ORCID Profile
0000-0003-4948-1880
Current Organisation
University of Queensland
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Crop and Pasture Nutrition | Nanomaterials | Microbial Ecology | Plant Physiology | Environmental Biotechnology | Soil Sciences | Soil Sciences not elsewhere classified | Soil Chemistry (excl. Carbon Sequestration Science) | Crop and Pasture Production | Environmental Rehabilitation (excl. Bioremediation) | Bioremediation
ANZSRC Socio-Economic Objective (SEO)
Mining Soils | Environmentally Sustainable Plant Production not elsewhere classified | Management of Solid Waste from Mineral Resource Activities | Rehabilitation of Degraded Mining Environments | Rehabilitation of Degraded Farmland, Arable Cropland and Permanent Cropland Environments | Wheat | Chemical Fertilisers |
Related Links
Publications
Effects of long-term cultivation on phosphorus (P) in five low-input, subtropical Australian soils
Publisher: Elsevier BV
Date: 2018
Absorption of foliar applied Zn is decreased in Zn deficient sunflower (Helianthus annuus) due to changes in leaf properties
Publisher: Springer Science and Business Media LLC
Date: 25-10-2018
Silver sulfide nanoparticles (Ag2S-NPs) are taken up by plants and are phytotoxic
Publisher: Informa UK Limited
Date: 10-09-2015
DOI: 10.3109/17435390.2014.999139
Abstract: Silver nanoparticles (NPs) are used in more consumer products than any other nanomaterial and their release into the environment is unavoidable. Of primary concern is the wastewater stream in which most silver NPs are transformed to silver sulfide NPs (Ag2S-NPs) before being applied to agricultural soils within biosolids. While Ag2S-NPs are assumed to be biologically inert, nothing is known of their effects on terrestrial plants. The phytotoxicity of Ag and its accumulation was examined in short-term (24 h) and longer-term (2-week) solution culture experiments with cowpea (Vigna unguiculata L. Walp.) and wheat (Triticum aestivum L.) exposed to Ag2S-NPs (0-20 mg Ag L(-1)), metallic Ag-NPs (0-1.6 mg Ag L(-1)), or ionic Ag (AgNO3 0-0.086 mg Ag L(-1)). Although not inducing any effects during 24-h exposure, Ag2S-NPs reduced growth by up to 52% over a 2-week period. This toxicity did not result from their dissolution and release of toxic Ag(+) in the rooting medium, with soluble Ag concentrations remaining below 0.001 mg Ag L(-1). Rather, Ag accumulated as Ag2S in the root and shoot tissues when plants were exposed to Ag2S-NPs, consistent with their direct uptake. Importantly, this differed from the form of Ag present in tissues of plants exposed to AgNO3. For the first time, our findings have shown that Ag2S-NPs exert toxic effects through their direct accumulation in terrestrial plant tissues. These findings need to be considered to ensure high yield of food crops, and to avoid increasing Ag in the food chain.
Microbial sulfate reduction decreases arsenic mobilization in flooded paddy soils with high potential for microbial Fe reduction
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.ENVPOL.2019.05.086
Abstract: Arsenic (As) tends to mobilize in flooded paddy soil due to the reductive dissolution of the iron (oxyhydr)oxides to which As sorbs, resulting in elevated As accumulation in rice that poses a potential risk to the food safety and human health. Microbial sulfate reduction is an important biogeochemical process in paddy soils, but its impact on As mobilization remains poorly understood. In this study, we incubated eight As-contaminated paddy soils under flooded conditions to investigate the effect of sulfate addition on As mobility. Porewater Fe and As concentrations and As species were determined. Among the eight soils, an addition of 50 mg S kg
The overlooked functions of trichomes: Water absorption and metal detoxication
Publisher: Wiley
Date: 06-01-2023
DOI: 10.1111/PCE.14530
Abstract: Trichomes are epidermal outgrowths on plant shoots. Their roles in protecting plants against herbivores and in the biosynthesis of specialized metabolites have long been recognized. Recently, studies are increasingly showing that trichomes also play important roles in water absorption and metal detoxication, with these roles having important implications for ecology, the environment, and agriculture. However, these two functions of trichomes have been largely overlooked and much remains unknown. In this review, we show that the trichomes of 37 plant species belonging to 14 plant families are involved in water absorption, while the trichomes of 33 species from 13 families are capable of sequestering metals within their trichomes. The ability of trichomes to absorb water results from their decreased hydrophobicity compared to the remainder of the leaf surface as well as the presence of special structures for collecting and absorbing water. In contrast, the metal detoxication function of trichomes results not only from the good connection of their basal cells to the underlying vascular tissues, but also from the presence of metal‐chelating ligands and transporters within the trichomes themselves. Knowledge gaps and critical future research questions regarding these two trichome functions are highlighted. This review improves our understanding on trichomes.
Rhizotoxicity of aluminate and polycationic aluminium at high pH
Publisher: Springer Science and Business Media LLC
Date: 2005
Influence of texture in bauxite residues on void ratio, water holding characteristics, and penetration resistance
Publisher: Elsevier BV
Date: 09-2010
Chemical Speciation and Distribution of Cadmium in Rice Grain and Implications for Bioavailability to Humans
Publisher: American Chemical Society (ACS)
Date: 10-09-2020
Microbial energy and matter transformation in agricultural soils
Publisher: Elsevier BV
Date: 08-2017
Foliar application of zinc sulphate and zinc EDTA to wheat leaves: differences in mobility, distribution, and speciation
Publisher: Oxford University Press (OUP)
Date: 21-06-2018
DOI: 10.1093/JXB/ERY236
Calcium oxalate and calcium cycling in forest ecosystems
Publisher: Springer Science and Business Media LLC
Date: 22-10-2021
Producing Cd-safe rice grains in moderately and seriously Cd-contaminated paddy soils
Publisher: Elsevier BV
Date: 03-2021
Growth Response of Various Perennial Grasses to Increasing Salinity
Publisher: Informa UK Limited
Date: 09-2006
Time-resolved analyses of elemental distribution and concentration in living plants: An example using manganese toxicity in cowpea leaves
Publisher: Cold Spring Harbor Laboratory
Date: 04-12-2017
DOI: 10.1101/228577
Abstract: Knowledge of elemental distribution and concentration within plant tissues is crucial in the understanding of almost every process that occurs within plants. However, analytical limitations have hindered the microscopic determination of changes over time in the location and concentration of nutrients and contaminants in living plant tissues. We developed a novel method using synchrotron-based micro X-ray fluorescence (μ-XRF) that allows for laterally-resolved, multi-element, kinetic analyses of plant leaf tissues in vivo . To test the utility of this approach, we examined changes in the accumulation of Mn in unifoliate leaves of 7-d-old cowpea ( Vigna unguiculata ) plants grown for 48 h at 0.2 and 30 μM Mn in solution. Repeated μ-XRF scanning did not damage leaf tissues demonstrating the validity of the method. Exposure to 30 μM Mn for 48 h increased the initial number of small spots of localized high Mn and their concentration rose from 40 to 670 mg Mn kg -1 fresh mass. Extension of the two-dimensional μ-XRF scans to a three-dimensional geometry provided further assessment of Mn localization and concentration. This method shows the value of synchrotron-based μ-XRF analyses for time-resolved in vivo analysis of elemental dynamics in plant sciences.
Use of Fluoride-Containing Water for the Irrigation of Soil–Plant Systems
Publisher: American Chemical Society (ACS)
Date: 06-05-2015
Abstract: Many groundwaters used for irrigation contain elevated concentrations of F, but much remains unknown regarding how this F behaves within soils and plants. The present study investigated the adsorption and desorption of F from several soils in short- to medium-term irrigation systems and related foliar F concentrations in three forage plant species to the maximum tolerable level (MTL) in the diets of grazing animals (being 1.8 μmol/g for young cattle, for ex le). Although adsorption isotherms could be successfully used to predict the behavior (adsorption and desorption) of F within the soil, this was not related to the subsequent accumulation of F in plant foliage. In addition, the extent to which F accumulated in the foliage depended on the plant species. Regardless, F generally did not accumulate in plant foliage to levels exceeding the MTL when used at rates equivalent to irrigation for 25 years. In addition to uptake by roots, F may accumulate in foliar tissues directly due to retention from overhead irrigation. The data presented here regarding the behavior of F in soils and plants will assist in the rigorous regulation of F-containing irrigation water to ensure maximum plant growth while simultaneously minimizing potential harm.
Dataset on seed details of wheat genotypes, solution treatments to measure seedling emergence force and the relation between seedling force and strain
Publisher: Elsevier BV
Date: 12-2018
Non-target impacts of pesticides on soil N transformations, abundances of nitrifying and denitrifying genes, and nitrous oxide emissions
Publisher: Elsevier BV
Date: 10-2022
DOI: 10.1016/J.SCITOTENV.2022.157043
Abstract: Agriculture is the leading contributor to global nitrous oxide (N
Changes in soil chemistry after the application of gypsum and sulfur and irrigation with coal seam water
Publisher: Elsevier BV
Date: 03-2019
Toxic effects of Cu2+ on growth, nutrition, root morphology, and distribution of Cu in roots of Sabi grass
Publisher: Elsevier BV
Date: 08-2009
DOI: 10.1016/J.SCITOTENV.2009.04.041
Abstract: Sabi grass (Urochloa mosambicensis (Hack.) Dandy) (a C4 species of Poaceae) is commonly used to revegetate disturbed sites in low-rainfall environments, but comparatively little is known regarding copper (Cu) toxicity in this species. A dilute nutrient solution culture experiment was conducted for 10 d to examine the effects of elevated Cu(2+) activities ({Cu(2+)}) on the growth of Sabi grass. Growth was inhibited by high Cu in solution, with a 50% reduction in the relative fresh mass occurring at 1.0 microM {Cu(2+)} for the roots and 1.2 microM {Cu(2+)} for the shoots. In solutions containing 1.2-1.9 microM {Cu(2+)}, many of the roots ruptured due to the tearing and separation of the rhizodermis and outer cortex from the underlying tissues. Transmission electron microscopy revealed that Cu-rich deposits were found to accumulate predominantly within vacuoles. Due to limited translocation of Cu from the roots to the shoots, phytotoxicity is likely to be more of a problem in remediation of Cu-toxic sites than is Cu toxicity of fauna consuming the above-ground biomass.
Changes in exchangeable cations and micronutrients in soils and grains of long-term, low input cropping systems of subtropical Australia
Publisher: Elsevier BV
Date: 2017
Improved agronomic biofortification of sweetcorn achieved using foliar rather than soil Zn applications
Publisher: Wiley
Date: 14-03-2022
DOI: 10.1002/CCHE.10539
Abstract: This field and glasshouse study evaluates the relative effectiveness of agronomic zinc biofortification strategies to increase the Zn concentration in sweetcorn ( Zea mays ) kernels for human health, using applications of Zn fertilizer to the root‐zone or to foliage. Plants accumulated additional Zn as the rate of Zn applied to the root‐zone increased, but most was retained in the stems and foliage and little was translocated into the kernels (≤7%). A large proportion of the additional Zn stored in the foliage was in the form of Zn‐phytate. In contrast, in field‐grown plants where soil Zn was adequate for maximizing commercial yields, Zn applications to foliage increased kernel Zn concentrations by up to 100%. ZnSO 4 ·7H 2 O was more effective to use in foliar applications compared with Zn‐EDTA. The elevated kernel concentrations recorded for two varieties (59.1 and 71.1 mg Zn kg −1 ) were greater than all previously reported biofortification responses from maize. These concentrations also matched or exceeded the HarvestPlus target of 60 mg Zn kg −1 for maize. With a total kernel Zn content of 3.6 mg Zn per cob, approximately 25%–45% of the recommended dietary Zn intake could be met with one cob of Zn‐biofortified sweetcorn.
Effects of changes in leaf properties mediated by methyl jasmonate (MeJA) on foliar absorption of Zn, Mn and Fe
Publisher: Oxford University Press (OUP)
Date: 21-06-2017
DOI: 10.1093/AOB/MCX063
Application of sewage sludge containing environmentally-relevant silver sulfide nanoparticles increases emissions of nitrous oxide in saline soils
Publisher: Elsevier BV
Date: 10-2020
Overhead-irrigation with saline and alkaline water: Deleterious effects on foliage of Rhodes grass and leucaena
Publisher: Elsevier BV
Date: 05-2016
Salinity decreases Cd translocation by altering Cd speciation in the halophytic Cd-accumulatorCarpobrotus rossii
Publisher: Oxford University Press (OUP)
Date: 08-08-2018
DOI: 10.1093/AOB/MCY148
Prediction of Pb speciation in concentrated and dilute nutrient solutions
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.ENVPOL.2007.09.012
Abstract: Despite the presence of numerous studies in the literature examining the phytotoxicity of Pb, there is a lack of precise quantitative data on limiting concentrations of Pb for plant growth. Using the PhreeqcI chemical equilibrium model, simulations were conducted to examine the speciation of Pb in concentrated and dilute nutrient solutions. Due to the higher P concentration of Hoagland's solution (1000microM), precipitation of chloropyromorphite (Pb5(PO4)3Cl) was predicted to occur at lower pH values, and at lower Pb concentrations, than for a dilute nutrient solution (2microM P). Although nutrient solutions prepared in the glasshouse were supersaturated (and Pb concentrations were substantially higher than predicted by modeling), they confirmed the importance of the P concentration in influencing the precipitation of Pb. Given the low solubility of Pb-phosphates, nutrient solutions with low P concentrations should be utilized, and plant growth should be related to measured Pb concentrations rather than to the quantity of Pb initially added.
Recovery of cowpea seedling roots from exposure to toxic concentrations of trace metals
Publisher: Springer Science and Business Media LLC
Date: 23-12-2010
Interactions between Ca, Mg, Na and K: alleviation of toxicity in saline solutions
Publisher: Springer Science and Business Media LLC
Date: 10-2011
Review of crop‐specific tolerance limits to acidity, salinity, and sodicity for seventeen cereal, pulse, and oilseed crops common to rainfed subtropical cropping systems
Publisher: Wiley
Date: 15-03-2021
DOI: 10.1002/LDR.3915
Abstract: Soil constraints limit crop water and nutrient extraction and lead to yield loss globally. In rainfed agriculture, the selection of crop species more likely to yield well under constrained conditions is an important management tool. However, information on the most appropriate crops is often difficult to access due to its publication in a wide range of disparate sources and the various measures of crop tolerance used. This study aimed to improve our ability to identify crops for constrained areas in rainfed subtropical cropping systems by compiling published information that had assessed the grain yield response to acidic, saline, or sodic conditions of 17 cereal, pulse, and oilseed crops. This information was used to develop a 'traffic light' system for salinity and acidity to provide guidance on when soil pH or the electrical conductivity of a saturated soil extract (EC e ) is likely to be 'good', 'potentially limiting', or 'poor' for grain yield. Crops were also ranked according to their likely ability to yield well under saline, acidic, or sodic conditions. For all crops, the point at which grain yield was affected by soil constraints was variable and there was often only a small amount of published information available to help guide the identification of tolerance limits and rankings, particularly for sodicity. Many studies were also conducted under experimental conditions that differed from rainfed farming, which can affect the transferability of results. Confidence in the tolerance limits and rankings is thus only moderate and further work is required to confirm their applicability.
Minimizing experimental artefacts in synchrotron-based X-ray analyses of Fe speciation in tissues of rice plants
Publisher: International Union of Crystallography (IUCr)
Date: 06-06-2019
DOI: 10.1107/S1600577519004351
Abstract: Iron (Fe) plays an important role within environmental systems. Synchrotron-based X-ray approaches, including X-ray absorption spectroscopy (XAS), provide powerful tools for in situ analyses of Fe speciation, but beam damage during analysis may alter Fe speciation during its measurement. XAS was used to examine whether experimental conditions affect the analysis of Fe speciation in plant tissues. Even when analyzed in a cryostat at 12 K, it was found that Fe III can rapidly (within 0.5–1 min) photoreduce to Fe II , although the magnitude of photoreduction varied depending upon the hydration of the s le, the coordination chemistry of the Fe, as well as other properties. For ex le, photoreduction of Fe III was considerably higher for aqueous standard compounds than for hydrated plant-root tissues. The use of freeze-dried s les in the cryostat (12 K) markedly reduced the magnitude of this Fe III photoreduction, and there was no evidence that the freeze-drying process itself resulted in experimental artefacts under the current experimental conditions, such as through the oxidation of Fe II , although some comparatively small differences were observed when comparing spectra of hydrated and freeze-dried Fe II compounds. The results of this study have demonstrated that Fe III photoreduction can occur during X-ray analysis, and provides suitable conditions to preserve Fe speciation to minimize the extent of beam damage when analyzing environmental s les. All studies utilizing XAS are encouraged to include a preliminary experiment to determine if beam damage is occurring, and, where appropriate, to take the necessary steps (such as freeze drying) to overcome these issues.
Using Synchrotron-Based Approaches To Examine the Foliar Application of ZnSO4 and ZnO Nanoparticles for Field-Grown Winter Wheat
Publisher: American Chemical Society (ACS)
Date: 11-2017
Abstract: The effects of foliar-applied ZnO nanoparticles (ZnO NPs) and ZnSO
The Role of Plants in Ironstone Evolution: Iron and Aluminium Cycling in the Rhizosphere
Publisher: Elsevier BV
Date: 2023
DOI: 10.2139/SSRN.4583801
Effect of 50 Years of No-Tillage, Stubble Retention, and Nitrogen Fertilization on Soil Respiration, Easily Extractable Glomalin, and Nitrogen Mineralization
Publisher: MDPI AG
Date: 08-01-2022
Abstract: In subtropical regions, we have an incomplete understanding of how long-term tillage, stubble, and nitrogen (N) fertilizer management affects soil biological functioning. We examined a subtropical site managed for 50 years using varying tillage (conventional till (CT) and no-till (NT)), stubble management (stubble burning (SB) and stubble retention (SR)), and N fertilization (0 (N0), 30 (N30), and 90 (N90) kg ha−1 y−1) to assess their impact on soil microbial respiration, easily extractable glomalin-related soil protein (EEGRSP), and N mineralization. A significant three-way tillage × stubble × N fertilizer interaction was observed for soil respiration, with NT+SB+N0 treatments generally releasing the highest amounts of CO2 over the incubation period (1135 mg/kg), and NT+SR+N0 treatments releasing the lowest (528 mg/kg). In contrast, a significant stubble × N interaction was observed for both EEGRSP and N mineralization, with the highest concentrations of both EEGRSP (2.66 ± 0.86 g kg−1) and N mineralization (30.7 mg/kg) observed in SR+N90 treatments. Furthermore, N mineralization was also positively correlated with EEGRSP (R2 = 0.76, p 0.001), indicating that EEGRSP can potentially be used as an index of soil N availability. Overall, this study has shown that SR and N fertilization have a positive impact on soil biological functioning.
