Polygonum Punctatum Research Articles

Comparative study of antioxidant properties of the extracts of Polygonum acre H.B.K.

Aims: This study aimed to characterize and compare the antioxidative potential ofextracts obtained by infusion, decoction, tincture, aqueous extraction, and hydroethanolicmaceration from the aerial parts of Polygonum acre H.B.K., which hasbeen traditionally used in herbal preparations, for different purposes. The therapeuticbenefits are attributed to phenolic compounds and their antioxidant properties.Methods: All extracts were characterized considering their quantitative contentof the total phenolics, flavonoids, condensed and, hydrolysable tannins, by colorimetricmethods. EHW-PA was selected for HPLC analysis as it showed a higheryield (10.58 % w/m) and a phenolic content > 200 mg GAE/g dry extract. Thephenolic profile showed a chromatogram with 20 peaks, and the presence of gallicacid, rutin, and quercetin was verified by comparison with the retention times ofstandard compounds. The antioxidant activities were determined by ABTS capturetest, ferric reducing antioxidant power test (FRAP), and the superoxide anionscavenging test. Results: Tinctures showed a higher average content of phenoliccompounds, present mainly as flavonoid content. A significant correlation coefficientwas observed between the total phenolic content and its antioxidant activity,determining by ABTS and FRAP assays. Differently, a low to moderate correlationbetween the flavonoid content and antioxidant activity was verified. Conclusion:This study reinforces the ethnopharmacological relevance of the Polygonumgenus and could contribute to the scientific basis for the use of P. acre preparations.

ANTIFUNGAL ACTIVITY AND STAINING PROPERTIES OF SOME SYMMETRICALLY FUNCTIONALIZED METAL PHTHALOCYANINE DYES

Effects of 1, 8, 15, 22-tetranitro Co(II) and Zn(II) phthalocyanines [3-NO2CoPc, 3-NO2ZnPc], 1,8,15,22-tetracyano Co(II) phthalocyanine [3-CNCoPc] and 2, 9, 16, 23-tetranitro iron(III)chlorophthalocyanine [4-NO2FePc] on the growth of the fungus Aspergillus niger were studied. All the four complexes inhibited the radial spread of the fungus selected for the study to different extents. A considerable inhibitory effect on growth was seen even in l ppm concentration. The order of inhibitory effect, measured for a period of 5 days is 3-NO2 ZnPc > 3-CNCoPc > 3-NO2CoPc > 4-NO2FePc. The presence of the peripherally substituted phthalocyanine complexes is found to alter the pigmentation property of the selected fungus. Safranin-phthalocyanine double staining technique using 3-NO2CoPc, 3-NO2ZnPc, 4-NO2FePc and 2, 9, 16, 23-tetrahydroxy iron(III)chlorophthalocyanine [4-OHFePc] on the stem sections of Hemidesmus indicus R Br and Polygonum punctatum Buch-Hum have been studied.

In vitro anthelmintic activity of Polygonum acre (Linnaeus, 1754) extracts against the ruminant nematode Haemonchus contortus (Rudolphi, 1803)

The genus Polygonum exhibits a variety of biological and therapeutic properties. The goal of this study was to determine the in vitro anthelmintic activity of Polygonum acre extracts against the nematode Haemonchus contortus, characterizing the phenolic profile of these extracts. Aerial parts of P. acre were subjected to hot aqueous and hydroethanolic extractions obtaining EHW-PA (aqueous) and ETOH-P, (hydroethanolic), respectively. The phenolic content of the extracts was analyzed by using high-performance liquid chromatography with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) and colorimetric assays. The egg hatch test (EHT) and larval migration test (LMT) were used for anthelmintic activity assays. For comparison, chlorogenic acid and rutin were selected for the EHT. The HPLC-ESI-MS/MS analysis revealed the presence of isoquercitrin, myricitrin, quercetin, rosmarinic acid, rutin, and taxifolin in both extracts. EHW-PA and ETOH-PA showed an egg hatch inhibitory effect. EHW-PA had an IC50 of 442.24 µg/mL on the EHT, which was statistically lower (P ≤ 0.05) than ETOH-PA (IC50 = 703.60 µg/mL). Chlorogenic acid had an IC50 of 8.66 µg/mL. Rutin presented no effect over parasite eggs. EHW-PA and ETOH-PA did not show any larvicidal effect. Even though, there is a need of new tests, this study has determined the possibility to develop biofriendly compounds based on Polygonum spp. constituents against H. contortus.

