Fungi associated with Eichhornia crassipes in South Africa and their pathogenicity under controlled conditions

Eichhornia crassipes Mart. Solms-Laubach (Pontederiaceae), water hyacinth, continues to be the world's worst aquatic weed. In South Africa, considerable research has been conducted on biological control agents associated with water hyacinth, with the release of six arthropods and one fungus, but little is known about the occurrence and impacts of native phytopathogenic fungi. Nation-wide surveys were conducted in 2010 and 2011 on various aquatic bodies of South Africa to identify the fungal pathogens associated with water hyacinth. Diseased plant parts were collected and fungi were isolated and identified. Some 250 isolates belonging to more than 25 genera were collected. Some of these represent new host records, as well as undescribed taxa. Isolates of Acremonium zonatum (Sawada) Gams, Alternaria eichhorniae Nag Raj and Ponnappa, Bipolaris hawaiiensis (M.B. Ellis) Uchida and Aragaki, Fusarium Link, Myrothecium roridum Tode ex Fr. and Ulocladium sp., showed the highest pathogenicity and have the potential to be useful in complementing the ongoing biocontrol programme on water hyacinth in South Africa.     

Growth of water hyacinth (Eichhornia crassipes (Mart.) Solms) in the middle Paraná River (Argentina)

The productivity of water hyacinth in the middle Paraná River was measured at three initial biomass levels by means of periodic harvesting of plants contained in 2 m² floating baskets. The measuring period extended between August 1981 and July 1982. Initial biomass densities were 2, 5 and 10 kg (fw) m^–2.Compared with inner island ponds, flowing waters connected to the main river showed better conditions for water hyacinth growth. The duration of the growth period was some 30% longer than in island ponds, probably due to the relatively warmer river waters. Productivity ranged between 108 and 164 g (fw) m ^–2 d^–1 (annual average) for the lower and higher initial biomass values, respectively.     

Production of biogas from water hyacinth (Eichhornia crassipes) (Mart) (Solms) in a two-stage bioreactor

A two-stage rumen-derived anaerobic digestion process was tested for the conversion of water hyacinth shoots and a mixture of the shoots with cowdung (7:3) into biogas. Under conditions similar to those of the rumen and loading rates (LR) in the range of 11.6–19.3g volatile solids (VS) l–1d–1 in the rumen reactor, the degradation efficiencies were 38% for the shoots and 43% for the mixture. The major fermentation products were volatile fatty acids (VFA) with a maximum yield of 7.92mmolg–1 VS digested, and biogas with a yield of 0.2lg–1 VS digested. The effect of varying LR, solid retention time (SRT) and dilution rates on the extent of degradation of the water hyacinth–cowdung mixture was examined. Overall conversion of the substrate was highest at the loading rate of 15.4gVS.l–1d–1. Varying the retention times between 60 and 120h had no effect on the degradation efficiency, but a decrease was observed at retention times below 60h. The overall performance of the reactor was depressed by changing the dilution rate from 0.5 to 0.34h–1. By applying a LR of 15.4VS. l–1d–1, a SRT of 90h and a dilution rate of 0.5h–1 in the rumen reactor, and connecting it to a methanogenic reactor of the upflow anaerobic sludge blanket type, 100% conversion efficiency of the VFA into biogas with a methane content of 80% was achieved. The average methane gas yield was 0.44lg–1 VS digested.     

Mineral nutrient demands of the water hyacinth (Eichhornia crassipes (Mart.) Solms) in the White Nile

The possibility that the stunted growth of the water hyacinth in Bahr el Ghazal river in Sudan is influenced by nutrient elements is considered. Greenhouse experiments were carried out to determine the effects of deficiency and mineral nutrient additions on the growth of this plant. The water hyacinth was found to grow at a wide range of nutrient levels. Maximum growth was recorded at 21 mg l^–1 N, 62 mg l^–1 P, and 0.60 mg l^–1 Fe.     

