Allelopathy of decomposed maize straw products on three soilborn diseases of wheat and the analysis by GC-MS

In northern China, the soil-born diseases of wheat have been getting more and more serious under a new farming system that returns maize straw to the field. In order to investigate the allelopathy of the decomposed maize straw products on three soil-born diseases of wheat, culture dish and pot experiments were conducted and the compounds in the products were identified by gas chromatography-mass spectrometry （GC-MS）. Culture dish experiments showed that the mycelial growth, sclerotia formation amount and total weight of Rhizoctonia cerealis were promoted at concentrations of 0.03, 0.06 and 0.12 g mL-1 and inhibited at concentration of 0.48 g mL-1 of the decomposed products. No significant effects were found of the product concentrations on average weight of the sclerotia. Mycelial growth of Gaeumannomyces graminis was promoted at almost all concentrations except the highest one. Mycelial growth and spore germination of Bipolaris sorokiniana were significantly inhibited by all concentrations of the decomposed products, with enhanced inhibition effects along with the increased concentrations. The length, number and dry weight of roots together with the root superoxide dismutase activity were promoted by the lowest concentration （0.03 g mL-1）, with a synthetic effect index of 0.012, and inhibited by other concentrations. The ion leakage of roots was increased and the root peroxidase activity of roots was lowered by all the treatments. Pot experiments revealed that occurrence of the sharp eyespot was reduced by 0.03 and 0.06 g mL-1 of decomposed products after irrigation. However, the incidence rates and disease indexes were significantly increased by 0.12, 0.24 and 0.48 g mL-1 of decomposed products. The results indicated that incidence rates and disease indexes of the take-all were significantly promoted after being irrigated with the decomposed products, while occurrences of the common rot didn＇t change, significantly. GC-MS results showed that the compounds of the decomposed products included organic acids, esters, hydrocarbons, amides and aldehydes, with the proportions 25.26, 24.01, 17.22, 14.39 and 7.73%, respectively. Further analysis investigated that the allelochemicals identified in straw decomposed products contained p-hydroxybenzoic acid （9.21%）, dibutyl phthalate （6.94%）, 3-phenyl-2-acrylic （5.06%）, 4-hydroxy-3,5-dimethoxybenzoic acid （2.26%）, hexanoic acid （1.73%）, 8-octadecenoic acid （1.06%）, 3-（4-hydroxy-3-methoxy-phenyl）-2-propenoic acid （1.04%）, 4-hydroxy-3-methoxy-benzoic acid （0.94%） and salicylic acid （0.94%）.

Allelopathy:Potential Role to Achieve New Milestones in Rice Cultivation

Rice fields are ecosystems with many types of plants, microbes, invertebrates, birds and animals. The rice farming protects the biodiversity of the region and maintains the ecosystem for the benefit of environment. Some rice varieties release biocidal allelochemicals which might affect major weeds, microbial and pathogenic diversity around rice plants, even soil characteristics. A large number of compounds such as phenolic acids, fatty acids, indoles and terpenes have been identified in rice root exudates and decomposing rice residues, as putative allelochemicals which can interact with surrounding environment. Since these allelopathic interactions may be positive, they can be used as effective contributor for sustainable and eco-friendly agro-production system. Genetic modification of crop plants to improve their allelopathic properties and enhancement of desirable traits has been suggested. Development of crops with enhanced allelopathic traits by genetic modification should be done cautiously, keeping in view of the ecological risk assessment(non-toxic and safe for humans and ecosystem, crop productivity, ratio of benefit and cost, etc.).

