Effects of uranium tailings on growth and physiological characteristics of Brassica seedlings
铀尾沙对油菜幼苗生长和生理特征的影响

As a by-product of the uranium enrichment process, uranium tailings (UT) has lower radioactivity than purified natural uranium and similar chemical toxicity to enriched or chemically purified natural uranium. When inhaled or ingested in sufficient doses, UT causes a distinct health hazard. However, few studies were reported on the hazard extent of plants under the treatment of UT. B. juncea, B. napus and B. rapa seedlings were cultivated in the mixture of uranium tailings and river sands at the proportions of 0(CK), 25%(T1), 50%(T2), 75%(T3), 100%(T4), respectively. The emergence rate and the biomass of seedlings, the contents of chlorophyll, malonyldialdehyde(MDA) and reductive glutathione(GSH), the activities of superoxide dismutase(SOD), catalase(CAT), peroxide enzyme (POD), ascorbate peroxidase(APX), and glutathione reductase(GR) were determined in B. juncea, B. napus and B. rapa seedlings. The results indicated that the emergence rate of seedlings was promoted by UT, but there was no significant difference among the treatments of UT. The biomass of seedlings was the highest under T2 for B. napus and B. rapa, while the biomass of seedlings was the highest under T3 in B. juncea. The MDA content was the lowest under T2 in B. napus and B. rapa, while that was the lowest under T3 in B. juncea. There was significantly negative correlation between MDA and Chlorophyll content. The activities of SOD, CAT, POD, APX, GR and the content of GSH were increased with increase of applied UT in the three Brassica species. The study showed that low proportion UT could promote the growth and the antioxidase system of Brassica plants. The three Brassica species have strong tolerance to UT and can grow in UT as the pioneer plants.