Peanut and sorghum are excellent phytoremediators of 14 C-tebuthiuron in herbicide-contaminated soil

Abstract

Background: Phytoremediation is a technique used in soils contaminated with residual herbicides, such as tebuthiuron. However, the herbicide presence in the soil and plant matrices are not generally quantified. Objective: This study aimed to select plant species to evaluate the phytoremediation of 14 C-tebuthiuron by showy rattlepod (Crotalaria spectabilis), sorghum (Sorghum bicolor), radish (Raphanus sativus), peanut (Arachis hypogaea), and alfalfa (Medicago sativa) in herbicide-contaminated soil. Methods: The selection of the five herbicide phytoremediation plants was with the application of five rates of tebuthiuron (300, 600, 1,200, 2,400, and 4,800 g a.i. ha-1) and compared to a control. Peanuts and sorghum (herbicide-tolerant plants) were sown in soil contaminated with tebuthiuron (600 g a.i. ha-1) applied through a working solution containing 17.47 kBq of14C-tebuthiuron. The total of herbicide was analyzed in the soil and plant at three phenological stages. Results: Showy rattlepod, radish, and alfalfa were sensitive to the herbicide even at the lowest application rate. Sorghum was tolerant to the herbicide up to 600 g ha-1 with the application of 1,200 g ha-1, there was 80% injury; peanut was tolerant even at the highest rate (4,800 g ha-1) with only 40% injury. Peanut and sorghum were able to phytoremediate the soil, although, peanut was more efficient in decreasing tebuthiuron contamination by 76%, while sorghum reduced at by 45% at 3rd phenological stage. Conclusions: Thus, both plants can be recommended in succession/ rotation with crops that had tebuthiuron applied from pre-emergence weed control.