Single-Shot Intensity- and Phase-Sensitive Compressive Sensing-Based Coherent Modulation Ultrafast Imaging.

Ultrafast imaging can capture the dynamic scenes with a nanosecond and even femtosecond temporal resolution. Complementarily, phase imaging can provide the morphology, refractive index, or thickness information that intensity imaging cannot represent. Therefore, it is important to realize the simultaneous ultrafast intensity and phase imaging for achieving as much information as possible in the detection of ultrafast dynamic scenes. Here, we report a single-shot intensity- and phase-sensitive compressive sensing-based coherent modulation ultrafast imaging technique, shortened as CS-CMUI, which integrates coherent modulation imaging, compressive imaging, and streak imaging. We theoretically demonstrate through numerical simulations that CS-CMUI can obtain both the intensity and phase information of the dynamic scenes with ultrahigh fidelity. Furthermore, we experimentally build a CS-CMUI system and successfully measure the intensity and phase evolution of a multimode Q-switched laser pulse and the dynamical behavior of laser ablation on an indium tin oxide thin film. It is anticipated that CS-CMUI enables a profound comprehension of ultrafast phenomena and promotes the advancement of various practical applications, which will have substantial impact on fundamental and applied sciences.

The role and transcriptomic mechanism of cell wall in the mutual antagonized effects between selenium nanoparticles and cadmium in wheat.

Selenium nanoparticles (SeNPs) has been reported as a beneficial role in alleviating cadmium (Cd) toxicity in plant. However, underlying molecular mechanisms about SeNPs reducing Cd accumulation and alleviating Cd toxicity in wheat are not well understood. A hydroponic culture was performed to evaluate Cd and Se accumulation, cell wall components, oxidative stress and antioxidative system, and transcriptomic response of wheat seedlings after SeNPs addition under Cd stress. Results showed that SeNPs application notably reduced Cd concentration in root and in shoot by 56.9% and 37.3%, respectively. Additionally, SeNPs prompted Cd distribution in root cell wall by 54.7%, and increased lignin, pectin and hemicellulose contents by regulating cell wall biosynthesis and metabolism-related genes. Further, SeNPs alleviated oxidative stress caused by Cd in wheat through signal transduction pathways. We also observed that Cd addition reduced Se accumulation by downregulating the expression level of aquaporin 7. These results indicated that SeNPs alleviated Cd toxicity and reduced Cd accumulation in wheat, which were associated with the synergetic regulation of cell wall biosynthesis pathway, uptake transporters, and antioxidative system via signaling pathways.

CuCo2O4 nanoneedle arrays growth on carbon cloth as a non-enzymatic electrochemical sensor with low detection limit ketoprofen recognition.

An electrochemical sensor for detecting ketoprofen was constructed by in-situ grown copper cobaltate (CuCo2O4) nanoneedle arrays on a carbon cloth (CC) substrate. The resulting porous nanoneedle arrays not only expose numerous electrochemically active sites but also significantly enhance the electrochemical apparent active area and current transmission efficiency. By leveraging its electrochemical properties, the sensor achieves an impressive detection limit for ketoprofen of 0.7 pM, with a linear range spanning from 2 pM ~ 2 µM. Furthermore, the sensor exhibits remarkable reproducibility, anti-interference capabilities, and stability. Notably, the developed sensor also performed ketoprofen detection on real samples (including drug formulations and wastewater) and demonstrated excellent recognition ability. These exceptional performances can be attributed to the direct growth of CuCo2O4 nanoneedle arrays on the CC substrate, which facilitates a robust electrical connection, provides abundant electrocatalytic active sites, and expands the apparent active area. Consequently, these improvements contribute to the efficient trace detection capabilities of the ketoprofen sensor.

Synergy of Active Sites and Charge Transfer in Branched WO3/W18O49 Heterostructures for Enhanced NO2 Sensing.

