Cd Concentrations In Plants Research Articles

Melatonin alleviates cadmium toxicity by reducing nitric oxide accumulation and IRT1 expression in Chinese cabbage seedlings.

Melatonin (MT) is reported as a kind of phytohormone, exerts various biological activities, mediating plant growth and development and responding to abiotic stresses. In the present research, we examined the possibility that MT could involve in the alleviation of cadmium (Cd) toxicity by reducing the accumulation of nitric oxide (NO). The research indicated that the addition of MT significantly increased the biomass and photosynthetic parameters of plants compared with the control treated under Cd stress. Besides, we found that compared with the control treatment, MT also reduced the level of Cd-induced nitric oxide, and at the same time, the enzyme activity related to NO synthesis and the expression of related genes were decreased. In addition, MT treatment significantly reduced the Cd content in Chinese cabbage seedlings compared with the control, which was partially reversed by the addition of SNP (NO donor). PTIO (NO scavenger) addition could reduce the Cd content when seedlings were exposed to Cd stress. At the same time, compared with the Cd stress, the concentration of Cd in MT-treated plants decreased significantly, and the expression levels of related transport genes IRT1 also decreased significantly. Taken together, these results further support the idea that under the stress of Cd, NO increases the expression of IRT1, thus further increasing the absorption of Cd and aggravating the stress of Cd in plants, while exogenously added MT can inhibit the synthesis of NO, reduce the content of Cd, and alleviate the stress caused by Cd.

PGPR inoculation of a contaminated soil affects plant growth and phytoavailability of Cd and Pb

ABSTRACT To evaluate the effects of cabbage varieties and PGPR inoculation on the mobility and phytoavailability of Pb and Cd in a contaminated soil, a factorial (3 × 6) pot experiment with completely randomized design and three replications was performed. The cabbage varieties were ornamental cabbage, broccoli and cabbage and the PGPR strains included Pseudomonas putida PTCC1694, Bacillus megaterium PTCC1656, Azotobacter chroococcum, Proteus vulgaris PTCC1079 and Bacillus subtilis PTCC1715. The results indicate that the PGPR inoculation increased the amounts of plant biomass, the Pb and Cd concentrations in the root and shoot, the Pb and Cd uptake performances, the mobility, phytoavailability and translocation factor. The Pb bound to Fe-Mn oxides (42.7%) and the Cd bound to carbonate (38.1%) were the predominant heavy metal fractions. The percentages of the Pb and Cd in the soluble, exchangeable and organic matter-bound fractions increased while those of the Pb and Cd in the carbonate and Fe-Mn oxide-bound fractions decreased by lowering the soil pH and increasing the concentration of dissolved organic carbon (DOC). It is concluded that inoculation of heavy metal contaminated soils by the PGPR strains, especially Bacillus megaterium PTCC1656, enhances the phytoremediation process by increasing the metal phytoavailability and biomass production of the plant. Abbreviations HMe: Heavy metals; PGPR: Plant growth-promoting rhizobacteria; DOC: Dissolved organic carbon; HCN: Hydrogen cyanide; IAA: Indole-3-acetic acid; MIC: Minimum Inhibitory Concentrations; LB: Liquid broth; EC: Electrical conductivity; OC: Organic carbon; FC: Field capacity; WS: Water soluble; EX: Exchangeable; CAR: Bound to carbonates; OX: Bound to Fe-Mn oxides; OM: Bound to organic matter; RES: Residual; BOA: Ornamental cabbage; BOC: Cabbag; BOI: Broccoli; Pp: Pseudomonas putida PTCC1694; Bm: Bacillus megaterium 107 PTCC1656; Ac: Azotobacter chroococcum; Pv: Proteus vulgaris PTCC1079; Bs: Bacillus subtilis 108 PTCC1715; C-: Uninoculated non-rhizosphere soil; C+: Uninoculated rhizosphere soil; TF: Translocation factor; MF: Mobility factor; ANOVA: Analysis of variance

Rhizosphere iron and manganese-oxidizing bacteria stimulate root iron plaque formation and regulate Cd uptake of rice plants (Oryza sativa L.)

