Evaluation of leaching and sensitivity in some plant species to atrazine using bioassay and chemical methods

Atrazine is one of the most important herbicides in the world and Iran, which has high stability and is likely to contaminate runoff and groundwater resources. The aim of this experiment was to determine the most sensitive of the eight plant species to atrazine and to measure the leaching front of this herbicide.

The first experiment did in order to sensitivity assessment of eight plant species (Canola, Soybean, Ryegrass, Wild Oat, Wheat, Canarygrass, Redroot Pigweed, and Corn) to simulated atrazine residues by GR50 index (the required dose of herbicide to reduce plant growth by 50% ) at 2019. The second experiment was conducted to determine leaching front of atrazine. Levels of atrazine treatments were: control, usual dose (1.25 kg.h-1) and high dose (2.5 kg.h-1). The treatments were injected into soil columns in 32 cm height PVC pipes and after three days, all 2 cm pieces of soil columns were exposed to bioassay and chemical analysis, simultaneously.In the first experiment probit regression analysis was used to identify the most atrazine-sensitive species and in second experiment with completely randomized basic design the data were investigated by regression analysis.

First experiment showed that canola was more susceptible to atrazine compared to other species. Evaluation of canola seedling weight profile and atrazine concentration simultaneously at different depths of soil showed that atrazine penetrated to 10 cm depth.

It seems that atrazine accumulation to 10 cm depth is related to higher organic matter and clay content. Due to the fact that the maximum weed seed bank was located in the surface layers of the soil, application of atrazine herbicide in this field can increase the efficiency of weed control.