title: Effects of potentised substances on growth rate of the water plant Lemna gibba L.
abstract: OBJECTIVE
  This study investigated, whether the growth rate of Lemna gibba L. (duckweed) can be influenced by the application of homeopathic potencies of gibberellic acid, kinetin, argentum nitricum, and lemna minor.
  
  
  METHODS
  Duckweed was grown in either potencies (14x-30x, decimal steps) or water controls (unsuccussed and succussed) over seven days. Frond (leaf-like structure) growth was measured using a non-destructive image analysis system. Growth rates were calculated for three time intervals (0-7, 0-3, 3-7 days). Five to six independent, randomized and blinded experiments were analysed for each of the four tested substances. Water control experiments were performed repeatedly to test the reliability of the experimental set-up (systematic negative controls).
  
  
  RESULTS
  The systematic negative control experiments did not yield any significant effects. Hence, false positive results could be excluded. The test system had a low coefficient of variation (1.5%). Out of the four tested substances gibberellic acid had the most pronounced effect (p=0.0002, F-test) on the main outcome parameter frond growth rate (r(area) day 0-7). Potency levels 15x, 17x, 18x, 23x and 24x reduced growth rate of Lemna gibba (p<0.05 against the pooled water control, LSD test).
  
  
  CONCLUSIONS
  Lemna gibba may be considered as a suitable test organism for further studies on the efficacy of homeopathic potencies. Evidence accumulates, that adjacent potency levels may strongly differ in their biological activity. Potential consequences for therapeutical application might be worth investigating.
authors.affiliation: Research Institute of Organic Agriculture (FiBL), Ackerstrasse, Frick, Switzerland. scherr@vfk.ch
authors.forename: Claudia
authors.initials: C
authors.lastname: Scherr
authors.forename: Meinhard
authors.initials: M
authors.lastname: Simon
authors.forename: Jörg
authors.initials: J
authors.lastname: Spranger
authors.forename: Stephan
authors.initials: S
authors.lastname: Baumgartner
mesh_terms: D000704:Analysis of Variance; D018849:Controlled Clinical Trials as Topic / Q000379:methods; D004305:Dose-Response Relationship, Drug; D005189:False Positive Reactions; D005875:Gibberellins / Q000494:pharmacology*; D006705:Homeopathy / Q000379:methods*; D007701:Kinetin / Q000494:pharmacology*; D019684:Magnoliopsida / Q000187:drug effects* / Q000254:growth & development; D010936:Plant Extracts / Q000494:pharmacology*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000254:growth & development; D012835:Silver Nitrate / Q000494:pharmacology*
chemical_list: D005875:Gibberellins; D010936:Plant Extracts; D010937:Plant Growth Regulators; D012835:Silver Nitrate; C007842:gibberellic acid; D007701:Kinetin