Common Water Hyacinth Research Articles

Habitat Preference of Lesser Whistling Ducks (Dendrocygna javanica) in Selected Wetlands within Colombo Ramsar Wetland City

Lesser Whistling Ducks (LWD) (Dendrocygna javanica) mostly occur in flocks and inhabit lakes, ponds and marshes within freshwater wetlands. They feed mainly on plants taken from water (seed, shoots, tuber and leaves), vertebrates (fishes) and invertebrates (mollusks and worms). In this study, habitat preference of LWD in five selected wetlands in Colombo Ramsar Wetland City (CRWC); Beddagana Wetland Park (BWP), Diyasaru Park (DP), Heen Ela Marsh (HEM), Thalangama Marsh (TM) and Kimbulawala Wetland (KW) was studied from May 2021 to April 2022 as wetlands in urban areas act as the last resort for many resident and migratory bird species and play a major role in the assemblage and conservation of water birds. Habitats present in the selected wetlands were categorized as open water body, floating vegetation, trees, grassland, paddy field, shrubs, bare land. Percentage cover of each habitat type at each sampling site were estimated using quadrat method. LWD were surveyed using line transects of 100m in length, laid in each selected study site to cover representative habitats and observations were made up to 30m towards either side of each transect. Sampling was done in three time slots of the day, morning, mid-day and evening. Floating vegetation, open water body and grassland were the preferred habitat types of D. javanica in BWP, DP, HEM and TM. LWD were not recorded in KW. Floating vegetation (54.97%) was the most preferred habitat by LWD in each study site followed by open water body (24.70%) and grassland (15.82%) habitat types. Eicchornia crassipes (Common water hyacinth) and Salvinia molesta (Giant salvinia) were their most preferred floating vegetation type. Higher abundance of LWD was recorded in TM (83.22%) followed by DP (9.17%), BWP (4.16%) and HEM (3.45%). TM which had higher abundance of LWD had higher floating vegetation coverage (28%) and was rich with E. crassipes and S. molesta. Present study revealed that, LWD mostly used E. crassipes and S. molesta as their main foraging and resting sites. Management of invasive alien species have been undertaken in Colombo wetlands and as E. crassipes and S. molesta are alien species they are currently being removed. Therefore, outright removal of E. crassipes and S. molesta may not be suitable and a monitored removal program that will conserve this habitat type should be implemented in order to conserve the habitats preferred by LWD in CRWC. 
 Keywords: Lesser whistling ducks, Wetlands, Habitat preference

Common water hyacinth (Pontederia crassipes) invades Lakes Edward, George, and Kazinga Channel: A call for immediate action

Common water hyacinth, Pontederia (former Eichhornia) crassipes is a notorious aquatic invasive species. In African Great Lakes, the species is known for deleterious social, economic, and environmental impacts in lakes such as Victoria, Kyoga, Albert, Malawi, Tanganyika, Tana, and Naivasha. We report invasion and establishment of the species in Lake Edward, Kazinga Channel and possibly in Lake George. Lake Edward is one of the African Great Lakes. Common water hyacinth was observed at multiple locations on Lake Edward and Kazinga Channel. Presence of ‘mats’ of the weed with flowers is a sign of successful establishment. We observed free floating Common water hyacinth plants, indicating that the invasion is spreading. The invasion and establishment of the weed threatens a fishery of significant importance to rural livelihoods, fish species of conservation importance and tourism among others. At the current extent of invasion, mechanical removal and use of water hyacinth weevils, if expedited, could be adequate for stopping the expansion of the invasive weed. We recommend immediate action by government agencies responsible for the management of fisheries and protected areas to control the weed.

Deposition of diquat with different spray tips, efficiency on common water hyacinth, and effect on water quality