Partitioning of Soluble Calcium in the Water Hyacinth (Eichhornia crassipes (Martius) Solms) in Lake Victoria,Uganda

Abstract: An investigation of soluble calcium partitioning in organs of the water hyacinth growing along the shores of L. Victoria, bordering Jinja town was carried out. The levels of Na⁺, K⁺, Mg²⁺ and Ca²⁺ in the lake water were also estimated. The pH and electrical conductivity of lake water were determined. There was a differential accumulation of Ca and oxalate between component organs of the water hyacinth. The concentration of oxalate in the various organs was more than twice that of Ca. Soluble Ca decreased with age in all organs except the leaf, while oxalate increased with age in all organs except the rhizome. There were site variations in the partitioning of both Ca and oxalate in the water hyacinth.     

The attitudes of riparian communities to the presence of water hyacinth in the Wouri River Basin,Douala, Cameroon

Since publication of the first record of Eichhornia crassipes in Cameroon in 1997, the weed has become highly invasive in the Wouri River Basin. Between June and September 2014, a socio-economic survey using participatory and qualitative methods was undertaken in the riparian villages of the Wouri River Basin to assess the perception of respondents to the presence of water hyacinth. The survey revealed that water hyacinth was a significant threat to activities along the river, which included fishing, sand extraction and river transportation. The presence of water hyacinth mats reduced catch rates of several common fish species, river transportation by 75%, and significantly reduced the income for sand extraction. Cameroon employs manual clearing of water hyacinth; however, respondents indicated they would consider other control methods, provided they do not have any negative impacts.     

Feeding impact of the planthopper Taosa longula (Hemiptera: Dictyopharidae) on water hyacinth,Eichhornia crassipes (Pontederiaceae)

Taosa longula Remes Lenicov (Hemiptera: Dictyopharidae), a planthopper native to South America, is a candidate for the biological control of water hyacinth, Eichhornia crassipes (Mart.) Solms-Laubach (Pontederiaceae), a serious weed worldwide. Biological control requires agents that are not only specific but also effective. Damage caused by sap-sucking insects is difficult to assess. In this work we designed an experimental and analytical procedure to evaluate the potential damage of T. longula on water hyacinth. The damage that T. longula causes to the clonal reproduction, biomass production, and growth of water hyacinth was studied through a paired greenhouse trial with floating cages. The performance of the plant, starting from two plants per treatment, was evaluated at different insect densities (5, 10, 15 and 20 nymphs per cage) until all the nymphs moulted to adults. The tests showed that individual growth and biomass production of water hyacinth was reduced due to the effect of the insect feeding above five nymphs per cage. The number of new plants produced by clonal reproduction was only significantly different above 15 nymphs per cage. These results suggest that this planthopper could be an effective agent for the biological control of water hyacinth.     

Removal of Chlorpyrifos by Water Hyacinth (Eichhornia crassipes) and the Role of a Plant-Associated Bacterium

The objective of this research was to study the efficiency of water hyacinth (Eichhornia crassipes) and the role of any plant-associated bacteria in removing chlorpyrifos from water. The relative growth rate (RGR) of E. crassipes in the presence of 0.1 mg/L chlorpyrifos was not significantly different from that in its absence and only slightly decreased at concentrations of 0.5 and 1.0 mg/L by ～1.1- and ～1.2-fold, respectively, with an observed dry weight based RGR_DW for E. crassipes of 0.036–0.041 mg/g/d. The removal rate constants of chlorpyrifos in the absence of plants were low at 3.52, 2.29 and 1.84 h^?1 for concentrations of 0.1, 0.5 and 1.0 mg/L, respectively, but were some 3.89- to 4.87-fold higher in the presence of E. crassipes. Chlorpyrifos removal was markedly facilitated by the presence of a root-associated bacterium, preliminarily identified as Acinetobacter sp. strain WHA. The interaction of E. crassipes and Acinetobacter sp. strain WHA provide an efficient and ecological alternative to accelerate the removal and degradation of chlorpyrifos pollution from aquatic systems including wastewater.     

Distribution of cytokinin-like activity in different plant parts of the water hyacinth, Eichhornia crassipes

Cytokinin-like activity in extracts of leaf laminae, petioles, shoots, roots and flowers of young plants of the water hyacinth, Eichhornia crassipes S. was analyzed following Sephadex LH-20 column chromatography using the soybean callus bioassay. In all plant parts analyzed, two prominent peaks of cytokinin activity having elution volumes similar to zeatin and zeatin riboside were detected. Putative cytokinin gluco-side-like activity was detected only in leaves and flowers. The cytokinin complements of the leaves and the roots were qualitatively different. It would appear that cytokinins supplied by the roots are metabolized in the leaves or certain cytokinins are synthesized in the leaves themselves. The possible significance and distribution of cytokinins in different plant parts in relation to roots is discussed.     

