Influence of concentration, exposure time and physicochemical properties on the root uptake and translocation of plant protection products in hydroponically grown maize, wheat and soybean

• Plant species strongly influence pesticide uptake and translocation behavior. • Lipophilic pesticides showed higher root accumulation than hydrophilic pesticides. • Increasing exposure decreased root accumulation but increased translocation. • Longer exposure led to higher root accumulation across all crops and compounds. • Translocation changes with longer exposure varied by plant species and pesticide. The root uptake by crops is an important process to consider when evaluating the environmental fate of plant protection products (PPPs). Bioaccumulation and mobility of PPPs largely depend on their physicochemical properties and the crop characteristics. Therefore, the hydroponic root uptake and subsequent translocation of imidacloprid, metalaxyl-M, fluopyram, and tebuconazole were investigated in maize, wheat, and soybean. Analysis via HPLC-HRMS revealed that no single crop showed consistently higher accumulation across all tested PPPs. Soybean exhibited the highest degree of root accumulation, with RCFs ranging from 4.3 to 59. Wheat exhibited the greatest propensity for translocation into the shoots, with TFs peaking at 5.9. Maize ranked intermediate in both aspects. Lipophilic PPPs generally exhibited greater bioaccumulation then hydrophilic ones, and the highest translocation has been observed in wheat and maize for metalaxyl and in soybean for imidacloprid with TFs for these compounds ranging between 3.0 and 5.9. Increasing PPP concentrations in the nutrient solution from 0.01 to 10 µM resulted in reduced root accumulation, as reflected by a decline in RCF from 3.8 to 0.61 in the most pronounced case. Conversely, acropetal transport increased over the same concentration range, with TF rising from 0.35 to 2.6 under the strongest observed response. A longer exposure time resulted in more pronounced root accumulation, while the change in acropetal transport varied and depended on the plant species and the physicochemical properties of the PPPs. These new insights highlight crop-specific uptake and translocation behavior in plants and could help to refine plant uptake models.