Objectives: A bioassay with duckweed (Lemna gibba L.) was used to study the effects of homeopathic potencies on the plant's growth rate. Screening included 12 substances: argentum nitricum, copper sulfate, gibberellic acid, 3-indole acetic acid, kinetin, lactose, lemna minor, methyl jasmonate, metoxuron, phosphorus, potassium nitrate, and sulfur. Each substance was tested in the potency range 14x-30x. Controls were unsuccussed and succussed water.
Design: In randomized and blinded experiments, duckweed was grown in either potentized substances or water controls over 7 days. Frond (leaf) growth was measured regularly with a computerized image analysis system and growth rates were calculated for different time intervals (day 0-7, 0-3, 3-7). Additionally, a water control run with unsuccussed water as the only test substance was performed to determine the variability of the bioassay.
Results: For the water control run, the between-group coefficient of variance for groups of five replicates was 0.87% for the frond area-related average specific growth rate r(area) compared to 1.60% for the frond number-related average specific growth rate r(num). Thus, the former is the preferred parameter to be used. Of twelve tested substances, potentized argentum nitricum, phosphorus, and kinetin significantly (p<0.05, analysis of variance F-test) affected the main parameter: frond area-related average specific growth rate (day 0-7). Segmented area growth rates (day 0-3 or 3-7) were affected by potentized argentum nitricum, gibberellic acid, lactose, and phosphorus.
Conclusions: The described experimental set-up with L. gibba as test organism appears to be a promising new model system to investigate effects of potentized substances. Yet larger sets of replication experiments with selected test substances and systematic negative controls are necessary to verify the effects found.