Uptake of cyantraniliprole into tomato fruit and foliage under hydroponic conditions: application to calibration of a plant/soil uptake model.

Measured uptake of cyantraniliprole (3-bromo-1-(3-chloro-2-pyridinyl)-N-[4-cyano-2-methyl-6-[(methylamino)carbonyl]phenyl]-1H-pyrazole-5-carboxamide) into tomatoes following hydroponic exposure allowed calibration of a novel soil uptake model. The total mass of plant parts in treated plants was derived from the weights of successively harvested control plants (no cyantraniliprole provided) over 18 days following the first sampling of ripe tomatoes. Transpired water measured during plant growth was coupled with the calculated increase in plant mass to determine a transpiration coefficient constant (L/kg plant fresh weight) for use in the model. Cyantraniliprole concentrations in mature fruit, fresh foliage, and plant uptake solutions were used as the basis for a nonlinear least-squares optimization that consistently resolved to values that were empirically valid compared to metabolism studies in whole plants. This calibrated reference model adequately described uptake from soil pore water into plant fruit, and served as the basis for describing residues in fruit following commercial greenhouse growing conditions.