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: In order to explore the copper absorption characteristics of Anodonta woodiana, this study was based on the juveniles with higher Cu absorption efficiency as the experimental subjects. Five concentration gradients (2.0, 1.0, 0.1, 0.01 and 0.005 mg·L-1) of aquatic Cu were set according to its 96 h-EC50 to the mussels and China Fisheries Water Quality Standard (GB11607-89). This exposure experiment was conducted for 24 h. The results showed that the Cu absorption efficiency increased rapidly with the increase of exposure concentration, and the highest value was (0.69±0.11) μg/(g·h) in 2.0 mg·L-1 exposure group. However, the Cu removal rate showed a general decreasing trend, in which the removal rate of 0.005 mg·L-1 exposure group was the highest 84.8%, and the removal rate of 1.0 mg·L-1 exposure group was the lowest 28.9%. In conclusion, the high Cu uptake efficiency of juvenile A. woodiana indicates that it has a very high application potential in the prevention and control of heavy metal Cu pollution in freshwater fishery waters and in the development of model organisms for monitoring and evaluating the environmental Cu pollution in freshwater fishery waters. [ABSTRACT FROM AUTHOR]

To understand the effects of silicon on the growth and development of rice roots, a hydroponic experiment with 3 levels of silicon, i.e., no silicon (T1), 125 mmol silicon·L-1 (T2), and 2 mmol silicon·L-1 (T3), was conducted, using rice cultivars TN1 and Baixiangjing with high silicon uptake efficiency and Juanyejing and Hitomebore with low silicon uptake efficiency as test materials. The results showed that with the increase of silicon supply, the root dry mass, root-shoot ratio, lateral root number, and total root length of all test rice cultivars decreased, while the dry mass of above-ground parts, root number, and root diameter increased. Relatively higher silicon supply was beneficial to the differentiation and development of indefinite roots, but not favorable to the lateral roots. Under lower silicon supply, the root dry mass and root-shoot ratio of TN1 and Baixiangjing were significantly higher than those of Juanyejing and Hitomebore. Furthermore, the number of lateral roots and the total root length of Baixiangjing were also significantly higher than those of Juanyejing and Hitomebore. It was concluded that total root length and lateral root number were the main factors affecting rice silicon uptake efficiency. [ABSTRACT FROM AUTHOR]