|Nedumpara, Mercy - IOWA STATE UNIVERSITY|
|Jayachandran, Krishnaswamy - IOWA STATE UNIVERSITY|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 1995
Publication Date: N/A
Technical Abstract: We determined the effects of vesicular-arbuscular mycorrhizal (VAM) fungi on the growth of soybean and corn in soils treated with herbicides atrazine and trifluralin at rates designed to simulate herbicide carryover. Herbicides were applied prior to planting to low P soils with native VAM population, inoculated with Glomus epigaeum, and soil without VAM. Soybean and corn growth was significantly enhanced by VAM fungi at all levels of herbicide. Relative reductions in growth of VAM-colonized and non-VAM plants were similar over the range of herbicide concentrations. Atrazine reduced VAM infection in corn by 20%, but the effect of trifluralin was negligible. Excised and whole root systems infected with VAM fungi showed 28-244% greater uptake of herbicides than non-VAM roots. Direct hyphal uptake of 14C-atrazine was demonstrated in two-chambered pots which restricted root access to the 14C-atrazine. Our results suggest that any potential negative effects on plant growth due to enhanced uptake of herbicides by VAM fungi are counteracted by the beneficial effects from P uptake.