Eichhornia crassipes, known as common water hyacinth, has a high growth rate and produces large amounts of biomass when there are imbalances in water bodies, making it one of the worst aquatic weeds in the world. A study was carried out under small water reservoir field conditions to evaluate the herbicide diquat (960 g ha−1) in controlling this species, at the adult stage development. Four spray tips (AI 11002VS, XR 11002VS and, TXVK-8 with spray volume of 200 L ha−1 and XR 11003VS with 400 L ha−1) were tested. Spraying was performed using a CO2-pressurized sprayer under constant pressure attached to a boat. Plant control was visually evaluated at 1, 3, 7, 11, 14, 21, 29, 60, 87, and 98 days after herbicide application and dry matter accumulation was determined at the end of the experimental period, as well as the spray solution deposition in the application area and water physical and chemical quality. The herbicide diquat was efficient in controlling E. crassipes plants at the dose applied and in development stage of the studied plants, regardless of the type of spray tip at the end of the evaluations. At the beginning of evaluations, the spray tip XR 11002VS was the least effectivity in controlling water hyacinth plants. Spray solution losses were high in all tips tested for control of E. crassipes plants, and the spray tips AI 11002VS and XR 11003VS provided the lowest losses during spraying. No water physical or chemical characteristics were negatively affected by diquat application.

Excess aluminum tolerance of the common water-hyacinth (Eichhornia crassipes) under greenhouse conditions

Aluminum is a heavy metal toxic to living organisms and is released into soils with a strong acidic composition. The floating aquatic weed Eichhornia crassipes (Mart.) Solms is reported as the most widespread invasive vascular plant in the world and is distributed all over Colombia ranging from sea level to the cold Andean highlands. As a consequence of the solubility of Al3+ in soils, it flows into fresh water sources where E. crassipes grows as an invasive plant. A greenhouse study was conducted in Tunja, Colombia, with the objective of evaluating the growth of aquatic weed in an aqueous substrate with Al3+ content similar to those recorded in lakes (0.0, 0.2, 0.4, 0.6, and 0.8 mg L-1 Al3+). Biomass production, leaf area, evapotranspiration, water use efficiency, and other allometric variables were evaluated. An increase of 18.2% in the transpiration rate and a reduction between 9.7%-41.8% in the leaf area were found. The latter reduced the value of variables such as the specific leaf area between 9.9%-34.6% and leaf area ratio between 16.7%-40.4%. However, the total dry weight, DM partitioning, root to shoot ratio, leaf weight ratio, and the absolute and relative growth rates did not show significantly different values between treatments. Therefore, Al content found in water sources in Colombia, despite being in the ranges reported as toxic for some aquatic plants, did not significantly affect the growth of E. crassipes due to its phenotypic plasticity and anthropic alteration of water sources but rather favor its growth.

Trace metals concentration in water hyacinth implicates the saltwater barrage altered hydrography of Kochi backwaters, southwest Coast of India

This study in the Kochi backwaters (KBW) presents the distribution of 9 trace metals (Fe, Zn, Cu, Mn, Ni, Co, Cr, Cd, Pb) in different parts (root, stolon and leaf) of the common water hyacinth Eichhornia crassipes during three different seasons [Pre-Monsoon (PRM), Southwest Monsoon (SWM), and Northeast Monsoon (NEM)]. The hyacinth was collected from 4 sections upstream of the KBW where a saltwater barrage [Thannermukkom Barrage (TB)] prevents saltwater intrusion. Results showed that regardless of seasons, all the trace metals concentration in different parts of Eichhornia varied in the following order: roots > stolon > leaves. All the trace metals except Fe showed their highest concentration during the PRM when TB introduces stagnancy of the water upstream through flow restrictions. Instead, Fe was high during the SWM associated with increased river influx at that time. Overall results showed that the hydrographical alterations of TB upstream of KBW have clear imprints on the trace metals concentrated in the hyacinth Eichhornia crassipes.

Rural Water Quality Monitoring and Exploring Low-Cost Treatment Technology with Water Hyacinth