Swine Wastewater Treatment in Constructed Wetland Systems: Hydraulic and Kinetic Modeling

The use of constructed wetland systems (CWS) is presented as an alternative for the treatment of effluents since these have reduced implementation costs and relative ease of operation. The present research was undertaken to evaluate to study the hydrodynamic and the fitting of first-order mathematical kinetic models for the removal of pollutants in CWS. Three CWS were built, using expanded clay as filter support: one cultivated with Polygonum punctatum (CWSw), another cultivated with Chrysopogon zizanioides (CWSV), and a control unit (CWSc). The actual retention time was 3.12 days in the CWSc, whereas, in the CWSw and CWSv, we observed values of 4.14 and 4.11 days, respectively. The dispersion values were high in all CWS. The values of chemical oxygen demand (COD) across the length of the CWS were used to fit the kinetic models that describe the first-order decay of organic matter over the CWS. The models that showed a better fit to the experimental data were the plug-flow with residual concentration, the continuous stirred tank reactor, and Shepherd’s models.

Diversity of Aphids (Homoptera: Aphididae) Infesting Polygonaceous Plants (Angiospermae: Caryophyllales: Polygonaceae) in India

The present checklist demonstrates that at least 30 species of plants of the family Polygonaceae are infested by 75 species/subspecies of aphids belonging to 4 subfamilies, such as Aphidinae (Tribe Aphidini: 19 species; Tribe Macrosiphini: 53 species), and Eriosomatinae, Greenideinae and Lachninae (1 species each) in India. Maximum number of aphid species (21 aphid species) are colonised on Persicaria nepalensis and Rumex nepalensis (16 species each), Polygonum punctatum (12 species), Persicaria barbata and Persicaria chinensis (11 species each), and Persicaria decipiens (10 species) and less number of species on rest of the plant species. Similarly, maximum number of plant species (14 plant species) were colonised by Aphis (Aphis) gossypii Glover followed by Capitophorus hippophaes javanicus Hille Ris Lambers (12 plant species), Capitophorus mitegoni Eastop (11 plant species), Aphis (Aphis) spiraecola Patch (9 plant species), Akkaia bengalensis Basu (8 plant species), Myzus (Nectarosiphon) persicae (Sulzer) (8 plant species), Trichosiphonaphis (Xenomyzus) polygoni (van der Goot) (8 plant species), Myzus (Myzus) ornatus Laing (7 plant species), Aphis (Aphis) craccivora Koch and Aphis (Aphis) fabae Scopoli (5 plant species each) and less than 5 plant species in case of other aphid species.

Aboveground biomass distributions and vegetation composition changes in Louisiana's Wax Lake Delta

The Wax Lake Delta (WLD) is an actively prograding delta in the Mississippi River Delta Plain that is otherwise experiencing widespread degradation and submergence of its coastal wetlands. The WLD is actively accumulating mineral and organic sediment that increases soil surface elevation, changing emergent wetland communities as the young delta develops. There is uncertainty in how the dynamics of community composition respond to net changes in soil elevation and determine aboveground biomass and carbon storage. This study utilizes high resolution imaging spectrometer data captured on October 17, 2016, to map the delta's dominant vegetation species and wetland types. We validated this vegetation map (overall accuracy = 77.62%, Kappa = 0.72) and compared it with a published species map that used WorldView-2 data collected five years earlier on October 16, 2011. This allowed us to map changes resulting from five years of delta development to determine changes in wetland forest species (Salix nigra), two dominant herbaceous wetland species (Colocasia esculenta and Polygonum punctatum), and various grass species. Results show an increase in C. esculenta and a marginal increase in forested wetlands (S. nigra). C. esculenta's expansion occurred largely from the delta island heads toward the fringes into wetland area previously occupied by P. punctatum, which saw a corresponding decline. Additionally, this study leveraged these species distributions with a published aboveground biomass (AGB) dataset to examine the dominant plant types' growth patterns across elevational gradients. We characterized variability in AGB by marsh platform elevation and across different elevational zones categorized by hydroperiod, or hydrogeomorphic zones. We found that the herbaceous plant species peak in AGB in the low intertidal zone and decrease with elevation before increasing slightly in the higher elevations, consistent with previous field-based mesocosm experiments for C. esculenta. With vegetation distributions, succession, and growth patterns in the WLD characterized, this study may inform future restoration efforts throughout the Mississippi River Delta Plain regarding the changing vegetation composition that may emerge following changes in surface elevation with sediment deposition.