Analysis on Dynamic Heterosis for Allelopathy in Rice Under Different Environment Conditions

In this study, 5 parental rice varieties with different allelopathic potentials were employed in diallel cross [P(P+1)/2] to get a set of genetic materials including parental lines and two generations of F1s. The dynamic heterosis for allelopathy in rice under different environmental conditions, was analyzed by using additive-dominant developmental genetic model. The results indicated that heterosis in both F1 and F2 showed inhibitory effects on shoot and root length of receiver plant(Lactuca sativa L.). Heterosis over mid-parent based on population mean(HMP)in F2 was lower than that in differental environmental conditions, showing 1/2 HMP in F1 The heterosis in rice allelopathy was much higher under the field environmental conditions with lower temperature and weaker sunlight than that under favorable environment, implying that the allel-opthic potential could be increased by stress environment. This finding interpreted the genetic reason that plant could produce more allelochemicals under unfavorable environment.

Induced Effects of Exogenous Phenolic Acids on Allelopathy of a Wild Rice Accession(Oryza longistaminata,S37)

Four exogenous phenolic acids, including salicylic acid, fumalic acid, p-coumaric acid and p-hydroxybenzonic acid, were used to investigate the regulatory effects on allelopathy of a wild rice accession of S37 （Oryza Iongistaminata）, which is a known allelopathic rice. The four exogenous phenolic acids induced the enhancement of the allelopathic potential of wild rice S37 in target weeds though the weed-suppressive activities were low, and the inducible effects were dependent on the specific phenolic acid, concentration and treatment time. After foliar application of exogenous phenolic acids, the inhibition rates for plant height, root length and fresh weight of barnyard grass （Echinochioa crus-galli） were significantly higher than those of the control. Especially at the concentration of 100 mg/L, the inhibition rates for plant height and fresh weight of barnyard grass by fumalic acid were 38.12% and 26.31% higher than those of the control, showing that fumalic acid was more effective compared with other phenolic acids in inhibiting monocotyledon weed growth. Furthermore, the weedsuppressive activity of aqueous extract from the leaves of wild rice S37 treated with exogenous phenolic acids was increased, and it peaked at 48 h after the treatment with the aqueous extract, and then gradually declined.

<i>In Vitro</i>Bioassay of Allelopathy in Four Bamboo Species;<i>Bambusa multiplex, Phyllostachys bambusoides, P. nigra, Sasa kurilensis</i>, Using Sandwich Method and Protoplast Co-Culture Method with Digital Image Analysis

Moderately strong allelopathic activities were found in four bamboo species, Bambusa multiplex cv. Houraichiku;Phyllostachys bambusoides cv. Madake;P. nigra cv. Hachiku;Sasa kurilensis cv. Chishimazasa, which are of different classification or of different ecological distributions, using the “Sandwich Method”, which assays the dried leaves on growth of lettuce seedlings. Only small difference of activity was found among the four bamboo species. In addition, “Protoplast Co-culture Method” for assay of allelopathy in a 50 μL liquid medium using a 96 well culture plate, was applied to the suspension cultures of the four bamboo species. Protoplasts were isolated from two-week cultured suspension cells of four bamboo species using Cellulase RS and Pectolyase Y-23 in 0.6 M mannitol. At low protoplast densities of bamboo, B. multiplex and P. bambusoides stimulated the recipient lettuce growth, i.e., non-spherically cell enlargement and cell divisions observed under an inverted microscope, while protoplasts of P. nigra and S. kurilensis were less stimulatory or inhibitory. Inhibitory effect of S. kurilensis was the strongest among four bamboo species. Furthermore, highly inhibitory effects of S. kurilensis protoplasts on yellow color accumulation of lettuce protoplasts were clearly observed by analysis of a scanned digital image of a 96-well culture plate. Differences and causes of the allelopathic activities were discussed comparing with other plant species studied using the same assay methods.

