Subterranean clover (Trifolium subterraneum L.) in symbiosis
with Glomus mosseae (Nicol. & Gerd.) Gerdemann
& Trappe was grown in compartmented pots. Side compartments were filled
with
soil where recently added (1 wk)
radio-labelled cadmium (Cd) at three levels of non-labelled Cd could be
accessed
by either roots or arbuscular
mycorrhizal hyphae. All treatments were replicated with non-mycorrhizal
plants.
After a growth period of 52 d roots and shoots were analysed for
109Cd, and lengths of roots and hyphae in respective labelled
compartments determined. Cadmium uptake by roots was not significantly
influenced
by the mycorrhizal status of the plant.
Uptake of Cd from hyphal compartments was higher in mycorrhizal than in
non-mycorrhizal plants, corresponding
to 96, 127 and 131% of that in non-mycorrhizal plants when 1, 10 and 100
mg
Cd kg−1 was added, respectively.
A large proportion of the increased Cd content of mycorrhizal plants was
sequestered in the roots. It is concluded
that extraradical hyphae of AM fungi can transport Cd from soil to plants,
but
that transfer from fungus to plant
is restricted due to fungal immobilization. No reduction of hyphal growth
into
soil with up to 20 mg extractable Cd kg−1 was observed.