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

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Summary

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.

Ancillary