Allelochemicals and allelopathy from microorganisms in wheat rhizosphers

Allelochemicals from fungi and bacteria in wheat rhizosphere,as well as their allelo- pathic effects on wheat and maize have been conducted.Fungi and bacteria were incubated at tem- perature 28-30℃.The extracts were tested for bioassay.Some samples identified to be responsi- ble for allelopathy have been determined by GC-MS.Some chemicals identified were selected to test again their bioactivity.The results showed that acidic extracts were more toxic to germination of wheat and maize seeds(statistic significant difference P<0.01 or P<0.05)and basic extracts were less toxic and stimulated effects on germination in some cases.A good relationship has been observed between the data of chemical analysis and bioassay. A wide variety of chemicals such as phenolic acids,organic acids,aldehydes,alcohol,ke- tones,nitrogen-containing chemicals,were identified by GC-MS.Some phenols and organic acids were identified to be inhibit and nitrogens-containing compounds were to be stimulate to germina- tion of seeds and extension of root and shoot of wheat and maize.

Research advances in allelopathy of Quercus L.

The term allelopathy refers to biochemical interaction between all types of plants including microorganisms through production of chemical compounds that escape into the environment and exist widely in Quercus L. The development of investigations into types of allelochemicals, their compounding and spreading pathways, as well as expression of allelopathy in Quercus L. are reviewed in this paper： We have closely and systematically emphasized the functional mechanisms of allelopathy in forest plants for our next research project on allelopathy in Quercus L.

Adverse Effects of Allelopathy from Legume Crops and Its Possible Avoidance

Plant releases many bioactive chemicals from its various parts such as leaves, stem, root and sometimes decomposed body through different mechanism into its surrounding environment. These bioactive chemicals are often termed as allelochemicals because they interact with the surrounding environment. This interaction is either positive or negative. Effects of allelochemicals to the agricultural and biological ecosystem are well documented. In leguminosae family many species are involved in releasing of allelochemicals. Many researchers found that this allelochemicals have both positive and detrimental effects on the successive legume crops. Legume monoculture is common in many parts of the world where they cause a numbers of ecological and economic problems such as decline in crop yield due to soil sickness, regeneration failure and replant problem. These negative effects of allelochemicals open a great concern on allelopathy research. This article reviews the adverse effects of allelochemicals, their extraction and isolation, mechanism inside the plant body. These all are done to find out the possible selection methods of succeeding crops to avoid the allelopathic effects in the next crop of a monoculture farm field. The main purpose of this article is to highlight the adverse allelopathic effects of legume crops to provide ways for sustainable development in agro-ecosystem.

Allelopathy of Gaseous Volatiles of Eupatorium adenophorum on Seed Germination and Seedling Growth of Pinus yunanensis

[ Objective] The paper was to understand allelopathy of gaseous volatiles of Eupatorium adenophorum stems and leaves on seed germination and seedling growth of P/nus yunnanens/s. [ Method] P. yunnanens/s seeds were treated by fresh stems and leaves of E. adenophorum in translucent airtight container under high concentration （0.069 4 g/cm3 ）, middle concentration （0.023 1 g/cm3 ） and lower concentration （0. 007 7 g/cm3 ）, respectively. [ Result] Gaseous volatiles affected seed germination process; with the increasing processing concentration, the day on which seeds began to germinate and the day reaching germination peak were delayed, and the germination quantity on the day reaching germination peak was decreased ; the day on which the germination quantity began to significantly re- duce was delayed ; the process curve was developed from sudden increase and sudden decrease to gentle change, and nearly became a beeline at high concentration. The effects of gaseous volatiles on seed germination （ seed germination rate, germination potential, germination index） and seedling growth （fresh weight, dry weight, radicle length, hypceotyl length） of P. yunnanens/s were basically consistent, showing a regularity that high concentration had stronger inhibition effect and the inhibition effect became weaker with the decreasing concentration of E. adenophorum. E. adenophorum was widely distributed under P. yunnanens/s forests, and might affect natural regeneration and growth of P. yunnanens/s via allelopathy. [ Conclusion ] The paper provides reference for scientific management of P. yunnanens/s forests.