Ground water in general is clean and fresh. However, industrialization and urbanization together with intensified agricultural activity have led to increasing demands on one hand but to the potential for large scale release of contaminants on the other. Water pollution disturbs the normal uses of water for agriculture, public water supply, aquatic life, wild life and industry. An understanding of the various types of pollutants is of considerable importance to the efficient management of water resources. Inorganic pollutants discharged into natural waters consist of mineral acids, inorganic salts, metal compounds, complexes of metal and trace elements. The proposed investigation will evaluate the underground water quality of hand pump water and Tap water of Sirgitti in rural area and its surrounding industrial areas near 7 km from Bilaspur C.G. With this objective in mind, A new and low-cost technology for purification for water by water hyacinth (Eichhornia crassipes), is a feasible solution. Water samples were collected during the growth of water hyacinth. Water purification with low-cost treatment technology using water hyacinth. The common Water Hyacinth is vigorous growers known to double its population in only 12 to 15 days. In the Water Hyacinth area and the nearby area, water pH showed a decrease between the August and September sampling followed by an upward trend and stayed stable around 9.3 in the far water hyacinth area. Water transparency showed a slow increase in August and September, and then a gradual decline in October; generally, transparency was significantly lower in the water hyacinth area than in other areas. Water Hyacinth has been used in aquatic systems worldwide for waste water purification. It has tremendous capacity of absorbing nutrients and other substances from the water and hence brings the pollution load down. In the present study an attempt was made to find the potential of Water Hyacinth in the treatment of Tap and hand pump water near industrial area of Sirgitti. The parameters studied were pH, EC, DO, BOD, TDS, Salinity, Alkalinity and Turbidity. Six months of experimental investigation showed that water hyacinth reduced considerably all the physicochemical parameters and but increased the Dissolved Oxygen (DO) to a significant level therefore it is concluded that Water Hyacinth (Eichhornia crassipes) is highly efficient in purification of water in respect of physicochemical parameters.

Involvement of a unique chemodosimeter in the selective estimation of noxious cyanide in common water hyacinth (Eichhornia crassipes): an environmental refinement.

A naphthaldehyde-pyridoxal conjugated chemodosimeter (NPLC) was developed and employed for the sensitive and selective detection and estimation of cyanide in common water hyacinth (Eichhornia crassipes), a free floating macrophyte used in the phytoremediation process since ancient times. The non-fluorescent nature of the probe NPLC, directed by the possibility of excited state intramolecular proton transfer process (ESIPT), was promptly changed due to CN- induced di-deprotonation of the probe. The naked eye color change and turn on vivid fluorescent color of NPLC was attributed to the inhibition of the ESIPT mechanism in the deprotonated NPLC (NPLC-D). The selective detection of cyanide ion in the nanomolar range (81 nM), among other interfering anions, makes it exclusive. The involvement of the probe in a chemodosimetric fashion toward cyanide was elucidated by experimental and computational studies.

Improving Productivity in Integrated Fish-Vegetable Farming Systems with Recycled Fish Pond Sediments

The increasing intensification of aquaculture systems requires the development of strategies to reduce their environmental impacts such as pollution caused by the discharge of nutrient rich sediments into local water bodies. Recycling of fish pond sediments (FPS) as fertilizer has been proposed as a possible solution that may also reduce the reliance on synthetic fertilizers. With a case study in the Mekong Delta, Vietnam, we determined suitable mixtures of striped catfish (Pangasianodon hypophthalmus) pond sediment (PPS) and locally sourced organic amendments of rice straw (RS), or common water hyacinth (WH) to fertilize cucumber plants (Cucumis sativus L.) in an integrated cucumber–giant gourami fish (Osphronemus goramy) farming system. Highest nutrient concentrations were found when mixing 30% PPS with 70% RS or WH. When used in combination with chemical fertilizer, it was found that a 25% to 75% reduction in chemical fertilizer application could be achieved, while also increasing cucumber yields, with the highest yields found when RS was used in organic amendments. In combination with the additional income from fish production, integrated farming systems such as that demonstrated in this study, may increase both farm income and production diversity.

Harnessing the potential of common water hyacinth as an industrial raw material for the production of quality biofuel briquettes

Eichhornia crassipes has a high cellulose and hemicellulose content, which are easily converted to simple sugars, thus making the plant suitable for the production of biofuel briquettes. The main purpose of this proposed work, therefore, was to investigate the production of bio briquettes from E. crassipes. The plant was harvested from a wastewater effluent management system, chopped, sun-dried and pulverized to a particle size of < 5 mm and mixed with various binders (Eucalyptus globulus leaves powder, molasses and phytoplankton scum). The binders were appropriately prepared and added to E. crassipes at the ratios of 10%, 20% and 30%. The quality of biofuel briquettes was evaluated using compressed density, relaxed density, water resistance, durability and calorific values (CV) parameters and compared to those of charcoal briquettes already on the market. The results showed a water resistance capacity of 45%, relaxation ratios of between 1.08 and 1.33, CV of 1148.35 kJ/kg for 20% molasses-based briquettes, CV of 1090.43 kJ/kg for 20% E. globulus leaf-based briquettes and CV of 1422.97 kJ/kg for charcoal-based briquettes. In conclusion, therefore, E. crassipes may become a viable raw material for producing quality biofuel briquettes that are durable with the desired calorific value and may be able to withstand mechanical handling and be useful for household and cottage industries locally.

