Weeds constitute a huge group of undesirable plants, widespread throughout the world. They represent a big problem for most farmers, who implement different methods to fight against them. Thanks to their wide occurrence, weeds however, can be an excellent indicator of the quality of soil and the whole environment where they are present. In this paper, we present the impact of four alkylimidazolium chlorides with a natural terpene component introduced into the soil: (1R,2S,5R)-(–)-menthol and alkyl substituents containing 1, 4, 9 or 12 carbon atoms, on the growth and development of selected weed species. Compounds with the highest phytotoxic activity towards gallant soldier, white goosefoot and common sorrel were chlorides with methyl and butyl substituents, while compounds with nonyl and dodecyl substituents demonstrated a weak effect on these weeds. Phytotoxicity of the salts tested was largely dependent on the applied concentration of the compound and the genetic make-up of plant species used in the experiment. This was reflected in the inhibition of plants’ length and their roots, as well as changes in the content of dry matter and photosynthetic pigments.
Ionic liquids have attracted considerable interest in various areas as new, non-volatile and non-flammable organic solvents, catalysts, reaction additives, ligands, drugs and other dedicated materials etc. Their general use, sometimes in bulky quantities, requires determination of their potential ecotoxicity on selected organisms. In the present work, influence of triphenylmethylphosphonium iodide (1) and triphenylhexadecylphosphonium iodide (2), introduced to soil, on germination and early stages of growth and development of superior plants was investigated using the plant growth test based on the OECD/OCDE 208/2006. In this test, the seeds of selected species, i.e. land superior plants - spring barley (Hordeum vulgare) and common radish (Raphanus sativus L. subvar. radicula Pers.) were planted in pots containing soil to which a test chemical compound had been added and in pots with control soil. To evaluate the phytotoxicity of ionic liquids 1 and 2 germination and weight (dry and fresh) of control plant seedlings were determined and compared with the germination and weight (dry and fresh) of the seedlings of plants grown in the soil watered with appropriate amounts of the test chemicals. The visual assessment of any types of damage to the test species, such as growth inhibition, chlorosis and necrosis, was also carried out and documented by digital photographs. Based on the obtained results, magnitudes of the LOEC - the lowest concentration causing observable effects in the form of reduction in growth and germination compared with the control and the NOEC - the highest concentration not causing observable, toxic effects - were also determined.