Aquatic Plant Eichhornia Crassipes Research Articles

Environmental concentrations of 6PPD and 6PPD-Q cause oxidative damage and alter metabolism in Eichhornia crassipes

N-(1,3-dimethylbutyl)-N ′-phenyl-p-phenylenediamine (6PPD) and N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone (6PPD-Q) are ubiquitous in the environment and can cause toxicity to aquatic animals. However, research on the toxicological effects of 6PPD and 6PPD-Q on aquatic plants remains limited. The present study investigated the physiological, biochemical, and metabolic responses of the floating aquatic plant Eichhornia crassipes (E. crassipes) to environmentally relevant concentrations (0.1, 1, and 10 μg·L−1) of 6PPD and 6PPD-Q. We found that 6PPD and 6PPD-Q elicited minimal effects on plant growth, but 6PPD induced a concentration-dependent decrease in the content of photosynthetic pigments. Low doses (0.1 μg·L−1 and 1 μg·L−1) of 6PPD-Q significantly elevated Reactive Oxygen Species (ROS) content in E. crassipes roots, indicating oxidative damage. Furthermore, 6PPD-Q induced a more pronounced osmotic stress compared to 6PPD. Metabolic analyses revealed that carbohydrates were significantly altered under 6PPD and 6PPD-Q treatments. The findings of this study enhance the understanding of the environmental risks posed by 6PPD and 6PPD-Q to plants and reveal the potential mechanisms of phytotoxicity.

Design of a sustainable system for wastewater treatment and generation of biofuels based on the biomass of the aquatic plant Eichhornia Crassipes

Colombia’s continuous contamination of water resources and the low alternatives to produce biofuels have affected the fulfillment of the objectives of sustainable development, deteriorating the environment and affecting the economic productivity of this country. Due to this reality, projects on environmental and economic sustainability, phytoremediation, and the production of biofuels such as ethanol and hydrogen were combined. The objective of this article was to design and develop a sustainable system for wastewater treatment and the generation of biofuels based on the biomass of the aquatic plant Eichhornia crassipes. A system that simulates an artificial wetland with live E. crassipes plants was designed and developed, removing organic matter contaminants; subsequently, and continuing the sustainability project, bioreactors were designed, adapted, and started up to produce bioethanol and biohydrogen with the hydrolyzed biomass used in the phytoremediation process, generating around 12 g/L of bioethanol and around 81 ml H2/g. The proposed research strategy suggests combining two sustainable methods, bioremediation and biofuel production, to preserve the natural beauty of water systems and their surroundings.

Trade-off of abiotic stress response in floating macrophytes as affected by nanoplastic enrichment

Nanoparticles have been found in large-scale environmental media in recent years, causing toxic effects in various organisms and even humans through food chain transmission. The ecotoxicological impact of microplastics on specific organisms is currently receiving much attention. However, relatively little research to date has examined the mechanisms through which nanoplastic residue may exert an interference effect on floating macrophytes in constructed wetlands. In our study, the aquatic plant Eichhornia crassipes was subjected to 100 nm polystyrene nanoplastics at concentrations of 0.1, 1 and 10 mg L-1 after 28 days of exposure. E. crassipes can decrease the concentration of nanoplastics in water by 61.42∼90.81% through phytostabilization. The abiotic stress of nanoplastics on the phenotypic plasticity (morphological and photosynthetic properties and antioxidant systems as well as molecular metabolism) of E. crassipes was assessed. The presence of nanoplastics reduced the biomass (10.66%∼22.05%), and the functional organ (petiole) diameters of E. crassipes decreased by 7.38%. The photosynthetic efficiency was determined, showing that the photosynthetic systems of E. crassipes are very sensitive to stress by nanoplastics at a concentration of 10 mg L-1. Oxidative stress and imbalance of antioxidant systems in functional organs are associated with multiple pressure modes from nanoplastic concentrations. The catalase contents of roots increased by 151.19% in the 10 mg L-1 treatment groups compared with the control group. Moreover, 10 mg L-1 concentrations of the nanoplastic pollutant interfere with purine and lysine metabolism in the root system. The hypoxanthine content was reduced by 6.58∼8.32% under exposure to different concentrations of nanoplastics. In the pentose phosphate pathway, the phosphoric acid content was decreased by 32.70% at 10 mg L-1 PS-NPs. In the pentose phosphate pathway, the phosphoric acid content was decreased by 32.70% at 10 mg L-1 PS-NPs. Nanoplastics disturb the efficiency of water purification by floating macrophytes, which reduces the chemical oxygen demand (COD) removal efficiency (from 73% to 31.33%) due to various abiotic stresses. This study provided important information for further clarifying the impact of nanoplastics on the stress response of floating macrophytes.

