Growth of tomato plants following exposure to fluroxypyr vapour

Summary Four‐week‐old tomato plants were exposed to fluroxypyr vapour at four concentrations between 0⋅37 pg l −1 and 5⋅5 pg l −1 for 48 h. Leaf epinasty and stem elongation were observed during this period and the rate of net CO 2 exchange in the light by the plants exposed to the highest vapour concentration also began to decline. Visible symptoms of phytotoxicity were present on all treated plants 4 weeks after exposure, indicating that assimilation of fluroxypyr vapour had taken place at concentrations as low as 0⋅37 pg l −1 . Only the plants exposed to 5⋅5 pg l −1 had reduced shoot dry weights but the others were generally taller and had lower dry matter contents, compared with untreated plants.