标准化测试种子发芽和根伸长毒性试验的基质应用研究

种子发芽和根伸长毒性试验是研究和评价新化学物质对陆生生物危害性的重要手段之一。为探究在标准化测试中能否使用非推荐基质,以及使用推荐基质时能否用灭菌法替代酸洗法处理石英砂,选取8种植物种子在5种基质中进行试验。结果表明,不同基质对种子发芽率的影响较小,但基质较低的养分含量和特殊的物理结构易对部分种子根长形成胁迫,甚至直接制约根系发育。生菜、水稻在5种基质中的发芽率和根长无显著性差异;绿豆、甘蓝、西瓜在酸洗石英砂中的根长分别为25.1、24.5、29.0 mm,在其余4种基质中根长显著缩短;青瓜在吸水纸和发芽纸中发芽率偏低,仅为83.3%;玉米在酸洗石英砂和灭菌石英砂中的发芽率和根长无明显差异,为100%/45.7 mm和93.3%/44.8 mm,其他基质中显著偏低。标准化测试条件下,以推荐的酸洗石英砂上各种子的发芽率和根长为评判依据,生菜和水稻试验可使用本研究中任意基质,绿豆、甘蓝和西瓜试验仅可使用酸洗石英砂作为基质,青瓜和玉米试验可使用干热灭菌法替代酸洗法处理石英砂,并且青瓜试验还可使用滤纸基质。以上结果为测试机构在工作实践中优化试验条件提供理论依据。

Study of Substrate Application in a Standardized Toxicity Test of Seed Germination and Root Elongation

Seed germination and root elongation toxicity test is one of the important technical means to study and evaluate the hazard of chemicals on terrestrial plants. Eight kinds of plant seeds were selected and tested in five different substrates in order to explore if non-recommended substrates could be used in the standardized test and if sterilization could replace pickling for pre-treatment when using the recommended substrates. The results showed little effect of different substrates on seed germination, but their lower nutrient content and special physical structure were likely to affect root length of some plants, or even directly constrained the root development. The seed germination and root length of lettuce and paddy had no significant differences when tested in all five substrates. The root lengths of mungbean, cabbage and watermelon in acid-washed quartz sand were 25.1, 24.5 and 29.0 mm, respectively, which were shortened significantly in other 4 substrates. The seed germination of cucumber was only 83.3% in blotting paper and germination paper. The seed germination and root length of corn were 100%/45.7 mm and 93.3%/44.8 mm when tested in acid-washed and sterilized quartz sand, which were significantly better than those in the other 3 substrates. So in a standardized test with the seed germination and root length of various seeds in acid-washed quartz sand being the criteria, (a) the lettuce and paddy tests can use any substrate in this study; (b) the mungbean, cabbage and watermelon tests can only use recommended substrates; (c) the cucumber and corn tests can use both acid-washed and sterilized quartz sand; (d) the filter paper can also be used as substrate in cucumber test. These results provide a theoretical basis for QC institutes to optimize test conditions in practice.