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1.1 This guide covers practices for conducting plant toxicity tests using terrestrial plant species to determine effects of test substances on plant growth and development. Specific test procedures are presented in accompanying annexes.

1.2 Terrestrial plants are vital components of ecological landscapes. The populations and communities of plants influence the distribution and abundance of wildlife. Obviously, plants are the central focus of agriculture, forestry, and rangelands. Toxicity tests conducted under the guidelines and annexes presented herein can provide critical information regarding the effects of chemicals on the establishment and maintenance of terrestrial plant communities.

1.3 Toxic substances that prevent or reduce seed germination can have immediate and large impacts to crops. In natural systems, many desired species may be sensitive, while other species are tolerant. Such selective pressure can result in changes in species diversity, population dynamics, and community structure that may be considered undesirable. Similarly, toxic substances may impair the growth and development of seedlings resulting in decreased plant populations, decreased competitive abilities, reduced reproductive capacity, and lowered crop yield. For the purposes of this guide, test substances include pesticides, industrial chemicals, sludges, metals or metalloids, and hazardous wastes that could be added to soil. It also includes environmental samples that may have had any of these test substances incorporated into soil.

1.4 Terrestrial plants range from annuals, capable of completing a life-cycle in as little as a few weeks, to long-lived perennials that grow and reproduce for several hundreds of years. Procedures to evaluate chemical effects on plants range from short-term measures of physiological responses (for example, chlorophyll fluorescence) to field studies of trees over several years. Research and development of standardized plant tests have emphasized three categories of tests: (1) short-term, physiological endpoints (that is, biomarkers); (2) short-term tests conducted during the early stages of plant growth with several endpoints related to survival, growth, and development; and (3) life-cycle toxicity tests that emphasize reproductive success.

1.5 This guide is arranged by sections as follows:

1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8.

5.1 Terrestrial phytotoxicity tests are useful in assessing the effects of environmental samples or specific chemicals as a part of an ecological risk assessment (3-6, 12, 13).

5.2 Though inferences regarding higher-order ecological effects (population, community, or landscape) may be made from the results, these tests evaluate responses of individuals of one or more plant species to the test substance.

5.3 This guide is applicable for: (a) establishing phytotoxicity of organic and inorganic substances; (b) determining the phytotoxicity of environmental samples; (c) determining the phytotoxicity of sludges and hazardous wastes, (d) assessing the impact of discharge of toxicants to land, and (e) assessing the effectiveness of remediation efforts.