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1D - Soil and Sediment Contamination (TUP/1) Non-Target Plant Testing: Variation of plant growth in relation to the plant species. Fiebig, Silke1, Makus, Petra1, McVean, Kirsten1, Noack, Udo1, 1 DR.U.NOACK-LABORATORIUM FÜR ANGEWANDTE BIOLOGIE, Sarstedt, Niedersachsen, Germany ABSTRACT- In the new OECD Guideline 208 (draft) the testing of pesticides and chemicals in terrestrial (non-target) plant tests is regulated. Pesticides will be tested in a multiple rate test to establish the EC50 and EC25 for different endpoints. Endpoints measured are the biomass (fresh or dry shoot weight and shoot height) and visual detrimental effects. Validity criteria which must be meet in the control replicates are that the mean seedling growth should not exhibit visible phytotoxic effects and the survival of the plants must be at least 90 % at the end of the test. Up to now no validity criteria exist to gauge the biomass growth or the variability of plant growth in the control replicates. Since a low variation in the control replicates is essential for a reproducible calculation of EC-values, the German authorities discussed to establish additional validity criteria for the growth of the control plants. A proposal for an additional validity criterion was that the growth variation of the control plants should be less than 20 %. Since the variation of biomass growth is very different for the various tested plant species, an equal critical value of 20 % is not practicable. The percent variation for biomass growth should be choose depending on the growth characteristics of each individual plant species. For some plant species (e.g. oats or corn) a variation of biomass growth < 15 % could be reached while for other plant species (e.g. onion) a variation of biomass growth < 20 % could be reached barely. The dependence of biomass growth variation on the plant species will be presented. Key words: Pesticides, Non-Target Plants, Validity Criteria, Variation of Biomass Growth |