Growth and Production of Pakchoy Under Various Type of Organic Fertilizer

This study was conducted in Wiringpalenna village, Tempe sub-district of Wajo district, with the aim to determine the effect of the type of organic matter on the growth and production of pakchoy plants. The study was arranged based on a Randomized Block Design with five treatments namely: without organic matter, chicken manure, Blotong (Filter press mud), bokashi common water hyacinth, bokashi rice straw. The results showed that from variables tested; plant height, the number of leaves, the width of leaves, fresh weight of plants, fresh weight of plants per plot, and fresh weight per hectare, treatment with bokashi common water hyacinth obtained the best result

Assessment of Current Status of Invasive Aquatic Plants in Louisiana

Invasive aquatic plants include plants and algae that grow partially or entirely submerged in water. The United States Department of Agriculture Early Detection and Distribution Mapping system (USDA EDD Maps) was used to collate number of positive observations for all the aquatic invasive species in Louisiana. United States Geological Survey Non-indigenous aquatic species (USGS NAS) database was used to collate each species years of first and last observations and number of affected HUC in Louisiana State. The collated data were recorded and formatted using Excel spreadsheet. The analyses of the data were done using Excel software to generate different charts. The main objective of this paper was to evaluate the current impacts and management of invasive aquatic plants in Louisiana and also to assess whether several resources expended on eradication of these plants have resulted in improved water quality of the State. From the collated data from USGS and USDA EMM Maps, it shows earliest date of observation of invasive aquatic plant in Louisiana from 1884. Common Water hyacinth has the highest number of observations to date. About 41 hydrological unit areas have been affected by infestation of Alligator weed as well. The continuous spread of invasive aquatic plants in Louisiana could be due to favorable weather conditions, excessive nutrients runoff from agricultural practices, reduction of government allocated funds, and uncooperative human community. The current State of Louisiana statewide management plan has done little in the control of the major notorious aquatic plant invaders such as giant Salvinia and water hyacinth. Although, several biological, chemical and mechanical management controls are being implemented yearly, there is a need for interagency collaboration, establishment of efficient State database, and stricter laws on voluntary anthropogenic activities such as sales of invasive weeds as ornamental plants and smuggling of unwanted species through the waterways into the states.

The Use of Spirodela polyrrhiza (Duckweed) and Eichhornia crassipes (Water Hyacinth) to Phytoremediate Wastewater in Guyana

Spirodela polyrhiza (orth. var. S. polyrrhiza) is a species of duckweed known by the common names common duckmeat,[1] greater duckweed,[2] great duckmeat,[3] common duckweed, and duckmeat. It can be found nearly worldwide in many types of freshwater habitat. S. polyrhiza is an ideal system for biofuels, bioremediation, and carbon cycling due to its aspects of fast-growing, direct contact with media, and smallest genome size (~150 Mb).[4] A comprehensive genomic study of S. polyrhiza was published in February 2014. The results provide insights into how this organism is adapted to rapid growth and an aquatic lifestyle.[5] Eichhornia crassipes, commonly known as common water hyacinth, is an aquatic plant native to the Amazon basin, and is often a highly problematic invasive species outside its native range. Water hyacinth is a free-floating perennial aquatic plant (or hydrophyte) native to tropical and sub-tropical South America. With broad, thick, glossy, ovate leaves, water hyacinth may rise above the surface of the water as much as 1 meter (3 feet) in height. They have long, spongy and bulbous stalks. The feathery, freely hanging roots are purple-black. An erect stalk supports a single spike of 8–15 conspicuously attractive flowers, mostly lavender to pink in colour with six petals. When not in bloom, water hyacinth may be mistaken for frog's-bit (Limnobium spongia)[6] or Amazon frogbit (Limnobium laevigatum). This research was conducted to study the phytoremediation effect of Spirodela polyrrhiza and Eichhornia crassipes respectively on domestic wastewater in East Bank of Essequibo, Essequibo Islands, West Bank Regions, Region Three, Canal Number Two Polder, Belle West, Guyana, South America. The analysis of the quantity of the influent and effluent wastewater residues (mg/L): Chloride, Sulphate, Phosphate, Potassium and Lead. Data was statistically analysed using: Levene`s F Test, Paired –Wise T-Test, Analysis of Variance – two way, and the Fisher`s Least Significant Difference Test using R-Studio. Data were analysed at the 95% confidence level with the p-value of 0.05. Results showed from this experiment indicated that influent wastewater was highly contaminated with Sulphate and was least contaminated with Lead; there was a statistically significant difference between the influent and effluent wastewater residues and also between the measured intervals (day 5, 10 and 15) for E. crassipes and S. polyrrhiza respectively; both aquatic species showed significant phytoremediation effect from as early as five days when tested. Results also showed that E. crassipes showed a great affinity for Sulphate throughout the measured intervals when compared to the other residues whereas S. polyrrhiza showed a great affinity for Phosphate throughout the measured intervals when compared to the other residues and the result showed that S. polyrrhiza showed a greater phytoremediation effect than E. crassipes since it removed > 90% of the residues in effluent wastewater.

