Phytotoxicity Assessment of Biofertilizer Produced from Bioreactor Composting Technology Using Lettuce (Lactuca sativa L.) Seeds

Establishing reliable technological information on the safety of biofertilizers produced from a bioreactor composting technique is a must prior to its commercialization. A phytotoxicity study of biofertilizer made from the bioreactor composting technology at Aklan State University, Banga, Aklan, Philippines was conducted for fourteen (14) days using commercially available lettuce seeds (Lactuca sativa L.). Standard phytotoxicity attributes such as hypocotyl length, radicle length, relative germination percentage, and relative radicle growth observed during the germination stage were evaluated. Results revealed no significant difference in the radicle lengths of the germinated lettuce seeds as affected by the varying levels of biofertilizer dilution at H(3) = 10.567, p = 0.061 > 0.05. On the other hand, the hypocotyl length of the lettuce showed significant differences in response to varying levels of biofertilizer dilution with Welch’s F(5, 5.163) = 8.175, p = 0.017 < 0.05. Also, the different levels of biofertilizer affected significantly the germination percentage of lettuce seeds F(5, 12) = 5.822, p = 0.006 < 0.05. All levels of biofertilizer treatments indicated a decrease in relative germination percentage. However, those seeds applied with 10% biofertilizer have the highest reduction of germination percentage, equivalent to 86.9% (RGP = 13.10%). All levels of biofertilizer showed an increase in radicle growth in contrast to the negative control plant except for the one given a 10% level of biofertilizer. Seeds that received 10% biofertilizer showed an extremely high reduction in radicle growth, equivalent to 72.22% (RRG = 27.78%). The study shows that applying low levels of the bioreactor-produced biofertilizer will observably reduce the measure of the germination characteristics of lettuce seeds, but not necessarily low enough to be considered phytotoxic. However, the application of at least 10% bioreactor-produced biofertilizer can presumptively lead to phytotoxicity.

Isolation, identification, derivatization and phytotoxic activity of secondary metabolites produced by Cladosporium oxysporum DH14, a locust-associated fungus

Three main phytotoxic compounds including lunatoic acid A （1）, 5Z-7-oxozeaenol （2） and zeaenol （3） were isolated from the fermentation broth of Cladosporium oxysporum DH14, a fungus residing in the locust （Oxya chinensis ） gut. Two additional derivative compounds, compound la and lb, were synthesized by methylation and chlorination of compound 1, respectively. The structures of such compounds were identified on the basis of spectroscopic analysis and by comparison of the corresponding data to those previously reported in the literature. Compounds 1-3 exhibited significantly phytotoxic activities against the radicle growth of Amaranthus retroflexus L. with the 50% inhibitory concentrations （ICso values） of 4.51, 4.80 and 8.16 μg· mL^-1, respectively, which is comparable to that positive control 2,4-dichlorophenoxyacetic acid （IC50=1.95 μg· mL^-1）. Furthermore, the compound 1 showed selective phytotoxic activity with the inhibition rate of less than 22% against the crops of Brassica rapa L., Sorghum durra, Brassica campestris L,, Capsicum annucm and Raphanus safivus L. under the concentration of 100 μg· mL^-1 Both derivatives of compound 1 had moderate phytotoxic activity against the radicle growth of A. retroflexus L. The findings of our present study suggest that these compounds provide new promising candidates for the potential management strategies of weeds.

Phytotoxicity assessment of phenanthrene, pyrene and their mixtures by a soil-based seedling emergence test

Seedling emergence tests were conducted in a meadow brown soil using five plant species(i.e., Chinese cabbage, green onion, tomato, turnip and wheat) to determine the phytotoxicity of phenanthrene, pyrene and their mixtures. The soil was amended with up to 1000 mg/kg soil of phenanthrene or 600 mg/kg soil of pyrene. Seedling emergence and root growth were measured. The results indicated that root elongation was more sensitive than seedling emergence. Root length decreased with increasing phenanthrene or pyrene concentrations(p≤0 05). Phenanthrene was more phytotoxic than pyrene. The lowest observable adverse effect concentration(LOAEC) was 10 mg/kg for phenanthrene when tested with green onion, and 50 mg/kg for pyrene when tested with wheat. Among the five species, wheat was found to be the most sensitive. When amended jointly at or below their respective LOAEC, phenanthrene and pyrene produced a synergistic toxic effect.

