Sites of exudation of 14C-labelled compounds from wheat roots.

Summary The combination of autoradiography and a filter paper ‘sandwich’technique using wheat plants labelled with 14C has shown that roots of wheat exude two types of compounds, viz. (a) non-diffusible material released from the apices of both primary and lateral roots and (b) diffusible material released along the whole length of the roots. The high amount of non-diffusible material compared with diffusible material suggests that the former may be more significant than previously anticipated in relation to root functions and microorganisms in the rhizosphere.