Iron plaque is the amorphous and/or crystalline layer of Fe and Mn (hydr)oxides formed on the root surface of wetland plants. It could adsorb and co-precipitate metal(loid)s at the rhizosphere, thus modulating the uptake and accumulation of metal elements in plants. In this study, the Fe(II)/Mn(II)-oxidizing bacteria Burkholderia sp. D416 (D416) and Pseudomonas sp. YGL (YGL) were isolated from Cd-contaminated rice field, both hydroponic experiment and pot experiment were performed to assess the impact of bacterial inoculation on iron plaque formation, elemental content of the plaque, plant dry mass, antioxidant enzyme activity and Cd content in rice plants. The results revealed that inoculation with D416, YGL, and D416+YGL stimulated iron plaque formation on the root surface of the hydroponic rice. The content of C, N, O, Na, Mg, Al, Si, P, S, Cl, K, Fe and Ca in the root plaque were affected by the bacterial inoculation and varied among different plant growth stages. The pot experiment indicated that inoculation with D416 increased the root dry biomass by 58.89%, and the combined inoculation of D416 and YGL increased the dry biomass of root, shoot and grain by 16.89%, 21.66% and 23.26%, respectively. Importantly, YGL inoculation decreased the Cd translocation from root to shoot and from glume to brown rice grain by 50.00% and 50.27%, respectively, and the Cd content in shoot and brown rice grain were decreased by 20.00% and 34.48%, respectively. Taken together, the elemental content of the iron plaque and Cd content in rice plants varied among different plant growth stages and when plants were inoculated with different bacterial strains. YGL dramatically reduced the Cd content in brown rice grain, thus it could potentially be used to reduce Cd content in rice crop grown in Cd-contaminated soils.

Evaluation of the Fuel Value and Soil Application Potential of the Cadmium Contaminated Biochar Obtained after Water Treatment

Spent biochar obtained after water treatment especially metal adsorption could be used as a solid fuel. In this study, soil application potential and fuel value of cadmium contaminated biochar was investigated. Biochar prepared from Parthenium (PBC) and the thermally modified biochar (MPBC) was artificially contaminated with different concentrations (1, 10, 50, 100 and 200 mg/l) of Cd solution. The contaminated PBC-Cd and MPBC-Cd was applied to a red soil, and their impact on soil biological activity, maize growth and Cd bioaccumulation was assessed. Maize growth was retarded due to the contaminated biochar. Soil and plant Cd concentrations increased significantly. The soil dehydrogenase (DHA) and fluorescein diacetate hydrolases enzyme activities were adversely affected. DHA reduced from 324 to 97 mg TPF/kg/24 h in MPBC-1 to MPBC-200, while in PBC-1 to PBC-200, DHA decreased from 422 to 112 mg TPF/kg/24 h. Cd contaminated biochars obtained after waste water treatment could not be used for soil application. Fuel values of contaminated biochar were analysed by the higher heating value of biochars and their fusibility indices. The high heating value of the biochar is comparable with the lignite. Raw biochar contains significant amount of alkali elements that affected their use as a fuel. However after adsorption, the washing of the biochar alkalies significantly improved the fuel properties, especially the propensity for slagging and fouling. Biochar used for treatment of contaminated waste water could be sustainably used as a solid fuel; however further studies are needed to manage the metal enriched ash generated after combustion of these contaminated biochar.

Arbuscular mycorrhizal fungi mitigate the negative effects of straw incorporation on Trifolium repens in highly Cd-polluted soils

Arbuscular mycorrhizal fungal (AMF) and straw incorporation may influence cadmium (Cd) status in soils and plants. Therefore, the objective of this experiment was to explore the influences of Cd addition (0, 10, 20 and 50 mg kg−1 soil), arbuscular mycorrhizal fungal (AMF) inoculation (without or with mycorrhizal inoculation), rape straw residue application (0 and 0.8% w/w) and their interactions on the plant performance and element absorption of Trifolium repens and soil enzyme activities in Cd-contaminated soils. When the Cd addition rate was less than 20 mg Cd kg−1, mycorrhizal inoculation significantly promoted plant biomass, shoot height, chlorophyll contents regardless of whether straw incorporation occurred. In the high-Cd-addition group (50 mg Cd kg−1), compared with treatments without straw incorporation, straw incorporation significantly decreased plant biomass, chlorophyll contents, shoot P and K concentration in the absence of AMF. On the other hand, in the presence of AMF, straw incorporation significantly promoted plant biomass and P concentration and reduced the plant Cd concentration in the 50 mg Cd kg−1 addition treatments. Straw incorporation also significantly increased catalase, urease, β-glucosidase and acid phosphatase activities in the 50 mg Cd kg−1 addition treatment group. The maximum acid phosphatase activity occurred in the treatment combining mycorrhizal inoculation and straw incorporation in the 50 mg Cd kg−1 addition treatment. It was concluded that the promotion of acid phosphatase activity and P uptake and the reduction in Cd toxicity via a dilution effect could help alleviate the negative effects of straw incorporation on the growth of T. repens in highly Cd-polluted soils.

