Ecotoxicity - Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test (OECD 208; 2006).
This test is designed to evaluate the effects on seedling germination and the initial growth of plants after exposure to the test substance incorporated in the soil or applied to the surface of the soil.
The seeds are placed in contact with the soil treated with the test substance by one of the two indicated methods (incorporation to the soil or application on the surface) and evaluated to determine the effects between 14 and 21 days after germination occurred in 50% of the seedlings in the control group, not exposed to the product under evaluation. The evaluation criteria are the visual observation of the germination of the seedlings, the measurements of biomass (dry or wet) of the plants, the height of the shoots and the harmful effects visible in different parts of the plant.
This Standard does not indicate the number of species to be included in the tests, since it depends on the relevant regulatory requirements, which must be consulted with the competent authorities. The Standard does indicate that the plant species selected for the test must correspond to different plant families to consider the taxonomic diversity in the plant kingdom and obtain reliable and reproducible results. In the choice of species, one must take into account their taxonomic diversity in the plant world, their distribution, the abundance of specific characteristics of the life cycle of the species and the regional natural existence. Typically, 6 to 10 plant species are chosen according to the specific properties of the substance to be tested and the intended use. In general, you can use species of crops, as well as other species not usually cultivated. Among the crop species can be considered as usual: tomato, cucumber, lettuce, soy, cabbage, carrot, oats, corn, onion or forage. For species not habitually cultivated, we recommend requesting information from regulatory authorities to include those that are really suitable for the area of product use.
The test can be performed with multiple concentrations to determine the dose-response curve, or with a single concentration as a limit test (with a maximum concentration of 1,000 mg/kg of dry soil), depending on the objective of the study. An appropriate statistical analysis is used to determine the concentration or proportion that causes a toxic effect (ECx: Effect concentration; ERx: Effect rate) with an undesirable alteration or damage for each species (germination, weight of biomass, final number of plants present, visible alteration). In addition, if the limit test is performed, the concentration in which no effects are observed (NOEC: No Observed Effect Concentration) and the lowest concentration where effects are observed (LOEC: Lowest Observed Effect Concentration) can be calculated.
To carry out the tests, the following information must be provided to the laboratory: test to be evaluated according to the expected route of exposure (incorporation to soil or surface application); concentration range to be evaluated; nature of the product and its solubility (if it is insoluble in water, indicate what is the recommended organic solvent); type of plants against which you want to evaluate (from usual crops or others), if possible consulting with the relevant registration authorities in case they require special.