Determination of the Degree of Heavy Metals Accumulation in Macrophytes of Bogotá River, Colombia

This paper presents the degree of heavy metals accumulation in existing Macrophytes in the water of the Bogota River to establish the potential of native species for the phytoremediation of contaminated aquatic ecosystems. The research was developed in four phases. The first one refers to the characterization of heavy metals in the water of the Bogota River in the study area; in the second phase it was determined the most abundant macrophytes species; in the third one, a preliminary determination of accumulation of heavy metals in the 3 dominant species using energy dispersive X-ray spectroscopy coupled to scanning electron microscopy (EDS-SEM) was then made. In the fourth phase, once it was selected the species with the greatest accumulation, an in vitro propagation under certain optimal nutrient conditions took place. Finally using a new measurement of EDS-SEM, it was determined the degree of accumulation of heavy metals. The results indicate that in the Bogota River, there are important concentrations of Zinc (Zn), Total Iron (Fe) and Chromium (Cr), which are associated with the industrial sector of the area. Also, it was determined that the most abundant species of macrophytes were Polygonum punctatum, Eichhornia crassipes and Myriophyllum aquaticum which showed characteristics of hyperaccumulating plants of Aluminum (Al) and Iron. Among them, Eichhornia crassipes stands out for its variety of accumulated metals, which is why, after the in vitro propagation and final analysis in EDS-SEM, it is concluded that it is an ideal species for phytoremediation of water bodies affected by iron, copper (Cu) and tin (Sn).

The amphibian macrophyte Polygonum punctatum as a temporary habitat and feeding ground for fish

Plants that colonize wet habitats may become temporarily submerged forming a new habitat for fish in the flood period. In this study, the amphibian macrophyte Polygonum punctatum was evaluated as a temporary habitat and feeding ground for fish (≤ 108 mm) during the flood period in a river–floodplain ecosystem. The fish were sampled in January and February of 2015 in a lake of the Upper Parana River floodplain, inside patches dominated by P. punctatum (flood-formed, temporary habitat) and Eichhornia azurea (permanent aquatic habitat, used as control). The abiotic data did not differ between the two plants, unlike their biomass, which was higher for E. azurea. Fish abundance did not differ between macrophytes but the composition and richness did, with more species registered in E. azurea. The foraging efficiency of fish was significantly lower in individuals using the amphibian macrophyte for most species. Differences in the diet composition were verified for half of the species, but the main items consumed were the same in both macrophytes, changing only the proportion. The niche breadth was similar in the patches of both macrophytes. The results suggest that during flood periods, the new habitat provided by the macrophyte P. punctatum was colonized by small fish that probably used this new habitat as a refuge and feeding ground. However, the lower foraging efficiency in this macrophyte suggests that it does not provide an amount of food resources comparable to the permanent habitat represented by E. azurea.

Removal of chlorpyrifos insecticide in constructed wetlands with different plant species

ABSTRACT The objective of this study was to evaluate the remediation of water containing the insecticide chlorpyrifos by using constructed wetlands (CW) cultivated with Polygonum punctatum, Cynodon spp. and Mentha aquatica, operated under different hydraulic retention times: 24, 48, 96, 144 and 192 h. The system efficiency was based on reduction of the initial concentration of chlorpyrifos and toxicity of the contaminated water. The results showed that constructed wetlands are an excellent alternative for remediation of the insecticide chlorpyrifos in aqueous medium. It was observed that the average overall removal efficiency of the insecticide was 98.6%, and in the first hydraulic retention time, 24 h, chlorpyrifos was removed to levels below the detection limit in all CW. This result is mainly attributed to adsorption and microbial degradation. For the qualitative standard acute toxicity tests with Daphnia similis, for most samples there was a reduction in toxicity greater than 80%. It was reported that the ecotoxicological tests with the effluents of the constructed wetland are a good option as an indicator of the effectiveness of treatments and a promising alternative to complement the physical and chemical analyses.