Localization and Chemical Speciation of Pb in Roots of Signal Grass (Brachiaria decumbens) and Rhodes Grass (Chloris gayana)
Publisher: American Chemical Society (ACS)
Date: 17-05-2008
DOI: 10.1021/ES702627C
Abstract: Lead (Pb) contamination of soils is of global importance but little is known regarding Pb uptake, localization, or the chemical forms in which Pb is found within plants, or indeed how some plants tolerate elevated Pb in the environment. Two grasses, signal grass (Brachiaria decumbens Stapf) (Pb-resistant) and Rhodes grass (Chloris gayana Kunth)(Pb-sensitive), were grown for 14 d in dilute nutrient solutions before examination of roots using transmission electron microscopy (TEM) to determine the distribution and speciation of Pb in situ. In both grasses, Pb was initially present primarily in the cytoplasm of rhizodermal and cortical cells before being sequestered within vacuoles as the highly insoluble (and presumably nontoxic) chloropyromorphite (Pb5(PO4)3Cl). In signal grass, Pb also accumulated within membranous structures (perhaps the Golgi apparatus), prior to apoplastic sequestration as chloropyromorphite. These findings suggest that the ability of signal grass to sequester insoluble Pb in the cell wall represents an additional and potentially important mechanism of Pb tolerance not possessed by the Pb-sensitive Rhodes grass.
Absorption of foliar-applied Zn in sunflower (Helianthus annuus)
Publisher: Oxford University Press (OUP)
Date: 17-07-2019
DOI: 10.1093/AOB/MCY135
Cadmium reduces zinc uptake but enhances its translocation in the cadmium-accumulator, Carpobrotus rossii, without affecting speciation
Publisher: Springer Science and Business Media LLC
Date: 29-06-2018
Risk of Silver Transfer from Soil to the Food Chain Is Low after Long-Term (20 Years) Field Applications of Sewage Sludge
Publisher: American Chemical Society (ACS)
Date: 28-03-2018
Abstract: The increasingly widespread usage of silver (Ag) nanoparticles has raised concerns regarding their environmental risk. The behavior of Ag and its transfer risk to the food chain were investigated using a long-term field experiment that commenced in 1942 in which Ag-containing sewage sludge was repeatedly applied to the soil (25 applications during 20 years). The speciation of the Ag in both the sludge and the soils retrieved from the long-term experimental archive was examined using synchrotron-based X-ray absorption spectroscopy, and extractable Ag concentrations from soils were determined using 0.01 M Ca(NO
In Situ Distribution and Speciation of Toxic Copper, Nickel, and Zinc in Hydrated Roots of Cowpea
Publisher: Oxford University Press (OUP)
Date: 27-04-2011
Abstract: The phytotoxicity of trace metals is of global concern due to contamination of the landscape by human activities. Using synchrotron-based x-ray fluorescence microscopy and x-ray absorption spectroscopy, the distribution and speciation of copper (Cu), nickel (Ni), and zinc (Zn) was examined in situ using hydrated roots of cowpea (Vigna unguiculata) exposed to 1.5 μm Cu, 5 μm Ni, or 40 μm Zn for 1 to 24 h. After 24 h of exposure, most Cu was bound to polygalacturonic acid of the rhizodermis and outer cortex, suggesting that binding of Cu to walls of cells in the rhizodermis possibly contributes to the toxic effects of Cu. When exposed to Zn, cortical concentrations remained comparatively low with much of the Zn accumulating in the meristematic region and moving into the stele approximately 60% to 85% of the total Zn stored as Zn phytate within 3 h of exposure. While Ni concentrations were high in both the cortex and meristem, concentrations in the stele were comparatively low. To our knowledge, this is the first report of the in situ distribution and speciation of Cu, Ni, and Zn in hydrated (and fresh) plant tissues, providing valuable information on the potential mechanisms by which they are toxic.
In Situ Speciation and Distribution of Toxic Selenium in Hydrated Roots of Cowpea
Publisher: Oxford University Press (OUP)
Date: 08-07-2013
In situ analysis of foliar zinc absorption and short-distance movement in fresh and hydrated leaves of tomato and citrus Using synchrotron-based X-ray fluorescence microscopy
Publisher: Oxford University Press (OUP)
Date: 14-11-2015
DOI: 10.1093/AOB/MCU212
Speciation and accumulation of Zn in sweetcorn kernels for genetic and agronomic biofortification programs
Publisher: Springer Science and Business Media LLC
Date: 12-04-2019
DOI: 10.1007/S00425-019-03162-X
Abstract: In sweetcorn (Zea mays L.), embryo Zn is accumulated mainly as Zn-phytate, whereas endosperm Zn is complexed with a N- or S-containing ligand. Understanding the speciation of Zn in crop plants helps improve the effectiveness of biofortification efforts. Kernels of four sweetcorn (Zea mays L.) varieties were analysed for Zn concentration and content. We also assessed the speciation of the Zn in the embryo, endosperm, and pericarp in situ using synchrotron-based X-ray absorption spectroscopy. The majority of the Zn was in the endosperm and pericarp (72%), with the embryo contributing 28%. Approximately 79% of the Zn in the embryo accumulated as Zn-phytate, whereas in the endosperm most of the Zn was complexed with a N- or S-containing ligand, possibly as Zn-histidine and Zn-cysteine. This suggests that whilst the Zn in the endosperm and pericarp is likely to be bioavailable for humans, the Zn in the embryo is of low bioavailability. This study highlights the importance of targeting the endosperm of sweetcorn kernels as the tissue for increasing bioavailable Zn concentration.
Mg induced Ca deficiency under alkaline conditions
Publisher: Springer Science and Business Media LLC
Date: 02-2005
Examining a synchrotron-based approach for in situ analyses of Al speciation in plant roots
Publisher: International Union of Crystallography (IUCr)
Date: 2020
DOI: 10.1107/S1600577519014395
Abstract: Aluminium (Al) K - and L -edge X-ray absorption near-edge structure (XANES) has been used to examine Al speciation in minerals but it remains unclear whether it is suitable for in situ analyses of Al speciation within plants. The XANES analyses for nine standard compounds and root tissues from soybean ( Glycine max ), buckwheat ( Fagopyrum tataricum ), and Arabidopsis ( Arabidopsis thaliana ) were conducted in situ . It was found that K -edge XANES is suitable for differentiating between tetrahedral coordination (peak of 1566 eV) and octahedral coordination (peak of 1568 to 1571 eV) Al, but not suitable for separating Al binding to some of the common physiologically relevant compounds in plant tissues. The Al L -edge XANES, which is more sensitive to changes in the chemical environment, was then examined. However, the poorer detection limit for analyses prevented differentiation of the Al forms in the plant tissues because of their comparatively low Al concentration. Where forms of Al differ markedly, K -edge analyses are likely to be of value for the examination of Al speciation in plant tissues. However, the apparent inability of Al K -edge XANES to differentiate between some of the physiologically relevant forms of Al may potentially limit its application within plant tissues, as does the poorer sensitivity at the L -edge.
Hydrolysis and Speciation of Al Bound to Pectin and Plant Cell Wall Material and Its Reaction with the Dye Chrome Azurol S
Publisher: American Chemical Society (ACS)
Date: 09-04-2010
DOI: 10.1021/JF100201X
Abstract: Hydrolysis of aluminum (Al) in solution increases at pH >or= 4 and with an Al concentration. Pectin, an important anionic polysaccharide of plant cell walls, adsorbs Al, but this phenomenon is poorly understood. This study showed that Al(3+) hydrolysis results in binding of Al to pectin in excess of the stoichiometric equivalent, leading to oversaturation of the pectin with Al. However, the degree of pectin methyl-esterification did not affect the extent of Al hydrolysis. Binding of Al to purified cell wall material also resulted in Al hydrolysis in a pH- and soluble Al concentration-dependent manner, but the source of cell wall material had no effect at fixed pH. Staining of Al-treated pectin and cell wall material from wheat ( Triticum aestivum L.) and sunflower ( Helianthus annuus L.) with the Al-specific dye, chrome azurol S (CAS), resulted in the formation of a purple color, with the intensity related to the extent of Al hydrolysis.
Selection for rapid germination and emergence may improve wheat seedling establishment in the presence of soil surface crusts
Publisher: Springer Science and Business Media LLC
Date: 22-03-2018
Sulfur dynamics in sub-tropical soils of Australia as influenced by long-term cultivation
Publisher: Springer Science and Business Media LLC
Date: 07-01-2016
Tolerance of two perennial grasses to toxic levels of Ni2+
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/EN08054
Abstract: Environmental context. Nickel (Ni) may be present in soil at phytotoxic levels as a result of weathering of ultramafic (serpentine) minerals or activities such as mining and metal ore processing. We assessed the tolerance of two grasses to excess Ni and used electron microscopy to examine the distribution of the Ni within the root tissue. This study provides information on the influence of excess Ni on the growth of these two grasses with consideration to their suitability for the revegetation of areas contaminated with Ni. Abstract. Toxic effects of Nickel (Ni) in solution were evaluated in signal grass and Rhodes grass, two species commonly used for the revegetation of contaminated sites in the tropics and sub-tropics. Both grasses had a similar response to Ni, a Ni2+ activity ({Ni2+}) of 14 × 10–6 M, which reduced the fresh mass by 50%. The sub-cellular distribution of Ni in the roots was similar for both species, with Ni accumulating primarily as particles nm in the vacuoles of rhizodermal and outer cortical cells. The reduction in growth at elevated {Ni2+} caused a loss of apical dominance in the roots and a Ni-induced Fe deficiency in the shoots. Root hair growth was not reduced by Ni2+ toxicity and was prolific even at the highest {Ni2+} (35 × 10–6 M). The translocation of Ni to the plant tops of both grasses resulted in concentrations that exceeded the guidelines for Ni toxicity to grazing animals (100 μg g–1) when grown with ≥11 × 10–6 M {Ni2+} in solution.
“A Terrible Beauty”: Iris Murdoch’s Irish Novel, The Red and the Green
Publisher: Informa UK Limited
Date: 17-11-2019
Long-term changes in land use influence phosphorus concentrations, speciation, and cycling within subtropical soils
Publisher: Elsevier BV
Date: 07-2021
Comparison of Zn accumulation and speciation in kernels of sweetcorn and maize differing in maturity
Publisher: Oxford University Press (OUP)
Date: 30-11-2019
DOI: 10.1093/AOB/MCZ179
Abstract: Understanding the speciation of Zn in edible portions of crops helps identify the most effective biofortification strategies to increase the supply of nutrients for improving the health and nutrition of consumers. Kernels of 12 sweetcorn and three maize (Zea mays) varieties were analysed for Zn concentration and content. The speciation of the Zn in the embryos, endosperms and whole kernels at 21, 28 and 56 days after pollination (DAP) was then examined for one maize and one sweetcorn variety using synchrotron-based X-ray absorption spectroscopy (XAS). Averaged across all sweetcorn and maize varieties at 21 DAP, the embryo contributed 27–29% of the whole kernel Zn whilst the endosperm contributed 71–73 %. While sweetcorn embryos contributed a lower proportion to the total kernel Zn than those of maize, the proportion of total Zn in the embryo increased as kernels aged for both varieties, reaching 33 % for sweetcorn and 49% for maize at 28 DAP. Using XAS, it was predicted that an average of 90 % of the Zn in the embryos was present as Zn-phytate, while in the endosperm the Zn was primarily complexed with an N-containing ligand such as histidine and to a lesser extent with phytate. However, in maize endosperms, it was also observed that the proportion of Zn present as Zn-phytate increased as the kernel matured, thereby also probably decreasing its bioavailability in these mature maize kernels. The apparent low bioavailability of Zn supplied in maize at its consumption stage (i.e. mature kernels) probably undermines the effectiveness of biofortification of this crop. Conversely, successful biofortification of Zn in sweetcorn and green maize consumed as immature kernels could potentially provide a good source of bioavailable Zn in human diets.
Identification of the Primary Lesion of Toxic Aluminum in Plant Roots
Publisher: Oxford University Press (OUP)
Date: 10-02-2015
Abstract: Despite the rhizotoxicity of aluminum (Al) being identified over 100 years ago, there is still no consensus regarding the mechanisms whereby root elongation rate is initially reduced in the approximately 40% of arable soils worldwide that are acidic. We used high-resolution kinematic analyses, molecular biology, rheology, and advanced imaging techniques to examine soybean (Glycine max) roots exposed to Al. Using this multidisciplinary approach, we have conclusively shown that the primary lesion of Al is apoplastic. In particular, it was found that 75 µm Al reduced root growth after only 5 min (or 30 min at 30 µm Al), with Al being toxic by binding to the walls of outer cells, which directly inhibited their loosening in the elongation zone. An alteration in the biosynthesis and distribution of ethylene and auxin was a second, slower effect, causing both a transient decrease in the rate of cell elongation after 1.5 h but also a longer term gradual reduction in the length of the elongation zone. These findings show the importance of focusing on traits related to cell wall composition as well as mechanisms involved in wall loosening to overcome the deleterious effects of soluble Al.
Genetic biofortification of wheat with zinc: Opportunities to fine-tune zinc uptake, transport and grain loading.
Publisher: Wiley
Date: 30-12-2022
DOI: 10.1111/PPL.13612
Abstract: Zinc (Zn) is an important micronutrient in the human body, and health complications associated with insufficient dietary intake of Zn can be overcome by increasing the bioavailable concentrations in edible parts of crops (biofortification). Wheat (Triticum aestivum L) is the most consumed cereal crop in the world therefore, it is an excellent target for Zn biofortification programs. Knowledge of the physiological and molecular processes that regulate Zn concentration in the wheat grain is restricted, inhibiting the success of genetic Zn biofortification programs. This review helps break this nexus by advancing understanding of those processes, including speciation regulated uptake, root to shoot transport, remobilisation, grain loading and distribution of Zn in wheat grain. Furthermore, new insights to genetic Zn biofortification of wheat are discussed, and where data are limited, we draw upon information for other cereals and Fe distribution. We identify the loading and distribution of Zn in grain as major bottlenecks for biofortification, recognising anatomical barriers in the vascular region at the base of the grain, and physiological and molecular restrictions localised in the crease region as major limitations. Movement of Zn from the endosperm cavity into the modified aleurone, aleurone and then to the endosperm is mainly regulated by ZIP and YSL transporters. Zn complexation with phytic acid in the aleurone limits Zn mobility into the endosperm. These insights, together with synchrotron-X-ray-fluorescence microscopy, support the hypothesis that a focus on the mechanisms of Zn loading into the grain will provide new opportunities for Zn biofortification of wheat.
Metal uptake and organic acid exudation of native Acacia species in mine tailings
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/BT16189
Abstract: Phytostabilisation with native plant species has been advocated as a cost-effective approach to rehabilitate mine tailings containing phytotoxic metal-bearing minerals. For this purpose, five Acacia species (natural colonisers) native to north-west Queensland region of Australia were investigated for metal uptake and root exudation characteristics in response to growth for 3 weeks in three different mine tailings (Cu and Cu-Pb-Zn) differing in their degree of weathering. Root tissues of the plant species grown in the three types of tailings accumulated up to 0.9 mg Cd kg–1, 10 mg Co kg–1, 177 mg Cu kg–1, 38 mg Pb kg–1 and 4800 mg Zn kg–1 (DW basis) – being suitable for phytostabilisation purposes. However, elevated levels of root exudates in rhizosphere tailings enhanced the bioavailability of metals, leading to the accumulation of high levels of some metals in Acacia shoots (e.g. shoot concentrations of 140 mg Zn kg–1 in Acacia acradenia F.Muell. and 230 mg Zn kg–1 in Acacia hilliana Maiden). Positive correlations (P 0.05) between citric acid levels and metal root uptakes suggested that citric acid production in these plant species may be the main driver for metal mobilisation. The results suggest that the native acacia species have the potential to mobilise metals (albeit in mineral forms) in the tailings, when used for phytostabilisation.
Ferric minerals and organic matter change arsenic speciation in copper mine tailings
Publisher: Elsevier BV
Date: 11-2016
DOI: 10.1016/J.ENVPOL.2016.08.007
Abstract: Arsenic (As) is commonly associated with Cu ore minerals, with the resultant risk that As can be released offsite from mine tailings. We used synchrotron-based fluorescence X-ray absorption near-edge spectroscopy (XANES) imaging to provide in situ, laterally-resolved speciation of As within tailings which differed in magnetite content (5-12%) and organic matter content (0-5%). Although the total As content was lower in tailings with low magnetite (LM), the soluble (pore water) As was actually 7-times higher in LM tailings than in high magnetite (HM) tailings. Additionally, amendment with 5% sugarcane mulch residues (SMR) (for revegetation) further increased soluble As due to the dissolution and oxidation of arsenopyrite or orpiment. Indeed, in HM tailings, arsenopyrite and orpiment initially accounted for 88% of the total As, which decreased to 48% upon the addition of SMR - this being associated with an increase in As
Soil and the intensification of agriculture for global food security
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.ENVINT.2019.105078
Abstract: Soils are the most complex and erse ecosystem in the world. In addition to providing humanity with 98.8% of its food, soils provide a broad range of other services, from carbon storage and greenhouse gas regulation, to flood mitigation and providing support for our sprawling cities. But soil is a finite resource, and rapid human population growth coupled with increasing consumption is placing unprecedented pressure on soils through the intensification of agricultural production - the increasing of crop yield per unit area of soil. Indeed, the human population has increased from ca. 250 million in the year 1000, to 6.1 billion in the year 2000, and is projected to reach 9.8 billion by the year 2050. The current intensification of agricultural practices is already resulting in the unsustainable degradation of soils. Major forms of this degradation include the loss of organic matter and the release of greenhouse gases, the over-application of fertilizers, erosion, contamination, acidification, salinization, and loss of genetic ersity. This ongoing soil degradation is decreasing the long-term ability of soils to provide humans with services, including future food production, and is causing environmental harm. It is imperative that the global society is not shortsighted by focusing solely on the near-immediate benefits of soils, such as food supply. A failure to identify the importance of soil within increasingly intensive agricultural systems will undoubtedly have serious consequences for humanity and represents a failure to consider intergenerational equity. Of utmost importance is the need to unequivocally recognize that the degradation of soils leads to a clear economic cost through the loss of services, with such principles needing to be explicitly considered in economic frameworks and decision-making processes at all levels of governance. We contend that the concept of the Water-Food-Energy nexus must be expanded, forming the Water-Soil-Food-Energy nexus.
