Alkyl chain length affecting uptake of imidazolium based ionic liquids by ryegrass (Lolium perenne L.)

•Alkyl chain length affected the uptake of imidazolium based ILs by ryegrass.•A higher uptake efficiency was observed for ILs with a shorter chain length.•A longer alkyl chain length of ILs had a more negative effect on the plant growth.•ILs contents in the roots and leaves decreased with increasing alkyl chain lengths.