Achieving reliable detection of trace levels of NO2 gas is essential for environmental monitoring and protection of human health protection. Herein, a thin-film gas sensor based on branched WO3/W18O49 heterostructures was fabricated. The optimized WO3/W18O49 sensor exhibited outstanding NO2 sensing properties with an ultrahigh response value (1038) and low detection limit (10 ppb) at 50 °C. Such excellent sensing performance could be ascribed to the synergistic effect of accelerated charge transfer and increased active sites, which is confirmed by electrochemical impedance spectroscopy and temperature-programmed desorption characterization. The sensor exhibited an excellent detection ability to NO2 under different air quality conditions. This work provides an effective strategy for constructing WO3/W18O49 heterostructures for developing NO2 gas sensors with an excellent sensing performance.

Variations in Cadmium and Lead Bioaccessibility in Wheat Cultivars and Their Correlations with Nutrient Components.

To reduce the health risks of exposure to Cd and Pb in wheat, a field experiment was conducted to investigate the differences in Cd and Pb bioaccessibility among the grains of 11 wheat cultivars and their relationships with the nutrient compositions of grains. The grain concentrations (Cd: 0.14-0.56 mg kg-1, Pb: 0.08-0.39 mg kg-1) and bioaccessibility (5.28-57.43% and 0.72-7.72% for Cd and Pb in the intestinal phase, respectively) of Cd and Pb differed significantly among the 11 cultivars. A safe wheat cultivar (Shannong16) with a relatively low health risk and the lowest grain Cd and Pb concentrations was selected. Ca, Mg, phytate, and methionine played key roles in affecting Cd and Pb bioaccessibility in wheat, with Ca and phytate significantly negatively correlated with Cd and Pb bioaccessibility. These findings can be used to optimize the selection strategy for safe wheat cultivars for healthy grain production in Cd-polluted farmland.

Transcriptome and ultrastructural analysis revealed the mechanism of Mercapto-palygorskite on reducing Cd content in wheat.

Large areas of crop yields in northern China have faced with cadmium (Cd) contamination problems. Mercapto-modified palygorskite (MP), as a highly efficient immobilization material, could reduce Cd absorption in wheat and alleviate its biotoxicity. However, the molecular mechanism underlying MP-mediated Cd reduction and detoxification processes in wheat is not well understood. This aim of this study was to investigate the biochemical and molecular mechanisms underlying the reduction in Cd accumulation in wheat (Triticum aestivum L.). The results showed that MP application decreased the Cd concentration by 68.91-74.32% (root) and 70.68-77.2% (shoot), and significantly increased the glutathione (GSH) and phytochelatins (PCs) contents in root and shoot. In addition, with the application of MP, the percentage of Cd in the cell walls and organelles of wheat decreased, while that of Cd in soluble components was increased. The content of Cd in all components was significantly reduced. Ultrastructural analysis revealed that MP thickened the cell wall, promoted vesicle formation in the membrane and protected the integrity of intracellular organelles in wheat. Transcriptome analysis further confirmed the above results. MP upregulated the expression of several genes (CCR, CAD COMT and SUS) involved in cell wall component biosynthesis and promoted vesicle formation on cell membranes by upregulating the expression of PLC and IPMK genes. In addition, genes related to antioxidant synthesis (PGD, glnA and GSS) and photosynthesis (Lhca, Lhcb) were altered by MP to alleviate Cd toxicity in wheat. This present work will help to more thoroughly elucidate the molecular mechanism by which wheat defends against Cd contamination under MP application and provide and important research basis for the application of this material in the future.

Mathematical uniqueness of multimode ptychographic imaging.

By writing diffracted intensities as a set of linear equations with the self-correlation of sample's Fourier components as unknown terms and the self-correlation of illumination's Fourier components as coefficients, it was found that the number of unknown terms to be determined is much larger in partially coherent PIE than that in purely coherent PIE. When a partially coherent illumination composed of N modes was applied a unique reconstruction can be determined by scanning the sample to at least 4N positions and recording 4N frames of diffraction patterns. While mathematically illustrating the physical mechanism of multimode ptychography and numerically demonstrating its capability in generating unique reconstruction under partially coherent illumination, this study showed for the first time that multimode ptychography could be an analytic imaging method.