Defining the ecogeomorphic succession of land building for freshwater, intertidal wetlands in Wax Lake Delta, Louisiana

Land building in deltaic environments occurs when sediment discharged from a river mouth is deposited subaqueously and transitions to subaerial land. The transition from subaqueous deposition to subaerial land is a critical process that marks the creation of relatively stable land, yet it is unclear what controls the speed and style of this transition. We define how this transition, herein termed the land building succession, varies in time and space for the freshwater, intertidal wetlands in Wax Lake Delta, LA. Using remote sensing and field data we classify land cover into sediment, water, or vegetation classes at maximum and minimum biomass. We see two succession patterns within Wax Lake Delta. Deltaic islands near the apex are initially covered by sediment and open water. Through time, open water and sediment coverage decreases as vegetation coverage increases. On the other hand, distal islands show little sediment exposure through time. In both cases, all deltaic islands become covered with vegetation by 2015. As vegetation colonizes the island, the topography organizes into two platforms vertically separated by ∼0.35 m. The lower, intertidal platform occurs in the island interiors and is commonly inundated by water and dominated by subaqueous or floating vegetation. The upper, subaerial platform occurs along island edges and is dominated by a variety of vegetation species including Salix nigra, Colocasia esculenta, and Polygonum punctatum. It takes an average of ∼10 years for the intertidal platform to transition to the subaerial platform. These two platforms are separated by the tidal range measured in Atchafalaya Bay, and the different vegetation communities occupying each platform suggest they are a manifestation of multiple stable states and arise due to vegetation and sedimentation feedbacks.

Tratamento de águas residuárias de suinocultura em sistemas alagados construídos, com Chrysopogon zizanioides e Polygonum punctatum cultivadas em leito de argila expandida

RESUMO No presente estudo avaliou-se a remoção de demanda bioquímica de oxigênio (DBO), nitrogênio total (NT) e fósforo total (PT) da água residuária de suinocultura (ARS) em sistemas alagados construídos (SACs) de escoamento horizontal subsuperficial, além da contribuição das espécies vegetais cultivadas: Polygonum punctatum (erva-de-bicho) e Chrysopogon zizanioides (capim-vetiver). Foram implantados três SACs, utilizando-se argila expandida como meio suporte, sendo um cultivado com P. punctatum (SACE), outro cultivado com C. zizanioides (SACV) e um mantido como controle, sem cultivo (SACC). Para um tempo de retenção hidráulica nominal (τ) de 3,2 dias, observou-se remoção de DBO, NT e PT, ao longo do período experimental, com eficiências médias de 85, 38 e 51% (SACC), 89, 48 e 69% (SACE) e 81, 36 e 45% (SACV), respectivamente. O melhor desempenho foi observado no SACE. Foram obtidas, em termos de matéria seca, produtividades de 2,79 e 1,91 g m-2 d-1 e remoções de NT de 1,54 e 1,01% e de PT de 0,81 e 1,19%, da carga aplicada, para a erva-de-bicho e o capim-vetiver, respectivamente.

Cover thresholds for impacts of an exotic grass on the structure and assembly of a wet prairie community

