Effects and metabolism of the phenylurea herbicide isoproturon in the submerged macrophyte Ceratophyllum demersum L.

Phenylurea herbicides such as isoproturon (IPU) restrain photosynthesis by connection to the D1 protein in the photosynthetic apparatus in target plants such as weeds in crop fields. Direct effects of herbicides on organisms, which are not a target of the pesticide, have been examined seldom. Since a many of agriculturally used pesticides are found in surface waters in agricultural areas, we determined the effects on the photosynthetic oxygen production of the submerged macrophyte Ceratophython demersum using concentrations of IPU ranging from 0.2 mu g/L to 200 mu g/L IPU. At environmental relevant concentrations of IPU, the photosynthetic oxygen release was impaired. A reduction of the photosynthetic oxygen release showed a time dependency with the assigned herbicide concentrations. Furthermore, this study presents the first indications for metabolism of IPU in the aquatic plant C. demersum.