Use of Sugar Beet as a Bioindicator Plant for Detection of Flucarbazone and Sulfentrazone Herbicides in Soil

Abstract

Determination of herbicide residues can be challenging due to the very low herbicide concentrations that can persist and remain bioactive in soil. Detection of residual herbicides is of great importance since these miniscule herbicide amounts may cause injury to sensitive rotational crops. Plant bioassays are a valuable alternative to instrumental procedures for determination of herbicides in soil. Instrumental methods such as gas chromatography or high performance liquid chromatography require solvent or solid phase extractions before sample analysis, and these highly efficient extractions enable the determination of total amount of herbicide in soil. In contrast, bioavailable herbicide is determined by bioassay procedures because plant response varies with soil type and generally decreases in soils of high organic matter and clay contents and low soil pH (Thirunarayanan et al. 1985; Renner et al. 1988; Che et al. 1992; Wang & Liu 1999; Wehtje et al. 1987; Grey et al. 1997; Szmigielski et al. 2009). Typically bioassay detection of herbicides that belong to different groups with different modes of action requires use of different plant species and/or measuring different plant parameters. Use of herbicides with different modes of action applied either in rotation or as pre-mixed combinations has become a common practice in farming to combat weed resistance problems. Thus performing more than one bioassay may be necessary for assessment of herbicide residues in soil after field applications of herbicides with different modes of action.