Potential impacts of an exotic grass, Hemarthria altissima, on restoration of wet prairie community structure (species richness and cover of indicator species) and assembly processes (temporal turnover rates of plant species) on the Kissimmee River floodplain in Central Florida, USA, were evaluated over a 12-year period before and after restoration of hydrologic regimes (2001), and implementation of herbicide treatments (2006–2007) to control its spread. Thresholds for impacts were derived from comparisons of sample sites with variable levels of H. altissima cover. Prior to herbicide treatments, cover of H. altissima exhibited a logistic increase over time, with peak colonization and expansion occurring during major flood events. Mean post-restoration cover of three native wet prairie indicator species (Polygonum punctatum, Panicum hemitomon, and Luziola fluitans) increased to 37.8 ± 3.4 % in plots in which H. altissima cover was 30 %. Prior to and after herbicide treatments, these indicator species largely accounted for observed differences in wet prairie community structure (i.e., cover of wetland forbs and grasses) between heavily infested sites and plots with low or no cover of H. altissima. The cover threshold at which H. altissima began to have these community-level effects was 40–50 %, but lower species richness was found only where H. altissima cover was >80 %. Increasing cover of H. altissima led to a significant decline in temporal turnover rates of plant species (P 75 %) cover of H. altissima. Mean temporal turnover rates of plant species increased significantly (P = 0.03) after herbicide treatments and subsequently were highest during an ensuing flood pulse. However, 2–3 years after herbicide treatments, regrowth of H. altissima reestablished high cover (mean = 59 ± 9.5 %) in over half of the treated plots. The ability of H. altissima to establish dominant cover in restored hydrologic conditions on the Kissimmee River floodplain, and documented regrowth following herbicide treatments, increase the potential for this exotic grass species to be a pervasive threat to successful reestablishment of wet prairie community structure and assembly processes.

Ação genotóxica e antiproliferativa de Polygonum punctatum Elliott (Polygonaceae) sobre o ciclo celular de Allium cepa L.

RESUMO:A espécie Polygonum punctatum Elliott (Polygonaceae) é amplamente utilizada pela população como planta medicinal. O objetivo deste trabalho é o de avaliar o potencial genotóxico e mutagênico de P. punctatum utilizando raízes de bulbos e radículas em sementes germinadas de Allium cepa através do teste in vivo, e realizar comparações da extração do material vegetal por calor (infusões) e extração a frio (extrato). Para isso, foram preparadas dois tipos de soluções, infusões e extratos foliares de P. punctatum, em duas concentrações 0,4 g mL-1 e 2,4 g mL-1. A infusão foi preparada pela adição das folhas secas em água destilada fervente (100ºC), permanecendo por 10 minutos enquanto o extrato foi preparado através da maceração das folhas secas em água destilada fria. Para o teste em A. cepa foram utilizados, para cada tratamento, seis grupos de quatro bulbos e seis caixas gerbox com 50 sementes em cada caixa. Duas lâminas para cada tratamento foram obtidas através da técnica de esmagamento das raízes e coradas com orceína acética 2%. Foram contadas 2000 células por grupo de bulbos e 3000 células por grupo de sementes, observando-se a ocorrência de interrupções em metáfases, alterações cromossômicas estruturais, bem como a inibição ou aumento da divisão celular. Os valores do índice mitótico foram calculados e analisados estatisticamente pelo Teste χ2(p≤0,05). Os resultados demonstraram que as infusões e os extratos de folhas apresentaram redução nos valores de índices mitóticos nas concentrações utilizadas em relação ao controle em água destilada. Foram identificadas alterações cromossômicas na divisão celular, tais como pontes anafásicas, em todas as concentrações de infusões e extratos indicando assim que P. punctatum possui atividade antiproliferativa e genotóxica.

Volatile Terpenoids from Water Pepper (Polygonum punctatum) Against Pseudomonas aeruginosa and Staphylococcus aureus Virulence Strategies

Polygonum punctatum Elliot (water pepper) is a pungent herb ancestrally employed as a disinfectant in traditional medicine by Toba Indians of the north-eastern region of Argentina and also commonly used as spice in Japanese cuisine. GC-MS of whole diethyl ether extract (EE) from aerial parts allowed to identify 14 volatile terpenoids such as sesquiterpenes: α-bisabolol (3.4 %), polygodial and isotadeonal (34.0%); various methylated phenol like α-tocopherol or vitamin E (3.6 %), and phytosterols: stigmasterol (2.1%) and β-sitosterol (29.9 %). Thus, water pepper is a promising source of drimane sesquiterpenes and phytoestrogens with important bioactivities. Following a taste- guided fractionation by CC and HPLC, drimane-type sesquiterpenes, polygodial (1) and its stereoisomer isotadeonal (2) were isolated as main compounds from the EE. The antipathogenic effects on the bacterial growth, biofilm formation, and elastase activity of both pure compounds and EE were evaluated against two Staphylococcus aureus and two Pseudomonas aeruginosa strains at 10 and 100 µg/mL. The highest effects were observed for the non pungent drimane isotadeonal (2) which was able to reduce about 75 % the bacterial growth of all tested microorganisms and to inhibit Gram-positive biofilm formation (85 % mean) at 100 µg/mL. In addition, elastase activity of P. aeruginosa, another virulence strategy, was attenuated more than 50 % at 100 µg/mL by 2. These results provide evidence that support the antimicrobial use of P. punctatum against P. aeruginosa and S. aureus, as well as, demonstrating that isotadeonal (2), despite it has been suggested to lack biological properties, is a bioactive compound able to control biofilm formation and bacterial growth of both human pathogens.