Research Advances in Allelopathy of Plants in Arid Desert Regions of Northwest China

To investigate allelopathy of plants in desert ecosystems, related research achievements obtained in recent years, reported allelopathic plants, allelochemicals and releasing ways of alleochemicalds were summarized, and then the key problems of research into allelopathic plants in desert ecosystems were indicated. It was considered that the research of allelopathy of plants in desert regions has just started in China, and plants with atlelopathic potential were found in the Compositae, Leguminosae, Rosaceae, Scrophulariaceae and Gramineae; plants in desert regions re- lease allelochemicals mainly via natural volatilization, which is closely related to their growing environment; allelochemicals such as alkaloids, fla- vonoids, terpenoids have been identified. This study can provide theoretical basis and practical value for reasonable adoption of protection meas- ures of desert plants and comprehensive control of desertification.

UV-B irradiation and allelopathy by Sargassum thunbergii affects the activities of antioxidant enzymes and their isoenzymes in Corallina pilulifera

Intertidal macroalgae can cope with the dual effects of UV-B irradiation and allelopathy.To study the impacts of the two stressors,we co-cultured Corallina pilulifera with Sargassum thunbergii in 1:1 and 1:10 ratios under different doses of UV-B radiation.The response of the antioxidant defense system,focusing on activities of superoxide dismutase(SOD),ascorbate peroxidase(APX),peroxidase(POX)and glutathione reductase(GR),was monitored.In addition,isoenzyme patterns were analyzed using nondenaturing poly acry lamide gel electrophoresis.The results show that the activities of SOD,APX,and GR were all significantly affected by both UV-B radiation and allelopathy,and the effect of their interaction was significant.However,POX activity was only influenced by UV-B radiation.The enzymatic assay revealed four distinct bands of SOD.The SODⅢband weakened significantly when the co-cultures were exposed to extremely high dosage of UV-B irradiation under both co-culturing ratios of 1:1 and 1:10.When the coculturing ratio was 1:10,both POXⅡand APXⅡenzy me activities increased with different UV-B doses.GR activity was at its greatest when the co-culture ratio was 1:10 and exposure was to the higher UV-B doses.The activities of GRⅢand GRⅣwere elevated under all UV treatments whereas the activities of GRI and GRII were reduced under the lower UV-B treatments but were elevated under the higher UV-B treatments.However,lipid peroxidation,as indicated by the thiobarbituric acid-reacting substance(TBARS)assay,increased significantly under the dual stressors.Our data sugge st that allelopathy and UV-B radiation stre ss can each affect the antioxidant enzyme activities of C.pilulifera.Critically,the adverse effects of UV-B on C.pilulifera were intensified by the compounding effects of allelopathy.

Assessment of the Contribution of Foliar Trichomes towards Allelopathy

Plant trichomes vary in their structure and cellular composition.Glandular trichomes contain a bulk of specific(secondary)metabolites of diverse nature.Trichomes are connected with various adaptive processes,which include protection against herbivores and pathogens as well.Our study investigates the allelopathic contribution of structures present on the leaf surface of Nicotiana plumbaginifolia Viv.against seedling growth of Cicer arietinum L.The infusion obtained after dipping Nicotiana leaves in Dichloromethane(DCM)for 10 seconds(s)was the most phytotoxic among all the infusions.The observed inhibition in Cicer growth was not only dependent on type of infusion but also the concentration.Scanning electron microscopy of the leaf samples showed the modifications in trichomes under the influence of the different concentration of DCM.Glandular trichomes were most dehydrated at 10 seconds in DCM,suggesting their role for the observed allelopathy.Such study on the biochemistry of trichomes and their phytotoxicity may develop highly valuable objects for plant metabolic engineering.

