LAUSR

This study aims to investigate the effects of oxytetracycline on growth and photosynthetic capacity of rape (Brassica campestris L.). Four levels of oxytetracycline (0, 10, 100, and 200 mg kg-1) were added to the potted soil. Chlorophyll fluorescence parameters induced by five levels (90, 190, 420, 820, and 1,500 μmol photons m-2 s-1) of PAR (PAR, photosynthetically active radiation) were measured. Plant growth indices and leaf traits were also determined. Electron transport rate increased along with the increase of PAR, but an opposite trend was found for the effective quantum yield of PSII. The quantum yield of light-induced non-photochemical fluorescence quenching in higher oxytetracycline treatments (100 and 200 mg kg-1) gradually increased when PAR increased from 90 to 820 μmol photons m-2 s-1, but then declined under higher PAR gradients. The fractions of quantum yield of non-light-induced non-photochemical fluorescence quenching in PSII were significantly higher in all the oxytetracycline treatments than in the control. Oxytetracycline exposure was also found to alter the energy distribution in the photosynthetic electron transport chain. This study showed that oxytetracycline exposure evidently diminished the photosynthetic capacity of rape, which was further supported by the observations that growth indices and leaf traits were significantly inhibited by oxytetracycline.