Nitrate Removal Efficiency with Hydrophytes of Los Reyes Aztecas Lake Water, México

The study was carried out to evaluate six different hydrophytes which were tested associated by twos: 1) Lemna gibba and Ceratophyllum demersum, 2) Berula erecta and Lemna gibba, 3) Polygonum punctatum and Hydrocotyle ranunculoides, and 4) Polygonum punctatum and Azolla filiculoides, for the purpose of removing nitrate from the water of Reyes Aztecas Lake, which is located southeast of Mexico City in Tláhuac District, Mexico D.F. The average of removal efficiency was obtained in relation to the different hydrophytes associations based on five sampling stations. The statistical analysis revealed that there were no significant differences among hydrophytes, all show remarkable ability to remove nitrate in water.

Biomass and elemental composition (C, N, H) of the periphytic community attached to Polygonum punctatum Ell. in a subtropical reservoir and its relationship to environmental factors

Biomass and elemental composition (C, N, H) of the periphytic community attached to Polygonum punctatum Ell. in a subtropical reservoir and its relationship to environmental factors. The periphytic communities in Brazilian reservoirs have been studied widely due to their importance for the assimilation of nutrients and their role at the base of the food chain. The objective of the present work was to analyse the environmental variables that influence the development of periphytic communities attached to stalks of the aquatic macrophyte Polygonum punctatum Ell. Five sample collections were made during 2010 at two sites in the Itupararanga reservoir (Ibiuna, Sao Paulo, Brazil). The macrophyte was collected, and the periphytic community attached to its stalks was scraped off with a brush and jets of distilled water. Using a PLS analysis, we observed that 94.3 % of the variation in periphyton biomass could be explained by concentrations of nitrate, conductivity, dissolved oxygen, water clarity and dissolved inorganic phosphorous. According to the indices applied, in 2010 the biomass of the periphytic community in the reservoir was low and predominantly heterotrophic, and the concentration of carbon in the periphyton was lower than that found in previous studies of this community.

Hg, Cu, Pb, Cd, and Zn Accumulation in Macrophytes Growing in Tropical Wetlands

The concentrations of Hg, Cu, Pb, Cd, and Zn accumulated by regional macrophytes were investigated in three tropical wetlands in Colombia. The studied wetlands presented different degrees of metal contamination. Cu and Zn presented the highest concentrations in sediment. Metal accumulation by plants differed among species, sites, and tissues. Metals accumulated in macrophytes were mostly accumulated in root tissues, suggesting an exclusion strategy for metal tolerance. An exception was Hg, which was accumulated mainly in leaves. The ranges of mean metal concentrations were 0.035–0.953 mg g−1 Hg, 6.5–250.3 mg g−1 Cu, 0.059–0.245 mg g−1 Pb, 0.004–0.066 mg g−1 Cd, and 31.8−363.1 mg g−1 Zn in roots and 0.033–0.888 mg g−1 Hg, 2.2–70.7 mg g−1 Cu, 0.005–0.086 mg g−1 Pb, 0.001–0.03 mg g−1 Cd, and 12.6–140.4 mg g−1 Zn in leaves. The scarce correlations registered between metal concentration in sediment and plant tissues indicate that metal concentrations in plants depend on several factors rather than on sediment concentration only. However, when Cu and Zn sediment concentrations increased, these metal concentrations in tissues also increased in Eichhornia crassipes, Ludwigia helminthorriza, and Polygonum punctatum. These species could be proposed as Cu and Zn phytoremediators. Even though macrophytes are important metal accumulators in wetlands, sediment is the main metal compartment due to the fact that its total mass is greater than the corresponding plant biomass in a given area.

