Eco-Toxicology

The duckweed test measures the inhibition of growth of the freshwater macrophyte, Lemma sp. This test is based on the OECD Test Guideline 221 and involves exposing Lemna sp. to contaminated water for 2-d. Two toxicity test endpoints are generally measured in this toxicity test: inhibition in growth rate and changes in biomass. The aquatic plant Lemna sp. belongs to the family Lemnacae, which has a number of worldwide species and is commonly referred to as duckweed. Lemna glbba and Lemna minor are species representative of temperature areas and are the most commonly used species in toxicity tests. Both species have a floating or submerged disc old stem (frond), and a very thin root emanates from the centre of the lower surface of each frond. Lemna sp reproduces by vegetative producing new fronds. Young plants have shorter roots and consist of two to three fronds of different sizes. The small size of Lemna, its simple structure, asexual reproduction, and generation time makes plants of this genus very suitable for laboratory testing.