Overview - ISO 17126:2024 (Soil quality, lettuce seedling emergence)
ISO 17126:2024 specifies a screening test for the emergence of lettuce seedlings (Lactuca sativa L.) to determine effects of pollutants on soil flora. It is a rapid, cost‑effective biological method for assessing contaminated soils, soil materials, compost, sludge and chemical substances (excluding volatile contaminants). The test exposes lettuce seeds to mixtures of test material and a growth medium, incubates under controlled temperature and light, and records seedling emergence over a short period (typically 5 days, maximum 7 days). Results are expressed as ECx values (e.g., EC50) comparing emergence in test treatments with controls.
Key topics and technical requirements
- Test organism: Lettuce seeds (Lactuca sativa L.); avoid seeds coated with pesticides/fungicides.
- Test matrix: Contaminated soils, soil materials, compost, sludge, and chemical substances (water‑soluble and insoluble). Not applicable to volatile contaminants.
- Preparation & sampling: Sieve test material (preferably 2 mm), determine and record water content, water‑holding capacity, electrical conductivity, and pH before testing.
- Test series: Use a geometric dilution series (minimum five concentrations) between test material and growth medium; concentrations calculated on dry mass basis.
- Growth medium & cover: Washed fine quartz sand as growth medium; coarser sand as cover to allow aeration.
- Incubation conditions: First 48 h in darkness, then 16 h light / 8 h dark (≈4 300 lx ± 430 lx); temperature held constant (±2 °C) at a strain‑appropriate value.
- Endpoints & analysis: Count visible seedlings above the cover material; calculate EC50 (and optionally EC20) from emergence data.
- Chemical testing: Water‑soluble chemicals are added in moisturizing water; insoluble chemicals are applied via solvent followed by evaporation (include solvent controls).
- Equipment: Standard lab apparatus (Petri dishes, sieves, controlled environment chamber, magnifier, balance).
Applications and who uses this standard
- Environmental and ecotoxicology laboratories conducting soil quality assessment and biological screening.
- Regulatory agencies and consultants evaluating contaminated site risk and remediation effectiveness.
- Waste managers and compost/sludge producers assessing biological impacts of additives or contaminants.
- Researchers comparing soils of known and unknown quality or screening chemicals for phytotoxicity.
Benefits: fast turnaround, low cost, minimal specialized training or equipment, and direct biological relevance for plant emergence and soil health.
Related standards
Keywords: ISO 17126, soil quality, lettuce seedling emergence, Lactuca sativa, screening test, EC50, soil contaminants, seedling emergence test, ecotoxicology.
Open preview (PDF)Soil quality — Determination of the effects of pollutants on soil flora — Screening test for emergence of lettuce seedlings (Lactuca sativa L.)