Atrazine suppression of fine root growth in corn

Abstract

Atrazine, a widely used herbicide, has been shown to inhibit the biological function of corn roots, but very little is known about what effect atrazine has on the production of fine roots in corn. To test the effect of atrazine on fine root growth we planted corn in 25 liter pots filled with a well-fertilised mixture of peat, composted manure, and commercial potting soil. We then isolated one nodal root per plant inside treatment tubes 90 cm (length) by 15 cm (diam.) containing the same synthetic soil as the pot. Based on a field application rate of atrazine of 1.68 1 ha^-1 we tested four levels of atrazine on the nodal roots in the treatment tubes: 0.0, 0.75, 1.5, and 3.0 times the field application rate. The plants grew for 50 days following the isolation of the nodal roots and their treatment with atrazine. The root length density of fine, lateral roots harvested 50-70 cm behind the tip of the nodal root was significantly reduced approximately 50% by all four levels of atrazine. The root tube was effective at eliminating root-shoot interactions created by the treatments as there were no significant differences in aboveground production. Atrazine could reduce yield of corn under conditions of drought stress if fine root growth is reduced by the herbicide in the field as it was in this greenhouse experiment.