Analysis of the surfactant properties of Eichhornia crassipes for application in the remediation of environments impacted by hydrophobic pollutants

The invasive aquatic plant Eichhornia crassipes may enable the generation of novel compounds with aggregate value for use in bioremediation processes. Thus, the surfactant properties of the plant extract were investigated. The critical micelle concentration (CMC) of the extract was 1.4 ± 0.1 g/L and the surface tension at this point was 25.84 ± 0.7 mN/m. The extract proved to be stable and non-toxic to the bioindicators evaluated. The emulsification index was higher than 65.00 ± 1.8% for motor oil. The chemical characterisation suggested that the structure of the extract was formed by an unsaturated fatty acid. The plant extract was capable of dispersing 100% of oil in seawater. The motor oil removal from sand with the plant extract at twice the CMC reached values around 68.04 ± 0.7% both in the kinetic assay and in the static assay using packed columns. The removal of heavy metals reached rates of around 40.00 ± 2.6%. The plant-derived surfactant clearly demonstrated viability regarding its use as a biotechnological additive for environmental remediation processes. • Surfactant properties of Eichhornia crassipes plant extract were investigated. • The plant biosurfactant proved to be stable and non-toxic to the bioindicators. • The biosurfactant emulsified 65% of motor oil and removed 40% of heavy metals. • The plant biosurfactant was characterized as an unsaturated fatty acid. • The plant biosurfactant dispersed 100% of oil and removed 67% of oil from sand.

Accumulation, distribution and removal of triazine pesticides by Eichhornia crassipes in water-sediment microcosm

After application, pesticides remained in the field may contaminate water resources through surface runoff and leaching, posing a threat to aquatic ecosystem. In the current study, the accumulation, translocation, distribution and removal of four triazine pesticides (simazine, atrazine, terbuthylazine and metribuzin) by free floating aquatic plant Eichhornia crassipes (E. crassipes) in water-sediment microcosm were investigated and the removal mechanisms were explored. E. crassipes was exposed to an initial concentration of 50 μg·L−1 and the pesticide levels in water, sediment, roots and shoots of E. crassipes were monitored during 30 days. The results demonstrated that E. crassipes was capable of accumulating triazine pesticides with the bio-concentration factor (BCF) ranging from 0.8 to 18.4. Triazine pesticides were mainly stored in roots, and root accumulation and translocation amount depend on the hydrophobicity of the pesticides. The removal of the pesticides in water were significantly accelerated by the presence of E. crassipes, with the removal efficiency ranging from 66% to 79% after 30 days of treatment. Though phytoaccumulation only constituted 2–18% of the total spiked pesticides in the microcosm, E. crassipes played a vital role in removing simazine, atrazine and metribuzin. However, microbial degradation in sediment was the main pathway for the removal of terbuthylazine in the microcosm. This study demonstrated the potential application of E. crassipes to accelerate removal of contaminants from aquatic environment.

Taxonomic notes on Malaconothridae (Acari, Oribatida) associated with water hyacinth in Egypt.

