ABSORPTION OF PHOSPHORUS FROM SOILS BY MYGORRHIZAL PLANTS

Abstract

Transfer of 32P to the shoots of non‐mycorrhizal and mycorrhizal plants of Pinus radiata growing in soil and in expanded perlite has been comparedby assaying the amount reaching the shoot apex. In expanded perlite and in soils with low phosphorus‐sorption capacities movement of 32P to the shoot apex of non‐mycorrhizal plants was rapid during an initial phase but reduced in rate during a prolonged second phase. Movement of 32P to the shoot‐tip of mycorrhizal plants, however, was at a relatively steady rate, which eventually exceeded that in non‐mycorrhizal plants. In soils of high phosphorus‐sorption capacity the rate of movement was reduced but followed the same course as that from expanded perlite. Transfer of 32P to the shoots of both mycorrhizal and non‐mycorrhizal plants was negligible over a short period from a soil of very high phosphorus‐sorption capacity. It is suggested that the apparent solubilizing effects of mycorrhizas on soil phosphorus may simply be a consequence of the rapid withdrawal of labile phosphorus by the mycorrhizal sheath. Copyright © 1962, Wiley Blackwell. All rights reserved