铀胁迫对植物光合特性的影响及植物对铀的吸收转移

Effects of uranium stress on plant photosynthetic characteristics and uptake and translocation of uranium in plants

在铀污染土壤的二次修复中,采用7科12种植物,研究铀胁迫对植物光合作用、叶绿素荧光特性的影响以及植物对铀的吸收、富集情况,为铀污染土壤的植物修复提供理论和方法依据。结果表明:(1)铀胁迫显著影响红圆叶苋、苍耳、美洲商陆、刺天茄和苘麻5种植物的光合效率,具体表现为叶片净光合速率(Pn)降低,胞间CO2浓度(Ci)增加,初始荧光(F0)增加,光系统II最大光化学效率(Fv/Fm)、光化学猝灭(qP)和最大相对电子传递速率(rETRmaxr)降低;而反枝苋、菊苣、鬼针草、向日葵和牛皮菜则对铀胁迫表现出较好的耐性。(2)酸模、鬼针草、苍耳和向日葵吸收富集铀的能力较强,在铀含量为485 mg/kg的二次修复土壤中生长3个月,体内积累的铀含量分别为363.57、91.87、75.80和65.42 mg/kg;而反枝苋、牛皮菜和美洲商陆吸收富集铀的能力较弱,体内的铀含量分别为16.20、15.11和12.36 mg/kg。(3)铀在植物体内的转移能力较差,器官间的铀富集能力一般表现为根>叶>茎>果。综合比较而言,酸模、向日葵和鬼针草对铀的耐性较强、体内铀含量高,可作为铀污染土壤二次修复植物。

Effects of uranium stress on plant photosynthetic characteristics and the uptake and translocation of uranium in 12 species plants were investigated during course of the second phytoremediation of the uranium contaminated soil,in order to study the theoretical and methodological basis of uranium-contaminated soil remediation. The results showed that:( 1) The photosynthetic efficiency of Iresine herbstii‘Aureo-reticulata',Xanthium sibiricum,Phytolacca Americana L.,Solanum indicum and Abutilon theophrasti was inhibited under uranium stress,and the main phenomenon was leaf net photosynthetic rate( Pn) decreased,intercellular CO2 concentration( Ci) increased,the initial fluorescence( F0) increased,photosystem II photochemical efficiency( Fv / Fm),photochemical quenching( qP) and the maximum relative electron transport rate( rETRmaxr) reduced. Nevertheless,the photosynthetic characteristics of Amaranthus retroflexus L.,Cichorium intybus L.,Bidens pilosa,Helianthus annuus and Beta vulgaris var. cicla exhibited better resistance to uranium stress.( 2) Rumex acetosa,Bidens pilosa,Xanthium sibiricum and Helianthus annuus had a strong ability to accumulate uranium,in the second phytoremediation of 485 mg /kg uranium content soil for three months,and the uranium contents in plants were363. 57,91. 87,75. 80 and 65. 42 mg /kg,respectively; but Amaranthus retroflexus L.,Beta vulgaris var. cicla and Phytolacca Americana L. had a weak ability to accumulate uranium,and the uranium contents in plants were 16. 20,15. 11 and 12. 36 mg /kg,respectively.( 3) The translocation capacity of uranium in plants was weak,and the uranium content of organs in descending order were root,leaf,stem and fructification. In summary,Rumex acetosa,Helianthus annuus and Bidens pilosa could be used as potential remediation plants in the second phytoremediation of uranium-contaminated soil because of the better tolerance to uranium and higher uranium accumulation capacity.