Hopf Bifurcations in a Predator-Prey System of Population Allelopathy with Discrete Delay

A delayed Lotka-Volterra two-species predator-prey system of population allelopathy with discrete delay is considered. By linearizing the system at the positive equilibrium and analyzing the associated characteristic equation, the asymptotic stability of the positive equilibrium is investigated and Hopf bifurcations are demonstrated. Furthermore, the direction of Hopf bifurcation and the stability of the bifurcating periodic solutions are determined by the normal form theory and the center manifold theorem for functional differential equations (FDEs). Finally, some numerical simulations are carried out for illustrating the theoretical results.

Allelopathy of Cold Water Extracts from Origanum vulgare ssp. vulgare L.

Secondary metabolites in medicinal plants could lead to discovery of new classes of herbicides. Recently aromatic plants have gained interest as a source of allelopathic secondary metabolites. Origanum vulgare ssp. vulgare L. infusions in hot water are used in folk medicine and possess proved beneficial biological activity. Plant-to-plant variability of metabolites due to genetic heterogeneity is established in Lamiaceae family. From this point of view, studies on plants from different geographic regions might reveal important sources of variability. The objective of this study was to evaluate allelopathic activity of cold water extracts made from the aerial parts of O. vulgare ssp. vulgare growing wild in Northeast Bulgaria in laboratory conditions. The allelopathic effect was evaluated using root elongation test and Allium cepa-test. Oregano extracts (17.5 g/l, 52.5 g/l) significantly decreased root length of Triticum aestivum L. (P ≤ 0.001). The root growth reduction could serve as a sign for presence of water soluble allelopathic secondary metabolites in the plant tested. Oregano (3.5 g/l) inhibited cell division in Allium root meristematic cells. The decline of the mitotic index indicates the occurrence of a cytotoxic effect. Oregano induced abnormalities in mitotic and interphase cells, so can be also considered as genotoxic. The observed macroscopic and microscopic effects of tested extracts indicated presence of water soluble allelochemicals in O. vulgare ssp. vulgare. This characteristic could be further studied as a possibility to be used in weed management programs.

Chemical Basis for the Phytotoxicity of Indoles in Relation to the Allelopathy of Cereals

Phytotoxic activity of an indole series substituted with electron-acceptor and electron-donor groups in the aromatic ring was determined. They are potential decomposition products, of natural indole alkaloids in cereals plants with allelopathic properties. Phytotoxic selectivity was evaluated from antialgal activity against the microalga Chlorella vulgaris, seed germination seeds and biomass weight of seedling of barley, rye, wheat, oat and maize species and the weed Lolium rigidum. Lipophilia character of the compounds was determined by RP-HPLC method. Both, the electronic character of the substituents, evaluated from σp parameter, and the lipophilia character of the molecules measured from logPHPLC parameter, are involved in the phytotoxic activity. The three bio indicators has shown that the compounds with the higher electron-acceptor groups showed the higher level of phytotoxicity and the molecules with electron-donor groups showed the lowest activity, although, in some cases, this behavior is modified by the lipophilic properties of the molecules. These results are rationalized in terms of polarization of N-H bond of heterocyclic ring. Compounds with the higher logPHPLC values showed the higher phytotoxic activity. Further evidence on the role of lipophilicity was obtained from linear regression between the average inhibitions percentages of biomass and logPHPLC values. The activity increased linearly by increasing the lipophilic character of the compounds. Therefore, quantitative effects in the phytotoxic activity of the electronic properties of the substituents in the aromatic ring and lipophilic character of the indoles can be inferred from σp and logPHPLC parameters, respectively. The results strongly suggest that the potential decomposition products of the natural indole alkaloids from cereals or other natural sources may be in connection with the allelopathic phenomenon of plants when are released into the soil.

