【作者】 李思亮；

【导师】 倪吾钟；

【作者基本信息】 浙江大学 ， 植物营养学， 2013， 博士

【摘要】 土壤镉污染是一个日益严峻的环境问题。植物提取是一种环境友好的土壤镉污染治理方法,主要使用超富集植物或作物同时配施螯合剂,但利用富集植物进行植物提取的很少。植物重金属耐性的调控及土壤中重金属的活化是促进植物重金属吸收及提高其提取效率的关键。本论文通过水培试验和盆栽试验,结合仪器分析和生理生化测试等手段,研究铅锌矿区生长的紫花香薷对镉(Cd)的耐性和富集特性,探讨尿囊素、乳酸和聚乳酸对紫花香薷积累Cd的影响,取得了以下主要结果：1水培条件下,Cd处理紫花香薷茎、叶、地上部和根的生物量(除25μM Cd处理的地上部生物量显著高于对照)均与对照无显著性差异,50μM Cd处理紫花香薷叶的生物量和Cd处理紫花香薷叶、地上部、根和全株的生物量均显著小于对照(P<0.05)。紫花香薷地上部Cd浓度随Cd处理浓度的增大而增大,20、25、30和Cd处理的紫花香薷地上部Cd浓度分别为104.3、125.2、164.5和237.9：ng kg-1,均高于Cd超富集植物的临界浓度100mg kg-1;各处理的转运系数(地上部Cd浓度与根部Cd浓度的比值)均小于1,矿区紫花香薷可确定为Cd的耐性和富集植物。25-15μMCd处理的Fv/Fo (植物的光合能力)、Fv/Fm(光合系统(?)光化学量子效率)、qP(光化学淬灭系数)和5-10μM Cd处理的ΦPSΠ(光合系统ΓI电子传递量子产量)、ETR(电子传递速率)和Fv’/Fm’(光合系统ΓI有效光化学量子产量)均显著高于对照(P<0.05);20-50μM Cd处理的Fv/Fo、Fv/Fm、qP和15-50μM Cd处理的ΦPSΠ、ETR和Fv’/Fm’均与对照没有显著性差异,但上述所有参数在100μM Cd处理时均显著低于对照(P<0.05)。5-30μM Cd处理的净光合速率显著高于对照(P<0.05),但50和100μM Cd处理的净光合速率显著低于对照(P<0.05)。50和100μM Cd处理的气孔导度显著低于对照(P<0.05)。上述结果表明高镉处理抑制净光合速率不仅与气孔抑制有关,还与初始的光化学过程受到抑制有关。紫花香薷在其镉耐性范围内保持其稳定的叶绿素荧光特性和光合活性是其耐性机制之一。3水培条件下,在Cd处理基础上,5-30μM尿囊素处理的紫花香薷地上部生物量、根系表面积、根系体积及根系直径均显著大于(P<0.05)对照(40μMCd处理)。5和1OμM尿囊素处理的净光合速率、叶绿素值(SPAD)值显著大于(P<0.05)对照。5和10gM尿囊素处理的紫花香薷地上部Cd浓度显著高于对照(P<0.05)。5-30μM尿囊素处理的紫花香薷地上部Cd积累量显著高于对照(P<0.05)。在Cd处理基础上,所有尿囊素处理(5-30μM)的紫花香薷地上部生物量均显著大于(P<0.05)对照Cd处理)。5-10gM尿囊素处理的SPAD值显著大于(P<0.05)对照。紫花香薷地上部Cd浓度在所有处理的间均无显著性差异。5-30μM尿囊素处理的紫花香薷地上部Cd积累量均显著大于对照(P<0.05)。在Cd处理基础上,叶面喷施316、632和948μM尿囊素处理的紫花香薷地上部生物量和Cd积累量均显著大于(P<0.05)对照(喷水处理)。紫花香薷地上部Cd浓度在所有处理的间均无显著性差异(除316μM尿囊素处理外,叶面喷施316μM尿囊素处理的地上部Cd浓度显著高于对照)。尿囊素处理能提高紫花香薷对Cd胁迫的耐性,促进其生长及地上部Cd积累。4水培条件下,在Cd处理基础上,≥2000μM乳酸处理显著抑制(P<0.05)紫花香薷的生长及地上部Cd的积累。进一步试验结果表明,40μM乳酸处理的紫花香薷地上部生物量显著大于(P<0.05)对照Cd处理),200和400μM乳酸处理与对照无显著性差异。40和200μM乳酸处理的紫花香薷地上部Cd浓度均显著高于(P<0.05)对照。40和200μM乳酸处理的紫花香薷地上部Cd积累量均显著高于(P<0.05)对照。在20Cd处理基础上,乳酸／镉比为0.5、1.0和2.0的紫花香薷地上部生物量和根系总表面积、根系总体积及侧根数均显著大于(P<0.05)对照,乳酸／镉比为0.5和1.0时紫花香薷净光合速率、SPAD值也显著大于(P<0.05)对照。乳酸／镉比为1.0时紫花香薷地上部Cd浓度显著高于(P<0.05)对照。施加乳酸处理的紫花香薷地上部Cd积累量显著大于(P<0.05)对照。乳酸处理能提高紫花香薷的光合作用强度,促进其生长及地上部对Cd的积累。5采用四种模拟镉污染土壤(5mg kg-1Cd污染菜园土、10mg kg-1Cd污染菜园土、5mg kg-1Cd污染水稻土和10mg kg-1Cd污染水稻土)分别进行盆栽试验,结果表明,0.063和0.126g pot-1聚乳酸处理的紫花香薷地上部生物量、Cd积累量和紫花香薷镉提取率均显著高于(P<0.05)无聚乳酸添加处理,且均为0.126g聚乳酸处理显著高于(P<0.05)0.063g pof-1聚乳酸处理；施加量为0.063g或0.126g pot-1时,PLA1处理的紫花香薷地上部生物量、Cd积累量和紫花香薷镉提取率均显著高于(P<0.05)PLA2(PLA1分子量小于PLA2)处理。在四种镉污染土壤上,各处理紫花香薷地上部Cd浓度的差异不显著(除5mg kg-1Cd污染水稻上0.126g聚乳酸pot-1处理显著高于没有添加聚乳酸处理)。聚乳酸处理主要通过增加紫花香薷地上部生物量从而增加Cd的积累量,施加0.126g pot-1PLA1处理的镉提取率最高。更多还原

【Abstract】 Soil cadmium pollution has become a serious environmental problem. Phytoextration is regarded as an environmentally friendly method for cleaning up soils contaminated with cadmium, mainly using hyperaccumulator or crops with chelator amendment, rarely using accumulating plant. Increase in soil heavy metal bioavailability and plant tolerance to metals was the key aspect for enhancing plant uptake and extraction efficiency of metals from soil. The present study