Beyond application: How soil physicochemistry mediates pesticide uptake and bioaccumulation in rubber trees (Hevea brasiliensis)

Pesticides in agriculture and forestry carries significant environmental contamination risks due to inefficient delivery. Understanding how pesticides are absorbed and accumulated in plants is crucial for optimizing their effectiveness and minimizing their environmental impact. This study investigates the uptake and accumulation of seven pesticides: imidacloprid, tricyclazole, carbendazim, pyrimethanil, triadimefon, prothioconazole, and pyraclostrobin, in rubber tree tissues under hydroponic and soil conditions. The analysis focuses on the influence of physicochemical properties, and molecular weight (Log MW), as well as soil factors such as organic matter content and cation exchange capacity. The results showed the seven pesticides exhibited the following accumulation pattern of pesticides in rubber trees: pesticides with elevated octanol-water partition coefficient and molecular weight values tend to accumulate in roots, showing restricted translocation to stems and leaves. Pyraclostrobin, in particular, exhibited strong root retention attributable to its high hydrophobicity (log Kow). Soil organic matter and cation exchange capacity negatively correlated (|R²| > 0.66) with pesticide accumulation in roots, modulating pesticide bioavailability. Crucially, soil pore water concentrations—not total soil loads—predict root uptake (R² ≥ 0.77), establishing dissolved fractions as the ecologically relevant exposure metric. These mechanistic insights enable precision selection of low-mobility pesticides and optimized application protocols for rubber plantations, simultaneously enhancing pest management efficacy while reducing environmental contamination.