摘要
以镉超积累植物龙葵(Solanum nigrum L.)为材料研究了不同氮形态对其镉(Cd)积累的影响及其生理响应机制,为今后利用龙葵进行植物冶金和镉污染土壤修复提供理论依据。采用龙葵室内盆栽控制试验,采用不同浓度3种氮形态[铵态氮NH_4_2SO_4、硝态氮NaNO_3、硝态-铵态氮NH_4NO_3]处理,以植株生长为重要参考,研究其对镉积累、抗氧化系统和氮同化的影响。结果表明,(1)镉(10~160 mg·kg^(-1))显著影响龙葵生长,降低生物量积累;外施3种形态氮均能缓解40 mg·kg^(-1)镉毒害,提高地上部生物量、叶绿素含量和镉累积量,且铵态氮对生物量增产与镉累积效果优于其他形态氮肥,其中400mg·kg^(-1)的NH_4_2SO_4最为明显。(2)植株叶片过氧化氢(H_2O_2)水平随施铵态氮和铵态-硝态氮量增加而降低,随施硝态氮量增加而先降后升。(3)过氧化氢酶(CAT)和过氧化物酶(POD)随施硝态氮与硝态-铵态氮浓度增加而减低,超氧化物歧化酶(SOD)活性随施硝态氮量增加先升后降;POD活性随施加铵态氮浓度增加而逐渐升高,显示铵态氮能显著提升幼苗抗氧化能力。(4)随硝态氮施加量增加,硝酸还原酶(NR)和谷氨酰胺合成酶(GS)活性先升后降;而GS活性在铵态氮施加量为100 mg·kg^(-1)时达到最大,随后逐渐降低。同时,谷氨酸脱氢酶(GDH)活性随着3种不同形态氮施加量的增加逐渐降低。从植物修复角度出发,铵态氮对龙葵的强化修复效果优于硝态氮与硝态-铵态氮,尤其是400 mg·kg^(-1)的NH_4^+为龙葵镉修复的最佳浓度。
Solanum nigrum L. has been discovered to be a Cd hyperaccumulating species, and is therefore used for phytomining and phytoextracting Cd from contaminated soils. The effects of different nitrogen forms [(NH4)2SO4, NaNO3, NH4NO3] on plant growth, Cd accumulation, antioxidant system and nitrogen assimilation were investigated in the hyperaccumulator plantSolanum NigrumL. The results showed that: (1) Cd treatments (10~160 mg·kg-1) significantly impacted biomass and diameter of root and shoot, and decreased the accumulation. However, the addition of three doses of nitrogen forms significantly alleviate the toxic effects of 40 mg·kg-1 cadmium, which mainly due to the promotion of shoot biomass, Cd accumulation and chlorophyll contents. Moreover, (NH4)2SO4 (400 mg·kg-1) is more effective in the accumulation of biomass than others. (2) The content of leaf hydrogen peroxide (H2O2) was decreased with increasing (NH4)2SO4and NH4NO3 doses, while its level was declined first and then ascended with increasing NaNO3 doses. (3) Similarly, activities of catalase (CAT) and peroxidase (POD) were decreased with increasing NaNO3 and NH4NO3 doses, while activity of superoxide dismutase (SOD) was declined first and then ascended with increasing NaNO3 doses. Interestingly, with increasing (NH4)2SO4 doses, POD activity was increased significantly, suggesting that (NH4)2SO4can markedly improve its antioxidant capacity. (4) The activities of nitrate reductase (NR) and glutamine synthetase (GS) were ascended first and then declined with increasing NaNO3 doses, while the GS activity was the maximum value at concentration of 100 mg·kg-1 (NH4)2SO4, and then gradually decreased. In addition, activity of glutamate dehydrogenase (GDH) was decreased with the increasing of nitrogen doses of three forms. Besides, the content of GSH did not showed significant differences among different NH4NO3doses. These indicate that the enhancing effect of (NH4)2SO4on Cd extraction is more obvious than that of NaNO3and NH4NO3. That is to say, (NH4)2SO4 should
出处
《生态环境学报》
CSCD
北大核心
2016年第4期715-723,共9页
Ecology and Environmental Sciences
基金
四川农业大学学科建设双支计划项目(03571458)
关键词
龙葵
氮形态
镉胁迫
氮同化
抗氧化系统
Solanum nigrum L.
nitrogen forms
cadmium stress
nitrogen assimilation
antioxidant system