Improved Zn bioavailability by its enhanced colocalization and speciation with S in wheat grain tissues after N addition
Publisher: Elsevier BV
Date: 03-2023
DOI: 10.1016/J.FOODCHEM.2022.134582
Abstract: Zinc bioavailability with the presence of other elements in wheat grains might be affected by fertilizers. A long-term field experiment was conducted to examine effects of N fertilizer on Zn bioavailability in wheat grain tissues, with changes in the concentrations, distribution, and speciation of Zn as well as P and sulfur S via synchrotron-based technology. Results showed that addition of N fertilizer was associated with changes in Zn concentrations and distributions in grain tissues, especially in the crease region and endosperm. Simultaneously, N addition enhanced Zn-S colocalization in the crease region and endosperm and lowered the P/Zn ratio and Zn-P colocalization. Addition of N fertilizer with P increased Zn-cysteine (9.2%) and decreased Zn-phytate (47.3%) in the crease region, leading to potentially higher grain Zn bioavailability. Thus, addition of N fertilizer improved concentrations and bioavailability of Zn, by coordinating the relationships among Zn, P and S within wheat grains.
Comment on “Graphene oxide regulates the bacterial community and exhibits property changes in soil” by J. Du, X. Hu and Q. Zhou, RSC Advances, 2015, 5, 27009
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5RA26329H
Abstract: Here we question the validity of a recent claim that addition of graphene oxide to soil promotes bacterial ersity.
Laterally resolved speciation of arsenic in roots of wheat and rice using fluorescence‐XANES imaging
Publisher: Wiley
Date: 11-11-2013
DOI: 10.1111/NPH.12595
Abstract: Accumulation of arsenic (As) within plant tissues represents a human health risk, but there remains much to learn regarding the speciation of As within plants. We developed synchrotron‐based fluorescence‐X‐ray absorption near‐edge spectroscopy (fluorescence‐ XANES ) imaging in hydrated and fresh plant tissues to provide laterally resolved data on the in situ speciation of As in roots of wheat ( Triticum aestivum ) and rice ( Oryza sativa ) exposed to 2 μM As(V) or As( III ). When exposed to As(V), the As was rapidly reduced to As( III ) within the root, with As(V) calculated to be present only in the rhizodermis. However, no uncomplexed As( III ) was detected in any root tissues, because of the efficient formation of the As( III )–thiol complex – this As species was calculated to account for all of the As in the cortex and stele. The observation that uncomplexed As( III ) was below the detection limit in all root tissues explains why the transport of As to the shoots is low, given that uncomplexed As( III ) is the major As species transported within the xylem and phloem. Using fluorescence‐ XANES imaging, we have provided in situ data showing the accumulation and transformation of As within hydrated and fresh root tissues.
Role of phytohormones in aluminium rhizotoxicity
Publisher: Wiley
Date: 12-08-2016
DOI: 10.1111/PCE.12786
Abstract: Elevated concentrations of soluble aluminium (Al) reduce root growth in acid soils, but much remains unknown regarding the toxicity of this Al as well as the mechanisms by which plants respond. This review examines changes in phytohormones in Al-stressed plants. Al often results in a rapid 'burst' of ethylene in root apical tissues within 15-30 min, with this regulating an increase in auxin. This production of ethylene and auxin seems to be a component of a plant-response to toxic Al, resulting in cell wall modification or regulation of organic acid release. There is also evidence of a role of auxin in the expression of Al toxicity itself, with Al decreasing basipetal transport of auxin, thereby potentially decreasing wall loosening as required for elongation. Increasingly, changes in abscisic acid in root apices also seem to be involved in plant-responses to toxic Al. Changes in cytokinins, gibberellins and jasmonates following exposure to Al are also examined, although little information is available. Finally, although not a phytohormone, concentrations of nitric oxide change rapidly in Al-exposed tissues. The information presented in this review will assist in focusing future research efforts in examining the importance of phytohormones in plant tissues exposed to toxic levels of Al.
Toxicity of Cd to signal grass (Brachiaria decumbens Stapf.) and Rhodes grass (Chloris gayana Kunth.)
Publisher: Springer Science and Business Media LLC
Date: 13-11-2009
A study over 33 years shows that carbon and nitrogen stocks in a subtropical soil are increasing under native vegetation in a changing climate
Publisher: Elsevier BV
Date: 06-2021
Engineered silver nanoparticles in terrestrial environments: a meta-analysis shows that the overall environmental risk is small
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8EN00486B
Abstract: The risk of engineered silver nanoparticles to terrestrial plants and fauna (including humans through trophic transfer) is small.
Soil carbon, nitrogen, and biotic properties after long-term no-till and nitrogen fertilization in a subtropical Vertisol
Publisher: Elsevier BV
Date: 03-2023
Translocation of Foliar Absorbed Zn in Sunflower (Helianthus annuus) Leaves
Publisher: Frontiers Media SA
Date: 02-03-2022
Abstract: Foliar zinc (Zn) fertilization is an important approach for overcoming crop Zn deficiency, yet little is known regarding the subsequent translocation of this foliar-applied Zn. Using synchrotron-based X-ray fluorescence microscopy (XFM) and transcriptome analysis, the present study examined the translocation of foliar absorbed Zn in sunflower ( Helianthus annuus ) leaves. Although bulk analyses showed that there had been minimal translocation of the absorbed Zn out of the leaf within 7 days, in situ analyses showed that the distribution of Zn in the leaf had changed with time. Specifically, when Zn was applied to the leaf for 0.5 h and then removed, Zn primarily accumulated within the upper and lower epidermal layers (when examined after 3 h), but when examined after 24 h, the Zn had moved to the vascular tissues. Transcriptome analyses identified a range of genes involved in stress response, cell wall reinforcement, and binding that were initially upregulated following foliar Zn application, whereas they were downregulated after 24 h. These observations suggest that foliar Zn application caused rapid stress to the leaf, with the initial Zn accumulation in the epidermis as a detoxification strategy, but once this stress decreased, Zn was then moved to the vascular tissues. Overall, this study has shown that despite foliar Zn application causing rapid stress to the leaf and that most of the Zn stayed within the leaf over 7 days, the distribution of Zn in the leaf had changed, with Zn mostly located in the vascular tissues 24 h after the Zn had been applied. Not only do the data presented herein provide new insight for improving the efficiency of foliar Zn fertilizers, but our approach of combining XFM with a transcriptome methodological system provides a novel approach for the study of element translocation in plants.
Synchrotron-based X-Ray approaches for examining toxic trace metal(loid)s in soil-plant systems
Publisher: Wiley
Date: 11-2017
Abstract: Elevated levels of trace metal(loid)s reduce plant growth, both in soils contaminated by industrial activities and in acid agricultural soils. Although the adverse effects of trace metal(loid)s have long been recognized, there remains much unknown both about their behavior in soils, their toxicity to plants, and the mechanisms that plants use to tolerate elevated concentrations. Synchrotron-based approaches are being utilized increasingly in soil-plant systems to examine toxic metal(loid)s. In the present review, brief consideration is given to the theory of synchrotron radiation. Thereafter, we review the use of synchrotron-based approaches for the examination of various trace metal(loid)s in soil-plant systems, including aluminum, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, and cadmium. Within the context of this review, X-ray absorption spectroscopy (XAS) and X-ray fluorescence microscopy (μ-XRF) are of particular interest. These techniques can provide in situ analyses of the distribution and speciation of metal(loid)s in soil-plant systems. The information presented here serves not only to understand the behavior of trace metals in soil-plant systems, but also to provide ex les of the potential applications of synchrotron radiation that can be used to advantage in other studies.
Evaluating effects of iron on manganese toxicity in soybean and sunflower using synchrotron-based X-ray fluorescence microscopy and X-ray absorption spectroscopy
Publisher: Oxford University Press (OUP)
Date: 2019
DOI: 10.1039/C9MT00219G
Abstract: Increased Fe in solution decreased Mn accumulation on soybean unifoliate leaves and in trichomes of sunflower lower alternate leaves.
Optimising the foliar uptake of zinc oxide nanoparticles: Do leaf surface properties and particle coating affect absorption?
Publisher: Wiley
Date: 09-09-2020
DOI: 10.1111/PPL.13167
Development of an electrostatic model predicting copper toxicity to plants
Publisher: Oxford University Press (OUP)
Date: 20-10-2011
DOI: 10.1093/JXB/ERR254
Abstract: The focus of the present study was to investigate the mechanisms for the alleviation of Cu toxicity in plants by coexistent cations (e.g. Al(3+), Mn(2+), Ca(2+), Mg(2+), H(+), Na(+), and K(+)) and the development of an electrostatic model to predict 50% effect activities (EA50s) accurately. The alleviation of Cu(2+) toxicity was evaluated in several plants in terms of (i) the electrical potential at the outer surface of the plasma membrane (PM) (Ψ(0)(°)) and (ii) competition between cations for sites at the PM involved in the uptake or toxicity of Cu(2+), the latter of which is invoked by the Biotic Ligand Model (BLM) as the sole explanation for the alleviation of toxicity. The addition of coexistent cations into the bulk-phase medium reduces the negativity of Ψ(0)(°) and hence decreases the activity of Cu(2+) at the PM surface. Our analyses suggest that the alleviation of toxicity results primarily from electrostatic effects (i.e. changes in both the Cu(2+) activity at the PM surface and the electrical driving force across the PM), and that BLM-type competitive effects may be of lesser importance in plants. Although this does not exclude the possibility of competition, the data highlight the importance of electrostatic effects. An electrostatic model was developed to predict Cu(2+) toxicity thresholds (EA50s), and the quality of its predictive capacity suggests its potential utility in risk assessment of copper in natural waters and soils.
Does the APSIM model capture soil phosphorus dynamics? A case study with Vertisols
Publisher: Elsevier BV
Date: 11-2021
Aluminum Complexation with Malate within the Root Apoplast Differs between Aluminum Resistant and Sensitive Wheat Lines
Publisher: Frontiers Media SA
Date: 03-08-2017
Management of the major chemical soil constraints affecting yields in the grain growing region of Queensland and New South Wales, Australia – a review
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/SR18233
Abstract: In the grain growing region of Queensland and New South Wales, Australia, crop production occurs predominantly under semiarid, rainfed conditions. Vertosols dominate the soils used and many are prone to structural problems. In this region, providing that crop nutrition is adequate, optimising yield is largely dependent on maximising the infiltration, storage and plant use of soil water. Soil constraints such as sodicity, salinity, acidity, subsoil compaction and surface sealing can limit these processes, leading to high yield losses. This review examines management options to treat these constraints, focusing on management where multiple constraints exist, and where these occur in the subsoil. The main strategies reviewed include (a) use of gypsum to treat sodicity and lime to treat acidity, which can lead to yield increases of & % in some circumstances, (b) cultivation or deep ripping to break up compacted sodic layers and surface seals, (c) incorporating soil organic matter to improve conditions for plant growth and (d) selecting species, cultivars and management practices most appropriate for constrained sites. Future research must be directed to improving the profitability of ameliorant use for sodicity by increasing our understanding of how to identify soils responsive to ameliorants, and which combination of ameliorants will be cost effective when sodicity occurs in combination with other constraints. In addition, research needs to target ways to economically apply ameliorants in subsoil environments, and better identify which crop species or cultivars are productive on constrained sites, particularly those with multiple constraints.
Examination into the Accuracy of Exchangeable Cation Measurement in Saline Soils
Publisher: Informa UK Limited
Date: 10-2006
An empirical model for prediction of wheat yield, using time-integrated Landsat NDVI
Publisher: Elsevier BV
Date: 10-2018
Zinc and lead encapsulated in amorphous ferric cements within hardpans in situ formed from sulfidic Cu-Pb-Zn tailings
Publisher: Elsevier BV
Date: 09-2019
DOI: 10.1016/J.ENVPOL.2019.06.069
Abstract: Hardpans are massively indurated layers formed at the top layer of sulfidic tailings dams, which develop cementation structures and result in heavy metal immobilization. However, the micro-structural and complex forms of the cementing materials are not fully understood, as well as the mechanisms by which Zn and Pb are stabilized in the hardpans. The present study deployed synchrotron-based X-ray fluorescence microscopy (XFM) to have characterized the cementing structures, examined the distribution of Fe, Zn and Pb, and obtained laterally-resolved speciation of Zn within the hardpans using fluorescence X-ray absorption near-edge structure (XANES) imaging. The XFM analyses revealed that the Fe-rich cement layers consisted of Fe (oxyhydr)oxides coupled with amorphous Si materials, immobilizing Zn and Pb. Through laterally-resolved XANES imaging analyses, Zn-ferrihydrite-like precipitates were predicted to account for >76% of the total Zn within the Fe-rich cement layers. In contrast, outside of the cement layers, 9-63% of the Zn was estimated as labile ZnSO
In situ analyses of inorganic nutrient distribution in sweetcorn and maize kernels using synchrotron-based x-ray fluorescence microscopy
Publisher: Oxford University Press (OUP)
Date: 23-10-2019
DOI: 10.1093/AOB/MCY189
Growth of Eucalyptus species in a Brown Kandosol, and changes in soil phosphorus fractionation following fertilisation
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/SR06147
Abstract: As observed with many soils, much of the P in the Brown Kandosol soils of Weipa (Australia) is associated with organic matter. However, following bauxite mining, much of this organic matter is either lost due to mineralisation, or is ‘diluted’ by the mixing of the soil profile. Using a sequential P extraction, the partitioning of P following fertiliser application was examined in an ‘undisturbed’ (Surface) soil and a Mixed soil. In addition, the effect of split-P applications on the growth of 2 native Eucalyptus species was examined. Following its addition to the soil, much of the P was converted comparatively rapidly to forms with reduced availability by the time of the first measurement (4 weeks) only approximately 10% of the added P remained as the readily available AER-P. For the Surface soil, much of this added P was initially converted to organic P (Po) (measured as hydroxide-Po), before progressively moving into the hydroxide-Pi fraction. In comparison, in the mixed soil, competition for P from microbial biomass was lower (due to a lower organic matter content) and the P was rapidly converted to the hydroxide-Pi fraction before moving to unavailable forms (residual P). Although the use of split-P applications was expected to increase plant growth, maximum growth of Eucalyptus tetrodonta and Eucalyptus leptophleba was generally achieved when all P fertiliser was applied in the first few weeks of growth. Indeed, splitting the P application beyond 16 weeks caused a significant reduction in growth.
Principles of plant-based remediation of contaminated soils.
Publisher: CABI
Date: 2010
Kinetics and mechanisms of cowpea root adaptation to changes in solution calcium
Publisher: Springer Science and Business Media LLC
Date: 28-02-2014
Increased arsenic mobilization in the rice rhizosphere is mediated by iron-reducing bacteria
Publisher: Elsevier BV
Date: 08-2020
Phosphorus speciation in the fertosphere of highly concentrated fertilizer bands
Publisher: Elsevier BV
Date: 12-2021
Toxicities of soluble Al, Cu, and La include ruptures to rhizodermal and root cortical cells of cowpea
Publisher: Springer Science and Business Media LLC
Date: 14-12-2007
Cadmium accumulation is enhanced by ammonium compared to nitrate in two hyperaccumulators, without affecting speciation
Publisher: Oxford University Press (OUP)
Date: 06-07-2016
DOI: 10.1093/JXB/ERW270
Synchrotron-Based X-Ray Fluorescence Microscopy as a Technique for Imaging of Elements in Plants
Publisher: Oxford University Press (OUP)
Date: 14-08-2018
DOI: 10.1104/PP.18.00759
Manganese distribution and speciation help to explain the effects of silicate and phosphate on manganese toxicity in four crop species
Publisher: Wiley
Date: 11-2017
DOI: 10.1111/NPH.14878
Abstract: Soil acidity and waterlogging increase manganese (Mn) in leaf tissues to potentially toxic concentrations, an effect reportedly alleviated by increased silicon (Si) and phosphorus (P) supply. Effects of Si and P on Mn toxicity were studied in four plant species using synchrotron-based micro X-ray fluorescence (μ-XRF) and nanoscale secondary ion mass spectrometry (NanoSIMS) to determine Mn distribution in leaf tissues and using synchrotron-based X-ray absorption spectroscopy (XAS) to measure Mn speciation in leaves, stems and roots. A concentration of 30 μM Mn in solution was toxic to cowpea and soybean, with 400 μM Mn toxic to sunflower but not white lupin. Unexpectedly, μ-XRF analysis revealed that 1.4 mM Si in solution decreased Mn toxicity symptoms through increased Mn localization in leaf tissues. NanoSIMS showed Mn and Si co-localized in the apoplast of soybean epidermal cells and basal cells of sunflower trichomes. Concomitantly, added Si decreased oxidation of Mn(II) to Mn(III) and Mn(IV). An increase from 5 to 50 μM P in solution changed some Mn toxicity symptoms but had little effect on Mn distribution or speciation. We conclude that Si increases localized apoplastic sorption of Mn in cowpea, soybean and sunflower leaves thereby decreasing free Mn
Influence of Soil Moisture Content on Soil Solution Composition
Publisher: Wiley
Date: 03-2008
Greater emergence force and hypocotyl cross sectional area may improve wheat seedling emergence in sodic conditions
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.PLANTSCI.2018.09.007
Abstract: Surface crusting of sodic soils is a major problem in the semi-arid tropics when rapid drying after sowing follows light showers, leading to reduced seedling emergence and grain yield. The magnitude of the force exerted by germinating seeds affects the ability of the seedlings to rupture the crust and emerge. This study aimed to determine whether the seed germination and seedling emergence force of wheat (Triticum aestivum L.) seedlings vary among different genotypes at different sodicity levels. Germination and emergence force of seedlings of four wheat genotypes was determined in assays using four solutions with sodium adsorption ratio (SAR) values ranging from 0 to 60. Seed germination and seedling emergence force varied between genotypes at different sodicity levels, with the emergence force of the coleoptile correlated to the cross sectional area of the hypocotyl. The results suggest that the selection of wheat genotypes with rapid germination, higher seedling emergence force and larger hypocotyl cross sectional area, offers a strategy to improve seedling emergence in crusted sodic soils.
