Effects of Homeopathic Preparations of Mercurius corrosivus on the Growth Rate of Mercury-Stressed Duckweed Lemna gibba L. as a Function of Different Stress Levels

Background and Aims: We developed a bioassay with mercury-stressed duckweed (Lemna gibba L.) to study potential effects of homeopathically potentised mercury(II) chloride (Mercurius corrosivus). Furthermore, the response of this bioassay to homeopathic treatments as a function of stress intensity was also of interest.

Methods: A bioassay with arsenic-stressed duckweed (Lemna gibba L.) was adapted for the use of mercury as stressor. Plants were poisoned with mercury(II) chloride at two different intensities (slight/severe) for 48 hours. Afterwards plants grew in either Mercurius corrosivus (24x to 30x) or water controls for seven days. Growth rates of the frond (leaf) area were determined using a computerised image analysis system. Six independent experiments with potentised Mercurius corrosivus were performed, three for each stress level. Additionally, six systematic negative control (SNC) experiments with water were conducted (three for each stress level) to investigate the stability of the experimental set-up. All experiments were randomised and blinded.

Results: Highly standardised conditions were achieved by using a specific growth chamber, leading to very small coefficients of variance (≈ 2%). The SNC experiments did not yield any significant effects, providing evidence for the stability of the experimental system. Growth rates of slightly stressed duckweed were significantly enhanced after application of Mercurius corrosivus 24x–30x compared to the controls. Growth rates of severely stressed duckweed were significantly reduced compared to the controls.

Conclusion: The test system with Lemna gibba L. yielded evidence for specific effects of Mercurius corrosivus 24x–30x, namely a growth enhancement for duckweed that was slightly stressed and a growth reduction for duckweed that was severely stressed by mercury. The Lemna gibba L. bioassay is developing into a very useful tool for homeopathic basic research, since it revealed specific effects of potentized Arsenicum album after arsenic stress, and effects of potentized Mercurius corrosivus after mercury stress, and might be used in the future for investigation of the Simile principle.

Keywords: Mercury-stressed plant bioassay, stress intensity, Mercurius corrosivus, duckweed, Lemna gibba L.