Assessment of Current Status of Invasive Aquatic Plants in Louisiana

Invasive aquatic plants include plants and algae that grow partially or entirely submerged in water. The United States Department of Agriculture Early Detection and Distribution Mapping system (USDA EDD Maps) was used to collate number of positive observations for all the aquatic invasive species in Louisiana. United States Geological Survey Non-indigenous aquatic species (USGS NAS) database was used to collate each species years of first and last observations and number of affected HUC in Louisiana State. The collated data were recorded and formatted using Excel spreadsheet. The analyses of the data were done using Excel software to generate different charts. The main objective of this paper was to evaluate the current impacts and management of invasive aquatic plants in Louisiana and also to assess whether several resources expended on eradication of these plants have resulted in improved water quality of the State. From the collated data from USGS and USDA EMM Maps, it shows earliest date of observation of invasive aquatic plant in Louisiana from 1884. Common Water hyacinth has the highest number of observations to date. About 41 hydrological unit areas have been affected by infestation of Alligator weed as well. The continuous spread of invasive aquatic plants in Louisiana could be due to favorable weather conditions, excessive nutrients runoff from agricultural practices, reduction of government allocated funds, and uncooperative human community. The current State of Louisiana statewide management plan has done little in the control of the major notorious aquatic plant invaders such as giant Salvinia and water hyacinth. Although, several biological, chemical and mechanical management controls are being implemented yearly, there is a need for interagency collaboration, establishment of efficient State database, and stricter laws on voluntary anthropogenic activities such as sales of invasive weeds as ornamental plants and smuggling of unwanted species through the waterways into the states.

Efficiency of common water hyacinth (Eichhornia crassipes) in controlling growth of fungal and bacterial clinical strains

In this paper we have studied the anti-bacterial and anti-fungal potential of Eichhornia crassipes (Mart.) Solms (the common water hyacinth). The main aim was to find a new source against selected bacterial and fungal species was fractionated. Five fractions i.e. n-hexane, aqueous, chloroform, methanolic extracts and ethyl acetate were prepared and tested against four bacterial strains including MRSA (Methicilline resistance staphylococcus aurous), Streptococcus mutansand, Staphylococcus aurous and Serratia marcescense and four fungal strains i.e Alternaria alternate, polyspondylium pallidum, Fusarium oxysporum, Aspergillus flavous. The highest anti-bacterial activity was displayed by n-hexane fraction (46-48%) and the lowest activity was shown by crude methanolic extracts (38-44%) against all the selected bacterial strains. However in ant-fungal activities the highest activity was shown by crude methanolic extracts (35-65%) against the four selected fungal species and lowest activity was displayed by the aqueous fractions. The other fractions have also shown significant activites. Keywords: Antibacterial; Antifungal; Eichhornia crassipes; Inhibition; Water Hyacinth http://dx.doi.org/10.19045/bspab.2019.80163

Sessile rotifers (Rotifera) exhibit strong seasonality in a shallow, eutrophic Ramsar site in Mexico

