Ecotoxicological evaluation methodology using seeds germination in nutrient gel as culture medium

Tests in studies aimed at developing ecotoxicological assessments should necessarily be conducted at the same pH value. In order for trials to be trusted, they should be performed in culture medium with identical pH values, even after addition of the stressors. This work aimed to develop a technique of ecotoxicological tests using seeds as test organisms in culture medium using gel as a support layer. The gel preparation was developed by a Dilution Water containing optimal concentrations of nutrients whose pH value had been preset and fixed by a buffer solution containing part of the desired nutrients. For ecotoxicological assessments, we added stressor concentrations in the preparation of dilution water (one for each concentration of the stressor) and we added also Agar (17 g L-1) and heated at 85 °C for complete dissolution. Volumes of solution (20 mL), still hot, were placed in glass containers (250 mL) and allowed to cool to room temperature to form a firm gel layer. About 50 seeds were placed on the top of the gel layer and the container was sealed and placed in a location with ambient light (no direct sunlight). The methodology involves simple techniques and does not require manipulation during embryo development, allowing for effective assessment of ecotoxicological tests with secure analysis of seed germination and development of the essential structures of seedlings with equal pH values, and has very low analytical cost (US $ 0.04).