Biochar affects carbon composition and stability in soil: a combined spectroscopy-microscopy study
Publisher: Springer Science and Business Media LLC
Date: 26-04-2016
DOI: 10.1038/SREP25127
Abstract: The use of biochar can contribute to carbon (C) storage in soil. Upon addition of biochar, there is a spatial reorganization of C within soil particles, but the mechanisms remain unclear. Here, we used Fourier transformed infrared-microscopy and confocal laser scanning microscopy to examine this reorganization. A silty-loam soil was amended with three different organic residues and with the biochar produced from these residues and incubated for 237 d. Soil respiration was lower in biochar-amended soils than in residue-amended soils. Fluorescence analysis of the dissolved organic matter revealed that biochar application increased a humic-like fluorescent component, likely associated with biochar-C in solution. The combined spectroscopy-microscopy approach revealed the accumulation of aromatic-C in discrete spots in the solid-phase of microaggregates and its co-localization with clay minerals for soil amended with raw residue or biochar.The co-localization of aromatic-C:polysaccharides-C was consistently reduced upon biochar application. We conclude that reduced C metabolism is an important mechanism for C stabilization in biochar-amended soils.
The effect of salinity on plant-available water
Publisher: Springer Science and Business Media LLC
Date: 17-06-2017
Tools for the Discovery of Hyperaccumulator Plant Species and Understanding Their Ecophysiology
Publisher: Springer International Publishing
Date: 31-10-2017
Soil chloride content influences the response of bacterial but not fungal diversity to silver nanoparticles entering soil via wastewater treatment processing
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.ENVPOL.2019.113274
Abstract: Silver nanoparticles (NPs) are among the most widely used nanomaterials and are entering soil ecosystems, mainly via biosolids in agriculture. When added directly to soils, metallic Ag-NPs have been shown to affect microbial communities, which underpin important ecosystem functions. During wastewater treatment processing, metallic Ag-NPs are rapidly converted to Ag
Plant-Available Phosphorus in Highly Concentrated Fertilizer Bands: Effects of Soil Type, Phosphorus Form, and Coapplied Potassium
Publisher: American Chemical Society (ACS)
Date: 13-07-2020
An electrostatic model predicting Cu and Ni toxicity to microbial processes in soils
Publisher: Elsevier BV
Date: 02-2013
What is missing to advance foliar fertilization using nanotechnology?
Publisher: Elsevier BV
Date: 2023
DOI: 10.1016/J.TPLANTS.2022.08.017
Abstract: An urgent challenge within agriculture is to improve fertilizer efficiency in order to reduce the environmental footprint associated with an increased production of crops on existing farmland. Standard soil fertilization strategies are often not very efficient due to immobilization in the soil and losses of nutrients by leaching or volatilization. Foliar fertilization offers an attractive supplementary strategy as it bypasses the adverse soil processes, but implementation is often h ered by a poor penetration through leaf barriers, leaf damage, and a limited ability of nutrients to translocate. Recent advances within bionanotechnology offer a range of emerging possibilities to overcome these challenges. Here we review how nanoparticles can be tailored with smart properties to interact with plant tissue for a more efficient delivery of nutrients.
Fate of ZnO Nanoparticles in Soils and Cowpea (Vigna unguiculata)
Publisher: American Chemical Society (ACS)
Date: 14-11-2013
DOI: 10.1021/ES403466P
Abstract: The increasing use of zinc oxide nanoparticles (ZnO-NPs) in various commercial products is prompting detailed investigation regarding the fate of these materials in the environment. There is, however, a lack of information comparing the transformation of ZnO-NPs with soluble Zn(2+) in both soils and plants. Synchrotron-based techniques were used to examine the uptake and transformation of Zn in various tissues of cowpea ( Vigna unguiculata (L.) Walp.) exposed to ZnO-NPs or ZnCl2 following growth in either solution or soil culture. In solution culture, soluble Zn (ZnCl2) was more toxic than the ZnO-NPs, although there was substantial accumulation of ZnO-NPs on the root surface. When grown in soil, however, there was no significant difference in plant growth and accumulation or speciation of Zn between soluble Zn and ZnO-NP treatments, indicating that the added ZnO-NPs underwent rapid dissolution following their entry into the soil. This was confirmed by an incubation experiment with two soils, in which ZnO-NPs could not be detected after incubation for 1 h. The speciation of Zn was similar in shoot tissues for both soluble Zn and ZnO-NPs treatments and no upward translocation of ZnO-NPs from roots to shoots was observed in either solution or soil culture. Under the current experimental conditions, the similarity in uptake and toxicity of Zn from ZnO-NPs and soluble Zn in soils indicates that the ZnO-NPs used in this study did not constitute nanospecific risks.
Effect of pH on Na induced Ca deficiency
Publisher: Springer Science and Business Media LLC
Date: 02-2005
Global changes in soil stocks of carbon, nitrogen, phosphorus, and sulphur as influenced by long‐term agricultural production
Publisher: Wiley
Date: 11-10-2016
DOI: 10.1111/GCB.13513
Abstract: Quantifying changes in stocks of C, N, P, and S in agricultural soils is important not only for managing these soils sustainably as required to feed a growing human population, but for C and N, they are also important for understanding fluxes of greenhouse gases from the soil environment. In a global meta-analysis, 102 studies were examined to investigate changes in soil stocks of organic C, total N, total P, and total S associated with long-term land-use changes. Conversion of native vegetation to cropping resulted in substantial losses of C (-1.6 kg m
Differential Gene Expression in the Model Actinomycete Streptomyces coelicolor A3(2) Supports Nitrogen Mining Dependent on the Plant Carbon to Nitrogen Ratio
Publisher: MDPI AG
Date: 06-12-2018
DOI: 10.3390/AGRICULTURE8120192
Abstract: Nitrogen mining is the process whereby microbial communities catabolise recalcitrant long-term organic matter (OM) to meet nutritional requirements that are not ensured by labile OM. Microbial degradation of recalcitrant OM impacts soil fertility and contributes to greenhouse gas emissions in agricultural systems. Here we conducted a transcriptomics study to track differential gene expression in the model soil Actinomycete Streptomyces coelicolor A3(2) during the decomposition of mung bean (Vigna radiata L.) and wheat (Triticum aestivum L.) residues of relatively low and high carbon-to-nitrogen (C:N) ratios (17.3 and 35.7, respectively) at 1, 7, and 14 days of incubation. A negative binomial general linear model showed that plant variety predominantly affected transcription (p 0.001), although time of incubation also had an effect (p = 0.01). In the high C:N ratio treatment, the expression of cellulases, chitinase, N-acetylglucosaminidase, secreted peptidases, and mineral nitrogen (N) metabolism were increased after 24 h. The low C:N ratio treatment demonstrated preferential expression of glutamate dehydrogenase, transporters involved in glutamate uptake and glycolysis, indicating more efficient N and carbon (C) assimilation. After 14 days, the low C:N ratio treatment showed increased transcription of extracellular enzymes, glutamate dehydrogenase, and glutamate transport. These results show an important role for added plant organic N content in determining when the transcription of genes associated with N mining occurs.
Characterizing the uptake, accumulation and toxicity of silver sulfide nanoparticles in plants
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6EN00489J
Abstract: Plants take up Ag 2 S-NPs without a marked selectivity in regard to particle size and without substantial transformation during upward translocation.
Evaluation of pyritic mine tailings as a plant growth substrate
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.JENVMAN.2017.06.046
Abstract: At the Kidston gold mine, Australia, the direct establishment of vegetation on tailings was considered as an alternative to the use of a waste rock cover. The tailings acid/base account was used to predict plant growth limitation by acidity, and thus methods capable of identifying tailings that would acidify to pH 4.5 or lower were sought. Total S was found to be poorly correlated with acid-generating sulfide, and total C was poorly correlated with acid-neutralizing carbonate, precluding the use of readily determined total S and C as predictors of net acid generation. Therefore, the selected approach used assessment of sulfide content as a predictor of acid generation, and carbonate content as a measure of the acid-neutralizing capacity available at pH 5 and above. Using this approach, the majority of tailings (67%) were found to be non-acid generating. However, areas of potentially acid-generating tailings were randomly distributed across the dam, and could only be located by intensive s ling. The limitations imposed by the large s le numbers, and costly analysis of sulfide and carbonate, make it impractical to identify and ameliorate acid-generating areas prior to vegetation establishment. However, as only a small proportion of the tailings will acidify, a strategy of re-treating acid areas following oxidation is suggested. The findings of the present study will assist in the selection of appropriate methods for the prediction of net acid generation, particularly where more conservative measurements are required to allow vegetation to be established directly in tailings.
Development of ZnO Nanoparticles as an Efficient Zn Fertilizer: Using Synchrotron-Based Techniques and Laser Ablation to Examine Elemental Distribution in Wheat Grain
Publisher: American Chemical Society (ACS)
Date: 07-04-2020
The rhizotoxicity of metal cations is related to their strength of binding to hard ligands
Publisher: Wiley
Date: 02-01-2014
DOI: 10.1002/ETC.2435
Abstract: Mechanisms whereby metal cations are toxic to plant roots remain largely unknown. Aluminum, for ex le, has been recognized as rhizotoxic for approximately 100 yr, but there is no consensus on its mode of action. The authors contend that the primary mechanism of rhizotoxicity of many metal cations is nonspecific and that the magnitude of toxic effects is positively related to the strength with which they bind to hard ligands, especially carboxylate ligands of the cell-wall pectic matrix. Specifically, the authors propose that metal cations have a common toxic mechanism through inhibiting the controlled relaxation of the cell wall as required for elongation. Metal cations such as Al(3+) and Hg(2+), which bind strongly to hard ligands, are toxic at relatively low concentrations because they bind strongly to the walls of cells in the rhizodermis and outer cortex of the root elongation zone with little movement into the inner tissues. In contrast, metal cations such as Ca(2+), Na(+), Mn(2+), and Zn(2+) , which bind weakly to hard ligands, bind only weakly to the cell wall and move farther into the root cylinder. Only at high concentrations is their weak binding sufficient to inhibit the relaxation of the cell wall. Finally, different mechanisms would explain why certain metal cations (for ex le, Tl(+), Ag(+), Cs(+), and Cu(2+)) are sometimes more toxic than expected through binding to hard ligands. The data presented in the present study demonstrate the importance of strength of binding to hard ligands in influencing a range of important physiological processes within roots through nonspecific mechanisms.
Rhizotoxic effects of silver in cowpea seedlings
Publisher: Wiley
Date: 04-08-2010
DOI: 10.1002/ETC.236
Abstract: Silver (Ag) is highly toxic to aquatic organisms, including algae, invertebrate animals, and fish, but little information exists on Ag rhizotoxicity in higher plants. In two solution culture experiments with approximately 1,000 microM Ca(NO3)2 and 5 microM H3BO3 (pH 5.4), 20 to 80% of added Ag (< or =2 microM) was lost from solution within approximately 30 min, with a further decrease after 48 h root growth. Using measured Ag concentrations at the start of the experiments, the median effective concentration (EC50) for root elongation rate of cowpea (Vigna unguiculata [L.] Walp. cv. Caloona) was 0.010 microM Ag in the first 4 h of exposure (0.021 microM in the first 8 h). This demonstrates that Ag (as Ag+) is rapidly rhizotoxic to cowpea seedlings at concentrations similar to those that are toxic to freshwater biota. Rupturing of rhizodermal and outer cortical layers was evident after 48 h with 0.13 to 0.57 microM Ag initially in solution, being most severe at 0.13 or 0.25 microM Ag. An additional experiment showed that ruptures were first evident after 20 h exposure to 0.17 microM Ag, with increased severity of rupturing over time. The rhizotoxic effects of Ag are similar to those of some other trace metals (e.g., Cu, Al, La) that bind strongly to hard ligands and weakly to soft ligands. The similarity of rupturing effects, despite the difference in strong binding to soft ligands by Ag and to hard ligands by the other metals, suggests a distinctive metabolic effect of Ag that binds only weakly to hard ligands.
Organic amendments and gypsum reduce dispersion and increase aggregation of two sodic Vertisols
Publisher: Elsevier BV
Date: 11-2022
Comparative hydrolysis and sorption of Al and La onto plant cell wall material and pectic materials
Publisher: Springer Science and Business Media LLC
Date: 23-02-2010
A Review of the Use of the Basic Cation Saturation Ratio and the “Ideal” Soil
Publisher: Wiley
Date: 03-2007
Long term follow up of high risk children: Who, why and how?
Publisher: Springer Science and Business Media LLC
Date: 17-11-2014
Stable isotope fractionation of cadmium in the soil-rice-human continuum
Publisher: Elsevier BV
Date: 03-2021
Fast X-ray fluorescence microscopy provides high-throughput phenotyping of element distribution in seeds
Publisher: Oxford University Press (OUP)
Date: 24-11-2022
Abstract: The concentration, chemical speciation, and spatial distribution of essential and toxic mineral elements in cereal seeds have important implications for human health. To identify genes responsible for element uptake, translocation, and storage, high-throughput phenotyping methods are needed to visualize element distribution and concentration in seeds. Here, we used X-ray fluorescence microscopy (μ-XRF) as a method for rapid and high-throughput phenotyping of seed libraries and developed an ImageJ-based pipeline to analyze the spatial distribution of elements. Using this method, we nondestructively scanned 4,190 ethyl methanesulfonate (EMS)-mutagenized M1 rice (Oryza sativa) seeds and 533 erse rice accessions in a genome-wide association study (GWAS) panel to simultaneously measure concentrations and spatial distribution of elements in the embryo, endosperm, and aleurone layer. A total of 692 putative mutants and 65 loci associated with the spatial distribution of elements in rice seed were identified. This powerful method provides a basis for investigating the genetics and molecular mechanisms controlling the accumulation and spatial variations of mineral elements in plant seeds.
Trace metal phytotoxicity in solution culture: a review
Publisher: Oxford University Press (OUP)
Date: 06-01-2010
DOI: 10.1093/JXB/ERP385
Abstract: Solution culture has been used extensively to determine the phytotoxic effects of trace metals. A review of the literature from 1975 to 2009 was carried out to evaluate the effects of As(V), Cd(II), Co(II), Cu(II), Hg(II), Mn(II), Ni(II), Pb(II), and Zn(II) on plants grown in solution. A total of 119 studies was selected using criteria that allowed a valid comparison of the results reported toxic concentrations varied by five orders of magnitude. Across a range of plant species and experimental conditions, the phytotoxicity of the trace metals followed the trend (from most to least toxic): Pb approximately Hg >Cu >Cd approximately As >Co approximately Ni approximately Zn >Mn, with median toxic concentrations of (muM): 0.30 Pb, 0.47 Hg, 2.0 Cu, 5.0 Cd, 9.0 As, 17 Co, 19 Ni, 25 Zn, and 46 Mn. For phytotoxicity studies in solution culture, we suggest (i) plants should be grown in a dilute solution which mimics the soil solution, or that, at a minimum, contains Ca and B, (ii) solution pH should be monitored and reported (as should the concentrations of the trace metal of interest), (iii) assessment should be made of the influence of pH on solution composition and ion speciation, and (iv) both the period of exposure to the trace metal and the plant variable measured should be appropriate. Observing these criteria will potentially lead to reliable data on the relationship between growth depression and the concentration of the toxic metal in solution.
Engagement and performance in a first year natural resource science course
Publisher: Wiley
Date: 21-02-2018
DOI: 10.1111/JCAL.12236
Mapping element distributions in plant tissues using synchrotron X-ray fluorescence techniques
Publisher: Humana Press
Date: 10-2013
DOI: 10.1007/978-1-62703-152-3_9
Abstract: Synchrotron-based X-ray fluorescence (XRF) is allowing substantial advances in several disciplines of plant science by allowing the in situ examination of elements within plant tissues. Continual improvements in detector speed, sensitivity, and resolution are increasing the ersity of questions that can be addressed using this technique, including the in situ analysis of elements (such as nutrients or toxicants) within fresh and hydrated tissues. Here, we describe the general principles for designing and conducting experiments for the examination of elemental distributions in plant material using micro-XRF.
Chemical and physical influence of sodic soils on the coleoptile length and root growth angle of wheat genotypes
Publisher: Oxford University Press (OUP)
Date: 07-06-2019
DOI: 10.1093/AOB/MCZ094
Abstract: High exchangeable sodium percentage (ESP) and bulk density of sodic soils can reduce seedling emergence. This study examined variation in seedling coleoptile length and seminal root angle of wheat (Triticum aestivum. L) genotypes to determine whether these traits vary between genotypes that differ in their tolerance to sodic soils. Wheat genotypes were grown in three different experiments. First, four wheat genotypes were grown using soils of three ESPs (4, 10 and 17 %) and secondly in soils of three different bulk densities (1.2, 1.4 and 1.5 g cm–3) and ESP 10 %. Thirdly, seedling coleoptile length and seminal root angle were determined for 16 genotypes grown in a soil of ESP 10 % and bulk density 1.2 g cm–2. Seminal root angle and coleoptile length measurements from the current study were compared with seedling emergence rate and force measured previously. The seedling coleoptile length of all genotypes decreased with increasing soil ESP and bulk density, but with no significant differences between genotypes. In contrast, seminal root angles differed significantly between genotypes, but were not significantly affected by ESP or bulk density. There was an inverse relationship between the seminal root angle of the 16 genotypes and seedling emergence rate (R2 = 0.89) and also between seminal root angle and seedling emergence force (R2 = 0.61). Lack of significant variation in coleoptile length between genotypes suggests that this may not be a suitable characteristic to identify wheat tolerance to sodic conditions. However, a narrower seminal root angle was correlated with rate and force of seedling emergence, traits likely to improve establishment. The mechanism underlying this correlation is not yet clear. Genotypes with a narrow root angle had greater root depth. One possible mechanism might be that genotypes with narrow root angles were able to take up more soil moisture at depth, leading to a higher proportion of seedling emergence.