Bioavailability of bound residue derived from ^(14)C-labeled chlorsulfuron in soil and its mechanism of phytotoxicity

The bioavailability of bound residue(BR) derived from 14 C-labeled chlorsulfuron in soil and effect of the main components of the BR on growth of rape(brassica napus) and rice(Oryza sativa L.) were investigated. The results showed that the BR with the concentration of 0 28 and 0 56 nmol/g air-dried soil, which was calculated by special radioactivity of 14 C-labeled chlorsulfuron parent compound, resulted in significant depression effect on growth of rape seedling. It was assured that the main components(2-amino-4-methoxyl-6-methyl-1,3,5-triazine, 2-amino-4-hydroxyl-6-methyl-1,3,5-triazine, and 2-chloro-benzenesul-f onamide) of the BR did not inhibit the growth of rape and rice. LC-MS analysis demonstrated that the parent compound previously bound to the soil matrix could be again released and transformed into methanol-extractable residue during the course of rape growth. It was concluded that the molecular leading to the phytotoxicity to rape and rice in the BR is still the parent compound.

Phytotoxicity of four herbicides on Ceratophyllum demersum,Vallisneria natans and Elodea nuttallii

The physiological effects of 4 herbicides （butachlor, quinclorac, bensulfuron-methyl and atrazine） on 3 submerged macrophytes （Ceratophyllum demersum, Vallisneria natans and Elodea nuttallii） were tested in laboratory. The variables of the relative growth rate and the photosynthetic pigment content showed that all of the tested herbicides affected the growth of the plants obviously, even at the lowest concentration （0.0001 mg/L）. Except for the C. demersum treated with quinclorac at 0.005 and 0.01 mg/L, the relative growth rates of the plants were inhibited significantly （p 〈 0.01）. Statistical analysis of chlorophyll a （Chl-a） contents was carded out with both the t-test and one-way ANOVA to determine the difference between the treatment and control. The results showed that Chl-a contents of the plants in all treatment groups were affected by herbicides significantly, except for the C. demersum treated with bensulfuron-methyl at 0.0005 mg/L. The decrease in Chl-a content was positively correlated to the dosage of the herbicides in most treatment groups. It was suggested that herbicides in water bodies might potentially affect the growth of aquatic macrophytes. Since the Chl-a content of submerged macrophytes responded to the stress of herbicides sensitively and directly, it could be used as a biomaker in environmental monitoring or in the ecological risk assessment of herbicide contamination.

Chemical composition and phytotoxic activity of the volatile oil of invasive Xanthium italicum Moretti from Xinjiang,China