AbstractTo better understand the sessile rotifer community of a shallow, eutrophic lake, we monitored over a 1‐year period the monthly changes in the density and diversity of rotifers on the roots of the common water hyacinth, Eichhornia crassipes, which served as a representative hydrophyte. Selected physical and chemical parameters of the water were also determined. Mean annual density of all sessile species was 630 individuals per ml. Species of Collothecacea (n = 7) were most abundant. Of the 12 species of Flosculariaceae (Flosculariidae), Sinantherina socialis occurred seasonally, while Ptygura beauchampi was most common across all seasons. The Shannon–Wiener diversity index was highest (H′ = 2.8) in April, but decreased in January (H′ = 1.3). Applying the concept of the guild ratio (functional‐based analysis) we found that raptorial species (Collothecacea) were dominant over most of the year (June–February), while microphagous Flosculariidae were dominant during the warm, drier season (March–May). BEST (optimal matching of biota to environment, including stepwise search) analysis and canonical correspondence revealed that temperature, dissolved oxygen, pH, turbidity, and transparency strongly influenced sessile rotifer dynamics. We also found significant correlations between the density of some species and physicochemical variables. These species included Collotheca ambigua, C. coronetta, C. ornata, C. campanulata, C. tenuilobata, and Stephanoceros millsii in the Collothecacea; and Beauchampia crucigere, Limnias melicerta, L. ceratophylli, Ptygura crystallina, P. melicerta, and Sinantherina ariprepes in the Flosculariidae. Our study shows that the communities of sessile rotifers were structured by abiotic factors and that the guild ratio is useful for understanding the relationship between sessile rotifers and their substrata.

Diversity of Noctuid Caterpillars belonging to Subfamily Amphipyrinae, Catocalinae, Cuculiinae, Heliothinae, Noctuinae and Plusiinae on Host Crops/Plants of Jammu &amp; Kashmir State (India)

This paper deals with a total of 22 species of 14 genera, belonging to noctuid moth caterpillars, under subfamily Amphipyrinae (2 spp.), Catocalinae (1sp.), Cuculiinae (3 spp.), Heliothinae (2 spp.), Noctuinae (8 spp.) and Plusiinae (6 spp.). These noctuid species have been found to be feeding on 56 spp. of agricultural crops, economically important plants and water weed. Of the total caterpillar species, under 6 sub-families, 14 spp. of various sub-families, excepting Cuculiinae, are associated with different agricultural crops. This accounts for 63.63% of noctuid-fauna studied. The highest number of caterpillar species i.e. 13 (Cuculines, Heliothines, Noctuines and Plusiines), feed on 28 spp. of medicinal / aromatic plants. This is followed by8 spp. of noctuids, devouring vegetable crops (9 spp.). 6 spp. of caterpillars are associated with 4 spp. of cereal / food crops, 4 spp. with legumes (5spp.), 3 spp. feeding fodder crops (3 spp.), 2 spp. each associated with fruit crop/tree (2 spp.), ornamental plants (2 spp.) and rape seed, and 1 sp. each of caterpillar feeding on mulberry and common water hyacinth, belonging to different subfamilies of noctuid moths. An up-to-date systematic Checklist of noctuids, associated with crops and plant species, has been provided. Besides, species diversity of noctuid-fauna on host crops/ plants, has been included.

CAN WATER HYACINTH (EICHHORNIA CRASSIPES) BE CONTROLLED BY REDUCING NITROGEN AND PHOSPHORUS POLLUTION OF WATER BODIES?

Increasing concentration of nutrients in water is regarded as one of the most important external factors responsible for the invasion of the common water hyacinth. In order to test whether nutrient availability limits the growth and spread of this species, we investigated the influence of water nitrogen (N) and phosphorus (P) concentrations on growth using both greenhouse and field experiments. We found that in the greenhouse experiment, only high P concentration (>1.25 mg l -1 ) can significantly increase numbers of ramets and leaves, and N concentration exceeding 62.5 mg l -1 can greatly increase water hyacinth biomass in a tank. In the field experiment, the clonal growth of water hyacinth was not correlated with N and P concentrations in water bodies where the range of N and P concentrations was narrow compared with their range in the greenhouse. This suggests that controlling water hyacinth through minimizing sewage discharging is impractical, the importance of the ability of water hyacinth to grow clonally should be considered.

