铀尾沙对油菜幼苗生长和生理特征的影响

采用沙培盆栽试验,以铀尾沙所占比例分别为0%(CK)、25%(T1)、50%(T2)、75%(T3)、100%(T4)的培养基质,研究了铀尾沙对芥菜型油菜、甘蓝型油菜和白菜型油菜出苗率、幼苗生物量、叶绿素含量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)活性和还原型谷胱甘肽(GSH)含量的影响.结果表明:不同比例的铀尾沙对油菜出苗率的影响差异不显著(P＞0.05).3种油菜的生物量均随铀尾沙处理量的增加而呈先增后降的现象,甘蓝型油菜和白菜型油菜在T2时生物量最大,芥菜型油菜在T3时生物量最大.MDA含量则呈先降低后升高,甘蓝型油菜和白菜型油菜在T2时MDA含量最低,芥菜型油菜在T3时的MDA含量最低,并与叶绿素含量呈显著的负相关.随铀尾沙处理量的增加,3种类型的油菜SOD、CAT、POD、APX和GR活性逐渐增加,GSH含量也持续升高.铀尾沙对油菜幼苗生长和抗氧化酶系统产生了一定的诱导作用,而这3种油菜也对铀尾沙也表现出较强的耐受能力.

Effects of uranium tailings on growth and physiological characteristics of Brassica seedlings

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.