Phytotoxicity Testing with Higher Plants

Spirodela Duckweed Toxicity Tests


duckweed Toxicity Test TK63 largeThe SPIRODELA DUCKWEED TOXKIT contains all materials needed to preform 2 growth inhibition tests on Spirodela polyrhiza.  Tests are preformed in 48 well microplates for a total of 5 test concentrations in 8 replicates.

The kit contains tubes with "turions" (vegetative buds) which can be stored and germinated on demand.  No need for cultures.




Please review the step-by-step presentation on the SPIRODELA DUCKWEED growth inhibition test Procedure:

Duckweed Toxicity Test Presentation

duckweed ToxicityTesting Kit Presentation

Click here to download the Spirodela duckweed Power Point.

Comparison Data of MicroBioTests

comparison Data MicroBiotests

Click here for comparison data.

Duckweed Toxicity Test Protocol

duckweed ToxicityTest TK63

Click here to download the Duckweed short protocol.

Test criterion

  • The Spirodela duckweed Toxkit is a 72 hour growth inhibition of the "first frond" after a 3 day exposure.  Growth is determined by measurement of the area of the first frond at T=0 and T=72.


  • Turions of high quality are produced 
    in strictly controlled conditions.
  • High uniform quality of the growth and dilution media is acheived by dilutions in deionized water and Steinberg medium.
  • Standard test containers constructed of biological inert materials ensure uniform exposure conditions.
  • Quality Control Test with a reference chemical is described in detail allowing for accuracy and reproducibility.


  • The dromat "turions" can be germinated "on-demand", eliminating the need and the costs of continuous culturing and maintenance of stocks of test organisms.
  • Minimal equipment required (laboratory incubator or temperature controlled room with illumination and conventional laboratory glassware).
  • Shelf life of the turions is guaranteed for several months when stored correctly.


  • Tubes with dormant turions, concentrated growth and dilution media, germination/test containers.
  • Detailed Standard Operational Procedures, abbreviated Bench Protocol and Data treatment sheets.
  • Specification sheets with batch numbers and 72 hour EC50 values for Quality Control Tests on the reference chemical (Potassium Chloride KCL).


  • Simple handlings and scorings.
  • Total performance time of the assay approximately 3 hours.
  • Area measurements of the first fronds are made on a photo of the multiwell test container, without any prior manipulation of the test organisms.
  • Excel program for easy data treatment and calculations of the 72 hour EC50 can be obtained easily.


  • Comparable to the sensitivity of the Lemna duckweed species used in conventional duckweed assays.


  • Duckweed assays are used in many laboratories globally for toxicity screening.
  • The precision of the standardized Spirodela duckweed microbiotest has been determined in an extensive "International Interlaboratory Comparison" with participation of more than 50 laboratories from 20 countries.