PENETRATION OF TRIOLEIN AND METHYL OLEATE THROUGH ISOLATED PLANT CUTICLES AND THEIR EFFECT ON PENETRATION OF [C-14] QUIZALOFOP-ETHYL AND [C-14] FENOXAPROP-ETHYL

The penetration of two model seed oil compounds, [C-14]triolein (TRI) and [C-14]methyl oleate (MEO) through plant cuticles and their effects on the penetration of [C-14]quizalofopethyl and [C-14]fenoxaprop-ethy l were investigated. Experiments were carried out using isolated cutic les from rubber plant (Ficus elastica Roxb.) leaves and from tomato (L ycopersicon esculentum Mill.) and pepper (Capsicum annuum L.) fruits. Chemicals were deposited in droplets on to cuticle discs maintained on agar blocks under controlled conditions. TRI and MEO were used at 1% (VN). The transfer of radiolabel through cuticles was negligible for T RI and varied from 6 to 13% after 72 h, according to species, for MEO. The penetration results obtained for quizalofop-ethyl (0.084 mg mL(-1 )) and fenoxaprop-ethyl (0.189 mg mL(-1)) were very similar and varied according to species. The greatest diffusion into agar was observed f or pepper (12.8% and 10.7% after 72 h, for quizalofopethyl and fenoxap rop-ethyl respectively), the lowest for rubber plant cuticles (1.4 and 1.3% respectively). Addition of MEO produced significant increases in the penetration of quizalofop-ethyl and fenoxaprop-ethyl through rubb er plant and tomato cuticles. TRI had an enhancing effect on the two h erbicides only with rubber plant cuticles. Results are discussed with particular consideration of the variations between plant species and t he possible mode of action of seed oil adjuvants.