investigated cadmium tolerance and accumulation characteristics of Elsholtzia argyi, a plant origining from a mining site, and explore the effects of allantoin, lactic acid and poly-lactic acid on plant growth and Cd removal by hydroponic and pot experiments with instrument and physiological-biochemical analyses. The main results were as follows:1The results of hydroponic experiment indicated that the dry biomass of stems, leaves, shoots and roots were similar to that of control underz≤<40μM Cd, except for25μM Cd, shoot biomass was significantly higher (P<0.05) than that of control under this treatment. Leaf biomass of50μM Cd treatment and leaf, shoot, root and total plant biomass of100μM Cd treatment was significantly lower (P<0.05) than that of control. Shoot Cd concentration increased with the increase of Cd level in nutrient solution, shoot Cd concentrations of20,25,30and40μM Cd treatments were104.3,125.2,164.5, and237.9mg kg-1, respectively, which were higher than100mg kg-1, normally used as the threshold concentration for identifying the Cd hyperaccumulating plant. Translocation factors (ratio of shoot Cd concentration to root Cd concentration) of all Cd treatments were lower than1. It could be concluded that E. argyi origining from a mining site was identified as a Cd tolerant and accumulating plant species.2In the hydroponic test, Fv/Fo, Fv/Fm, qP of5-15μmol L-1Cd treatments and ΦPSΠ, ETR, Fv’/Fm’ of5-10μmol L-1Cd treatments were significantly higher (P<.05) than that of control, and these parameters were similar to control until50μmol L1Cd, but all above parameters were significantly (P<0.05) decreased at100 μmol L-1Cd. Compared with control, Pn was significantly increased (P<0.05) under5-30μmol L-1Cd. However,50and100μmol L-1Cd significantly reduced (P<0.05) it. Gs was substantially decreased at50-100μmol L-1Cd. Cd-induced decrease of Pn at high Cd stress is not only connected to stomatal limitation but also to the inhibition some of primary photochemical processes. Maintain chlorophyll fluorescence and photosynthesis parameters were one of tolerance mechanisms of E. argyi under its Cd tolerance threshold (小≤40μM).3In the hydroponic test, compared with the control (40μM Cd without allantoin added), shoot biomass, root surface area, root volume and root diameter of E. argyi increased significantly (P<0.05) under5-30μM allantoin treatments. Net photosynthesis rate and SPAD value increased significantly (P<0.05) under5and10μM allantoin. Shoot Cd concentrations of5and10μM allantoin were significantly higher (P<0.05), so were shoot Cd accumulations of5-30μM allantoin. Compared with the control (50μM Cd without allantoin added), shoots biomass and Cd accumulation of all allantoin treatments were significant higher (P<0.05), so were SPAD value of5and10μM allantoin. The differences of shoot Cd concentration among all treatments