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Tham khảo tài liệu 'waste water evaluation and management part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | The Use of Methods of Environmental Analysis and Ecotoxicological Tests in the Evaluation of Wastewater 19 comparison with other Brassicaceae and are yellow or whiteyellow of a round shape. They reach to 1.5 - 4 mm in diameter. After germination simple root with hypocotyle grows up. The high quality seeds of Sinapis alba are exposed to solution of tested compounds at temperature 20 2 C in the darkness incubator for 72 hours. The seeds 30 pieces for every tested concentration are placed on filter paper in Petri-dishes. Paper is moistened with solution of tested compounds. Dilution series of tested compounds were prepared by dilution of stock solution of tested compounds in diluent medium. Diluent medium was prepared by filling up of 2.5 ml from stock solution of every salt to 1 l volume flask. Stock solution of CaCl2. 2H2O was prepared by solution of 11.76g CaCl2. 2H2O in 1l volume flask. The other stock solution was prepared by solution of 4 93 g of each salt MgSO4 . 7H2O Na HCO3 KCl in 1l volume flask. Two replicates were done for every dilution series. For calculation values of IC50 the lengths of hypocotyls of germinated seeds in tested and in control group were measured. The inhibition of root growth the endpoint for effect calculation was measured after 72 hours. The test was considered valid if the number of germinated seeds in control was at least 90 organisms in the control did not exceed 10 . 3.1.4 Lemna growth inhibition test The test has been used for toxicity of solutions and suspensions testing. A higher freshwater plant duckweed Lemna minor L. is used. From this point of view we can talk about semichronic exposition where immediate effect as well as long-term effect is involved and visible in growth of new generation of plants. Taxonomically Lemna minor L. belongs to angiosperms Angiospermophyta monocotyledonous plants Monocotyledonopsida Lemnaceae. These macrophytes take place at maintained water areas where they serve as feed e.g. for fish and water