Selenate reduced wheat grain cadmium accumulation by inhibiting cadmium absorption and increasing root cadmium retention.

Selenium (Se) fertilizer has been recently used to reduce cadmium (Cd) accumulation in plant. A pot culture was performed to analyze Cd uptake, translocation, and distribution in wheat plants during the reproductive growth period in a Cd-contaminated soil after selenate was applied to the soil, and a hydroponic culture was carried out to investigate the effects of selenate application on Cd2+ influx, subcellular Cd distribution, and Cd accumulation in wheat seedlings. Results showed that selenate application had no significant effect on DTPA-Cd and Cd fraction in soil. The application of selenate greatly inhibited the whole-plant Cd absorption by 14%-23%. In addition, selenate prompted the retention of Cd in root by increasing the Cd distribution in the vacuole, which reduced the root-to-shoot Cd translocation by 18%-53%. The application of selenate increased the Cd concentration in nodes, inhibited Cd remobilization from nutritive organs to grain, and ultimately reduced Cd accumulation in wheat grain. Further, heading to grain filling was the key growth stage for exogenous selenate to regulate grain Cd accumulation. In summary, soil selenate application is an effective method to reduce grain Cd concentration in wheat, which provided scientific basis for remediation of Cd-contaminated soil.

Mercapto-palygorskite efficiently immobilizes cadmium in alkaline soil and reduces its accumulation in wheat plants: A field study.

Cadmium (Cd) contamination in wheat fields has become a major environmental issue in many regions of the world. Mercapto-palygorskite (MPAL) is a high-performance amendment that can effectively immobilize Cd in alkaline wheat soil. However, MAPL as an in-situ Cd immobilization strategy for alkaline wheat soil remains to be evaluated on a field-scale and the underlying mechanisms requires further evaluation. Here, MPAL were used as soil amendment to evaluate their immobilization efficiency on Cd-contaminated alkaline soil in the field experiments. The field experiments showed that MPAL application significantly reduced wheat grain Cd concentration from 0.183 mg/kg to 0.056 mg/kg, with Cd concentration in wheat grain treated with MPAL all falling below the limit value of 0.1 mg/kg as defined in China's food safety standard (GB 2762-2022). The maximal immobilization efficiency of MPAL on soil Cd figured out by diethylenetriaminepentaacetic acid (DTPA) extraction was 61.5%. The mechanisms involved in Cd immobilization by MPAL were mainly related to the enhanced sorption of Cd onto Fe oxides, and the removal of amorphous or free Fe oxides from soil had a substantial impact on Cd immobilization efficiency by MPAL. Furthermore, the antagonistic effect between Mn and Cd uptake may also contribute to the reduction of wheat Cd accumulation after MPAL application. The current research can provide theoretical and technical support for the large-scale application of MPAL in Cd-contaminated wheat fields.

[Effects of Nano-copper Oxide on Physiobiochemical Properties of Brassica chinensis L. and Its Heavy Metal Accumulation Under Cadmium Stress].

