Bioaccumulation and degradation of ametryn in Medicago sativa, ryegrass, wheat and maize

Importance of the work and objectives: Ametryn as a selective and uptake triazines herbicide is widely used for killing annual grasses and weeds in China and other countries. However, overuse of ametryn results in... [ view full abstract ]

Importance of the work and objectives:
Ametryn as a selective and uptake triazines herbicide is widely used for killing annual grasses and weeds in China and other countries. However, overuse of ametryn results in contamination to soil environment. The purpose of the study was to test the accumulation and degradation of ametryn in different plants (wheat, ryegrass, alfalfa and maize).
Methodologies:
Soil enzyme activities and the antioxidant and degradation enzyme activities in ryegrass tissues were determined by spectrophotometer. Ametryn and low molecular weight organic acids (LMWOAs) in plants and soil were quantified using HPLC.
Main results and conclusion:
When tested wheat, ryegrass, alfalfa and maize were exposed to ametryn concentrations at 1.0 mg kg-1, wheat, alfalfa and maize had larger accumulation of ametryn than ryegrass, resulting in pesticide concentration in plants. The lowest ametryn residue was found in soil planted with ryegrass and ryegrass accumulated lowest amount of ametryn. Ryegrass had the highest value of translocation factor (TF) and the strong capacity of phytoextraction from soil contaminated ametryn. The activities of CAT, GST and LAC in ametryn-exposed ryegrass tissues were significantly increased in free-ametryn ryegrass tissues. The activities of soil enzymes in soil contaminated ametryn were affected by planted different plants. The content of malonic acid, citric acid and malic acid in soil planted with wheat were highest. Above the result showed that ryegrass had a potential ability removing ametryn from contaminated soil, which may permit to develop ryegrass-based clearing-up systems for bioremediation of herbicide-contaminated soil environment.