TRANSLOCATION AND TRANSFER OF NUTRIENTS IN VESICULAR‐ARBUSCULAR MYCORRHIZAS

Abstract

SUMMARY Trifolium repens (white clover) or Allium cepa (onion) infected with the mycorrhizal fungus Glomus mosseae were grown in split‐plate cultures, so that nutrients could be supplied to the external hyphae only. The uptake and translocation of 32 P, 65 Zn and 35 S by hyphae of the fungus was measured. A lag phase of 2‐3 days in the appearance of 32 P in the shoot was caused by a delay in the uptake and translocation of P by the hyphae, rather than in transfer from fungus to host. The calculated maximum translocation rate of P for onion was 6.4 × 10 −16 mole s −1 , and the P flux in the hyphae about 2 × 10 −10 mole cm −2 s −1 . The molar amounts of P, S and Zn translocated were in the ratio of 35:5:1 and the mean fluxes in the ratio of 50:8:1 with clover.