Three Egyptian species of the oribatid mite family Malaconothridae, all found on roots of the floating aquatic plant Eichhornia crassipes in the River Nile, are analyzed. Trimalaconothrus crassipes Ramadan, Ismail Mustafa, 2017 is recombined to Tyrphonothrus crassipes (Ramadan, Ismail Mustafa, 2017) (comb. nov.). Malaconothrus ramadani Ramadan, Ismail Mustafa, 2018 and M. transversus Ramadan, Ismail Mustafa, 2018 are both considered to be tritonymphs of Ty. crassipes (=M. ramadani syn. nov.; =M. transversus syn. nov.).

Efficiency of Pb, Zn, Cd, and Mn Removal from Karst Water by Eichhornia crassipes.

This study experimentally investigated heavy metal removal and accumulation in the aquatic plant Eichhornia crassipes. Pb, Zn, Cd, and Mn concentrations, plant morphology, and plant functional groups were analyzed. Eichhornia crassipes achieved high removal efficiency of Pb and Mn from karst water (over 79.5%), with high proportion of Pb, Zn, and Cd absorption occurring in the first eight days. The highest removal efficiencies were obtained at initial Pb, Zn, Cd, and Mn concentrations of 1 mg/L, 2 mg/L, 0.02 mg/L, and 0.2 mg/L, respectively. Eichhornia crassipes exhibited a high bioconcentration factor (Mn = 199,567 > Pb = 19,605 > Cd = 3403 > Zn = 1913) and a low translocation factor (<1). The roots accumulated more Pb, Zn, Cd, and Mn than the stolons and leaves due to the stronger tolerance of roots. The voids, stomas, air chambers, and airways promoted this accumulation. Pb, Cd, Zn, and Mn likely exchanged with Mg, Na, and K through the cation exchange. C≡C, C=O, SO42−, O-H, C-H, and C-O played different roles during uptake, which led to different removal and accumulation effects.

Diversity of planktonic and epiphytic microinvertebrates associated with the macrophyte Eichhornia crassipes (Mart.) in River Nile at El-Qanater El-Khiria region, Egypt

The present work aims to study the relationship between some physico-chemical parameters and both planktonic and epiphytic microinvertebrates associated with the floating plant Eichhornia crassipes in River Nile at Qanater region. Water samples, planktonic and epiphytic microinvertebrates were collected seasonally from eight sites in the investigated region. The results indicated that the maximum occurrence of planktonicinvertebrates (810 org./L) was recorded during Winter. Rotifera formed the highest percentage of zooplankton (96.77 %), followed by Copepoda (1.88 %) and Cladocera (1.10 %). Meroplankton and Protozoa formed the lowest dominant groups. Thirty seven planktonicspecies were recorded belonging to Rotifera (30 species), Cladocera (2 species), Copepoda (1 species), Protozoa (2 species) and Meroplankton (2 species). On the other hand, the maximum occurrence of epiphytic invertebrates (1612100 org./m2 plant) was recorded during spring. Forty five species were recorded belonging to Rotifera (27 species), Protozoa (5 species), Cladocera (9 species), Copepoda (2 species) and Oligochaeta (2 species). The epiphytic microinvertebrates associated with the floating plant Eichhornia crassipes in River Nile at Qanater region recorded the highest number of species and groups than planktonic invertebrates. This indicates that the aquatic plant Eichhornia crassipes habitats are more diverse and have high species richness. The principal component analysis (PCA) was conducted between physico-chemical parameters and planktonic and microinvertebrates.

Clonal integration increases growth performance and expansion of Eichhornia crassipes in littoral zones: A simulation study

Clonal integration can improve the spread and growth of invasive plants in response to various disturbances. However, little is known about its role in floating aquatic clonal plants that expand from aquatic into terrestrial habitats in littoral zones. Thus, in this study, we simulated the expansion of the invasive clonal aquatic plant Eichhornia crassipes from aquatic to terrestrial habitats through two modes of clonal integration. We subjected E. crassipes parent plants and offspring ramets to three levels of natural light in terrestrial habitats: 100%, 60%, and 10%. The stolon connections were either severed or kept intact. Our findings showed that clonal integration had positive effects on plants exposed to shade in the terrestrial habitats and produced negative effects on plants in the aquatic habitats. Overall, clonal integration significantly increased whole-plant growth performance. Parent plants and offspring ramets in the terrestrial environments can enhance their adaptability to shade by increasing the maximum quantum yield of photosystem II and chlorophyll content. Clonal integration can support the expansion of E. crassipes from aquatic into terrestrial habitats with limited light conditions through significantly elevated growth traits. Thus, E. crassipes has a high ability for clonal integration and may be a potential threat to littoral zone ecosystems.

