Selectivity of Euphorbia lathyris L., to chlortoluron results from the accumulation of the herbicide in the leaves

$\text{Euphorbia lathyris L.}$, was treated for 24 h. with 0.1, 1 and 10 ppm chlortoluron. The induction kinetic of the fluorescence on the whole leaf was registered during the following 15 days. A recovery of $\text{E. lathyris}$ seedlings and an accumulation of chlortoluron in leaves was observed. The fluorescence levels obtained on the leaves emerged after the treatments were similar to the one observed on the control plants. This explains the detoxification mechanism as an accumulation of chlortoluron in the leaves present during the treatment.