Comparative responses of two water hyacinth (Eichhornia crassipes) cultivars to different planting densities

Two water hyacinth cultivars, i.e., common water hyacinth (CWH) and purple root water hyacinth (PRWH), were used to investigate the effect of planting densities (i.e., 8, 16 and 24 plants per bucket with a volume of 1.1m×1m (diameter×depth)) on root traits, physiological characteristics, and microbial diversity. The results indicated that the planting density significantly influenced root traits, photosynthesis, radial oxygen loss (ROL), dissolved oxygen (DO), and microbial diversity of water hyacinths. The root porosity, root diameter, and root chlorophyll of PRWH were higher than those of CWH, and CWH had higher chlorophyll and Pn in leaves. The microbial diversity decreased significantly with increasing plant density for CWH, while it increased and then decreased in PRWH and peaked at 16plantsbucket−1. The results suggested that the aerenchyma of PRWH was more developed than those of CWH, and CWH had higher leaf photosynthesis. However, higher root chlorophyll a in PRWH indicated that its capacity for photon capture was higher than in CWH. The result of ROL suggests that larger Δ root length and root porosity could help improve the dissolved oxygen of water column. The photosynthesis of CWH and PRWH can release oxygen into water column, and the capacity of PRWH was better than those of CWH.

Effects of temperature and light intensity on growth and physiology in purple root water hyacinth and common water hyacinth (Eichhornia crassipes)

In this study, the interaction between temperature and light intensity was investigated in common water hyacinth (CWH) and purple root water hyacinth (PRWH). Effects of different temperatures (11/5, 18/11, 25/18, and 32/25 °C day/night) simultaneously applied at various light intensities (100, 300, and 600 μmol m(-2) s(-1)) to the plants were detected by measuring changes in the root lengths, protein content, sugar content, malondialdehyde (MDA) content, photosynthesis, and dissolved oxygen (DO). Temperature and light intensity significantly influence the growth of water hyacinths, and there was significant interaction among these environmental factors. The results suggest that several environmental factors act synergistically on the growth and physiology of water hyacinths. The higher new root length (NRL) in PRWH indicated that its root growth capacity is higher than in CWH. The soluble sugar content in leaves of CWH was higher than PRWH, indicating that relatively higher sugar content in CWH to low-temperature stress may support its tolerant nature. Lower temperature and light intensity can stimulate the accumulation of MDA content. The net photosynthetic rate (Pn) in leaves of CWH was higher than PRWH. In low temperature, increase light intensity can stimulate the Pn of PRWH and CWH. In CWH and PRWH, Pn showed a similar trend as noted for stomatal conductance (Cond) and transpiration rate (Tr). The capacity of PRWH in adding oxygen to the water column is better than those of CWH.

Electric double layer capacitor and its improved specific capacitance using redox additive electrolyte

Halogen (iodide, I−) added aqueous electrolyte facilitates the capacitive behaviour of biomass derived activated carbon based electric double layer capacitors. To produce economically viable electrodes in large scale for supercapacitors (SCs), the activated carbons (ACs) prepared from Eichhornia crassipes (common water hyacinth) by ZnCl2 activation. The prepared ACs were characterized by XRD, Raman, FT-IR and surface area, pore size and pore volume analysis. The electrochemical properties of the SCs were studied using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), electrochemical impedance spectroscopy (EIS) and cycling stability. The 3I−/I3−, 2I−/ I2, 2I3−/3I2 and I2/IO3− pairs produce redox peaks in CV and a large Faradaic plateau in charge–discharge curves. Similarly, I− ions improves the good ionic conductivity (lower charge transfer resistance) at the electrode/electrolyte interface which was identified through EIS studies. The calculated specific capacitance and energy density was 472 F g−1 and 9.5 W h kg−1 in aqueous solution of 1 M H2SO4. Interestingly, nearly two-fold improved specific capacitance and energy density of 912 F g−1 and 19.04 W h kg−1 were achieved when 0.08 M KI was added in 1 M H2SO4 electrolyte with excellent cycle stability over 4000 cycles. Subsequently, this improved specific capacitance and energy density was compared with 0.08 M KBr added to 1 M H2SO4 (572 F g−1, 11.6 W h kg−1) and 0.08 M KI added to 1 M Na2SO4 (604 F g−1, 12.3 W h kg−1) as electrolytes.