Garden cress (Lepidium sativum) seed germination, root and shoot elongation test for ecotoxicity assssment of chemical substances

The garden cress contact test is based on the Hungarian Standard MSZ 21976-17/1988 and OECD 208 protocol. Solid phase samples (soil) and water samples are directly tested. Soil extracts or elutriates are not prepared. The water content of the examined soil samples is adjusted. We use uncontaminated brown forest soil and tapwater as negative control sample. The testorganism (garden cress, Lepidium sativum) is purchased in seed-shop. Germination rate of seeds must be 95 %.

Test methodology

A 5 member ten-fold dilution series of copper solution is shown, as an example. The applied stock solution has 4000 mg/L (4000 ppm) concentration.

The water samples:

- CuSO4 solution: 400 ppm; 40 ppm; 4 ppm; 0,4 ppm; 0,04 ppm

- Tap water control sample

1. put a filter paper disc into a Petri-dish.

2. pour 5 cm3 of the members of the dilution series of the copper solution samples onto the filter paper.

3. 16 garden cress seeds are deposited on the surface of the filter paper.

4. The test is carried out in dark place at 21,5 ⁰C for 3 days.

5. Evaluate the result of the test after 7 days (measuring root and shoot length with the help of a ruler).

Soil sample:

1. put 5 grams of soil into a Petri-dish.

2. Pour 3,5 cm³ tapwater.

3. 16 garden cress seeds are deposited on the surface of the soil.

4. The test is carried out in dark place at 21,5 ⁰C for 7 days.

5. Evaluate the result of the test after 72 hours (root and shoot elongation).

Necessary materials:

• 4000 ppm copper solution
• tap water
• garden cress seeds

Necessary tools:

• Test tube rack and test tubes
• balance and spoon (when measuring soil sample)
• petri dish of 9 cm diameter
• filter paper discs
• automatic pipettes and pipette tips
• Al-foil
• ruler
• 21.5 ° C thermostat

Data evaluation

The inhibition of root and shoot elongation is given with respect to the control sample in %.

H = (C - S / C )*100

H: inhibition of root and shoot elongation in %

C: average length of the root and shoot of the seeds in the control medium [mm]

S: average length of the root and shoot of the seeds in the examined Cu samples [mm]

The same evaluation is applied for each dilution series and soil samples.

X-ppm CuSO4 solution sample figure is drawn. ED20 and ED50 values are identified from the figure with the help of Origin 6.0 software.