Effects of 2,4-D on mature and juvenile plants of water hyacinth (Eichornia crassipes (Mart.) Solms)

The effects of various concentrations of the herbicide 2,4-D were investigated on two vegetative forms of water hyacinth including juvenile and mature forms. The results obtained suggest that efficient chemical control of water hyacinth may be best applied at the early stages of vegetative development of the water hyacinth, i.e. at the juvenile phase. This would require the use of 2,4-D at a concentration of 60 000 ppm (2.2 kg/ ha) which equals to half the rate of 2,4-D normally used for control of water hyacinth in the Sudan. The lower rate of 2,4-D not only means a considerable reduction in quantity and cost of the consumed herbicide but also a substantial minimisation in the level at which pollution may build up in the White Nile of the Sudan.     

The silent invasion of Eichhornia crassipes (Mart.) Solms. in Italy

This article provides general information and original data on the period of first introduction in Europe (1823–1825) and in Italy (first half of the 19th century), and on the current distribution and impacts in Italy of the invasive macrophyte Eichhornia crassipes. Two main pathways are responsible for the presence of this species in Italy: (i) introduction as an ornamental and (ii) research and use for phytoremediation. After a time lag of more than 100 years, E. crassipes has recently started invading the Italian freshwaters. A specific action plan for this species is required, including local eradication and awareness campaigns. Furthermore, regulations in the trade sector of invasive aquatic plant species need to be introduced and the possibilities for biological or integrated control evaluated.     

Ecological and socio‐economic impacts of invasive water hyacinth (Eichhornia crassipes): a review

1. Water hyacinth (Eichhornia crassipes) is one of the world’s most invasive aquatic plants and is known to cause significant ecological and socio‐economic effects. 2. Water hyacinth can alter water clarity and decrease phytoplankton production, dissolved oxygen, nitrogen, phosphorous, heavy metals and concentrations of other contaminants. 3. The effects of water hyacinth on ecological communities appear to be largely nonlinear. Abundance and diversity of aquatic invertebrates generally increase in response to increased habitat heterogeneity and structural complexity provided by water hyacinth but decrease due to decreased phytoplankton (food) availability. 4. Effects of water hyacinth on fish are largely dependent on original community composition and food‐web structure. A more diverse and abundant epiphytic invertebrate community may increase fish abundance and diversity, but a decrease in phytoplankton may decrease dissolved oxygen concentrations and planktivorous fish abundance, subsequently affecting higher trophic levels. 5. Little is known about the effects of water hyacinth on waterbird communities; however, increases in macroinvertebrate and fish abundance and diversity suggest a potentially positive interaction with waterbirds when water hyacinth is at moderate density. 6. The socio‐economic effects of water hyacinth are dependent on the extent of the invasion, the uses of the impacted waterbody, control methods and the response to control efforts. Ecosystem‐level research programmes that simultaneously monitor the effects of water hyacinth on multiple trophic‐levels are needed to further our understanding of invasive species.     

Population dynamics of Eichhornia crassipes (C. Mart.) Solms in the Nile Delta,Egypt