Soil Organic Carbon Stabilization: Mapping Carbon Speciation from Intact Microaggregates
Publisher: American Chemical Society (ACS)
Date: 17-10-2018
Abstract: The clearing of land for agricultural production depletes soil organic carbon (OC) reservoirs, yet despite their importance, the mechanisms by which C is stabilized in soils remain unclear. Using synchrotron-based infrared microspectroscopy, we have for the first time obtained in situ, laterally resolved data regarding the speciation of C within sections taken from intact free microaggregates from two contrasting soils (Vertisol and Oxisol, 0-20 cm depth) impacted upon by long-term (up to 79 y) agricultural production. There was no apparent gradient in the C concentration from the aggregate surface to the interior for any of the three forms of C examined (aliphatic C, aromatic C, and polysaccharide C). Rather, organo-mineral interactions were of critical importance in influencing overall C stability, particularly for aliphatic C, supporting the hypothesis that microaggregates form through organo-mineral interactions. However, long-term cropping substantially decreased the magnitude of the organo-mineral interactions for all three forms of C. Thus, although organo-mineral interactions are important for OC stability, C forms associated with the mineral phases are not entirely resistant to degradation. These results provide important insights into the underlying mechanisms by which microaggregates form and the factors influencing the persistence of OC in soils.
Soil chloride content influences the response of bacterial but not fungal diversity to silver nanoparticles entering soil via wastewater treatment processing
Publisher: Cold Spring Harbor Laboratory
Date: 26-07-2019
DOI: 10.1101/715839
Abstract: Silver nanoparticles (NPs) are among the most widely used nanomaterials and are entering soil ecosystems, mainly via biosolids in agriculture. When added directly to soils, metallic Ag-NPs have been shown to affect microbial communities, which underpin important ecosystem functions. During wastewater treatment processing, metallic Ag-NPs are rapidly converted to Ag 2 S, which is relatively insoluble and less toxic. Furthermore, recent evidence indicates that silver bioavailability is influenced by soil chloride content. Hence there is a need to understand the impacts of wastewater treatment processed Ag-NPs at varying levels of salinity on soil microbial ersity. In this study, we examined how the application of 0 g, 1 g and 2 g kg −1 NaCl to soil influence the effects of 0 mg, 1 mg and 10 mg kg −1 Ag, applied as wastewater treatment processed Ag-NPs, on bacterial and fungal ersity over time. Using high-throughput phylogenetic marker gene sequencing we demonstrate that, despite being theoretically less toxic, wastewater treatment processed Ag-NPs can affect the composition of soil bacterial and fungal communities, and influence bacterial alpha ersity. In addition, we found that silver-associated changes in bacterial community composition were affected by soil chloride content, with more acute responses to silver being observed in more saline soils. This work highlights that the release of Ag-NPs into soils via realistic exposure pathways can alter microbial ersity and that these effects may be influenced by soil chloride content. Soil chloride content influences the response of bacterial but not fungal ersity to wastewater treatment processed silver nanoparticles.
Effect of ionic strength and clay mineralogy on Na–Ca exchange and the SAR–ESP relationship
Publisher: Wiley
Date: 30-08-2005
The role of soil in defining planetary boundaries and the safe operating space for humanity
Publisher: Elsevier BV
Date: 2021
Fresh Water Leaching of Alkaline Bauxite Residue after Sea Water Neutralization
Publisher: Wiley
Date: 09-2009
DOI: 10.2134/JEQ2008.0511
Abstract: Processing of bauxite to extract alumina produces a strongly alkaline waste, bauxite refining residue, which is commonly stored in engineered structures. Once full, these waste dumps must be revegetated. In many alumina refineries, the waste is separated into fine-textured red mud and coarse-textured residue sand (RS). The sand component has physical characteristics that make it a suitable plant growth medium, provided the adverse chemical characteristics can be addressed. Neutralization of the highly saline-sodic RS with sea water lowers pH, reduces Na saturation, and adds plant nutrients. However, sea water-neutralized RS remains saline sodic and needs fresh water leaching before use as a plant growth medium. Columns containing sea water-neutralized RS were leached with 30 m depth-equivalent of fresh water to evaluate the effects of rainfall on the RS and its leachate. Entrained cations were rapidly displaced by the fresh water, lowering salinity to non-plant-limiting levels (< or =0.3 dS m(-1)). The percentage of the effective cation exchange capacity (ECEC) saturated by Na decreased from 71 to 62% due to a reduction in soil solution ionic strength (causing a decrease in the ECEC) and the preferential displacement of Na(+) (and K(+)) from the exchange. Fresh water leaching increased pH (leachate pH increased from 8.0 to 10.1). This pH increase is attributed to the slow dissolution of the Na-containing mineral sodalite. Under the current experimental conditions, the application of 30 m depth-equivalent of leaching reduced the total RS sodalite content by <10%.
Soil carbon and nitrogen dynamics in a Vertisol following 50 years of no-tillage, crop stubble retention and nitrogen fertilization
Publisher: Elsevier BV
Date: 2020
Cadmium contamination in agricultural soils of China and the impact on food safety
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.ENVPOL.2019.03.063
Abstract: Rapid industrialization in China during the last three decades has resulted in widespread contamination of Cd in agricultural soils. A considerable proportion of the rice grain grown in some areas of southern China has Cd concentrations exceeding the Chinese food limit, raising widespread concern regarding food safety. In this review, we summarize rice grain Cd concentrations in national Chinese markets and in field surveys from contaminated areas, and analyze the potential health risk associated with increased dietary Cd intake. For subsistence rice farmers living in some contaminated areas of southern China who mainly consume locally-produced Cd-contaminated rice, their estimated dietary Cd intake is now comparable to that for the population in the region of Japan where the Itai-Itai disease was first reported. Interventions must be taken urgently to reduce Cd intake for these farmers. We also analyze i) the main reasons causing elevated grain Cd concentrations in southern China, ii) the dominant biogeochemical processes controlling the solubility of Cd in paddy soils, and iii) molecular mechanisms for the uptake and translocation of Cd in rice plants. Based on these analyses, we propose a number of countermeasures to address soil Cd contamination, including i) mitigation of Cd transfer from paddy soils to rice grain, and ii) intervention in those farmers who consume home-grown Cd-contaminated rice. Liming to increase soil pH to 6.5 and gene editing biotechnology are effective strategies to decrease Cd accumulation in rice grain. For these local farmers with high-Cd exposure risk, local governments should monitor the Cd concentration in their home-grown rice and exchange those high-Cd rice with low-Cd rice in order to reduce their dietary Cd intake.
Control of nutrient solutions for studies at high pH
Publisher: Springer Science and Business Media LLC
Date: 2005
Nutrient accumulation and transcriptome patterns during grain development in rice
Publisher: Oxford University Press (OUP)
Date: 22-10-2022
DOI: 10.1093/JXB/ERAC426
Abstract: Rice is an important source of calories and mineral nutrients for more than half of the world’s population. The accumulation of essential and toxic mineral elements in rice grain affects its nutritional quality and safety. However, the patterns and processes by which different elements progressively accumulate during grain filling remain largely unknown. In the present study, we investigated temporal changes in dry matter, elemental concentrations, and the transcriptome in the grain of field-grown rice. We also investigated the effects of seed setting rate and the position of the grain within the rice panicle on element accumulation. Three different patterns of accumulation were observed: (i) elements including K, Mn, B, and Ca showed an early accumulation pattern (ii) dry matter and elements including N, P, S, Mg, Cu, Zn, Mo, As, and Cd showed a mid accumulation pattern and (iii) elements such as Fe showed a gradual increase pattern. These different accumulation patterns can be explained by the differences in the biogeochemical behavior of the various elements in the soil, as well as differences in plant nutrient redistribution, gene expression, and the sink–source relationship. These results improve our knowledge of the dynamics of elemental accumulation in rice grain and are helpful for identification of functional genes mediating the translocation of elements to grain.
Gypsum solubility in seawater, and its application to bauxite residue amelioration
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/SR04034
Abstract: The solubilities and dissolution rates of 3 gypsum sources [analytical grade reagent (AR), phosphogypsum (PG), mined gypsum (MG)] with 6 MG size fractions ( .0, 1.0–2.0, 0.5–1.0, 0.25–0.5, 0.125–0.25, .125 mm) were investigated in triple-deionised water (TDI) and seawater to examine their suitability for bauxite residue amelioration. Gypsum solubility was greater in seawater (3.8 g/L) than TDI (2.9 g/L) due to the ionic strength effect, with dissolution in both TDI and seawater following first-order kinetics. Dissolution rate constants varied with gypsum source (AR PG MG) due to reactivity and surface area differences, with 1 : 20 gypsum : solution suspensions reaching saturation within 15 s (AR) to 30 min (MG .0 mm). The ability of bauxite residue to adsorb Ca from solution was also examined. The quantity of the total solution Ca adsorbed was found to be small (5%). These low rates of solution Ca adsorption, combined with the comparatively rapid dissolution rates, preclude the application of gypsum to the residue sand/seawater slurry as a method for residue amelioration. Instead, direct field application to the residue would ensure more efficient gypsum use. In addition, the formation of a sparingly soluble CaCO3 coating around the gypsum particles after mixing in a highly alkaline seawater/supernatant liquor solution greatly reduced the rate of gypsum dissolution.
A web-accessible computer program for calculating electrical potentials and ion activities at cell-membrane surfaces
Publisher: Springer Science and Business Media LLC
Date: 23-10-2013
Fast X-Ray Fluorescence Microtomography of Hydrated Biological Samples
Publisher: Public Library of Science (PLoS)
Date: 02-06-2011
Amelioration of Cadmium Contaminated Soils Using Cation Exchangers
Publisher: Informa UK Limited
Date: 22-07-2009
Distribution of aluminium in hydrated leaves of tea (Camellia sinensis) using synchrotron- and laboratory-based X-ray fluorescence microscopy
Publisher: Oxford University Press (OUP)
Date: 08-04-2020
DOI: 10.1039/C9MT00300B
Abstract: Aluminium (Al) is highly toxic to plant growth, with soluble concentrations being elevated in the ∼40% of arable soils worldwide that are acidic. Determining the distribution of Al in plant tissues is important for understanding the mechanisms by which it is toxic and how some plants tolerate high concentrations. Synchrotron- and laboratory-based X-ray fluorescence microscopy (XFM) is a powerful technique to quantitatively analyse the distribution of elements, including in hydrated and living plants. However, analysis of light elements (z & phosphorus) is extremely challenging due to signal losses in air, and the unsuitability of vacuum environments for (fresh) hydrated plant tissues. This study uses XFM in a helium environment to avoid Al signal loss to reveal the distribution of Al in hydrated plant tissues of Tea (Camellia sinensis). The results show that Al occurs in localised areas across the foliar surface, whereas in cross-sections Al is almost exclusively concentrated in the apoplastic space above and in between adaxial epidermal cells. This distribution of Al is related to the Al tolerance of this species, and accumulation of phytotoxic elements in the apoplastic space, away from sensitive processes such as photosynthesis in the palisade mesophyll cells, is a common tolerance mechanism reported in many different plant species. This study develops an XFM method on both synchrotron and laboratory sources that overcomes the drawbacks of existing analytical techniques, permitting measurement of light elements down to Al in (fresh) hydrated plant tissues.
Synchrotron-based X-ray absorption near-edge spectroscopy imaging for laterally resolved speciation of selenium in fresh roots and leaves of wheat and rice
Publisher: Oxford University Press (OUP)
Date: 26-05-2015
DOI: 10.1093/JXB/ERV254
Zinc Accumulates in the Nodes of Wheat Following the Foliar Application of 65Zn Oxide Nano- and Microparticles
Publisher: American Chemical Society (ACS)
Date: 26-05-2021
Toxic effects of Ni2+ on growth of cowpea (Vigna unguiculata)
Publisher: Springer Science and Business Media LLC
Date: 06-03-2007
Effects of methyl jasmonate on plant growth and leaf properties
Publisher: Wiley
Date: 14-04-2018
Absorption of foliar-applied Zn fertilizers by trichomes in soybean and tomato
Publisher: Oxford University Press (OUP)
Date: 03-03-2018
DOI: 10.1093/JXB/ERY085
Silver Nanoparticles Entering Soils via the Wastewater–Sludge–Soil Pathway Pose Low Risk to Plants but Elevated Cl Concentrations Increase Ag Bioavailability
Publisher: American Chemical Society (ACS)
Date: 15-07-2016
Abstract: The widespread use of silver nanoparticles (Ag-NPs) results in their movement into wastewater treatment facilities and subsequently to agricultural soils via application of contaminated sludge. On-route, the chemical properties of Ag may change, and further alterations are possible upon entry to soil. In the present study, we examined the long-term stability and (bio)availability of Ag along the "wastewater-sludge-soil" pathway. Synchrotron-based X-ray absorption spectroscopy (XAS) revealed that ca. 99% of Ag added to the sludge reactors as either Ag-NPs or AgNO3 was retained in sludge, with ≥79% of this being transformed to Ag2S, with the majority (≥87%) remaining in this form even after introduction to soils at various pH values and Cl concentrations for up to 400 days. Diffusive gradients in thin films (DGT), chemical extraction, and plant uptake experiments indicated that the potential (bio)availability of Ag in soil was low but increased markedly in soils with elevated Cl, likely due to the formation of soluble AgClx complexes in the soil solution. Although high Cl concentrations increased the bioavailability of Ag markedly, plant growth was not reduced in any treatment. Our results indicate that Ag-NPs entering soils through the wastewater-sludge-soil pathway pose low risk to plants due to their conversion to Ag2S in the wastewater treatment process, although bioavailability may increase in saline soils or when irrigated with high-Cl water.
Disentangling the effect of nitrogen supply on the priming of soil organic matter: A critical review
Publisher: Informa UK Limited
Date: 06-10-2023
Alleviation of Cu and Pb Rhizotoxicities in Cowpea (Vigna unguiculata) as Related to Ion Activities at Root-Cell Plasma Membrane Surface
Publisher: American Chemical Society (ACS)
Date: 12-05-2011
DOI: 10.1021/ES1041404
Abstract: Cations, such as Ca and Mg, are generally thought to alleviate toxicities of trace metals through site-specific competition (as incorporated in the biotic ligand model, BLM). Short-term experiments were conducted with cowpea (Vigna unguiculata L. Walp.) seedlings in simple nutrient solutions to examine the alleviation of Cu and Pb toxicities by Al, Ca, H, Mg, and Na. For Cu, the cations depolarized the plasma membrane (PM) and reduced the negativity of ψ(0)(o) (electrical potential at the outer surface of the PM) and thereby decreased {Cu(2+)}(0)(o) (activity of Cu(2+) at the outer surface of the PM). For Pb, root elongation was generally better correlated to the activity of Pb(2+) in the bulk solution than to {Pb(2+)}(0)(o). However, we propose that the addition of cations resulted in a decrease in {Pb(2+)}(0)(o) but a simultaneous increase in the rate of Pb uptake (due to an increase in the negativity of E(m,surf), the difference in potential between the inner and outer surfaces of the PM) thus offsetting the decrease in {Pb(2+)}(0)(o). In addition, Ca was found to alleviate Pb toxicity through a specific effect. Although our data do not preclude site-specific competition (as incorporated in the BLM), we suggest that electrostatic effects have an important role.
Nanotechnology: A New Opportunity in Plant Sciences
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.TPLANTS.2016.04.005
Abstract: The agronomic application of nanotechnology in plants (phytonanotechnology) has the potential to alter conventional plant production systems, allowing for the controlled release of agrochemicals (e.g., fertilizers, pesticides, and herbicides) and target-specific delivery of biomolecules (e.g., nucleotides, proteins, and activators). An improved understanding of the interactions between nanoparticles (NPs) and plant responses, including their uptake, localization, and activity, could revolutionize crop production through increased disease resistance, nutrient utilization, and crop yield. Herewith, we review potential applications of phytonanotechnology and the key processes involved in the delivery of NPs to plants. To ensure both the safe use and social acceptance of phytonanotechnology, the adverse effects, including the risks associated with the transfer of NPs through the food chain, are discussed.
Effects of carbon nanotubes and derivatives of graphene oxide on soil bacterial diversity
Publisher: Cold Spring Harbor Laboratory
Date: 28-03-2019
DOI: 10.1101/591842
Abstract: Carbon nanotubes (CNTs), reduced graphene oxide (rGO) and ammonia-functionalized graphene oxide (aGO), are nanomaterials that possess varied and useful properties. However, following their use, their release into the environment is inevitable. While CNTs have been shown to influence soil bacterial ersity, albeit at very high concentration, the effects of rGO have only been examined using pure bacterial cultures, and those of aGO are unknown. Here, we investigated the effects of CNTs, rGO and aGO, at three time points (7, 14 and 30 days), and over a range of concentrations (1 ng, 1 µg and 1 mg kg dry soil -1 ), on soil bacterial ersity using 16S rRNA licon sequencing. Graphite was included to facilitate comparisons with a similar and naturally occurring carbon material, while the inclusion of GO allowed the effects of GO modification to be isolated. Bacterial community composition, but not alpha ersity, was altered by all treatments except the low GO, low rGO and high aGO treatments on day 14 only. In all cases, the nanomaterials led to shifts in community composition that were of similar magnitude to those induced by graphite and GO, albeit with differences in the taxa affected. Our study highlights that nanocarbon materials can induce changes in soil bacterial ersity, even at doses that are environmentally realistic.
