Diffusion of Carbon Compounds Away from Wheat Roots

Abstract

The exudation of organic compounds from intact roots has been reported for many plant species, but most of these results record only the water-soluble exudates and provide no information on the sites of the exudation. Pearson and Parkinson (1961) and Schroth and Snyder (1961) reported greater exudation of compounds which reacted with ninhydrin and silver nitrate from the root tip and the elongating zone of the roots of seedlings of broad bean and French bean than from the older parts of the roots; while McDougall (1968) has reported greater exudation of 14C-labelled compounds from the lateral root zones of wheat than from the tip region. Bowen (1968) found that with Pinus radiata seedlings proportionately greater loss of 36Cl occurred from the apical region of the roots than from the basal region.