Abstract:

To evaluate the aquatic ecological safety of metamitron application, the growth inhibition and toxicity of metamitron on Lemna minor and Myriophyllum spicatum were studied. The number of lobes, fresh weight, plant length and fresh weight were taken as the analysis indexes and the measurement was conducted on the 7 ^th and 14^th day after the exposure treatment under different concentrations of metamitron. The results showed that: E_rC₅₀ and E_yC₅₀ of Lemna minor was 0.519 mg/L and 0.322 mg/L on lobes and 0.518 mg/L and 0.328 mg/L on fresh weight respectively on the 7 ^th day, while that of Myriophyllum spicatum was 6.240 mg/L and 4.248 mg/L on plant length and 4.092 mg/L and 2.616 mg/L on fresh weight respectively on the 14 ^th day. Metamitron had certain toxicity on Lemna minor and Myriophyllum spicatum, and inhibited their growth. In conclusion, the inhibition rate increases with the increase of metamitron concentration in a certain dose range; however, metamitron shows significant taxonomic effects on Lemna minor and Myriophyllum spicatum.

Key words: metamitron, Lemna minor, Myriophyllum spicatum, growth inhibition, ecotoxicity, EC₅₀