The Combination of Achnatherum inebrians Extracts and Soil Microorganisms Inhibited Seed Germination and Seedling Growth in Elymus nutans

In a greenhouse experiment,the effects of soil microorganisms and extracts of Achnatherum inebrians on the seed germination and seedling growth of Elymus nutans were studied.The results showed that both the extracts from aboveground and belowground parts of A.inebrians significantly inhibited the germination rate,germination potential,germination index,vigor index,seedling height,root length,and fresh weight of E.nutans,but increased malondialdehyde content,catalase,peroxidase and superoxide dismutase activity of E.nutans seedlings(p<0.05).The allelopathy of aqueous extracts of the aboveground parts of A.inebrians was stronger than that of the pre-cipitates.Aqueous extracts of the aboveground parts of A.inebrians decreased seed germination rate,germination potential,germination index,vigor index,seedling length,root length,and seedling fresh weight by 10.45%-74.63%,24.18%-32.50%,19.03%-73.36%,37.83%-88.41%,21.42%-53.14%,2.65%-40.21%,and 20.45%-61.36%,respectively,and malondialdehyde content,peroxidase,catalase,and superoxide dismutase activity increased by 8.09%-62.24%,27.83%-86.47%,22.90%-93.17%,and 11.15%-75.91%,respectively.The above indexes were higher in live soil than in sterilized soil.Soil microorganisms increased the allelopathy of A.inebrians.The seed germination rate,germination potential,germination index,vigor index,seedling length,and seedling fresh weight of E.nutans planted in live soil decreased by 8.22%-48.48%,10.00%-51.85%,8.19%-53.26%,16.43%-60.03%,12.91%-28.81%,and 9.09%-22.86%compared with sterilized soil,respectively.Malondialdehyde content,peroxidase,catalase,and superoxide dismutase activity of E.nutans planted in live soil increased by 53.91%-81.06%,15.71%-57.34%,33.33%-86.31%,and 9.78%-52.51%compared with sterilized soil,respectively.The existence of soil microorganisms enhanced the allelopathy of the secondary metabolites of A.inebrians.A combination of microorganisms and aqueous extracts from the aboveground parts of A.inebrians had the strongest allelopathic effect on E.nutans.

Enhanced allelopathy and competitive ability of invasive plant Solidago canadensis in its introduced range

Aims Why invasive plants are more competitive in their introduced range than native range is still an unanswered question in plant invasion ecology.Here,we used the model invasive plant Solidago canaden-sis to test a hypothesis that enhanced production of allelopathic compounds results in greater competitive ability of invasive plants in the invaded range rather than in the native range.We also exam-ined the degree to which the allelopathy contributes increased com-petitive ability of S.canadensis in the invaded range.Methods We compared allelochemical production by S.canadensis growing in its native area(the USA)and invaded area(China)and also by populations that were collected from the two countries and grown together in a'common garden'greenhouse experiment.We also tested the allelopathic effects of S.canadensis collected from either the USA or China on the germination of Kummerowia striata(a native plant in China).Finally,we conducted a common garden,greenhouse experiment in which K.striata was grown in monocul-ture or with S.canadensis from the USA or China to test the effects of allopathy on plant-plant competition with suitable controls such as adding activated carbon to the soil to absorb the allelochemicals and thereby eliminating any corresponding allopathic effects.Important findings Allelochemical contents(total phenolics,total flavones and total saponins)and allelopathic effects were greater in S.canadensis sampled from China than those from the USA as demonstrated in a field survey and a common garden experiment.Inhibition of K.stri-ata germination using S.canadensis extracts or previously grown in soil was greater using samples from China than from the USA.The competitive ability of S.canadensis against K.striata was also greater for plants originating from China than those from the USA.Allelopathy could explain about 46%of the difference.These find-ings demonstrated that S.canadensis has evolved to be more allelo-pathic and competitive in the introduced range and that allelopathy significantly contributes to increased competitiveness for this inva-sive species.

