Uptake of Atrazine by Hyphae ofGlomusVesicular-Arbuscular Mycorrhizae and Root Systems of Corn (Zea maysL.)

Abstract

A system, including a specialized treatment vessel for pesticide uptake studies, was developed and experiments were carried out to determine the ability ofGlomus intraradices(Schenck & Smith),G. vesiculiferium(Thaxter), and indigenous vesicular-arbuscular mycorrhizae (VAM) fungi to influence14C-atrazine uptake and transfer to corn. Uptake by root systems with and without VAM infection was compared to uptake by VAM hyphal systems by controlling access to14C-atrazine-treated soil. Hyphal systems ofGlomusspecies were able to remove14C-residue from soil and transfer these to corn. Amount of14C-residue transferred to corn through hyphal systems was highly correlated to the level of VAM root infection which varied among VAM species. In root systems, variations in14C-residue uptake resulting from mycorrhization were largely explained in terms of the negative correlation between level of infection and root mass located in14C-atrazine-treated soil. Allocation of14C-residue to shoot tissues of corn was greater when14C-residues were taken up through root systems rather than through hyphal systems. There were significant effects of VAM species on14C-residue compartmentalization between methanol extractable and nonextractable portions of corn tissues. Data from these experiments in a confined soil system were related to VAM cost-benefit relationships and indicate a significant role for VAM in determining atrazine fate in agricultural systems.