Eichhornia crassipes су өсімдігінің жапырақ және тамырындағы биологиялық белсенді заттар

Currently relevant are studies of plants, which contain a large number of biological active substances of different composition, that are sources of biotechnological products. The main purpose of this research work in the conditions of model experience was to determine the level of accumulation of biologically active substances contained in the aquatic plant Eichhornia crassipes, distributed in the lakes of Almaty region.&nbsp;&nbsp; Eichhornia crassipes can be considered as a promising object of higher aquatic plants, for which the composition of biologically active substances has not yet been studied. The practical significance of the study is to determine the medical value of biologically active substances of plants in lakes and reservoirs.We have determined the quantitative and qualitative composition of biological active substances from vegetative aboveground (leaves and stems) and underground parts (roots) of Eichhornia crassipes plant. According to the results of qualitative indicators were identified the biological active substances prevailing in composition, such as phenolic acids, flavonoids and polysaccharides. According to the results of quantitative indicators, in the aboveground part of plants the content of tannins amounted to 6.73%, polysaccharides 5.91%, flavonoids 3.39%, phenolic acids 1.06%, coumarins 0.82%, the most common biological active materials are tannins 7.48%, polysaccharides 2.64%, anthraquinones 2.59%, proteins 0.73%, alkaloids 0.13%.&nbsp;&nbsp; The obtained results are used as laboratory work to perform laboratory work at for&nbsp; research experiments in the&nbsp;&nbsp; laboratory&nbsp;&nbsp; biotechnology specialties and to determine the content of biologically active substances of plants. Keywords: Eichhornia crassipes, biologically active substances, tannins, polysaccharides.

Metabolites from the Fungal Endophyte Aspergillus austroafricanus in Axenic Culture and in Fungal-Bacterial Mixed Cultures.

The endophytic fungus Aspergillus austroafricanus isolated from leaves of the aquatic plant Eichhornia crassipes was fermented axenically on solid rice medium as well as in mixed cultures with Bacillus subtilis or with Streptomyces lividans. Chromatographic analysis of EtOAc extract of axenic cultures afforded two new metabolites, namely, the xanthone dimer austradixanthone (1) and the sesquiterpene (+)-austrosene (2), along with five known compounds (3-7). Austradixanthone (1) represents the first highly oxygenated heterodimeric xanthone derivative. When A. austroafricanus was grown in mixed cultures with B. subtilis or with S. lividans, several diphenyl ethers (8-11) including the new austramide (8) were induced up to 29-fold. The structures of new compounds were unambiguously elucidated using 1D- and 2D-NMR spectroscopy, HRESIMS, and chemical derivatization. Compound 7 exhibited weak cytotoxicity against the murine lymphoma L5178Y cell line (EC50 is 12.6 μM). In addition, compounds 9 and 10, which were enhanced in mixed fungal/bacterial cultures, proved to be active against Staphylococcus aureus (ATCC 700699) with minimal inhibitory concentrations (MICs) of 25 μM each (6.6 μg/mL), whereas compound 11 revealed moderate antibacterial activity against B. subtilis 168 trpC2 with an MIC value of 34.8 μM (8 μg/mL).