To investigate the effects of nano-copper oxide (CuO NPs) on plant growth, physio-biochemical characteristics, and heavy metal content under cadmium stress, a hydroponics experiment was conducted on the effects of single and combined treatments of CuO NPs (0, 10, 20, and 50 mg·L-1) and Cd (0, 1, and 5 µmol·L-1) on the fresh weight, photosynthetic pigment content, MDA content, antioxidant enzyme activity (CAT, POD, SOD, and GR), and Cu and Cd contents in Brassica chinensis L. The results showed that under the single addition of CuO NPs, the fresh weight and activities of CAT, POD, and GR were inhibited as a whole. Photosynthetic pigment content and SOD activity increased first and then decreased with the increase in CuO NPs concentration, whereas MDA content in leaves and roots, and Cu content in subcells of B. chinensis L. increased with the increasing of CuO NPs. As compared with that in the control, CuO NPs promoted the growth of B. chinensis L., and the fresh weight increased by 8.70%-44.87% at 1 µmol·L-1 Cd. When the content of Cd was up to 5 µmol·L-1, a low content (10 mg·L-1) of CuO NPs promoted the growth of B. chinensis L., whereas a high concentration (50 mg·L-1) showed an inhibitory effect. The addition of CuO NPs could increase photosynthetic pigment and MDA contents under different Cd stress, and MDA content in leaves and roots of B. chinensis L. increased by 4.34%-36.27% and 13.43%-131.04%, respectively, than that in the control groups. Under the same concentration of 1 µmol·L-1 Cd, the addition of CuO NPs decreased the activities of CAT and GR, whereas the activity of POD increased. When the content of Cd was up to 5 µmol·L-1, CuO NPs increased the POD activity and inhibited the activity of SOD and GR. The activities of CAT and CAT in the leaves of B. chinensis L. initially showed an increasing and then decreasing trend. CuO NPs and Cd showed antagonistic effects, the maximum reduction of Cd content in leaves and roots of Brassica chinensis L. under 1 µmol·L-1 Cd treatment was 45.64% and 33.39%, and that under 5 µmol·L-1 Cd treatment was 18.25% and 25.35%, respectively. The content of Cu and Cd in subcellular organs of the plants decreased, but the proportion of soluble components increased. These results indicated that CuO NPs at low concentrations promoted plant growth under Cd stress and further inhibited the absorption of Cd but increased the oxidative damage to B. chinensis L.

Ionomic analysis reveals the mechanism of mercaptosilane-modified palygorskite on reducing Cd transport from soil to wheat.

Mercaptosilane-modified palygorskite (MP) can immobilize Cd in acid soil and reduce the enrichment of Cd in rice. However, the immobilization effect and its durability on alkaline field were unclear. Meanwhile, whether MP could reduce Cd in different wheat parts at different stages also needs further exploration. Here, we determined the dynamic change of Cd in soil and wheat at different periods, studied the interaction mechanism at key organs, and calculated the contribution of coexisting metals on the reduction of Cd to study the effect of MP on the transfer of Cd in soil-wheat system. Results showed MP was highly effective to immobilize Cd in alkaline farmland and could take effect during the whole growing season but not change pH values. DTPA-Cd and EXE-Cd of soil were reduced by 34.88-49.71% and 49.36-84.81%, respectively, while OX-Cd was increased by 34.61-43.60% at the whole stages. Cd in grains at maturity stage was reduced from 0.118 to 0.069 mg/kg, lower than the limit standard of the China and Codex Alimentarius Commission (0.1 mg/kg). Root and nodes were critical organs influenced by MP to reduce Cd in grains, and the reduction efficiency on wheat was relatively weak at flowering and filling stage. MP regulated the antagonism or synergy effects of coexisting elements on Cd to modulate the Cd accumulation in grains. Besides, the contributions of different elements on Cd were also evaluated by path models. This will provide an important basis for the precision remediation of Cd-polluted alkaline wheat fields.

Transcriptome analysis reveals the molecular mechanism of different forms of selenium in reducing cadmium uptake and accumulation in wheat seedlings.

Selenium (Se) can counteract cadmium (Cd) toxicity in wheat, but the molecular mechanism of different Se forms reducing Cd uptake and accumulation in wheat seedlings remain unclear. Here, a hydroponic experiment was conducted to investigate the effects of three Se forms (selenite (Se(IV)), selenate (Se(VI)) and seleno-L-methionine (SeMet)) on Cd2+ influx, Cd subcellular distribution, and Cd accumulation in wheat seedlings, and the underlying molecular mechanisms were investigated through transcriptome analysis. Consequently, Se(IV) and Se(VI) addition significantly reduced root Cd concentration by 74.3% and 80.8%, respectively, and all Se treatments significantly decreased shoot Cd concentration by approximately 34.2%-74.9%, with Se(IV) addition having the most pronounced reducing effect. Transcriptome analysis showed the reduction of Cd accumulation after Se(IV) addition was mainly due to the downregulation of Cd uptake genes. The inhibition of Cd accumulation after Se(VI) addition was not only associated with the downregulation of Cd uptake genes, but also related to the sequestration of Cd in vacuole. For SeMet addition, the reduction of Cd accumulation was mainly related to the sequestration of Cd in vacuole as GSH-Cd. The above findings provide novel insights to understand the effects of different forms of Se on Cd uptake and accumulation and tolerance in wheat.