Aerial parts of Xanthium italicum in an air tight container greatly inhibited root elongation of radish, implying that this invasive plant could release biologically active volatile organic compounds （VOCs） into the environment to affect other plants＇ growth. This phenomenon was further studied by evaluating the phytotoxic effects of X. italicum essential oil against two dicot plants, amaranth （Amaranthus mangostanus L.） and lettuce （Lectuca sativa L.）, and two monocot plants, wheat （Triticum aestivum Linn） and ryegrass （Lolium multiforum）, and analyzing the chemical composition of the oil. Among the 4 test species, amaranth was the most sensitive plant, 0.5μl/mL essential oil application resulted in a 50% reduction on root elongation, and 2.5 μl/mL essential oil almost completely inhibited its seedling growth. Wheat was the least sensitive species, whose root growth was reduced to 36% of control by 5 μl/mL essential oil. The essential oil exerted moderate inhibitory effect on both lettuce and ryegrass. Compared to a commercial herbicide-Harness, X. italicum oil exhibited stronger phytotoxicity on amaranth, lettuce and wheat, but weaker activity on ryegrass. The chemical composition of the essential oil isolated by hydrodistillation from the aerial parts of X. italicum Moretti was analyzed by GC/MS. Thirty two compounds were identified, representing 94.89% of total oil, which was found to be rich in monoterpene hydrocarbons （60.71%）. The main constituents of the oil were limonene （51.61%）, germacrene B （6.98%）, 6-cadinol （5.94%）, β-pinene （5.23%）, α-caryophyllene （5.1%） and bornyl acetate （3.15%）. Bioassay revealed the dominant constituent-limonene, was unlikely the responsible phytotoxic compound due to its low biological activity; rather, there might be other oil constituent（s） that either act alone, or work together, and possibly assisted by synergistic effect, to display the phytotoxic activity. Our results suggested that X. italicum might produce allelopathic VOCs to facilitate its invasion success. This is the first report on the phytotoxic activity and the chemical composition of the essential oil of X. itaficum Moretti from China.

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% （by weight） of digested sewage sludge （SS） and composted sludge （SC）. The additions of the both sludges caused a significant raise in all fractions, resulting in that exchangeable （EXCH） and organic matter （OM） became predominance for Zn and organic bound Cu occupied the largest portion. There was more available amount for Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate （CAR） and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to AEXCH and ACAR forms but also in AOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by AEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.

Phytotoxicity of Chromium on Germination, Growth and Biochemical Attributes of <i>Hibiscus esculentus</i>L.

Chromium is found in all phases of the environment, including air, water and soil. The contamination of environment by chromium has become a major area of concern. Chromium effluent is highly toxic to plant and is harmful to their growth and development. In present study, a pot experiment was carried out to assess the phytotoxicity of chromium in Hibiscus esculentus at different concentration (0.5, 2.5, 5, 10, 25, 50 and 100 mg·kg-1) of chromium metal. The phytotoxic effect of chromium was observed on seed germination, seedling growth, seedling vigor index, chlorophyll content and tolerance indices of Hibiscus esculentus. All results when compared with control show that chromium metal adversely affects the growth of Hibiscus esculentus by reducing seed germination and decreasing seedling growth. The toxic effects of chromium metal to seed germination and young seedling are arranged in order of inhibition as: 0.5 > 2.5 > 5 > 10 > 25 > 50 > 100 mg·kg-1 respectively. The toxicity of chromium metal to young seedling and their effects on chlorophyll content were increased with higher concentration of chromium in the soil system. The major inhibitory effect of chromium in Hibiscus esculentus seedling was determined as stress tolerance index (%). The present study represents that the seed and seedling of Hibiscus esculentus has potential to counteract the deleterious effects of chromium metal in soil.

Phytotoxic Effects of 4-Chlorophenol and 2,4-Dichlorophenol in the Germination of Seeds of <i>Phaseolus vulgaris</i>and <i>Zea mayz</i>

Soil contaminated with pesticides may reduce plant development due to their toxicity. The aim of this study was to evaluate the influence on the germination of Zea mayz and Phaseolus vulgaris of the two main intermediates of the 2,4-D degradation, which are 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP). Maize and bean seeds were treated with distilled water (control treatment) and increased concentrations of 4-CP and 2,4-DCP (0.006, 0.1, 1.0, 1.5 g·L-1). It was assessed seed germination and calculated various parameters. The parameter most affected by chlorophenols was the index of germination rate, being the P. vulgaris seeds most affected. 2,4-DCP was the compound most toxic for both plants. The germination index was dependent doses for both plant models tested. The results indicate that 4-CP and 2,4-DCP affected the index of germination rate but not influenced in other parameters of germination of Zea mayz and Phaseolus vulgaris. Maize was most tolerance to both chlorophenols in the assessed concentrations. 2,4-DCP was the most toxic of chlorophenols tested.