Growth and physiological responses of Eichhornia crassipes to clonal integration under experimental defoliation

Many notorious invasive plants are clonal, and clonal integration may improve their ability to cope with disturbances such as herbivory. We hypothesize that clonal integration positively affects the growth, physiology and biomass allocation of the invasive aquatic plant Eichhornia crassipes and thus improves its performance in response to defoliation. In a 7-week greenhouse experiment, we subjected E. crassipes ramets to three levels of experimental defoliation, i.e., 20 % (mild), 50 % (moderate) and 80 % (heavy) leaf clipping and an unclipped control, and the stolon connections to the mother plants were either severed or kept intact. Compared with the control, defoliation significantly decreased the growth (total biomass and ramet number), but increased the maximum quantum yield of photosystem II (F v/F m) and chlorophyll content of the target ramets. Stolon connection (clonal integration) greatly increased the growth, F v/F m and contents of non-structural carbohydrates (soluble sugar and total non-structural carbohydrates) of E. crassipes, and these effects were larger under heavier defoliation. Moreover, stolon connection significantly reduced the shoot/root ratio of E. crassipes ramets, and such effects were greater under heavier leaf clipping. These results support our hypothesis that E. crassipes can benefit from clonal integration in response to defoliation, suggesting that clonal integration may enhance the invasion potential of E. crassipes and potentially reduce the efficacy of biological control.

Study of Naidid worms community associated with two species of aquatic plants in River Tigris inside Baghdad City / Iraq

The present study is concern with the interaction between the naidid worms diversity and the species of aquatic plant within which the worms found . For this purpose, two species of aquatic plant were used, Ceratophyllum demersum and Eichhornia crassipes. 12 samples of aquatic plants were collected , as one sample monthly for a period from September 2012 to September 2013 from different site on Tigris river within Baghdad City. From C. demersum, 1428 individuals, were sorted during the study period, related to 17 species. 12 species of subfamily Naidinae which are Chaetogaster limnaei , C. diastrophus , Ophidonais serpentine , Dero ( Dero) digitata. , D.(D.) evelinae , Nais pseudobtosa , N.simplex, N.stolci , N.Paradalis , N.elingius , N. variabilis and N. communis. In addition to five species of subfamily Pristininae, two species of Pristina , which are P. longiseta and . P. aequiseta, and three species of pristinella, which are P. . Jenkinae , P. sima , and P. osborni. Dero ( Dero) digitata was recorded the higher number of 430 individuals,with a percentage of 28.11% of the total sorted worms. About the aquatic plant Eichhornia crassipes, a total of 829 worms were sorted from it, which are related to six species of Naidinae , which are diaphanous , Ophidonais serpentine, Stylaria lacustris , Slavina appendiculata , N. variabilis and finally the species Allonais inaequalis. There was no any species of Pristininae sorted from this plant. The highest number of 467 individuals was recorded by the species Slavina appendiculata, with a percentage of 52.3% of the total number and 228 individual with a percentage of 25.5% was recorded by Allonais inaequalis.

Study of Naidid worms community associated with two species of aquatic plants in River Tigris inside Baghdad City / Iraq

The present study is concern with the interaction between the naidid worms diversity and the species of aquatic plant within which the worms found . For this purpose, two species of aquatic plant were used, Ceratophyllum demersum and Eichhornia crassipes. 12 samples of aquatic plants were collected , as one sample monthly for a period from September 2012 to September 2013 from different site on Tigris river within Baghdad City. From C. demersum, 1428 individuals, were sorted during the study period, related to 17 species. 12 species of subfamily Naidinae which are Chaetogaster limnaei , C. diastrophus , Ophidonais serpentine , Dero ( Dero) digitata. , D.(D.) evelinae , Nais pseudobtosa , N.simplex, N.stolci , N.Paradalis , N.elingius , N. variabilis and N. communis. In addition to five species of subfamily Pristininae, two species of Pristina , which are P. longiseta and . P. aequiseta, and three species of pristinella, which are P. . Jenkinae , P. sima , and P. osborni. Dero ( Dero) digitata was recorded the higher number of 430 individuals,with a percentage of 28.11% of the total sorted worms. About the aquatic plant Eichhornia crassipes, a total of 829 worms were sorted from it, which are related to six species of Naidinae , which are diaphanous , Ophidonais serpentine, Stylaria lacustris , Slavina appendiculata , N. variabilis and finally the species Allonais inaequalis. There was no any species of Pristininae sorted from this plant. The highest number of 467 individuals was recorded by the species Slavina appendiculata, with a percentage of 52.3% of the total number and 228 individual with a percentage of 25.5% was recorded by Allonais inaequalis.