Sustainable exploitation and safe utilization of biochar: Multiphase characterization and potential hazard analysis.

Pyrolysis temperature determines the multiphase (solid and dissolved) structure of biochar (BC). In this study, the temperature-dependent evolution of characteristics and potential hazards of three crop (cotton, alfalfa, and wheat) residue BC were systematically investigated. The results showed that pyrolysis temperature significantly affected the elemental composition and morphology of BC. A higher pyrolysis temperature led to a higher aromatization and graphitization degree of BC. A numerical relationship between pyrolysis temperature and BC surface properties (functional groups, carbonization degree) was established. Pyrolysis temperature controlled the content, composition, and functional group evolution of BC-derived dissolved organic matter. Although the amount of potentially toxic elements (PTEs) in BC was concentrated after pyrolysis, the potentially risk of PTEs significantly decreased. The spin concentration of persistent free radicals in BC prepared at 500 °C was the highest. These findings will hopefully offer comprehensive guidance for sustainable utilization of crop straw and fit-for-purpose exploitation of BC.

Application of ferromanganese functionalized biochar simultaneously reduces Cd and Pb uptake of wheat in contaminated alkaline soils.

The reduction of Cd and Pb accumulation in wheat grains grown on Cd and Pb contaminated alkaline soils is a pressing issue that needs to be solved. In this study, ferromanganese functionalized biochar (FM-BC) was used to remediate Cd and Pb contaminated alkaline soils and mitigate Cd and Pb accumulation in wheat grains. The immobilization capacity and mechanism of FM-BC were investigated by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) characterization and chemical analysis. Fe and Mn loaded on FM-BC improved the removal efficiencies of DTPA-Cd and DTPA-Pb in soil with DTPA-Cd removal of 22.99%- 52.04% (JM22) and 25.54%- 53.32 (AK58) and DTPA-Pb removal of 11.39%- 22.36% (JM22) and 5.38%- 13.00% (AK58). The FT-IR and XRD results indicated that the complexation and precipitation of Cd and Pb with the Fe-Mn oxides and the oxygen-containing functional groups on biochar surface stabilized the Cd and Pb in soil for the observation of Cd2Mn3O8, PbHPO4, CdCO3, and PbO2 on FM-BC isolated from contaminated soils. FM-BC with excellent adsorption capacity reduced the available Cd and Pb in the soil, therefore, thereby inhibiting the Cd and Pb accumulation in wheat. In the 3% FM-BC treatment, Cd and Pb contents in wheat grains were lower than 0.10 mg/kg and 0.20 mg/kg, respectively, reaching the national safety standards. And FM-BC increased the Fe, Mn, Na and Zn contents in wheat grains, and improved the growth and yield of wheat. These findings suggest that FM-BC can be considered a prospective and effective material for remediation of alkaline soils contaminated with Cd and Pb.

Immobilization of Cd by mercapto-palygorskite in typical calcareous and acidic soil aggregates: Performance and differences.

