings was studied. The rise of radioactivity in the roots at 15 and 18 cm. below the cotyledons follows the same kinetics as the transport of radioactive gas down a thin polythene tube open at one end. It is therefore consistent with diffusion of oxygen through continuous gas spaces in the roots. Loss of oxygen to the surrounding tissue is small in the upper parts of the roots. The volume of the gas spaces was estimated from the equilibrium radioactivity and compared with data obtained by filling the spaces with paraffin oil.