Correlation of Quantitative Structure and Inhibition Phytotoxicity for Aromatic Compounds Using Ab Initio Method

29 aromatic compounds were computed at the HF/6-31G^＊ level. Based on linear solvation energy theory firstly, the parameters of molecular structure were taken as theoretical descriptors, and the corresponding linear solvation energy relationship （LSER） （r^2= 0.8993, q^2=0.8559） between the structural parameters and inhibition phytotoxicity to the seed germination rate of cucumis （-lgGC50） was thus obtained. Then the parameters of molecular structure and thermodynamics were taken as theoretical descriptors, and as a result the other corresponding correlation equation （r^2=0.9268, q^2=0.8960） relating to -lgGC50 was achieved. The two equations obtained in this work by HF/6-31G^＊ are both more advantageous than that from AM 1.

A Phytotoxic and Antifungal Metabolite (Pyrichalasin H) from a Fungus Infecting <i>Brachiaria eruciformis</i>(Signal Grass)

Brachiaria eruciformis (sm.) Griseb, locally known as “signal grass”, is a common weed in lawns and turfs in Mississippi, USA. During late spring and early summer months, leaves of B. eruciformis are infected with a fungus causing necrosis. The infected leaves ultimately turn brown and wither. As part of our search for potential new natural product-based agrochemicals, we studied this plant pathogen in order to investigate phytotoxic and fungitoxic metabolites produced by the fungus. The causative fungus was isolated from an infected leaf of B. eruciformis, cultured in potato dextrose agar plates and identified via molecular techniques as Pyricularia grisea. A phytotoxic compound was isolated from Czapek-Dox broth liquid culture medium and identified as pyrichalasin H by spectroscopic techniques. Pyrichalasin H was toxic to the fungal plant pathogen Colletotrichum fragariae in a TLC bioautography assay and phytotoxic to two monocot and one dicot plants. This is the first report of antifungal activity of pyrichalasin H against phytopathogens. Pyrichalasin H isolated from Pyricularia grisea, a pathogen infecting B. eruciformis (signal grass) was shown to be phytotoxic and fungicidal to Colletotrichum fragariae.

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.

Mitigating phytotoxicity of tetracycline by metal-free 8-hydroxyquinoline functionalized carbon nitride photocatalyst

Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytotoxins. Herein, we found that photooxidation of common antibiotic tetracycline hydrochloride(TCH) over a metal-free 8-hydroxyquinoline(8-HQ) functionalized carbon nitride(CN) photocatalyst significantly reduces the TCH phytotoxic effect. The phytotoxicity test of photocatalytic treated TCH-solution evaluated towards seed growth of Cicer arietinum plant model endowed natural root and shoot growth.This study highlights the conceptual insights in designing of metal-free photocatalyst for environmental remediation.

Effects of persulfate-assisted hydrothermal treatment of municipal sludge on aqueous phase characteristics and phytotoxicity

Hydrothermal technology (HT) has received much attention in recent years as a process to convert wet organic waste into hydrochar.The aqueous phase (HTAP) produced by this process is still a burden and has become a bottleneck issue for HT process development.In this study,we provide the?rst investigation of the HTAP characteristics,phytotoxicity,and their correlation with persulfate (PS)(PS,2.0 mmol/g TS)-assisted municipal sludge HT.The results showed that PS accelerated the hydrolysis of protein substances and increased the concentration of NH_(4)^(+)by 13.4%to 190.5%and that of PO_(4)^(3-)by 24.2%to 1103.7%in HTAP at hydrothermal temperatures of 120 to 240℃.PS can reduce the phytotoxicity of HTAP by reducing aldehydes,ketones,N heterocyclic compounds,and particle size and by increasing its humi?cation index.The maximum values of the root length and biomass of pakchoi(Brassica chinensis L.) seedlings occurred when electrical conductivity was 0.2 mS/cm of HTAP.This work provided a new strategy for the selection and design of HTAP management strategies.

