To evaluate combined effects of co-existed pesticides and nanomaterials on aquatic plants, the toxicity of herbicide atrazine (ATZ) on Iris pseudacorus in the presence and absence of Graphene oxide (GO) was investigated using chlorophyll a fluorescence transients. Results showed that GO reduced ATZ accumulation in plant. ATZ or ATZ combined with GO mainly blocked electron transport beyond QA at PSII as indicated by the sharp rise of the J-step level of fluorescence rise kinetics. The pronounced increase in Fm and the loss of I-step were observed when ATZ was at 2.0 mg·L- 1 implying the damage on the oxygen evolution complex and PSI. GO at environmentally relevant concentration did not exhibit significant photosynthetic inhibitory effects on I. pseudacorus. GO at 1.0 mg·L- 1 promoted photosynthesis of I. pseudacorus under ATZ stress at 2.0 mg·L- 1. These result indicated that the presence of GO alleviated the photosynthesis inhibition by ATZ at high levels.
Keywords: Aquatic plant; Chlorophyll a fluorescence rise kinetics; Combined toxicity; Nanomaterials; Pesticide.
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