The present study aims to evaluate the growth and seasonal allocation of the biomass of water hyacinth (Eichhornia crassipes) under natural conditions in the south Mediterranean region (the Nile Delta, Egypt). In this study, the population characteristics (density, morphology and primary production) over a one‐growing‐season cycle were described. In the Nile Delta, the biomass of the shoot and root systems of E.crassipes was sampled monthly along three water courses from April 2014 to November 2014 using five quadrats (each of 0.5 m × 0.5 m) at each water course. The shoot system started to grow in April (121 g/DM/m²), reached a maximum biomass of 887 g/DM/m² in July, and then decreased until reaching a minimum of 299 g/DM/m² in November. The biomass of the root system increased from 75 g/DM/m² in April to a maximum of 235 g/DM/m² in August and decreased to a minimum of 100 g/DM/m² in November. Water hyacinth allocated ca. 2% of its total biomass to stolons, 22% to laminae, 24% to roots and 52% to petioles. Peak density as high as 144 individual/m² occurred in May, but it reduced to 33–50 individual/m² during July to November. The average rate of change of biomass was maximum (17.3 g/DM/m²/day) during April and May and minimum (?8.9 g/DM/m²/day) during October and November. Relative growth rates were found to be lowest during the cooler months, October and November (?0.017 g/DM/g /day), whereas highest yields were recorded during the spring months, April and May (up to 0.044 g/DM/g/day). The correlation coefficients between the water characteristics and the first two canonical correspondence analysis axes indicated that the separation of the population parameters of water hyacinth along the first axis was negatively influenced by Zn. On the other hand, the second axis was positively correlated with electric conductivity, total N, total P, Mg, Na, K and Mn and negatively with pH.     

Bioaccumulation and translocation of nine heavy metals by Eichhornia crassipes in Nile Delta,Egypt: perspectives for phytoremediation

Abstract

The current research was carried out to estimate the potential of water hyacinth (WH) for removal of nine heavy metals (HMs) from three irrigation canals in Nile Delta. Sampling was achieved in monospecific and homogeneous WH stands at three irrigation canals in the study area, and WH biomass was sampled at monthly intervals from April 2014 to November 2014 using five randomly distributed quadrats (each 0.5?×?0.5?m) at each canal. All HM concentrations were significantly higher in the roots compared with the other WH organs. The WH was recognized by a bioaccumulation factor >1.0 for all HMs. The WH was recognized by translocation factor <1.0 for all HMs (except Pb). In many cases, the concentrations of the HMs in the different organs of WH were correlated with the same HMs in the water. Such correlations indicate that WH reflects the cumulative influences of environmental pollution from the water, and thereby suggesting its potential use in the bio-monitoring of most examined HMs. In conclusion, WH is a promising macrophyte for remediation of irrigation canals polluted with Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn.     

兰科植物黄花白及Bletilla ochracea内生真菌多样性分析

黄花白及Bletilla ochracea是一种地生兰科植物,也是中国传统中药材之一。以黄花白及为实验材料,对其叶和根组织中内生真菌类群组成及多样性进行分析。结果表明,从黄花白及植株的叶片和根组织块(段)中分离到可培养内生真菌140株,根据形态特征将它们鉴定为16个分类单元,其中包括10种子囊菌和6种担子菌。从叶片组织中分离的内生真菌有6种,其中刺盘孢属Colletotrichum真菌为叶片组织中的优势种类;从根组织中分离内生真菌有10种,瘤菌根菌属Epulorhiza和腊壳菌属Sebacina真菌构成了根组织内生真菌的优势类群。根组织可培养内生真菌的多样性(H′=1.968)要高于叶片组织(H′=1.459)。     

The influence of site and position in the plant community on the nutrient distribution in,and content of Eichhornia crassipes (Mart.) Solms

The distribution of 26 species of Blastocladiales, Saprolegniales, Lagenidiales and Peronosporales from temperate and sub tropical lakes, situated at different altitude in the same locality, is described. Seasonal periodicity is treated and found to be governed by temperature.     

Life History and Laboratory Host Range ofEccritotarsus catarinensis(Carvalho) (Heteroptera: Miridae), a New Natural Enemy Released on Water Hyacinth (Eichhornia crassipes(Mart.) Solms-Laub.) (Pontederiaceae) in South Africa

A mirid,Eccritotarsus catarinensis(Carvalho), was studied as a potentially damaging natural enemy for water hyacinth, (Eichhornia crassipes(Mart.) Solms-Laub.), in South Africa. In the laboratory, eggs were inserted into the leaf tissue parallel to the leaf surface. The four nymphal instars fed gregariously with the adults mainly on the undersurface of the leaves, causing severe chlorosis at high population levels. The duration of immature stages (egg and nymphs) was approximately 23 days, while the adults survived for approximately 50 days. Favorable biological characteristics ofE. catarinensisincluded a high rate of increase, gregarious habits, long-lived and mobile adults, and several generations per year. Laboratory host range of the mirid was determined by adult choice trials on 67 plant species in 36 families and adult no-choice trials on five species in the Pontederiaceae. Feeding was recorded on all Pontederiaceae tested and oviposition on four of the five species. However, these plant species proved to be inferior hosts forE. catarinensisin comparison to water hyacinth, suggesting thatE. catarinensiswould be an acceptable natural enemy for water hyacinth in South Africa.     

