AUTORADIOGRAPHY OF THE DEPLETION ZONE OF PHOSPHATE AROUND ONION ROOTS IN THE PRESENCE OF VESICULAR‐ARBUSCULAR MYCORRHIZA

Abstract

Using autoradiography a comparison was made of the depletion zones of 33P‐labelled phosphate around mycorrhizal Glomus mosseae and non‐mycorrhizal onion roots grown in a silty clay loam for 42 days. Mycorrhizal inoculation increased the growth and 33P content of the onion plants in both irradiated and non‐irradiated soil. Successive autoradiographs showed that for the mycorrhizal and non‐mycorrhizal roots most P uptake was within 0·2 and 0·1 cm respectively of the root surface. The effect of the mycorrhiza was similar to that of a cylinder of root hairs 0·1 cm long. Copyright © 1979, Wiley Blackwell. All rights reserved