A modified glass bead compartment cultivation system for studies on nutrient and trace metal uptake by arbuscular mycorrhiza

A modified glass bead compartment cultivation system is described in which glass beads continue to be used in the hyphal compartment but are replaced by coarse river sand in the compartments for host plant roots and mycorrhiz al hyphae. Arbuscular mycorrhizal (AM) associations were established using two host plant species, maize (Zea mays L.) and red clover (Trifolium prate nse L.) and two AM fungi, Glomus mosseae and G. versiforme. When the standa rd and modified cultivation systems were compared, the new method yielded m uch more fungal tissue in the hyphal compartment. Using G. versiforme as th e fungal symbiont, up to 30 mg of fungal dry matter (DM) was recovered from the hyphal compartment of mycorrhizal maize and about 6 mg from red clover . Multi-element analysis was conducted on samples of host plant roots and s hoots and on harvested fungal biomass. Concentrations of P, Cu and Zn were much higher in the fungal biomass than in the roots or shoots of the host p lants but fungal concentrations of K, Ca, Mg, Fe and Mn were similar to or lower than those in the plants. There were also significant differences in nutrient concentrations between the two AM fungi and these may be related t o differences in their proportions of extraradical mycelium to spores. The high affinity of the fungal mycelium for Zn was very striking and is discus sed in relation to the potential use of arbuscular mycorrhiza in the phytor emediation of Zn-polluted soils. (C) 2000 Elsevier Science Ltd. All rights reserved.