The microscale spatial heterogeneity and complexity of soil aggregates affect the properties and distribution of heavy metals (HMs). It has been confirmed that amendments can alter the distribution of Cd in soil aggregates. However, whether the Cd immobilization effect of amendments varies across soil aggregate levels remains unknown. In this study, soil classification and culture experiments were combined to explore the effects of mercapto-palygorskite (MEP) on Cd immobilization in soil aggregates of different particle sizes. The results showed that a 0.05-0.2% MEP application decreased soil available Cd by 53.8-71.62% and 23.49-36.71% in calcareous and acidic soils, respectively. The Cd immobilization efficiency of MEP in calcareous soil aggregates was in the following order: micro-aggregates (66.42-80.19%) > bulk soil (53.78-71.62%) > macro-aggregates (44.00-67.51%), while the efficiency in acidic soil aggregates was inconsistent. In MEP-treated calcareous soil, the percentage change in Cd speciation in micro-aggregates were higher than that in macro-aggregates, whereas there was no significant difference in Cd speciation between the four acidic soil aggregates. Mercapto-palygorskite addition in micro-aggregates of calcareous soil increased the available Fe and Mn concentrations by 20.98-47.10% and 17.98-32.66%, respectively. Mercapto-palygorskite had no effect on soil pH, EC, CEC, and DOC values, while the difference in soil properties between the four particle sizes was the main influencing factor of MEP treatments on Cd in calcareous soil. The effects of MEP on HMs varied across soil aggregates and soil types, but had strong specificity and selectivity for Cd immobilization. This study illustrates the influence of soil aggregates on Cd immobilization using MEP, which can be used to guide the remediation of Cd-contaminated calcareous and acidic soils.

Assessment of CuO NPs on soil microbial community structure based on phospholipid fatty acid techniques and phytotoxicity of bok choy seedlings.

In this study, a soil culture and a hydroponic experiment were conducted to assess the toxicology effects of copper oxide nanoparticles (CuO NPs) on soil microbial community structure and the growth of bok choy. Results showed CuO NPs had an inhibitory effect on soil microbial abundance, diversity, and activity, as well as the bok choy seedling growth, whereas CuO NPs at low concentrations did not significantly affect the soil microbial biomass or plant growth. In soil, CuO NPs at high dose (80 mg kg-1) significantly reduced the indexes of Simpson diversity, Shannon-Wiener diversity and Pielou evenness by 3.7%, 4.9% and 4.5%, respectively. In addition, CuO NPs at 20 and 80 mg kg-1 treatment significantly reduced soil enzymes (urease, alkaline phosphatase, dehydrogenase, and catalase) activities by 25.5%-58.9%. Further, CuO NPs at 20 mg L-1 significantly inhibited the growth of plant root by 33.8%, and catalase (CAT) activity by 17.9% in bok choy seedlings. The present study can provide a basis for a comprehensive evaluation of the toxicity effect of CuO NPs on soil microorganisms and phytotoxicity to bok choy seedlings.

Comparative effects of copper nanoparticles and copper oxide nanoparticles on physiological characteristics and mineral element accumulation in Brassica chinensis L.

In this study, the short-term toxicity of Cu NPs, CuO NPs, and CuSO4 on bok choy (Brassica chinensis L.) under hydroponic conditions was evaluated using indicators such as biomass, net photosynthesis rate, root morphology, enzyme activity, and Cu accumulation and subcellular distribution. Results showed that CuO NPs exposure notably increased the biomass, root length, and root tip number by 22.0%, 22.7%, and 82.9%, respectively, whereas Cu NPs and CuSO4 significantly reduced root biomass, net photosynthetic rate (PN), and root length by 31.2% and 44.2%, 24.5% and 32.2%, and 43.4% and 40.6%, respectively. In addition, Cu NPs, CuO NPs and CuSO4 exposure increased the distribution of Cu in soluble component and cell wall. Moreover, short-term exposure to different Cu forms significantly affected mineral element accumulation in bok choy. For instance, Cu NPs exposure reduced the concentrations of Mg, Ca and Mn in edible part by 21.7%, 16.1% and 23.2%, respectively. CuSO4 exposure reduced the concentrations of Mg and Ca in edible part by 12.3% and 50.1%, respectively. CuO NPs caused a significant increase of 30.4% for Ca concentration in root, 34.5% and 34.5% for K and Mn concentration in edible part. Over all, CuO NPs exposure was beneficial for plant growth. These findings help understand the phytotoxic effect of different Cu forms on bok choy, and CuO NPs has the potential to be applied to improve nutrition and prompt growth in edible plants.

Derivation and validation of soil cadmium thresholds for the safe farmland production of vegetables in high geological background area.