Methods for assessing laterally-resolved distribution, speciation and bioavailability of phosphorus in soils
Publisher: Springer Science and Business Media LLC
Date: 08-01-2022
Seawater neutralization and gypsum amelioration of bauxite refining residue to produce a plant growth medium
Publisher: Elsevier BV
Date: 04-2021
Silver Sulfide Nanoparticles Reduce Nitrous Oxide Emissions by Inhibiting Denitrification in the Earthworm Gut
Publisher: American Chemical Society (ACS)
Date: 13-08-2020
Kinetics and nature of aluminium rhizotoxic effects: a review
Publisher: Oxford University Press (OUP)
Date: 14-06-2016
DOI: 10.1093/JXB/ERW233
Abstract: Acid soils with elevated levels of soluble aluminium (Al) comprise ~40% of the world's arable land, but there remains much uncertainty regarding the mechanisms by which Al is rhizotoxic. This review examines the kinetics of the toxic effects of Al on the root elongation rate (RER), its effects on root tissues, and its location at a subcellular level. Depending upon the concentration and plant species, soluble Al decreases the RER in a median time of 73min, but in as little as 5min in soybean. This is initially due to a decreased rate at which cells expand anisotropically in the elongation zone. Thereafter, rhizodermal and outer cortical cells rupture through decreased cell wall relaxation. It is in this region where most Al accumulates in the apoplast. Subsequently, Al impacts root growth at a subcellular level through adverse effects on the plasma membrane (PM), cytoplasm, and nucleus. At the PM, Al alters permeability, fluidity, and integrity in as little as 0.5h, whilst it also depolarizes the PM and reduces H(+)-ATPase activity. The Al potentially crosses the PM within 0.5h where it is able to bind to the nucleus and inhibit cell ision sequestration within the vacuole is required to reduce the toxic effects of Al within the cytoplasm. This review demonstrates the increasing evidence of the importance of the initial Al-induced inhibition of wall loosening, but there is evidence also of the deleterious effects of Al on other cellular processes which are important for long-term root growth and function.
Evaluation of extractants for estimation of the phytoavailable trace metals in soils
Publisher: Elsevier BV
Date: 2007
DOI: 10.1016/J.ENVPOL.2006.03.021
Abstract: Despite its environmental (and financial) importance, there is no agreement in the literature as to which extractant most accurately estimates the phytoavailability of trace metals in soils. A large data set was taken from the literature, and the effectiveness of various extractants to predict the phytoavailability of Cd, Zn, Ni, Cu, and Pb examined across a range of soil types and contamination levels. The data suggest that generally, the total soil trace metal content, and trace metal concentrations determined by complexing agents (such as the widely used DTPA and EDTA extractants) or acid extractants (such as 0.1M HCl and the Mehlich 1 extractant) are only poorly correlated to plant phytoavailability. Whilst there is no consensus, it would appear that neutral salt extractants (such as 0.01 M CaCl(2) and 0.1 M NaNO(3)) provide the most useful indication of metal phytoavailability across a range of metals of interest, although further research is required.
Germination of leucaena and Rhodes grass seeds in saline and alkaline conditions
Publisher: International Seed Testing Association
Date: 31-12-2016
Effect of long-term no-tillage and nitrogen fertilization on phosphorus distribution in bulk soil and aggregates of a Vertisol
Publisher: Elsevier BV
Date: 2021
Use of X-ray tomography for examining root architecture in soils
Publisher: Elsevier BV
Date: 2022
Theoretical and experimental assessment of nutrient solution composition in short-term studies of aluminium rhizotoxicity
Publisher: Springer Science and Business Media LLC
Date: 14-04-2016
Biogeochemical cycling of iron oxides in the rhizosphere of plants grown on ferruginous duricrust (canga)
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.SCITOTENV.2020.136637
Abstract: Goethite-cemented duricrusts, also known as canga, commonly occur as a capping rock protecting underlying iron ore deposits. The processes that govern canga formation are still unclear but include recurrent partial dissolution and recrystallisation of goethite through biogeochemical cycling of iron, hypothesised to be catalysed by plants and bacteria. In the present study, the effect of plant exudates on mobilisation of iron in canga was examined using model plants grown on crushed canga in RHIZOtest devices, which separate roots from substrate by a semi-permeable membrane. Moderate plant-induced acidification of the canga was detected, however the primary driver of mineral dissolution was the synergistic effect of reductive and ligand-promoted dissolution, identified by an increase in organic acids concentration and the presence of low concentrations of free ferrous iron. Whilst organic acids exudation lasted, iron cations were stabilised in solution once the organic acids were degraded by microorganisms, the free cations precipitated as iron oxy-hydroxides. Mineralogical analysis and high-resolution microscopy confirmed our hypothesis that plants that grow in this iron-rich substrate contribute to iron dissolution indirectly (e.g., during phosphate solubilisation), and that the resulting surplus iron not taken up by the plants is redeposited, promoting the cementation of the residual minerals. Understanding the contribution of plants to the iron cycling in canga is crucial when formulating post-mining rehabilitation strategies for iron ore sites.
Assessing radiation dose limits for X-ray fluorescence microscopy analysis of plant specimens
Publisher: Oxford University Press (OUP)
Date: 28-11-2019
DOI: 10.1093/AOB/MCZ195
Abstract: X-ray fluorescence microscopy (XFM) is a powerful technique to elucidate the distribution of elements within plants. However, accumulated radiation exposure during analysis can lead to structural damage and experimental artefacts including elemental redistribution. To date, acceptable dose limits have not been systematically established for hydrated plant specimens. Here we systematically explore acceptable dose rate limits for investigating fresh sunflower (Helianthus annuus) leaf and root s les and investigate the time–dose damage in leaves attached to live plants. We find that dose limits in fresh roots and leaves are comparatively low (4.1 kGy), based on localized disintegration of structures and element-specific redistribution. In contrast, frozen-hydrated s les did not incur any apparent damage even at doses as high as 587 kGy. Furthermore, we find that for living plants subjected to XFM measurement in vivo and grown for a further 9 d before being reimaged with XFM, the leaves display elemental redistribution at doses as low as 0.9 kGy and they continue to develop bleaching and necrosis in the days after exposure. The suggested radiation dose limits for studies using XFM to examine plants are important for the increasing number of plant scientists undertaking multidimensional measurements such as tomography and repeated imaging using XFM.
Tolerance of perennial grasses to high copper in sand culture
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/EN08102
Abstract: Environmental context. Copper (Cu) is an essential element for the growth of plants, but various anthropogenic activities such as mining, smelting, disposal of wastes, and the use of Cu-containing fungicides have resulted in substantial Cu contamination at sites throughout the world. We used a sand-culture system to investigate the tolerance of seven perennial grasses to toxic levels of Cu. This study provides information to assist in the selection of grasses for the revegetation and stabilisation of Cu-contaminated sites. Abstract. Although perennial grasses are commonly used to revegetate and stabilise disturbed sites, comparatively little is known of their tolerance to Cu. High Cu in solution reduced growth in all grasses, with the critical solution Cu concentration (corresponding to a 50% reduction in shoot fresh mass) ranging -fold, from 1.7 μM in Queensland blue grass (Dichanthium sericeum (R.Br.) A. Camus) to 10 μM in Sabi grass (Urochloa mosambicensis (Hack.) Dandy cv. Saraji). An increase in Cu in solution resulted in elevated Cu concentration in shoots of all but one species, increasing from 6 to 11 μg g–1 at 0 μM Cu to 13 to 25 μg g–1 at 11 μM Cu. The comparatively small magnitude of this increase to a concentration below the animal toxicity threshold suggests that phytotoxicity is likely to be of more environmental concern than is the uptake of Cu into the shoots (and its subsequent consumption by fauna).
Plasma Membrane Surface Potential: Dual Effects upon Ion Uptake and Toxicity
Publisher: Oxford University Press (OUP)
Date: 30-11-2010
Quantitative determination of metal and metalloid spatial distribution in hydrated and fresh roots of cowpea using synchrotron-based X-ray fluorescence microscopy
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.SCITOTENV.2013.05.091
Abstract: Many metals and metalloids, jointly termed metal(loid)s, are toxic to plants even at low levels. This has limited the study of their uptake, distribution, and modes of action in plant roots grown at physiologically relevant concentrations. Synchrotron-based X-ray fluorescence microscopy was used to examine metal(loid)s in hydrated cowpea (Vigna unguiculata L.) roots exposed to Zn(II), Ni(II), Mn(II), Cu(II), Hg(II), Se(IV), Se(VI), As(III), or As(V). Development of a mathematical model enabled in situ quantitative determination of their distribution in root tissues. The binding strength of metals influenced the extent of their movement through the root cylinder, which influenced the toxic effects exerted-metals (e.g. Cu, Hg) that bind more strongly to hard ligands had high concentrations in the rhizodermis and caused this tissue to rupture, while other metals (e.g. Ni, Zn) moved further into the root cylinder and did not cause ruptures. When longitudinal distributions were examined, the highest Se concentration in roots exposed to Se(VI) was in the more proximal root tissues, suggesting that Se(VI) is readily loaded into the stele. This contrasted with other metal(loid)s (e.g. Mn, As), which accumulated in the apex. These differences in metal(loid) spatial distribution provide valuable quantitative data on metal(loid) physiology, including uptake, transport, and toxicity in plant roots.
Tailoring hydroxyapatite nanoparticles to increase their efficiency as phosphorus fertilisers in soils
Publisher: Elsevier BV
Date: 08-2018
Widespread Occurrence of the Highly Toxic Dimethylated Monothioarsenate (DMMTA) in Rice Globally
Publisher: American Chemical Society (ACS)
Date: 17-02-2022
Abstract: Arsenic (As) accumulation in rice is of global concern for human health and international trade. Rice is typically reported to contain inorganic As (iAs) and dimethylated arsenate (DMA), with current food guidelines limiting toxic iAs but not less-toxic DMA. Here, we show that the highly toxic dimethylated monothioarsenate (DMMTA) is also found in rice worldwide and has been unknowingly determined as less-toxic DMA by previous routine analytical methods. Using enzymatic extraction followed by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) analysis with a C18 column, DMMTA was detected in rice grains (
Bioavailability and movement of hydroxyapatite nanoparticles (HA-NPs) applied as a phosphorus fertiliser in soils
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8EN00751A
Abstract: Hydroxyapatite nanoparticles pose as a novel P fertiliser in acid soils.
Characterization of Lead Precipitate Following Uptake by Roots of Brassica juncea
Publisher: Wiley
Date: 11-2009
DOI: 10.1897/09-131.1
Abstract: Seedlings of Brassica juncea (L.) Czern. were grown in solution culture for 14 d prior to exposure to Pb₂+ at an activity of 31 microM for 72 h. Electron dense deposits found within the apoplast and symplast were analysed using scanning transmission electron microscopy-energy dispersive spectroscopy (STEM-EDS) to determine the chemical identity of the deposits and potential toxicity resistance mechanisms. Irrespective of the cellular compartment in which they were found, the deposits contained Pb, O, P and Cl. For the extracellular deposits, the average Pb: P : O atomic ratio was 1 : 0.54 : 3.0, which together with the hexagonal crystal system suggests that Pb is present as chloropyromorphite (Pb₅(PO₄)₃Cl). A weak Ca signal was also detected in about half of the spectra, possibly indicating the presence of small concentrations of phosphohedyphane (Pb₃Ca₂(PO₄)₃Cl). The evidence suggests that B. juncea resists Pb toxicity by storing precipitated Pb in the vacuole.
Time-resolved X-ray fluorescence analysis of element distribution and concentration in living plants: An example using manganese toxicity in cowpea leaves
Publisher: Elsevier BV
Date: 12-2018
Nitrogen‐rich microbial products provide new organo‐mineral associations for the stabilization of soil organic matter
Publisher: Wiley
Date: 22-12-2017
DOI: 10.1111/GCB.14009
Abstract: Understanding the cycling of C and N in soils is important for maintaining soil fertility while also decreasing greenhouse gas emissions, but much remains unknown about how organic matter ( OM ) is stabilized in soils. We used nano‐scale secondary ion mass spectrometry (Nano SIMS ) to investigate the changes in C and N in a Vertisol and an Alfisol incubated for 365 days with 13 C and 15 N pulse labeled lucerne ( Medicago sativa L.) to discriminate new inputs of OM from the existing soil OM . We found that almost all OM within the free stable microaggregates of the soil was associated with mineral particles, emphasizing the importance of organo‐mineral interactions for the stabilization of C. Of particular importance, it was also found that 15 N‐rich microbial products originating from decomposition often sorbed directly to mineral surfaces not previously associated with OM . Thus, we have shown that N‐rich microbial products preferentially attach to distinct areas of mineral surfaces compared to C‐dominated moieties, demonstrating the ability of soils to store additional OM in newly formed organo‐mineral associations on previously OM ‐free mineral surfaces. Furthermore, differences in 15 N enrichment were observed between the Vertisol and Alfisol presumably due to differences in mineralogy (smectite‐dominated compared to kaolinite‐dominated), demonstrating the importance of mineralogy in regulating the sorption of microbial products. Overall, our findings have important implications for the fundamental understanding of OM cycling in soils, including the immobilization and storage of N‐rich compounds derived from microbial decomposition and subsequent N mineralization to sustain plant growth.
Soil organic carbon is significantly associated with the pore geometry, microbial diversity and enzyme activity of the macro-aggregates under different land uses
Publisher: Elsevier BV
Date: 07-2021
Impact of land use change and soil type on total phosphorus and its fractions in soil aggregates
Publisher: Wiley
Date: 17-12-2020
DOI: 10.1002/LDR.3501
Measurement and Interpretation of Salinity Tolerance in Four Perennial Grasses
Publisher: Informa UK Limited
Date: 02-01-2009
Interaction between Cu toxicity and P deficiency in soil-grown cowpea (Vigna unguiculata (L.) Walp.)
Publisher: Springer Science and Business Media LLC
Date: 29-01-2011
Wetting and drying cycles, organic amendments, and gypsum play a key role in structure formation and stability of sodic Vertisols
Publisher: Copernicus GmbH
Date: 03-03-2023
Abstract: Abstract. In the natural environment, soils undergo wetting and drying (WD) cycles due to precipitation and evapotranspiration. The WD cycles have a profound impact on soil physical, chemical, and biological properties and drive the development of structure in soils. Degraded soils are often lacking structure, and the effect of organic amendments and WD cycles on structure formation of these soils is poorly understood. The aim of this study was to evaluate the role of biotic and abiotic factors on aggregate formation and stabilization of sodic soils after the addition of gypsum and organic amendments (feedlot manure, chicken manure, lucerne pallets, and anionic poly acrylamide). Amended soils were incubated at 25 ∘C over four WD cycles, with assessment of soil microbial respiration, electrical conductivity, pH, sodium adsorption ratio (SAR), aggregate stability in water (ASWAT), aggregate size distribution, and mean weight diameter. Our results demonstrate that WD cycles can improve aggregate stability after the addition of amendments in sodic Vertisols, but this process depends on the type of organic amendment. Lucerne pellets resulted in highest soil microbial respiration, proportions of large macroaggregates ( µm), and mean weight diameter. In contrast, dispersion was significantly reduced when soils were treated with chicken manure, whilst anionic polyacrylamide only had a transient effect on aggregate stability. When these organic amendments were applied together with gypsum, the stability of aggregates was further enhanced, and dispersion became negligible after the second WD cycle. The formation and stability of small macroaggregates (2000–250 µm) was less dependent on the type of organic amendments and more dependent on WD cycles as the proportion of small macroaggregates also increased in control soils after four WD cycles, highlighting the role of WD cycles as one of the key factors that improves aggregation and stability of sodic Vertisols.
Mobility and lability of phosphorus from highly concentrated fertiliser bands
Publisher: Elsevier BV
Date: 2023
Effect of Mn deficiency and legume inoculation on rhizosphere pH in highly alkaline soils
Publisher: Springer Science and Business Media LLC
Date: 05-2004
Toxicity of metals to roots of cowpea in relation to their binding strength
Publisher: Wiley
Date: 25-05-2011
DOI: 10.1002/ETC.557
Abstract: Metal phytotoxicity is important in both environmental and agricultural systems. A solution culture study examined the toxicity of 26 metals to roots of cowpea (Vigna unguiculata (L.) Walp.) new data were collected for 15 metals and published data for 11 metals. Metal toxicity, calculated as causing a 50% reduction in root elongation rate, was determined based on either the measured concentration in the bulk solution (EC50(b)) or the calculated activity at the outer surface of the plasma membrane (EA50(0)°). The EC50(b) values ranged from 0.007 µM for Tl to 98,000 µM for K, with the order of rhizotoxicity to cowpea, from most to least toxic, being Tl = Ag > Cu > Hg = Ni = Ga = Ru = In > Sc = Cd = Gd = La = Co = Cs = Pb > Zn = Al = H > Mn > Ba = Sr > Li > Mg > Ca = Na > K. The EA50(0)° values suggest that the binding of metals to hard ligands is an important, general, nonspecific mechanism of toxicity, a hypothesis supported by the similar toxicity symptoms to roots of cowpea by many metals. However, additional mechanisms, such as strong binding to soft ligands, substantially increase rhizotoxicity of some metals, especially Tl, Ag, and Cs. Besides direct toxic effects, osmotic effects or reduced activity of Ca(2+) at the outer surface of the root plasma membrane (and resultant Ca deficiency) may decrease short-term root growth.