Host specificity assessment and potential impact of Megamelus scutellaris (Hemiptera: Delphacidae) on waterhyacinth Eichhornia crassipes (Pontederiales: Pontederiaceae)

The delphacid Megamelus scutellaris Berg was evaluated for host specificity and potential impact as part of a biological control program targeting Eichhornia. crassipes. Survival and development of adults and nymphs were used as metrics with no-choice, two-choice, nymph transfer, and sustainability tests conducted under quarantine conditions. A total of 69 plant species were tested including 12 from the Pontederiaceae (including E. crassipes). Additionally, 27 native and 5 exotic associated wetland species and 11 economic species were tested. Megamelus scutellaris exhibited a high level of oviposition and developmental fidelity to E. crassipes by failing to sustain populations on any non-target test plant past the F₁ generation. Nymph transfer tests which simulated potential spill-over events found that survival was virtually non-existent on associated wetland plants, regardless of taxonomic relatedness, including on Pontederia cordata, an important and widespread native species. Eichhornia crassipes plants exposed to two consecutive generations of feeding produced 66.9% less biomass and 73.4% fewer leaves than those in the controls. We conclude that Megamelus scutellaris is safe to release on E. crassipes in the United States.     

银叶杜鹃和繁花杜鹃根部真菌的多样性

植物根系与真菌形成菌根, 在自然生态系统的物质能量循环中具有重要的生态功能。作者在四川省的中国杜鹃园选取银叶杜鹃(Rhododendron argyrophyllum)和繁花杜鹃(R. floribundum), 通过直接扩增杜鹃花根部真菌rDNA-ITS区片段, 来揭示该地区杜鹃花属植物根部真菌的多样性。ITS序列分析结果表明: 从两种杜鹃的根部共检测到41个真菌分类单元, 分别属于子囊菌纲的柔膜菌目(Helotiales)、散囊菌目(Eurotiales)、盘菌目(Pezizales)、假球壳目(Pleosporales)和担子菌纲的蜡壳耳目(Sebacinales)、伞菌目(Agaricales)、Erythrobasidiales、线黑粉菌目(Filobasidiales)。银叶杜鹃和繁花杜鹃根部真菌种类丰富, 包括了杜鹃花类菌根真菌、外生菌根真菌和其他类型真菌, 其中担子菌纲的蜡壳耳目和子囊菌纲的柔膜菌目占有较大比例。     

Arbuscular mycorrhizal fungi associated with the Meliaceae on Hainan island, China

Species richness, spore density, frequency of occurrence, and relative abundance of AM fungi were determined in rhizosphere soil samples from nine tropical rainforest sites on Hainan island, south China, and the arbuscular mycorrhizal (AM) status of members of the Meliaceae was examined. All 28 plant taxa investigated (25 species including two varieties of 1 species and three varieties of another) were colonized by AM fungi. The mean proportion of root length colonized was 56% (range 10–95%). Vesicles were observed in 27 and hyphal coils in 26 of the 28 plant taxa. Mycorrhizas were of the Paris-type or intermediate-type, with no Arum-type mycorrhizas observed. Species richness of AM fungi varied from 3 to 15 and spore density from 46 to 1,499 per 100 g rhizosphere soil. Of 33 AM fungal taxa in five genera isolated and identified, 18 belonged to Glomus, 9 to Acaulospora, 1 to Entrophospora, 2 to Gigaspora, and 3 to Scutellospora. Acaulospora and Glomus were the dominant genera identified. Glomus claroideum was the taxon most commonly isolated, with a frequency of occurrence of 56.5% and relative abundance of 10.4%. A positive correlation was found between percentage of root length colonization and species richness. However, there was no correlation between spore density and percentage of root length colonized by AM fungi.