Role of environmental factors on the reproducibility of Lemna test

Lemna minor is a species easy to collect and culture in laboratory, and can give rapid test results. However, in order to standardise toxicity tests u sing Lemna minor as test organism, it is important to find out what natural variability different populations might have. Five Lemna populations were used for comparison. It contained two standard cultures and three populatio ns collected in natural habitats. Potassium dichromate was applied as test material. Lemna populations cultured under the same conditions showed diffe rent T-D and LC50 values. There is an inverse relation between the sensitiv ity and T-D of the strains. It is supposed that growfh rate and sensitivity of Lemna populations depend on environmental factors characterising the ha bitat in which the given popluation originally lives.