【作者】 张鹏；

【导师】 张超兰；

【作者基本信息】 广西大学 ， 植物营养学， 2012， 硕士

【摘要】 由于生存环境的不同,湿地植物形成了有别于旱生植物的重金属耐性机制。为了探究湿地植物在重金属胁迫下的根系结构变化和根际土壤化学机制,本文以对Cd有较强耐性和累积性的湿地植物红蛋为研究材料,通过水培试验研究红蛋植株根系泌氧量、根孔隙度、根表铁膜含量等在Cd胁迫下的变化情况；同时,通过根箱土培试验,研究根区与非根区土壤有效S、有效P、土壤pH、土壤Eh以及Cd化学形态的变化情况。研究旨在探明湿地植物红蛋在镉胁迫下的根系结构变化与根际土壤化学机制,为更好的应用其修复重金属污染环境提供科学依据。本研究主要结果如下：1.红蛋主要是通过将Cd储存在地下部来降低其对植株的毒害作用,在5mgL-1和15mg L-1Cd胁迫下培养21天后,植株地下部Cd含量分别达到了1626.70mg kg-1和1782.85mg kg-1,而地上部Cd含量分别为294.67mg kg-1和366.19mgkg-1。2.红蛋植株根系存在泌氧,在空白处理下,植株根系泌氧量为14.08μmol O2/(plant-d)。随着Cd胁迫浓度的增加,植株根系泌氧量呈下降的趋势,培养21天后,5mg L-1和15mg L-1Cd胁迫下,植株根系泌氧量分别为10.06μmol O2/(plant-d)和7.05μmol O2/(plant-d)。3.随Cd胁迫浓度的增加,红蛋植株根表铁膜及铁膜中Cd含量呈逐渐升高的趋势,培养21天后,空白、5mg L-1和15mgL-1Cd胁迫下,植株根表铁膜的含量分别为10.23mg kg-1,25.47mg kg-1和33.64mg kg-1;空白处理植株根表铁膜中为检测出Cd,而在5mg L-1和15mg L-1Cd胁迫下,植株根表铁膜中Cd含量分别为24.28mg kg-1和41.84mg kg-1。4.相关性分析表明根表铁膜含量与根系泌氧量、根孔隙度呈极显著的负相关性,表明铁膜的增厚导致根系泌氧的减少和根孔隙度的降低。同时,根表铁膜含量与铁膜中Cd的含量呈显著的正相关性,表明根表铁膜对红蛋吸收Cd有着积极的作用。5.根系能谱扫描图片显示,红蛋根系具有很强的将Cd向地上部转运能力,同时,凯氏带对限制Cd向地上部转运有重要的作用,且这种阻碍作用占主导地位；6.淹水提高了红蛋植株生物量和体内Cd含量,更有利于植株的生长和对Cd的累积。在Cd胁迫下,植物地上部生物量提高了37.89-53.04%,地上部Cd含量提高了23.63-28.06%,植株地下部生物量提高了139.05-230.24%。在15mg L-1Cd胁迫下,淹水和非淹水根区土壤中酸提取态Cd含量分别增加了4.33%和4.03%,而在30mg L-1Cd胁迫下,酸提取态Cd含量分别增加了1.48%和3.17%,表明红蛋根系有活化土壤重金属的作用。更多还原

【Abstract】 The wetland plants, different from xerphytes, have unique heavy metal tolerance due to their flooding environment. Echinodorus Osiris plant was studied in order to investigate the response of root structure and rhizosphere soil chemistry of Echinodorus Osiris plant to cadmium. The hydroponic experiment was conducted to study the changes of root radial oxygen loss (ROL), porosity, Fe plaque under the treatment of Cd. Rhizbox experiment to compare the changes of soil pH, soil Eh, available P, available S, Cd speciation in rhizosphere and non-rhizospher of plant. By doing this, we aim to provides some supplement in wetland plants tolerance to heavy metals, and help better use Echinodorus Osiris plants in phytoremediation. The major results as follows:1. The root retention plays an important role in plant tolerance to Cd. After incubation21days in5mg L-1and15mg L-1Cd treatments, the content of Cd reached1626.70mg kg-1and1782.85mg kg-1in plant root,294.67mg kg-1and366.19mg kg-1in plant shoot, respectively.2. The ROL existed in Echinodorus Osiris root, which is14.08μmol O2/(plant·d) under the control treatment. The ROL decreased with the Cd treatment, which is10.06μmol O2/(plant·d) and7.05μmol O2/(plant-d) under the5mg L-1and15mg L-1Cd treatments, respectively.3. The content of root Fe plaque and Cd in root Fe plaque increased with the Cd treatments, which is10.23mg kg-1,25.47mg kg-1and33.64mg kg-1under the control,5mg L-1and15mg L-1Cd treatments, respectively. The content of Cd in root Fe plaque were not detected in control treatment, but, it reached24.28mg kg-1和41.84mg kg-1under the Cd treatments, respectively.4. There was a significant negative corerelation between the root Fe plaque and ROL, root porosity, which indicate that the increase of root Fe plaque resulted in the decrease of ROL and root porosity. The positive correlation between root Fe plaque and Fe plaque contained Cd showed that the exsit of Fe plaque was benefit for the plant uptake of Cd.5. The scanning electron microscopy with X-ray microanalysis photo indicates that the plant has high transport ability of Cd from root to above ground, however, the Casparian strips plays more important role in restrict of Cd transport into shoot.6. The higher plant Cd and biomass in flooded soils indicates that flooding benefits plant growth and tolerance to Cd. There is a37.89-53.04%and23.63-28.06%increase of shoot biomass and Cd, and a139.05-230.24%and23.81-21.99%increase of root biomass and Cd, respectively.There is a4.33%和4.03%increase of acid extractable Cd in flooded and non-flooded soil under15mg L-1Cd treatment while there is a1.48%和3.17%increase of that under30mg L-1Cd treatment. The plant root can activate the Cd in soil in certain Cd content.更多还原