Responses of the invasive aquatic plant water hyacinth to altered nutrient levels under experimental warming in China

Global warming and eutrophication may interact and increase the invasiveness of certain aquatic plants. To test this hypothesis, a mesocosm experiment was conducted to investigate the growth, biomass allocation and carbon/nitrogen balance of the invasive aquatic plant Eichhornia crassipes (Mart.) Solms in response to three nutrient levels representing oligotrophic to eutrophic water under simulated warming in a greenhouse. The growth and clonal propagation of E. crassipes were significantly promoted by simulated warming and elevated nutrient levels. The mean relative growth rate and mean clonal propagation rate of the plants increased 32% and 152% due to elevated nutrient levels, whereas those values increased 18.3% and 14.9% due to warming. The shoot/root ratio of E. crassipes was also greatly improved by simulated warming (50.2% increase) and elevated nutrient levels (475% increase). Moreover, the leaf and stembase N concentrations increased and C/N mass ratios decreased with elevated temperature and nutrient levels. These results suggest that the ecological invasion of the highly invasive aquatic plant E. crassipes will be exacerbated by increasing eutrophication under future climate warming in China.

Toxicity of CuO Engineered Nanoparticles to &lt;i&gt;Eichhornia crassipes&lt;/i&gt;

Nanomaterials are touching almost every aspect of modern life in recent years and attract the attention of scientists, becoming a hot research in a short time. The extensively use of engineered nanopaticles (ENPs) has increased the risk of ENPs entering into aquatic environments. This study outlines nanotoxicity on large aquatic plants which plays important role in aquatic system. A series of concentrations of copper oxide engineered nanoparticles (CuO ENPs) were used to test the nanotoxicity to aquatic plant Eichhornia crassipes. Results showed that inhibition of plant growth was significant after exposed to CuO ENPs at the concentration of 50 mg/L. the inhibition to the root lengh was obvious. The leaf epidermis was severely damaged. All the results showed that CuO ENPs had nanotoxicity to Eichhornia crassipes and the water system.

Overwintering survival and regrowth of the invasive plant Eichhornia crassipes are enhanced by experimental warming in winter

The distribution of the invasive aquatic plant Eichhornia crassipes is considered to be limited by winter survival. Therefore, winter warming, as well as characteristics of overwintering organs, are expected to affect its distribution and survival. An experiment was conducted to ana- lyze the effects of winter warming and stem base treatments (size or burial) on winter survival, regrowth and thus performance of floating or rooted plants of E. crassipes using a simulated warming system in a greenhouse. Winter warming significantly increased the percentage survival in both forms of the plant and facilitated its regrowth and clonal propagation. Stem base size played an important role in determining survival, regrowth and vegetative propagation. More- over, water cover and sediment burial of stem bases facilitated overwintering. After winter sur- vival, a larger fraction of the biomass of E. crassipes was allocated to shoots. These results suggest that, with climate warming, the invasive ability of E. crassipes will be enhanced, with distribution spreading to the north into central and north China, favouring plants with large stem bases.

