Modeling pesticide residue uptake by leguminous plants: a geocarpic fruit model for peanuts

Abstract

BACKGROUND: Pesticide residues are frequently found in leguminous plants; however, no modeling approaches predict residue concentrations in edible legume seeds. In this study, a geocarpic fruit model, simplified for neutral organic compounds, was proposed for high-throughput simulations (over 700 pesticides) of the residue uptake by peanut plants, which characterized three scenarios, namely (i) pesticide foliar application during the pre-seed development stage, (ii) foliar application during the seed development stage, and (iii) soil contamination before plant germination.RESULTS: In the foliar application scenario, in general, lipophilic pesticides have high simulated residue unit doses (RUDs, residue concentrationsinplantsper 1.0kg ha −1 of pesticide application) in peanutleavesowing tointensifieduptake via surface deposition,whereas hydrophilic pesticides have high simulated RUDs in peanuts because the uptake of residues via diffusion is enhanced. For the soilcontamination scenario, organic compounds with moderate lipophilicity have a high bioconcentration potential (i.e. the soil-plant system) in leaves and peanuts, due to large transpiration stream concentration factors (TSCFs) that boost the uptake via transpiration. CONCLUSIONS:The simulation results have some degrees of agreement with field measurements, indicating that the proposed model can be used as a screening tool for dietary risk assessment of pesticides in peanuts. In future research, pH-dependent physicochemical properties (e.g. soil-water partition coefficient and TSCF) and degradation rate constants of chemicals need to be refined to improve the simulation analysis.

Considering degradation kinetics of pesticides in plant uptake models: proof of concept for potato

“…geocarpic fruit growth) that complicate the simulation of pesticide degradation kinetics. 59 Many aboveground plants (e.g. wheat, apple, and banana) have multiple exposure pathways to pesticides, including leaf surface, fruit surface, and soil, resulting in greater uncertainty in simulation results compared to tuber plants.…”

“…groundnuts) have distinctive development patterns (e.g. geocarpic fruit growth) that complicate the simulation of pesticide degradation kinetics 59 . Many aboveground plants (e.g.…”