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

1-Alkylpyridinium bromide [C_npy]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), [C₃py]Br and [C₅py]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 [C₃py]Br and [C₅py]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. [C₃py]Br and [C₅py]Br increased MDA content in rape seedlings leaves in a concentration-dependent manner. It was also found that [C₅py]Br was more toxic to rape seedlings than [C₃py]Br. The toxicity of pyridine ILs such as [C₃py]Br and [C₅py]Br to plants should be highly concerned.