Molecular Characterization of Endophytic Bacteria from Metal Hyperaccumulator Aquatic Plant (Eichhornia crassipes) and Its Role in Heavy Metal Removal

In this study, among a collection of heavy metals resistant endophytic bacterial strains isolated from aquatic hyperaccumulator plant (Eichhornia crassipes), one plant growth promoting endophytic bacteria (PGPE), SVUB4 was selected for its ability to utilize 1-aminocyclopropane-1-carboxylic acid (ACC) as the sole N source and accumulate different heavy metals. The SVUB4 strain was characterized as Enterobacter sp. on the basis of its 16S rDNA sequences. Assessment of the parameters of plant growth promotion revealed the intrinsic ability of the strain for the production of IAA, siderophore and solubilization of insoluble phosphate. Furthermore, plasmid DNA analysis of Enterobacter sp. strain SVUB4 indicated the presence of a single large plasmid element. The results of plasmid curing experiments demonstrated that the ability of this strain to grow in presence of Cd and Zn was encoded by the 98 kb plasmid, whereas the ability to grow in the presence of Pb appeared to be encoded by the chromosome. The Cd and Zn removal capacity of the respective metal sensitive strain (plasmidless) were about 36 and 45 μg/g-1 DW, respectively, while the removal capacity of the both metal by metal resistant strain (p SVUB4) showed a significantly higher Cd and Zn removal capacity of 153 and 228 μg/g−1 DW, respectively. However, both strains exhibited a similar pattern of Pb accumulation. The present observation also showed that for wild-type strain SVUB4 (pSVUB4), the overall level of IAA production in the absence and in the presence of Cd2+ or Zn2+was approximately the same. Nevertheless, strain SVUB4M in this respect appeared to be more sensitive to heavy metals: a noticeable decrease in IAA production was observed under the effect of both metals, especially with Cd2+.

Toxicity and bioaccumulation potential of Cr (VI) and Hg (II) on differential concentration by Eichhornia crassipes in hydroponic culture

In this work, the phytoremediation of Cr (VI) and Hg (II) ion from water by an aquatic plant Eichhornia crassipes has been studied. Plants were cultured in a double distillated water with modified Hoagland's nutrient solution at pH 6.8 supplemented with 0, 0.75, 1.50, 2.50, and 4 mg Cr/L as potassium dichromate (K(2)Cr(2)O(7)) and 0, 5, 10, 15, and 20 mg Hg/L as mercuric chloride (HgCl(2)). They were separately harvested after 3, 6 and 9 days. Plants treated with 4 mg/L of Cr (VI) accumulated the highest concentration of metal in roots (1.22 mg/g, dry weight) and shoots (0.24 mg/g, dry weight) after 9 days; while those treated with 20 mg/L of Hg (II) accumulated the highest concentration of metal in roots (4.22 mg/g, dry weight) and shoots (2.43 mg/g, dry weight) after 9 days. Eichhornia crassipes biomass was characterised using AAS, SEM and FTIR. The accumulation and relative growth of metal ions at different concentrations of chromium and mercury solution significantly increased (P<0.05) with the passage of time. The maximum values of bio-concentration factor (BCF) for Cr (VI) and Hg (II) were found to be 413.33 and 502.40 L/kg respectively.

Clonal diversity and structure of the invasive aquatic plant Eichhornia crassipes in China

The information on diversity and spatial distribution of clones of an invasive clonal plant is crucial for the understanding of its clonal structure and invasive history. In this paper, random amplified polymorphic DNA (RAPD) markers were used to explore the clonal diversity and clonal structure of Eichhornia crassipes (Mart.) Solms in natural populations, and their possible effects on the plant success as an invader are also discussed. Five populations covering the entire distribution area in China were studied, sampling 43 individuals per population at an interval of 1 m in a sampling plot. Twelve RAPD primers produced 69 reproducible bands, with 22 being polymorphic. Only five RAPD phenotypes (clones) were detected in these five populations, but each population consisted of at least three clones, contrary to the traditional expectations that E. crassipes populations should be monoclonal. The diversity of clones within populations is thought to be mainly resulted from multiple introductions by humans. The evenness of distribution of clones varied slightly and most clones were widespread, suggesting clonal growth is the predominant mode of regeneration in all the populations. A single clone dominated each population and this clone might be the first one introduced into China or the genotype with a higher phenotypic plasticity, which could survive and reproduce via clonal growth in various habitats. The clones in each population were highly intermixed, especially in river populations, suggesting this species has a guerilla clonal structure which can be facilitated by water current.