were unsignificant. Based on50μM Cd stress, spraying allantoin (316,632and948μM) could significantly increase (P<0.05) shoot biomass and Cd accumulation. The differences of shoot Cd concentration among all treatments were unsignificant, except sparying316μM allantoin, which was significantly higher than the control. Allantoin with appropriate level can relieve Cd stress to E. argyi, promote plant growth and increase Cd accumulation in shoot.4In the hydroponic experiment, based on40μM Cd stress,≥2000μM Cd stress significantly inhibited (P<0.05) the growth and shoot Cd accumulation of the plant. Further study indicated, shoot biomass of40μM lactic acid was significantly higher (P<0.05) than that of control (40μM Cd alone), but shoots biomass of200and400μM lactic acid treatments were similar to control. Shoots Cd concentration increased significantly (P<0.05) under40and200μM lactic acid, so did shoots Cd accumulation. Compared with control (20μM Cd alone), shoot biomass, root surface area, root volume, and number of lateral tips increased significantly (P<0.05) under the ratios of lactic acid/Cd were0.5,1.0, and2.0, so did net photosynthesis rate and SPAD value under the ratios of lactic acid/Cd were0.5,1.0. Shoot Cd concentration increased significantly (P<0.05) under the ratio of lactic acid/Cd was1.0, so did shoot Cd accumulation under all lactic acid treatments. Based on above results, appropriate level of lactic acid can promote photosynthesis of E. argyi, and increase Cd concentration and accumulation in shoot.5The results of four pot experiments with four artificially contaminated soil (e.g. vegetable garden soil added with5mg kg-1Cd, vegetable garden soil added with10mg kg-1Cd, rice soil added with5mg kg-1Cd, rice soil added with10mg kg-1Cd) indicated that shoot biomass, shoot Cd accumulation and Cd phytoextraction efficiency of E. argyi grown on vegetable garden soil amended with0.063or0.126g poly-lactic acid pot-1were significantly higher (P<0.05) than no poly-lactic acid amended, and shoot biomass, shoot Cd accumulation and Cd phytoextraction efficiency of0.126g poly-lactic acid pot-1treatment was significantly higher (P<0.05) than that of0.063g poly-lactic acid pot-1treatment. Shoot biomass, shoot Cd accumulation and Cd phytoextraction efficiency of E. argyi grown on above four types of soil amended with0.063or0.126g pot-1PLA1was significantly higher (P<0.05) than that of PLA2(molecular weight of PLA2is higher than PLA1). The differences of shoot Cd concentration among all treatments were unsignificant, except for0.126g pot-1poly-lactic acid amended to5mg kg-1Cd rice soil, which was significantly higher (P<0.05) than no poly-lactic acid amended. Poly-lactic acid enhanced Cd accumulation in shoot of E. argyi mainly by increasing its biomass. Amendment of0.126g pot-1PLA1was optimal for shoot Cd accumulation.更多还原