Metal-induced cell rupture in elongating roots is associated with metal ion binding strengths
Publisher: Springer Science and Business Media LLC
Date: 10-02-2009
Correction to: Calcium oxalate and calcium cycling in forest ecosystems
Publisher: Springer Science and Business Media LLC
Date: 11-11-2021
Long-term land use change in Australia from native forest decreases all fractions of soil organic carbon, including resistant organic carbon, for cropping but not sown pasture
Publisher: Elsevier BV
Date: 05-2021
Microspectroscopic visualization of how biochar lifts the soil organic carbon ceiling
Publisher: Springer Science and Business Media LLC
Date: 02-09-2022
DOI: 10.1038/S41467-022-32819-7
Abstract: The soil carbon (C) saturation concept suggests an upper limit to the storage of soil organic carbon (SOC). It is set by the mechanisms that protect soil organic matter from mineralization. Biochar has the capacity to protect new C, including rhizodeposits and microbial necromass. However, the decadal-scale mechanisms by which biochar influences the molecular ersity, spatial heterogeneity, and temporal changes in SOC persistence, remain unresolved. Here we show that the soil C storage ceiling of a Ferralsol under subtropical pasture was raised by a second application of Eucalyptus saligna biochar 8.2 years after the first application—the first application raised the soil C storage ceiling by 9.3 Mg new C ha −1 and the second application raised this by another 2.3 Mg new C ha −1 . Linking direct visual evidence from one-, two-, and three-dimensional analyses with SOC quantification, we found high spatial heterogeneity of C functional groups that resulted in the retention of rhizodeposits and microbial necromass in microaggregates (53–250 µm) and the mineral fraction ( µm). Microbial C-use efficiency was concomitantly increased by lowering specific enzyme activities, contributing to the decreased mineralization of native SOC by 18%. We suggest that the SOC ceiling can be lifted using biochar in (sub)tropical grasslands globally.
Examination of the Distribution of Arsenic in Hydrated and Fresh Cowpea Roots Using Two- and Three-Dimensional Techniques
Publisher: Oxford University Press (OUP)
Date: 25-05-2012
Abstract: Arsenic (As) is considered to be the environmental contaminant of greatest concern due to its potential accumulation in the food chain and in humans. Using novel synchrotron-based x-ray fluorescence techniques (including sequential computed tomography), short-term solution culture studies were used to examine the spatial distribution of As in hydrated and fresh roots of cowpea (Vigna unguiculata ‘Red Caloona’) seedlings exposed to 4 or 20 µm arsenate [As(V)] or 4 or 20 µm arsenite. For plants exposed to As(V), the highest concentrations were observed internally at the root apex (meristem), with As also accumulating in the root border cells and at the endodermis. When exposed to arsenite, the endodermis was again a site of accumulation, although no As was observed in border cells. For As(V), subsequent transfer of seedlings to an As-free solution resulted in a decrease in tissue As concentrations, but growth did not improve. These data suggest that, under our experimental conditions, the accumulation of As causes permanent damage to the meristem. In addition, we suggest that root border cells possibly contribute to the plant’s ability to tolerate excess As(V) by accumulating high levels of As and limiting its movement into the root.
Kinetics of metal toxicity in plant roots and its effects on root morphology
Publisher: Springer Science and Business Media LLC
Date: 20-07-2017
Quantifying the economic impact of soil constraints on Australian agriculture: A case‐study of wheat
Publisher: Wiley
Date: 14-09-2018
DOI: 10.1002/LDR.3130
Avoiding the point of no return: Maintaining infiltration to remediate saline-sodic Vertosols in high rainfall environments
Publisher: Elsevier BV
Date: 08-2022
The within-field spatial variation in rice grain Cd concentration is determined by soil redox status and pH during grain filling
Publisher: Elsevier BV
Date: 06-2020
Healthy soil for healthy humans and a healthy planet
Publisher: Informa UK Limited
Date: 30-06-2023
The standard electrode potential (Eθ) predicts the prooxidant activity and the acute toxicity of metal ions
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.JINORGBIO.2011.08.024
Abstract: The standard electrode potential (E(θ)) has been known for many decades to predict the toxicity of metal ions. We have compiled acute toxicity data from fifteen studies and find that the toxicity of thirty metal ions correlates with E(θ) at r(2)=0.868 when toxicity is expressed as log concentration of comparably effective doses. We have discovered an even stronger relationship between the prooxidant activity (PA) of metal ions and E(θ) (and electronegativity, χ). Data compiled from thirty-four studies demonstrate that the PA of twenty-five metal ions correlates with E(θ) at r(2)=0.983 (and χ at r(2)=0.968). PA was commonly measured as metal-induced peroxidation of cell membranes or accumulation of reactive oxygen species. None of the redox metals (capable of Fenton-like reactions) in our studies (i.e., Mn, Fe, Co, Ni, and Cu) was prooxidative or toxic beyond what was expected from E(θ) or χ. We propose that the formation of superoxide-metal ion complexes is greater at greater E(θ) or χ values and that these complexes, whether free or enzyme-bound, function in PA without redox cycling of the complexed ion.
Alleviation of Al toxicity by Si is associated with the formation of Al-Si complexes in root tissues of sorghum
Publisher: Cold Spring Harbor Laboratory
Date: 06-12-2017
DOI: 10.1101/229625
Abstract: Silicon is reported to reduce the toxic effects of Al on root elongation but the in planta mechanism by which this occurs remains unclear. Using seedlings of soybean ( Glycine max ) and sorghum ( Sorghum bicolor ), we examined the effect of up to 2 mM Si on root elongation rate (RER) in Al-toxic nutrient solutions. Synchrotron-based low energy X-ray fluorescence (LEXRF) was then used for the in situ examination of the distribution of Al and Si within cross-sections cut from the apical tissues of sorghum roots. The addition of Si potentially increased RER in Al-toxic solutions, with RER being up to ca. 0.3 mm h −1 (14 %) higher for soybean and ca. 0.2 mm h −1 (17 %) higher for sorghum relative to solutions without added Si. This improvement in RER could not be attributed to a change in Al-chemistry of the bulk nutrient solution, nor was it due to a change in the concentration of Al within the apical (0-10 mm) root tissues. Using LEXRF to examine sorghum, it was demonstrated that in roots exposed to both Al and Si, much of the Al was co-located with Si in the mucigel and outer apoplast. These observations suggest that Si reduces the toxicity of Al in planta through formation of Al-Si complexes in mucigel and outer cellular tissues, thereby decreasing the binding of Al to the cell wall where it is known to inhibit wall loosening as required for cell elongation.
Toxic effects of low concentrations of Cu on nodulation of cowpea (Vigna unguiculata)
Publisher: Elsevier BV
Date: 2007
DOI: 10.1016/J.ENVPOL.2006.03.007
Abstract: Although Cu is phytotoxic at Cu(2+) activities as low as 1-2 microM, the effect of Cu(2+) on the nodulation of legumes has received little attention. The effect of Cu(2+) on nodulation of cowpea (Vigna unguiculata (L.) Walp. cv. Caloona) was examined in a dilute solution culture system utilising a cation exchange resin to buffer solution Cu(2+). The nodulation process was more sensitive to increasing Cu(2+) activities than both shoot and root growth whilst a Cu(2+) activity of 1.0 microM corresponded to a 10% reduction in the relative yield of the shoots and roots, a Cu(2+) activity of 0.2 microM corresponded to a 10% reduction in nodulation. This reduction in nodulation with increasing Cu(2+) activity was associated with an inhibition of root hair formation in treatments containing > or =0.77 microM Cu(2+), rather than to a reduction in the size of the Rhizobium population.
The impact, identification and management of dispersive soils in rainfed cropping systems
Publisher: Wiley
Date: 12-2020
DOI: 10.1111/EJSS.13070
Abstract: Dispersive soils limit crop growth and significantly impact world food production. Although numerous reviews have examined soil dispersion, many focus on irrigated systems and fail to differentiate the approaches required for rainfed agriculture. This review seeks to fill this gap by focusing on the impact, identification and management of dispersive soils in rainfed areas. Dispersive soils can have large impacts on crop production because of their adverse physical, chemical and biological effects, with this impact particularly large in rainfed systems where irrigation water is unavailable to supplement crop water supply and assist with amelioration. However, the identification of these soils is challenging and tests that can reliably relate soil characteristics to crop performance are lacking. Recent work has found that first identifying consistently lower yielding locations (using yield mapping or proximal/remote sensing) and then using traditional soil testing to identify the potential cause/s of the yield loss may be a promising approach, although this requires refinement. Knowledge of the type of dispersive soil (e.g., saline/non‐saline, acidic/alkaline/neutral) and where constraints occur in the profile (surface or subsoil) must also be determined during identification as this will affect management approaches, particularly where multiple constraints need to be treated together to achieve yield increase. Improved understanding of how to economically use ameliorants and combine them to achieve maximum benefit in the presence of multiple constraints is needed. Greater appreciation of how to use agronomic management to improve crop growth in the presence of dispersive behaviour is also likely to increase profitability in rainfed systems where amelioration is often impractical or uneconomical. Dispersive soils are a major challenge for rainfed cropping, and so the refinement of our management approach can help improve profitability and productivity. Dispersive soils limit crop growth and significantly impact world food production We examine the impact, identification and management of dispersive soils in rainfed agriculture Improvements in the identification of dispersive soils are required to improve management Refinement of ameliorant use and agronomic management will improve profitability and productivity
X‐ray elemental mapping techniques for elucidating the ecophysiology of hyperaccumulator plants
Publisher: Wiley
Date: 10-10-2017
DOI: 10.1111/NPH.14810
Abstract: Contents Summary 432 I. Introduction 433 II. Preparation of plant s les for X-ray micro-analysis 433 III. X-ray elemental mapping techniques 438 IV. X-ray data analysis 442 V. Case studies 443 VI. Conclusions 446 Acknowledgements 449 Author contributions 449 References 449 SUMMARY: Hyperaccumulators are attractive models for studying metal(loid) homeostasis, and probing the spatial distribution and coordination chemistry of metal(loid)s in their tissues is important for advancing our understanding of their ecophysiology. X-ray elemental mapping techniques are unique in providing in situ information, and with appropriate s le preparation offer results true to biological conditions of the living plant. The common platform of these techniques is a reliance on characteristic X-rays of elements present in a s le, excited either by electrons (scanning/transmission electron microscopy), protons (proton-induced X-ray emission) or X-rays (X-ray fluorescence microscopy). Elucidating the cellular and tissue-level distribution of metal(loid)s is inherently challenging and accurate X-ray analysis places strict demands on s le collection, preparation and analytical conditions, to avoid elemental redistribution, chemical modification or ultrastructural alterations. We compare the merits and limitations of the in idual techniques, and focus on the optimal field of applications for inferring ecophysiological processes in hyperaccumulator plants. X-ray elemental mapping techniques can play a key role in answering questions at every level of metal(loid) homeostasis in plants, from the rhizosphere interface, to uptake pathways in the roots and shoots. Further improvements in technological capabilities offer exciting perspectives for the study of hyperaccumulator plants into the future.
Engineering Crops without Genome Integration Using Nanotechnology
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.TPLANTS.2019.05.004
Abstract: Nanomaterial-based delivery systems can deliver functional genes or siRNA into intact plant cells and create transgene-free genetically engineered plants. This system allows highly efficient and organelle-specific delivery that can overcome host-range limitations. This approach will have a erse range of applications in plant biotechnology and plant biology.
Toxic effects of Pb2+ on the growth and mineral nutrition of signal grass (Brachiaria decumbens) and Rhodes grass (Chloris gayana)
Publisher: Springer Science and Business Media LLC
Date: 12-09-2007
Understanding the delayed expression of Al resistance in signal grass (Urochloa decumbens)
Publisher: Oxford University Press (OUP)
Date: 15-12-2019
DOI: 10.1093/AOB/MCZ206
Abstract: Signal grass (Urochloa decumbens) is a widely used pasture grass in tropical and sub-tropical areas due to its high aluminiun (Al) resistance. However, the underlying mechanisms conferring this resistance are not clearly understood. The Al concentrations of bulk root tissues and the intracellular compartment were examined, including the impact of a metabolic inhibitor, carbonyl cyanide m-chlorophenyl hydrazone (CCCP). Next, we examined changes in the properties of signal grass root tissues following exposure to toxic levels of Al, including the cell wall cation exchange capacity (CEC), degree of methylation and concentrations of cell wall fractions. Although signal grass was highly resistant to Al, there was a delay of 24–48 h before the expression of this resistance. We found that this delay in the expression of Al resistance was not related to the total Al concentration in the bulk apical root tissues, nor was it related to changes in the Al bound to the cell wall. We also examined changes in other properties of the cell wall, including the CEC, degree of methylation and changes in the concentration of pectin, hemicellulose and cellulose. We noted that concentrations of intracellular Al decreased by approx. 50 % at the same time that the root elongation rate improved after 24–48 h. Using CCCP as a metabolic inhibitor, we found that the intracellular Al concentration increased approx. 14-fold and that the CCCP prevented the subsequent decrease in intracellular Al. Our results indicate that the delayed expression of Al resistance was not associated with the Al concentration in the bulk apical root tissues or bound to the cell wall, nor was it associated with changes in other properties of the cell wall. Rather, signal grass has an energy-dependent Al exclusion mechanism, and this mechanism requires 24–48 h to exclude Al from the intracellular compartment.
Interaction of different-sized ZnO nanoparticles with maize (Zea mays): Accumulation, biotransformation and phytotoxicity
Publisher: Elsevier BV
Date: 11-2021
Land use affects temperature sensitivity of soil organic carbon decomposition in macroaggregates but not in bulk soils in subtropical Oxisols of Queensland, Australia
Publisher: Elsevier BV
Date: 04-2020
Toxic effects of Pb2+ on growth of cowpea (Vigna unguiculata)
Publisher: Elsevier BV
Date: 11-2007
DOI: 10.1016/J.ENVPOL.2007.01.011
Abstract: A concentration as low as 1 microM lead (Pb) is highly toxic to plants, but previous studies have typically related plant growth to the total amount of Pb added to a solution. In the present experiment, the relative fresh mass of cowpea (Vigna unguiculata) was reduced by 10% at a Pb2+ activity of 0.2 microM for the shoots and at a Pb2+ activity of 0.06 microM for the roots. The primary site of Pb2+ toxicity was the root, causing severe reductions in root growth, loss of apical dominance (shown by an increase in branching per unit root length), the formation of localized swellings behind the root tips (due to the initiation of lateral roots), and the bending of some root tips. In the root, Pb was found to accumulate primarily within the cell walls and intercellular spaces.
Probing the nature of soil organic matter
Publisher: Informa UK Limited
Date: 26-09-2021
Effect of Cu Toxicity on Growth of Cowpea (Vigna unguiculata)
Publisher: Springer Science and Business Media LLC
Date: 2006
Graphene oxide affects soil bacterial and fungal diversity even at parts-per-trillion concentrations
Publisher: Cold Spring Harbor Laboratory
Date: 26-01-2019
DOI: 10.1101/530485
Abstract: Graphene oxide (GO) is an oxidized form of graphene that is relatively cheap and easy to produce. This has heralded its widespread use in a range of industries, with its likelihood of release into the environment increasing accordingly. In pure culture, GO has been shown to influence bacteria and fungi, but its effects on environmental microbial communities remain poorly characterized, despite the important ecosystem services that these organisms underpin. Here, we characterized the effects of GO and graphite, over time and at three concentrations (1 ng, 1 µg and 1 mg kg dry soil -1 ), on soil bacterial and fungal ersity using 16S rRNA and ITS2 gene licon sequencing. Graphite was included as a reference material as it is widely distributed in the environment. Neither GO or graphite had significant effects on the alpha ersity of microbial communities. The composition of bacterial and fungal communities, however, was significantly influenced by GO and graphite. These effects were equally apparent between doses and varied over time. Predicted KEGG pathways and fungal guild structures were not significantly influenced by the treatments. Our study demonstrates that GO can influence soil microbial ersity, even at parts-per-trillion concentration, which is equivalent to the rates of release predicted for similar nanomaterials such as carbon nanotubes. Graphene oxide is a nanomaterial with broad and expanding industrial applications. Some evidence indicates that it can influence the growth of microorganisms, many of which support important ecosystem services, such as the provision of food and clean water. The amount of graphene oxide currently entering soils is not known but is likely to be similar to other nanomaterials, such as carbon nanotubes (i.e. parts-per-trillion to parts-per-billion per year). In this study, we demonstrate that graphene oxide added to soil at these concentrations (or higher) can alter the composition of bacterial and fungal communities. Nonetheless, we found that these changes were of similar magnitude to those associated with the addition of graphite, which is common and occurs naturally in soils. Further research is recommended to determine whether the changes in microbial community composition that we have shown can be induced by graphene oxide, have deleterious consequences for soil health.
Calculated activity of Mn2+ at the outer surface of the root cell plasma membrane governs Mn nutrition of cowpea seedlings
Publisher: Oxford University Press (OUP)
Date: 21-04-2011
DOI: 10.1093/JXB/ERR097
Dynamics of Dimethylated Monothioarsenate (DMMTA) in Paddy Soils and Its Accumulation in Rice Grains
Publisher: American Chemical Society (ACS)
Date: 10-06-2021
The Voltaic Effect as a Novel Mechanism Controlling the Remobilization of Cadmium in Paddy Soils during Drainage
Publisher: American Chemical Society (ACS)
Date: 25-01-2021
Ensuring planetary survival: the centrality of organic carbon in balancing the multifunctional nature of soils
Publisher: Informa UK Limited
Date: 10-01-2022
In vivo formation of natural HgSe nanoparticles in the liver and brain of pilot whales
Publisher: Springer Science and Business Media LLC
Date: 28-09-2016
DOI: 10.1038/SREP34361
Abstract: To understand the biochemistry of methylmercury (MeHg) that leads to the formation of mercury-selenium (Hg-Se) clusters is a long outstanding challenge that promises to deepen our knowledge of MeHg detoxification and the role Se plays in this process. Here, we show that mercury selenide (HgSe) nanoparticles in the liver and brain of long-finned pilot whales are attached to Se-rich structures and possibly act as a nucleation point for the formation of large Se-Hg clusters, which can grow with age to over 5 μm in size. The detoxification mechanism is fully developed from the early age of the animals, with particulate Hg found already in juvenile tissues. As a consequence of MeHg detoxification, Se-methionine, the selenium pool in the system is depleted in the efforts to maintain essential levels of Se-cysteine. This study provides evidence of so far unreported depletion of the bioavailable Se pool, a plausible driving mechanism of demonstrated neurotoxic effects of MeHg in the organism affected by its high dietary intake.