Kinetic study of phytotoxicity induced by foliar lead uptake for vegetables exposed to fine particles and implications for sustainable urban agriculture

At the global scale, foliar metal transfer occurs for consumed vegetables cultivated in numerous urban or industrial areas with a polluted atmosphere. However, the kinetics of metal uptake, translocation and involved phytotoxicity was never jointly studied with vegetables exposed to micronic and sub-micronic particles（PM）. Different leafy vegetables（lettuces and cabbages） cultivated in RHIZOtest？ devices were, therefore, exposed in a greenhouse for 5, 10 and 15 days to various Pb O PM doses. The kinetics of transfer and phytotoxicity was assessed in relation to lead concentration and exposure duration. A significant Pb accumulation in leaves（up to 7392 mg/kg dry weight（DW） in lettuce） with translocation to roots was observed. Lead foliar exposure resulted in significant phytotoxicity, lipid composition change, a decrease of plant shoot growth（up to 68.2% in lettuce） and net photosynthesis（up to 58% in lettuce）. The phytotoxicity results indicated plant adaptation to Pb and a higher sensitivity of lettuce in comparison with cabbage. Air quality needs, therefore, to be considered for the health and quality of vegetables grown in polluted areas, such as certain megacities（in China, Pakistan, Europe, etc.） and furthermore, to assess the health risks associated with their consumption.

Chemical composition, antimicrobial, insecticidal, phytotoxic and antioxidant activities of Mediterranean Pinus brutia and Pinus pinea resin essential oils

Essential oils of the resins of Pinus brutia and Pinus pinea were evaluated for their biological potential. Essential oils were characterized using GC-MS and GC/FID. In vitro antimicrobial, phytotoxic, antioxidant, and insecticidal activities were carried out using the direct contact and the fumigant assays, respectively. The chemical profile of the essential oils of the resins of P. pinea and P. brutia included mainly α-pinene(21.39% and 25.40%), β-pinene(9.68% and 9.69%), and caryophyllene(9.12% and 4.81%). The essential oils of P. pinea and P. brutia exerted notable antimicrobial activities on Micrococcus luteus and Bacillus subtilis, insecticidal activities on Ephestia kuehniella eggs, phytotoxic activities on Lactuca sativa, Lepidium sativum, and Portulaca oleracea, as well as antioxidant potential. Indications of the biological activities of the essential oils suggest their use in the formulation of ecofriendly and biocompatible pharmaceuticals.

The effects of temperature on decomposition and allelopathic phytotoxicity of boneseed litter

Decomposition of plant litter is a fundamental process in ecosystem function, carbon and nutrient cycling and, by extension, climate change. This study aimed to investigate the role of temperature on the decomposition of water soluble phenolics（WSP）, carbon and soil nutrients in conjunction with the phytotoxicity dynamics of Chrysanthemoides monilifera subsp. monilifera（boneseed） litter. Treatments consisted of three factors including decomposition materials（litter alone, litter with soil and soil alone）, decomposition periods and temperatures（5-15, 15-25and 25-35°C（night/day））. Leachates were collected on 0, 5, 10, 20, 40 and 60 th days to analyse physico-chemical parameters and phytotoxicity. Water soluble phenolics and dissolved organic carbon（DOC） increased with increasing temperature while nutrients like SO-24 and NO-13 decreased. Speed of germination, hypocotyl and radical length and weight of Lactuca sativa exposed to leachates were decreased with increasing decomposition temperature. All treatment components had significant effects on these parameters. There had a strong correlation between DOC and WSP, and WSP content of the leachates with radical length of test species. This study identified complex interactivity among temperature, WSP, DOC and soil nutrient dynamics of litter occupied soil and that these factors work together to influence phytotoxicity.