Effects of three stressors on vegetation in an oligohaline marsh

Summary1. When multiple stressors have interactive effects they can lead to important changes in ecosystem function. We examined how three stressors affected the plant community in an oligohaline marsh in southeastern Louisiana, U.S.A. These stressors included herbivory (mostly by the introduced rodent Myocastor coypus), disturbance (herbicide application) and nutrient enrichment (three levels of N–P–K fertilizer). Sampling was conducted six times over 4 years.2. Recovery after disturbance was slow, such that after 26 months biomass in disturbed plots was 36% that of controls. Slow recovery appeared to be due to herbivory, as exclusion of herbivores for 14 months led to much more biomass compared to non‐excluded plots. Exclusion did not, however, aid recovery of species richness; this recovery required 51 months in total.3. Nutrient enrichment increased biomass by 41% and decreased species richness by c. 20% in later sampling periods. Decreased species richness was due primarily to a reduced ability of dominant species to co‐exist (as determined with Hill’s diversity number N1). Nutrient enrichment did not interact with the other treatments.4. Disturbance favoured two grasses (Echinochloa crus‐galli and Leptochloa fascicularis), while lack of disturbance favoured two herbs (Sagittaria lancifolia and Polygonum punctatum) and two vines (Ipomoea sagittata and Cuscuta pentagona). Nutrient enrichment positively affected abundance of two species (C. pentagona and L. fascicularis). Herbivory did not affect species composition.5. The effect of one stressor (experimental disturbance) on plant biomass depended on the strength of another stressor (herbivory). Nutrient enrichment was also important in affecting the plant community, but only as a single stressor. All effects changed over time, and it was clear that to understand properly the effects of multiple stressors, long‐term, manipulative field experiments are necessary.

Avaliação do perfil cromatográfico em espécies de Polygonum e amostras comercializadas como "erva-de-bicho"

As espécies Polygonum punctatum, Polygonum hydropiperoides, Polygonum ferrugineum, Polygonum acuminatum foram analisadas quanto ao perfil cromatográfico e comparadas com amostras comercializadas como "erva-de-bicho". As análises foram realizadas empregando cromatografia líquida de alta eficiência. Verificou-se que as amostras analisadas exibem perfil cromatográfico distinto. O perfil cromatográfico das amostras comercializadas como "erva-de-bicho" foram semelhantes aos obtidos para as amostra de Polygonum acuminatum ou Polygonum ferrugineum ou não apresentaram picos nos cromatogramas. Foram monitorados na determinação do perfil cromatográfico os comprimentos de onda de 254 nm e 362 nm.

Caracterização isoenzimática de oito acessos de Erva-de-bicho

Na caracterização de oito acessos de Polygonum punctatum Ell., utilizou-se a técnica de eletroforese horizontal em gel de amido a 12%. Determinaram-se os fenótipos isoenzimáticos da malato desidrogenase (MDH), fosfatase ácida (ACP), peroxidase (PO), glutamato desidrogenase (GDH), leucina aminopeptidase (LAP), esterase (EST), álcool desidrogenase (ADH), glutamato oxaloacetato transaminase (GOT), isocitrato desidrogenase (IDH) e chiquimato desidrogenase (SKDH), utilizando extratos de folhas jovens de cada acesso. A eletroforese foi conduzida em géis de amido de milho e amido hidrolisado. O amido de milho mostrou resolução satisfatória na separação das bandas isoenzimáticas da IDH, ADH e MDH. No entanto, para os demais sistemas, o amido hidrolisado apresentou resolução superior à do amido de milho. Todos os sistemas enzimáticos estudados, com exceção do sistema LAP, apresentaram elevado polimorfismo, permitindo estabelecer padrões individuais em todos os acessos. Isso demonstrou o potencial das isoenzimas como marcadores genéticos no gênero Polygonum.