Uptake and accumulation of imidazolium ionic liquids in rice seedlings: Impacts of alkyl chain length.

The uptake and accumulation of three imidazolium ionic liquids with different alkyl chain lengths ([C2min]Br, [C4min]Br, [C8min]Br) in rice seedlings were investigated. All three different ILs were primarily accumulated in roots, while only a little amount of ILs were translocated and accumulated in stems and leaves. Accumulation and transportation of ILs in rice depend on the concentration and the alkyl chain length of ILs. ILs contents in the roots, stems and leaves decreased as ILs alkyl chain length increased. Growth inhibition results showed that the toxic effects of ILs on rice growth depends on the alkyl chain length: [C8min]Br >[C4min]Br >[C2min]Br. As markers of defense and phytotoxicity, the plant antioxidant enzymes and biochemical stress responses were also assessed. All different ILs significantly increased malondialdehyde (MDA), catalase (CAT), peroxidase (POD) and dismutase (SOD) activities in rice tissue. Compared to the control group, the contents of chlorophyll a reduced by 59.56%, 62.28% and 69.74% after addition of [C2min]Br, [C4min]Br, and [C8min]Br, respectively. This study provides important information for a better understanding on the uptake and accumulation of imidazolium ILs by agricultural plants.