Influence of biochar and soil properties on soil and plant tissue concentrations of Cd and Pb: A meta-analysis

The application of biochar to soils contaminated with potentially toxic elements (PTEs) has received particular attention due to its ability to reduce PTE uptake by the plants. Therefore, we conducted a meta-analysis to identify Cd and Pb concentrations in plant shoots and roots in response to biochar application and soil properties. We collected data from 65 peer-reviewed journal articles published from 2009 to 2020 in which 66% of manuscripts were published from 2015 to 2020. The data were processed using OpenMEE software. The results pinpointed that addition of biochar to soil caused a significant decrease in shoot and root Cd and Pb concentrations as compared to untreated soils with biochar (control), and the reduction rate was affected by plant types and both biochar and soil properties. The biochar size less than 2 mm, biochar pH higher than 10, pyrolysis temperature of 401–600 °C, and the application rate higher than 2% appeared to be effective in reducing shoot and root Cd and Pb concentration. Soil properties such as pH, SOC, and texture influenced the efficiency of biochar for reducing plant Cd and Pb uptake. Biochar application increased SOC (54.3%), CEC (48.0%), pH (0.08), and EC (59.4%), and reduced soil extractable Cd (42.1%) and Pb (47.1%) concentration in comparison to control. A detailed study on the rhizosphere chemistry and uptake mechanism will help to underpin the biochar application rates and their efficiency reducing PTE mobility and plant uptake.

Promotion of growth and phytoextraction of cadmium and lead in Solanum nigrum L. mediated by plant-growth-promoting rhizobacteria

Plant growth-promoting rhizobacteria (PGPR) are a specific category of microbes that improve plant growth and promote greater tolerance to metal stress through their interactions with plant roots. We evaluated the effects of phytoremediation combining the cadmium accumulator Solanum nigrum L. and two Cd- and Pb-resistant bacteria isolates. To understand the interaction between PGPR and their host plant, we conducted greenhouse experiments with inoculation treatments at Nanjing Agricultural University (Jiangsu Province, China), in June 2018. Two Cd- and Pb-resistant PGPR with various growth-promoting properties were isolated from heavy metal-contaminated soil. 16S rRNA analyses indicated that the two isolates were Bacillus genus, and they were named QX8 and QX13. Pot experiments demonstrated that inoculation may improve the rhizosphere soil environment and promote absorption of Fe and P by plants. Inoculation with QX8 and QX13 also enhanced the dry weight of shoots (1.36- and 1.7-fold, respectively) and roots (1.42- and 1.96-fold) of plants growing in Cd- and Pb-contaminated soil, and significantly increased total Cd (1.28–1.81 fold) and Pb (1.08–1.55 fold) content in aerial organs, compared to non-inoculated controls. We also detected increases of 23% and 22% in the acid phosphatase activity of rhizosphere soils inoculated with QX8 and QX13, respectively. However, we did not detect significant differences between inoculated and non-inoculated treatments in Cd and Pb concentrations in plants and available Cd and Pb content in rhizosphere soils. We demonstrated that PGPR-assisted phytoremediation is a promising technique for remediating heavy metal-contaminated soils, with the potential to enhance phytoremediation efficiency and improve soil quality.

PHYTOTOXICITY OF WASTEWATER CONTAINING CADMIUM (Cd) USING OLEANDER

This study was aimed to investigate the ability of N.oleander to remove Cadmium (Cd) from wastewater. A prolonged toxicity test was performed in a single exposure and run for 65 days with various concentrations of Cd. Plants were grown in sand medium and irrigated with simulated wastewater contaminated with Cd, using different concentrations (0, 10, 25, 50, 75 mg/L), which were chosen based on previous preliminary test. The results of physical observation of the plants didn’t show any withering symptoms. The Cd concentration in plants increased, while in water decreased. The results of plant analysis showed that Cd concentration in plant shoots (stems and leaves) was higher than that in roots for almost all exposure doses along the test duration. The concentration of Cd in water decreased significantly from the first week of the test and become (0 mg/l) on day-35 for 10 and 25 mg/l exposure doses, while exceeded the permissible limits for 50 and 75 mg/l exposure doses and were 0.14 and 0.91 mg/l, respectively. Wet weight and dry weight of Oleander decreased with increasing Cd concentration level except for 10 mg/l exposure dose where the plant wet weight and dry weight increased at the end of the test. Bioaccumulation factor (BAF) and Translocation Factor (TF) was found to be greater than 1, indicating that Oleander is a successful hyperaccumulator for Cd.

Effects of arbuscular mycorrhizal fungi on redox homeostasis of rice under Cd stress

Arbuscular mycorrhizal fungi (AMF) can enhance cadmium (Cd) tolerance and decrease Cd uptake of rice plant. However, in these processes, the essential role of reactive oxygen species (ROS)-antioxidants interactions is so far not investigated. We inoculated AMF, Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri), to upland rice subjected to 0, 2 or 10 mg Cd kg−1 in soil. ROS, antioxidants, chlorophyll, mesophyll cell ultrastructure, Cd concentration and Cd transporters were measured. Results showed that the levels of ROS (i.e., superoxide, hydrogen peroxide and lipid peroxidation) were mitigated in +AMF + Cd treatments, especially in +Ri + Cd, compared with −AMF + Cd. For antioxidants, lower levels of catalase, peroxidase and superoxide dismutase, whereas higher levels of glutathione and glutathione peroxidase were observed in +AMF + Cd compared with −AMF + Cd. Chlorophyll content and mesophyll cell ultrastructure were improved by AMF. Cd concentrations in plants were significantly decreased in +AMF + Cd (10 mg Cd kg−1) treatments. AMF not only decreased Cd accumulation in rice but also regulated the ROS scavenging activities. The variations of ROS and antioxidants were restrained to smaller ranges by AMF. AMF may assist in Cd restriction and thus helping the host to release glutathione for ROS scavenging.