Alleviation of Al Toxicity by Si Is Associated with the Formation of Al–Si Complexes in Root Tissues of Sorghum
Publisher: Frontiers Media SA
Date: 21-12-2017
Release of silver from nanoparticle-based filter paper and the impacts to mouse gut microbiota
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9EN01387C
Abstract: The high antibacterial properties of the filter paper containing silver nanoparticles (Ag-NPs) and subsequent impacts on mice.
Uptake, transformation, and environmental impact of zinc oxide nanoparticles in a soil-wheat system
Publisher: Elsevier BV
Date: 2023
DOI: 10.1016/J.SCITOTENV.2022.159307
Abstract: Zinc oxide nanoparticles (ZnO-NPs) are metal-based nanomaterials, but their long-term effects on plant growth and the soil environment in the field remain unclear with most previous studies using short-term laboratory and glasshouse studies. In this study, we used a field experiment to examine the long-term effects of ZnO-NPs in a soil-wheat (Triticum aestivum) system. It was found that although ZnO-NPs had no significant effect on either yield or the concentration of other nutrients within the grain, the application of ZnO-NPs significantly increased Zn concentrations. Indeed, for grain, the application of ZnO-NPs to both the soil and foliage (SFZnO) (average of 33.1 mg/kg) significantly increased grain Zn concentrations compared to the the control treatment (21.7 mg/kg). Using in situ analyses, nutrients were found to accumulate primarily in the crease tissue and the aleurone layer of the grain, regardless of treatment. Specifically, the concentration of Zn in the aleurone layer for the SFZnO treatment was 2-3 times higher than that in the control, being >300 mg/kg, whilst the Zn concentration in the crease tissue was ca. 600 mg/kg in the SFZnO treatment, being two times higher than for the control. Although the application of ZnO-NPs increased the total Zn within the grain, it did not accumulate within the grain as ZnO-NPs with this being important for food safety, but rather mainly as Zn-phytate, with the remainder of the Zn complexed with either cysteine or phosphate. Finally, we also observed that ZnO-NPs caused fewer changes to the soil bacterial community structure and that it had no nano-specific toxicity.
50 years of continuous no-tillage, stubble retention and nitrogen fertilization enhanced macro-aggregate formation and stabilisation in a Vertisol
Publisher: Elsevier BV
Date: 10-2021
Wastewater Treatment Processing of Silver Nanoparticles Strongly Influences Their Effects on Soil Microbial Diversity
Publisher: American Chemical Society (ACS)
Date: 14-10-2020
Distribution and speciation of Mn in hydrated roots of cowpea at levels inhibiting root growth
Publisher: Wiley
Date: 13-09-2012
DOI: 10.1111/J.1399-3054.2012.01674.X
Abstract: The phytotoxicity of Mn is important globally due to its increased solubility in acid or waterlogged soils. Short-term (≤24 h) solution culture studies with 150 µM Mn were conducted to investigate the in situ distribution and speciation of Mn in apical tissues of hydrated roots of cowpea [Vigna unguiculata (L.) Walp. cv. Red Caloona] using synchrotron-based techniques. Accumulation of Mn was rapid exposure to 150 µM Mn for only 5 min resulting in substantial Mn accumulation in the root cap and associated mucigel. The highest tissue concentrations of Mn were in the root cap, with linear combination fitting of the data suggesting that ≥80% of this Mn(II) was associated with citrate. Interestingly, although the primary site of Mn toxicity is typically the shoots, concentrations of Mn in the stele of the root were not noticeably higher than in the surrounding cortical tissues in the short-term (≤24 h). The data provided here from the in situ analyses of hydrated roots exposed to excess Mn are, to our knowledge, the first of this type to be reported for Mn and provide important information regarding plant responses to high Mn in the rooting environment.
Methods to Visualize Elements in Plants
Publisher: Oxford University Press (OUP)
Date: 23-01-2020
DOI: 10.1104/PP.19.01306
High phosphorus fertilization changes the speciation and distribution of manganese in wheat grains grown in a calcareous soil
Publisher: Elsevier BV
Date: 09-2021
Synchrotron-based Techniques Shed Light on Mechanisms of Plant Sensitivity and Tolerance to High Manganese in the Root Environment
Publisher: Oxford University Press (OUP)
Date: 22-09-2015
DOI: 10.1104/PP.15.00726
Iron–Manganese (Oxyhydro)oxides, Rather than Oxidation of Sulfides, Determine Mobilization of Cd during Soil Drainage in Paddy Soil Systems
Publisher: American Chemical Society (ACS)
Date: 11-02-2019
Abstract: The preharvest drainage of rice paddy fields during the grain filling stage can result in a substantial mobilization of Cd in soil and, consequently, elevated grain Cd concentration. However, the processes controlling the mobilization of Cd remains poorly understood. Using 12 field-contaminated paddy soils, we investigated the factors controlling the temporal changes in Cd solubility in paddy soils that were incubated anaerobically for 40 d followed by a 20 d oxidation period. Soluble and extractable Cd concentrations decreased rapidly upon flooding but increased during the oxidation phase, with Cd solubility (aqueous Cd/soil Cd) largely depending upon porewater pH. Furthermore, inhibiting sulfate reduction or inhibiting oxidation dissolution of Cd-sulfides had little or no effect on the mobilization of Cd in the subsequent oxidation phase. Both sequential extraction and X-ray absorption spectroscopy (XAS) analyses revealed that changes in Cd solubility were largely dependent upon the transformation of Cd between the Fe-Mn (oxyhydro)oxide fraction and exchangeable fraction. Mobilization of Cd upon soil drainage was caused by a decrease in soil pH resulting in the release of Cd from Fe-Mn (oxyhydro)oxides. Taken together, Fe-Mn (oxyhydro)oxides play a critical (and prevalent) role in controlling the mobilization of Cd upon soil drainage in paddy systems.
Separating multiple, short‐term, deleterious effects of saline solutions on the growth of cowpea seedlings
Publisher: Wiley
Date: 30-11-2010
DOI: 10.1111/J.1469-8137.2010.03551.X
Abstract: • Reductions in plant growth as a result of salinity are of global importance in natural and agricultural landscapes. • Short-term (48-h) solution culture experiments studied 404 treatments with seedlings of cowpea (Vigna unguiculata cv Caloona) to examine the multiple deleterious effects of calcium (Ca), magnesium (Mg), sodium (Na) or potassium (K). • Growth was poorly related to the ion activities in the bulk solution, but was closely related to the calculated activities at the outer surface of the plasma membrane, {I(z)}₀°. The addition of Mg, Na or K may induce Ca deficiency in roots by driving {Ca²+}₀° to Mg²+ > Na+ > K+. The addition of K and, to a lesser extent, Ca alleviated the toxic effects of Na. Thus, Ca is essential but may also be intoxicating or ameliorative. • The data demonstrate that the short-term growth of cowpea seedlings in saline solutions may be limited by Ca deficiency, osmotic effects and specific ion toxicities, and K and Ca alleviate Na toxicity. A multiple regression model related root growth to osmolarity and {I(z)}₀° (R²=0.924), allowing the quantification of their effects.
Soil organic matter is stabilized by organo-mineral associations through two key processes: The role of the carbon to nitrogen ratio
Publisher: Elsevier BV
Date: 2020
Combined Application of Lime and a Nitrification Inhibitor (3,4-Dimethylpyrazole Phosphate) Markedly Decreased Nitrous Oxide Emissions from an Acid Soil
Publisher: MDPI AG
Date: 27-04-2022
Abstract: High nitrous oxide (N2O) emissions (2–10% of fertiliser N) were observed previously from acid soils cropped with sugarcane (Saccharum officinarum) in Australia. We assessed the impact of lime, a nitrification inhibitor (NI, as 3,4-dimethylpyrazole phosphate, DMPP), and copper (Cu) on N2O emissions from an acid sugarcane soil in a laboratory experiment using (1) urea (U), (2) U + DMPP, (3) U + CuSO4.5H2O (U + Cu), and (4) U + DMPP + Cu. The treatments were applied to both an un-limed soil (pH 5.1) and a limed soil (pH 6.9) and incubated at 25 °C and 55% water holding capacity (WHC) for 28 d, and then increased to 90% WHC for another 8 d to favour denitrification. At 55% WHC, both the addition of the NI (U + DMPP) and the liming of the acid soil significantly decreased cumulative N2O emissions, due to significantly lower net nitrifications. Liming and DMPP decreased N2O emissions by 79% and 90%, respectively. However, where lime and DMPP were applied together, N2O emissions decreased by 94% compared to those in the un-limed (acid) U-treated soil. In contrast, the addition of Cu and the increase in water content to 90% WHC had no significant effect on N2O emissions. Therefore, the combined use of lime and DMPP provides the best option to decrease N2O emissions from the acid soil.
Metal ion effects on hydraulic conductivity of bacterial cellulose–pectin composites used as plant cell wall analogs
Publisher: Wiley
Date: 07-01-2010
DOI: 10.1111/J.1399-3054.2009.01306.X
Abstract: Low concentrations of some trace metals markedly reduce root elongation rate and cause ruptures to root rhizodermal and outer cortical cells in the elongation zone. The interactions between the trace metals and plant components responsible for these effects are not well understood but may be linked to changes in water uptake, cell turgor and cell wall extensibility. An experiment was conducted to investigate the effects of Al, La, Cu, Gd, Sc and Ru on the saturated hydraulic conductivity of bacterial cellulose (BC)-pectin composites, used as plant cell wall analogs. Hydraulic conductivity was reduced to approximately 30% of the initial flow rate by 39 microM Al and 0.6 microM Cu, approximately 40% by 4.6 microM La, 3 microM Sc and 4.4 microM Ru and approximately 55% by 3.4 microM Gd. Scanning electron microscopy (SEM) revealed changes in the ultrastructure of the composites. The results suggest that trace metal binding decreases the hydraulic conductivity through changes in pectin porosity. The experiment illustrates the importance of metal interactions with pectin, and the implications of such an interaction in plant metal toxicity and in normal cell wall processes.
Investigating the foliar uptake of zinc from conventional and nano-formulations: a methodological study
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/EN19019
Abstract: Environmental contextZinc, an essential micronutrient often applied to crops as a fertiliser, can be difficult to analyse in plants due to limitations of conventional techniques. Here, we use radiotracers and a non-destructive imaging technique to visualise how zinc applied as a nanofertiliser moves within wheat plants over time. This is an important step towards developing cost-effective fertilisers to help solve one of the world’s most widespread plant deficiencies. AbstractZinc (Zn) deficiency affects half of the world’s arable soil and one-third of the world’s human population. Application of Zn foliar fertilisers to cereal crops can be an effective way to increase grain Zn content however, commonly used formulations can scorch the leaf (e.g. soluble Zn salts) or are prohibitively expensive (e.g. chelated Zn, ZnEDTA). Zinc oxide nanoparticles (ZnO-NPs) may offer an efficient and cost-effective alternative, but little is known regarding the mechanisms of Zn uptake and translocation within the plant. Foliar-applied Zn is analytically challenging to detect, locate and quantify, as it is omnipresent. Furthermore, any single analytical technique does not have the detection limit or spatial resolution required. In this study, the uptake and mobility of foliar-applied ZnEDTA, ZnO-NPs and ZnO microparticles (ZnO-MPs) to wheat (Triticum aestivum L.) were investigated using inductively coupled plasma mass spectroscopy (ICP-MS), synchrotron-based X-ray fluorescence microscopy (XFM) and radiotracing techniques using 65Zn-labelled formulations. The three techniques were compared to highlight limitations and advantages of each. We also report, for the first time, a novel time-resolved invivo autoradiography imaging technique that can be used to visualise 65Zn in live plants treated with foliar applications of 65ZnO-NPs and MPs. The images were supplemented by gamma spectroscopy analysis for quantification. The results of this study provide important insights into the analytical challenges faced when investigating foliar-applied Zn nanofertilisers in plants. Potential solutions using nuclear techniques are also discussed, which in turn may ultimately lead to the development of more efficient foliar fertilisers.
Microspectroscopic visualization of how biochar elevates the soil organic carbon ceiling
Publisher: Research Square Platform LLC
Date: 10-09-2021
DOI: 10.21203/RS.3.RS-860309/V1
Abstract: The soil carbon saturation concept suggests an upper limit to store soil organic carbon (SOC), set by the mechanisms that protect soil organic matter from decomposition. Biochar has the capacity to protect new C including rhizodeposits and microbial necromass. However, the decadal scale mechanisms by which biochar influences the molecular ersity, spatial heterogeneity, and temporal changes of SOC persistence remain unresolved. Here we show that the soil C saturation ceiling of a Ferralsol under subtropical pasture could be elevated by 2 Mg (new) C ha-1 by the application of Eucalyptus saligna biochar 8.2 years after the first application. Using one, two-, and three-dimensional analyses, significant increases were observed in the spatial distribution of root-derived 13C in microaggregates (53-250 µm, 11 %) and new C protected in mineral fractions ( µm, 5 %). Microbial C-use efficiency was concomitantly improved by lowering specific enzyme activities, contributing to the decreased mineralization of native SOC by 18 %. We provide evidence that the global SOC ceiling can be elevated using biochar in Ferralsols by 0.01-0.1 Pg new C yr-1.
Time-resolved laboratory micro-X-ray fluorescence reveals silicon distribution in relation to manganese toxicity in soybean and sunflower
Publisher: Oxford University Press (OUP)
Date: 27-04-2020
DOI: 10.1093/AOB/MCAA081
Abstract: Synchrotron- and laboratory-based micro-X-ray fluorescence (µ-XRF) is a powerful technique to quantify the distribution of elements in physically large intact s les, including live plants, at room temperature and atmospheric pressure. However, analysis of light elements with atomic number (Z) less than that of phosphorus is challenging due to the need for a vacuum, which of course is not compatible with live plant material, or the availability of a helium environment. A new laboratory µ-XRF instrument was used to examine the effects of silicon (Si) on the manganese (Mn) status of soybean (Glycine max) and sunflower (Helianthus annuus) grown at elevated Mn in solution. The use of a helium environment allowed for highly sensitive detection of both Si and Mn to determine their distribution. The µ-XRF analysis revealed that when Si was added to the nutrient solution, the Si also accumulated in the base of the trichomes, being co-located with the Mn and reducing the darkening of the trichomes. The addition of Si did not reduce the concentrations of Mn in accumulations despite seeming to reduce its adverse effects. The ability to gain information on the dynamics of the metallome or ionome within living plants or excised hydrated tissues can offer valuable insights into their ecophysiology, and laboratory µ-XRF is likely to become available to more plant scientists for use in their research.
Applications and opportunities of click chemistry in plant science
Publisher: Elsevier BV
Date: 08-2023
Short‐term phosphorus sorption and desorption in contrasting cropped Vertisols
Publisher: Wiley
Date: 09-2023
DOI: 10.1111/EJSS.13418
Defining appropriate methods for studying toxicities of trace metals in nutrient solutions
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.ECOENV.2017.09.044
Abstract: The use of inappropriate experimental conditions for examining trace metal phytotoxicity results in data of questionable value. The present study aimed to identify suitable parameters for study of phytotoxic metals in nutrient solutions. First, the literature was reviewed to determine the concentration of six metals (Cd, Cu, Hg, Ni, Pb, and Zn) from solution of contaminated soils. Next, the effects of pH, P, Cl, NO
Online Engagement during COVID-19: Comparing a Course Previously Delivered Traditionally with Emergency Online Delivery
Publisher: Hindawi Limited
Date: 27-05-2022
DOI: 10.1155/2022/6813033
Abstract: The COVID-19 pandemic caused major disruptions worldwide to teaching and learning activities across the education sector. We investigated the impact of COVID-19 on student engagement and performance in a third-year undergraduate science course by comparing student activity during emergency online delivery and traditional mode delivery. We found that the rapid transition to fully online teaching without any physical face-to-face teaching caused by COVID-19 resulted in learning resources being accessed at a slower rate throughout the semester. Student engagement decreased as evidenced by lower attendance at tutorials, despite this being the only virtual face-to-face activity available to students in this course. Thus, despite the smooth transition to fully online mode, it was not sufficient to prevent a decrease in student activity and participation in the online environment, and we observed a downward spiral in student engagement and motivation. Results indicate the importance of providing structure and teacher-student-peer interaction in online delivery modes.
Tolerance of seven perennial grasses to high nickel in sand culture
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/EN09100
Abstract: Environmental context.High concentrations of Ni in soil may occur either naturally or as a result of human activities. We used a sand culture system to investigate the suitability of seven perennial grasses for the revegetation of Ni-contaminated sites. This study provides information on the toxic effects of Ni on plant growth and gives consideration to the health of animals consuming these plants, thereby increasing the accuracy of risk assessments. Abstract.Although grasses are commonly used to revegetate disturbed areas, comparatively little is known regarding the tolerance of perennial grasses to toxic levels of trace metals. A sand culture experiment was conducted to investigate the tolerance of seven perennial grasses to high concentrations of Ni. The activity of Ni2+ in solution that resulted in a 50% reduction in shoot growth ranged from 50 µM for Sabi grass (Urochloa mosambicensis (Hack.) Dandy cv. Saraji) to 13 µM for curly Mitchell grass (Astrebla lappacea (Lindl.) Domin). In most grasses, growth in the high-Ni2+ treatments resulted in shoot Ni concentrations at or above the toxicity threshold for consumption by cattle (100 µg Ni g–1). Based upon their tolerance to Ni, and the extent to which they translocate Ni to the shoots, Sabi grass, signal grass (Brachiaria decumbens Stapf. cv. Basilisk) and buffel grass (Cenchrus ciliaris (L.) cv. Biloela) appear well suited for the phytostabilisation of Ni-contaminated sites in subtropical and tropical regions.
Nanomaterials as fertilizers for improving plant mineral nutrition and environmental outcomes
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9EN00971J
Abstract: Nanomaterials can potentially be used as fertilizers to improve both plant nutrition and environmental outcomes.
Tandem Probe Analysis Mode for Synchrotron XFM: Doubling Throughput Capacity
Publisher: American Chemical Society (ACS)
Date: 11-03-2022
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