Antimicrobial,hemagglutination and phytotoxic activity of crude ethanolic and aqueous extracts of Seriphidium kurramense

OBJECTIVE: To investigate the antimicrobial activity, hemagglutination and phytotoxic activity of crude ethanolic and aqueous extracts of Seriphidium kurramense.METHODS: The extracts were analyzed by agar well diffusion assays against five bacterial species:Staphylococcus aureus(S. aureus), methicillin-resistant S. aureus, Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis, and Salmonella typhi. The extracts were also screened against six fungal species — Aspergillus niger, Aspergillus flavus, Alternaria solani, Rhizoctonia solani, Fusarium solani and Pleurotus florida — using the agar tube diffusion method. Additionally, hemagglutination and phytotoxic activities of the crude ethanolic and aqueous extracts were assessed.RESULTS: The crude ethanolic and aqueous extracts showed dose-dependent inhibition of the various tested fungal and bacterial strains. No hemagglutination activity was observed. Both the ethanolic and aqueous extracts showed dose-dependent phytotoxic activity toward Lemna minor.CONCLUSION: The crude ethanolic and aqueous extracts of Seriphidium kurramense possess good antimicrobial and phytotoxic activities, but no hemagglutination activity.

Assessment of phytotoxic, genotoxic and enzyme inhibition potential of Sterculia diversifolia

OBJECTIVE:To evaluate Sterculia diversifolia stem bark and leaves for phytotoxic,genotoxic and enzymes inhibition potential.METHODS:Phytotoxic activity of both stem bark and leaves were screened using Lemna minor.The genotoxic activity of Sterculia diversifolia stem bark and leaves extracts were tested using comet assay protocol while enzyme inhibition activity of crude extract and various fractions of both stem bark and leaves were evaluated using acetyl cholinesterase,lipoxygenase,β-glucuronidase,urease,xanthine oxidase and carbonic anhydrase.RESULTS:Phytotoxic activity showed significant results in dose dependant manner in both stem bark(ethyl acetate and n-butanol)and leaves(ethyl acetate,nbutanol and n-hexane)fractions.In genotoxic activity,dichloromethane fraction showed significant activity followed by ethyl acetate fraction.Acetyl cholinesterease inhibitory activity showed significant results in both stem bark and leaves fractions,while significant lipoxygenase inhibition was shown by ethyl acetate,dichloromethane,crude extract and n-hexane fractions of both stem bark and leaves.β-glucuronidase,urease and carbonic anhydrase inhibitory activity showed highly significant results in ethyl acetate fraction of both stem bark and leaves,while xanthine oxidase inhibition was shown by dichloromethane fraction of stem bark and leaves extracts.CONCLUSIONS:This study emphasizes the important phytotoxic,genotoxic and enzyme inhibition effects of Sterculia diversifolia stem bark and leaves.Hence,it is clear that Sterculia diversifolia stem bark and leaves possess phytotoxic,genotoxic and enzyme inhibitory agents.

Insights on mechanisms of aluminum phytotoxicity mitigation by canola straw biochars from different regions

To better understand the amendment effects and mechanisms of aluminum(Al(Ⅲ))phytotoxicity mitigation by differ-ent regional crop straw biochars,wheat seedling root elongation trials were conducted.The contributions of liming effect,oxygen-containing surface functional group adsorption,and oxyanions precipitation to Al(Ⅲ)phytotoxicity mitigation by Ca(OH)_(2),pristine and ash-free canola straw biochar were evaluated.The results indicated that biochars derived from canola straw collected from four different regions(Yingtan,Xuancheng,Nanjing,and Huaiyin)caused 22-70%wheat seedling root elongation,which might be linked to liming effect.Incorporation of the corresponding ash-free biochars caused 15-30%elongation,which could be attributed to the surface functional group adsorption.About 0-60%of changes could be explained by Al(Ⅲ)precipitation with inorganic oxyanions.These findings provide new insights into the physicochemical properties,potential applications,efficiencies,and underlying mechanisms of crop straw biochar in alleviating Al(Ⅲ)phytotoxicity,which is dependent on the cultivation soil,and indicate similar application of crop straw biochar for acidic soil amelioration,contaminated soil remediation,and arable soil improvement.