Excessive dietary intake of cadmium (Cd) poses toxicity risks to human health, and it is therefore essential to establish accurate and regionally appropriate soil Cd thresholds that ensure the safety of agricultural products grown in different areas. This study investigated the differences in the Cd accumulation in 32 vegetable varieties and found that the Cd content ranged from 0.01 to 0.24 mg·kg-1, and decreased in the order of stem and bulb vegetables > leafy vegetables > solanaceous crops > bean cultivars. A correlation analysis and structural equation model showed that pH, soil organic matter, and the cation exchange capacity had significant effects on Cd accumulation in the vegetables and explained 72.1 % of the variance. In addition, species sensitivity distribution (SSD) curves showed that stem and bulb vegetables were more sensitive to Cd than other types of vegetables. Using the Burr Type III function for curve fitting, we derived Cd thresholds of 6.66, 4.15, and 1.57 mg·kg-1 for vegetable soils. These thresholds will ensure that 20 %, 50 %, and 95 % of these vegetable varieties were risk-free, respectively. The predicted threshold of soil Cd was more than twice that of China's current National Soil Quality Standard (GB 15618-2018) for Cd values. Therefore, soil scenarios and cultivars should be considered comprehensively when determining farmland soil thresholds. The present results provide a new model for setting soil Cd criteria in high geological background areas.

Soil addition of MnSO4 reduces wheat Cd accumulation by simultaneously increasing labile Mn and decreasing labile Cd concentrations in calcareous soil: A two-year pot study.

Cadmium (Cd) pollution of wheat fields is a serious environmental and health problem that warrants attention. Manganese (Mn)-containing materials are considered effective for inhibiting Cd accumulation in Cd-contaminated acidic soils. However, information on the long-term remediation effects of Mn fertilizers on Cd accumulation in wheat and on the microbial community in calcareous soils remain limited. Here, a two-year pot experiment was conducted to assess the performance of 0.05-0.2% MnSO4 addition in Cd-contaminated calcareous soils (total Cd concentration: 3.65 mg/kg) on Cd accumulation in wheat as well as on the soil bacterial community. The formation of Mn oxides and transformation of exchangeable Cd to stable Cd fractions confirmed that the application of MnSO4 significantly decreased CaCl2-extractable Cd concentrations in soil (0-47.08%). In addition, MnSO4 addition improved the antagonistic effect of Cd and Mn ions in the wheat rhizosphere by increasing the available Mn concentration in the soil (1.04-3.52 times), thereby significantly reducing wheat Cd accumulation by 24.66-54.70%. Notably, the addition of MnSO4 did not affect the richness and diversity (P > 0.05) but altered the composition and function of bacterial communities, especially those involved in metabolism and genetic information processing. Importantly, the effects of MnSO4 on Cd immobilization in soil (10.66-47.08%) and the inhibition of Cd accumulation in wheat (12.13-54.30%) can last for two years after one addition. Furthermore, the maximum decrease in Cd concentration in grains was found in the low-Cd wheat cultivar, with values of 31.39-54.70% and 19.94-54.30% in the first and second years, respectively. Based on the present findings, the combination of MnSO4 with a low-Cd wheat cultivar is effective for the safe utilization of Cd-contaminated calcareous soils.

Selenium distribution, translocation and speciation in wheat (Triticum aestivum L.) after foliar spraying selenite and selenate.

Given the wide-spread consumption of wheat, the production of selenium (Se)-enriched wheat grain may be an effective method to increase the dietary Se intake in many Se-deficient areas. Herein, we biofortified wheat (Triticum aestivum L.) via the foliar spraying of selenate or selenite at low or high rate, and investigated the resulting Se distribution in different wheat parts and the crucial parts involved in grain Se accumulation. Results showed that Se concentration in grain after selenite spraying was 1.5 times higher than that of selenate. Grain Se accumulation was largely affected by leaves Se and the transfer of Se from node1 to internode1. Furthermore, the main speciation of Se in wheat grain was the organic Se. In addition, the optimal dosage was 15 g ha-1. In summary, foliar spraying 15 g ha-1 of Se is an effective and safe agronomic biofortification practice.