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OECD 227: Terrestrial Plant Test - Vegetative Vigour Test

Non-target plants, i.e. plants in natural and semi-natural habitats within the agricultural land such as hedgerows, field borders, meadows and other small biotopes, may unintentionally be exposed to plant protection products drifting from the agricultural fields, to veterinary medicinal products by fertilisation with manure from treated livestock, to biozides or chemicals.
The OECD guideline OECD 227 assesses the potential effects on plants following deposition of the test item on the seedlings at the 2-4 true leaf stage.

Study Design

Plant species

The plant species selected for the test should derive from different plant families to consider the taxonomic diversity in the plant kingdom and should give reliable and reproducible results. Usually 6 to 10 plant species are chosen according to the specific properties of the test item and the intended use. Among them could be for example Allium cepa (onion), Zea mays (corn), Brassica napus (oilseed rape), Cucumis sativus (cucumber), Glycine max (soybean), Helianthus annuus (sunflower), Solanum lycopersicon (tomato) or Stellaria media (common chickweed).

Test rates

Test rates are usually determined in a range-finding pre-test. For plant protection products the rates for the pre-test are calculated based on the maximum application rate.

Course of the test

Plants are grown from seeds to the 2- to 4- true leaf stage. The sowing takes place on different dates to ensure that all species are in this stage at the application day. The test item is then sprayed onto the seedlings. The test item concentration has to be confirmed analytically. After the application, the plants are evaluated weekly for effects (phytotoxticity) in comparison to water treated control plants for 21 days. At the test end the endpoints are measured and recorded.

Endpoints

Endpoints are mortality and fresh weight. If the test is conducted as multiple rate test effects on fresh weight are reported as ERX (effective rate) for each species individually or if the test is conducted as limit test as NOER (no observed effect rate). 

Additional parameters that can be assessed are height and dry weight. Effects on these parameters are reported as ERX for each species individually.

Phytotoxicity (e.g. chlorosis, necrosis, abnormal growth, growth reduction) and growth stages (BBCH code) are recorded.

Guidelines and Literature

  • OECD Guidelines for the Testing of Chemicals No. 227 “Terrestrial Plant Test: Vegetative Vigour Test”, adopted July 19, 2006
  • OCSPP 850.4150 “Vegetative vigour”, EPA 712-C-011, January 2012