A Modification of the Lemna Test for Phytotoxicity

Abstract

1. The count of fronds of Lemna minor is more suitable for the determination of the growth rate than that of the number of plants. 2. The minimum volume of Clark's nutrient solution for one plant with two fronds is 1 ml. per day. 3. The growth of Lemna minor in nutrient solution produces measurable changes in nutrient concentration in 24 hours. A daily change of the solution is, therefore, advisable. This applies also to the nutrient containing the toxic agent, as a decrease in concentration is likely to occur there as well. 4. The previous history of the plants manifests itself in an irregular growth rate during the first days of the experiment, if their history is different from the conditions of the experiment. Plants to be used for a test should, therefore, be cultivated under the conditions to be applied for the control until their growth rate is reasonably constant. 5. The modified method for the Lemna test for phytotoxicity is described.