Algal-bloom control by allelopathy of aquatic macrophytes—A review

Algal-bloom control is an important issue for water environment protection as it induces several negative impacts on the lives of aquatic organisms,aquaculture,landscaping,and human health.The development of an environment-friendly,cost-effective,and convenient alternative for controlling algal bloom has gained much concern.Using the allelopathy of aquatic macrophytes as a novel and safe method for algal-bloom control is a promising alternative.This paper reviews the development and potential application about allelopathy of aquatic plants on algae,including the allelopathic research history,the potential research problems,the research methodology,and the reported aquatic macrophytes and their inhibitory allelochemicals.Potential modes of inhibition action of allelochemicals on algae,possible ways for application,and future development directions of research on algal-bloom control by aquatic macrophytes were also presented.

Rice allelopathy and its properties of molecular ecology

Crop allelopathy is a promising and environmentally friendly method in weed control;however,the inducible genetic trait for allelopathy in the suppression of weeds needs to be overcome for practical use.Further study needs to be directed to this end to elucidate the molecular genetics and its physiologic mechanism.In this paper,the authors review recent advances in the investigation of rice allelopathy and its molecular regulatory mechanism,especially in responses to stressful conditions including biotic and abiotic factors in China.Previous studies show that rice allelopathy could be enhanced when the rice accession was exposed to stressful conditions,and further analysis by the transcriptomics and proteomics approaches conducted in our laboratory indicated that the increase in allelopathic potential of rice,when exposed to the stresses,was attributed to increased expression level of genes involved in phenolic synthetic metabolism.The increasing phenolic compounds have been confirmed as the main allelochemicals and they jointly act to suppress the target,especially in responses to stressful condition,but it seems to be the primary effect in phenolic allelopathy.We still wonder how the exudates from rice root,which were released into rhizosphere soil,are transformed by soil microorganism to produce the higher secondary effect of phenolic allelopathy in the suppression of weeds.Therefore,the authors suggest that rhizosphere biologic properties of allelopathy in rice and its mechanism are being the key research areas in the world now,and systems biology and its approaches,such as metagenomics and metaproteomics,would be helpful to reveal the process and its molecular ecological mechanism regarding rhizospheric biology of rice allelopathy.

Elemental allelopathy by an arsenic hyperaccumulating fern,Pteris vittata L.

Aims the functional advantages of arsenic(As)hyperaccumulation by plants are poorly understood.One proposed benefit,termed ele-mental allelopathy,occurs when hyperaccumulated As is cycled from the plant back into the top layer of soil,allowing As hyperaccu-mulators to gain an advantage over intolerant species by increasing soil As concentrations([As])underneath their canopy.to date,there are no studies that detail the presence of increased soil[As]associ-ated with As hyperaccumulators.In this study,we documented vari-ation in the soil[As]associated with the Chinese brake fern,Pteris vittata L.and also compared the effects of environmentally relevant soil and solution[As]on competitor plant growth.Methods Four populations of P.vittata were identified in central Florida,USA.P.vittata tissue samples and soil samples were collected at the base of and at 3 m away from ferns in each population(n=36).Five sample locations were randomly selected from each site,and soils from the base and 3 m away from each fern were collected to examine the effects of naturally occurring soil[As]on the germination and growth of a potential competitor plant(Oxalis stricta).Solutions with increasing[As]were also used to examine the threshold for negative effects of[As]on O.stricta growth.[As]were measured using inductively coupled plasma mass spectrometry(ICP-MS).Important Findings Overall,soil[As]from the base of ferns was nearly twice that of soil 3 m away indicating that ferns hyperaccumulate As.However,ferns and their associated soil,contained different[As]depending on their col-lection site,indicating that these populations accumulate and use[As]differently.O.stricta growth decreased and germination was delayed as solution and soil[As]increased.However,the relative distance from the fern that the soil was collected from did not affect growth,which would be expected with elemental allelopathy.Our results show that P.vittata is associated with higher soil[As]and these concentrations are sufficient to inhibit growth of competitors.However,the absence of a strong inhibitory relationship associated with proximity to the fern across all locations suggests that the possible functional advantages of elemental allelopathy may depend on site specific characteristics.