Effects of [C n py]Br (n=3,5) on the growth and physiology of rape seedlings

1-Alkylpyridinium bromide [C n py]Br is a common intermediate in chemical synthesis. With the discharge of industrial wastewater, it enters the environment and is toxic to plants. In this study, the impacts of two pyridine-based ionic liquids (ILs), [C 3 py]Br and [C 5 py]Br, on the growth and physiology of rape seedlings were investigated at concentrations of 10, 50, 100, 200, 300, and 400 mg/L. Within the concentration range (10–400 mg/L) of [C 3 py]Br and [C 5 py]Br treatment, the root length, plant height, activities of antioxidant enzymes (SOD, POD, and CAT), and the contents of Chla and Chlb showed an increase at low concentrations and a decrease at high concentrations. [C 3 py]Br and [C 5 py]Br increased MDA content in rape seedlings leaves in a concentration-dependent manner. It was also found that [C 5 py]Br was more toxic to rape seedlings than [C 3 py]Br. The toxicity of pyridine ILs such as [C 3 py]Br and [C 5 py]Br to plants should be highly concerned.