The migration of cadmium and lead in soil columns and their bioaccumulation in a multi-species soil system

A soil microcosm experiment was carried out to quantify the transfer of cadmium (Cd) and lead (Pb) in a multi-species soil system (MS·3). Red earth from Jiangxi (S1), fluvo-aquic soil from Henan (S2), fluvo-aquic soil from Beijing (S3), and black soil from Heilongjiang (S4) were used for soil column packing with S1, S3, or S4 as the 20–50 cm layer and S2, which was Cd- and Pb-contaminated, as the top 0–20 cm layer. For each soil combination, four treatments were set up: CK (no wheat and no earthworm), W (only wheat), E (only earthworm), and E + W (earthworm and wheat). The results showed that the coexistence of earthworm with wheat reduced Cd and Pb contents in wheat plants and earthworms, and increased plant biomass, but had no significant effect on the survival rate and mean weight change rate of earthworms. Total Cd and Pb decreased remarkably in the 0–20 cm layer while increased in the 20–50 cm layer, and approximately 32.8%–51.1% of Cd and 0.35%–7.0% of Pb migrated down into the 20–50 cm soil layers from the 0–20 cm soil layers. The migration varied between the treatments from S2 to S1, S2, and S3. In S2–S1 and S2–S4 columns, the amount of Cd migration decreased when the earthworms coexisted with wheat, while in S2–S3 column, there was no significant difference on such amount regardless of the coexistence of earthworms with wheat. Taken together, the results indicated that the migration of Cd and Pb was not only associated with wheat and earthworm, but also depended on soil types.

Effect of type of compost and application rate on growth and quality of lettuce plant

This study intends to assess the effect of compost types and rates on lettuce growth. A pot experiment was conducted at the greenhouse of the College of Agriculture and Veterinary Medicine experimental station, Saudi Arabia. Three types (chicken residues, animal residues, and mixed organic residues) and four rates (1%, 2%, 4%, and 6%) were added to sandy soil. Lettuce seeds were sown in a nursery. After two weeks, each seedling was transplanted to a pot that contained 15 kg of soil. The lettuce plants were irrigated regularly for 60 days, then harvested following dry weight (DW) and chemical analyses. The results showed great variation in the DW, nutrient content, and heavy metals concentrations between the different compost treatments. It noted that DW of lettuce decreased with increasing rates of compost in certain treatments. Moreover, no plant growth occurred in some treatments derived from the mixed organic residue with higher application rates. The nutrient status of lettuce tissues varies greatly among different types of compost. The concentration of heavy metals and microelements present within the lettuce tissues was significantly affected by the types of compost. Copper (Cu), Zinc (Zn), Lead (Pb), Cadmium (Cd), and Nickel (Ni) concentrations in lettuce tissues ranged between 7.4 and 9.6, 81.5 and 104, 23.3 and 28.2, 3.7 and 5.8, and 27 and 30 mg kg−1, respectively. It revealed that heavy metals concentration increased in lettuce tissues with an increasing application rate of composts. The content of Zn, Pb, Cd, and Ni in lettuce plants were higher and did not meet the requirement set by national standards.

Application of zinc and biochar help to mitigate cadmium stress in bread wheat raised from seeds with high intrinsic zinc

Cadmium (Cd) contamination in soil negatively impacts crop productivity, grain quality, and human health. Wheat seeds, with different concentrations of intrinsic zinc (Zn): low Zn (35 mg kg−1), medium (42 mg kg−1), and high Zn (49 mg kg−1), were planted in artificially contaminated soil (10 mg Cd kg−1 soil). Zinc (5 g kg−1) and biochar (20 g kg−1 soil) were applied alone or in combination at sowing. Cadmium contamination reduced wheat growth, productivity, and grain Zn concentration, relative to the respective no-Cd treatments, with greater reductions in plants with low intrinsic Zn. Among the soil amendments, Zn and/or biochar improved wheat productivity and grain Zn and reduced grain Cd concentration in plants grown from seed with varying intrinsic Zn levels. Plants from high intrinsic Zn seeds performed better under Cd stress with the application of soil amendments than seeds with low or medium intrinsic Zn levels. The combined application of Zn and biochar had the highest increases in grain yield (9.51%) and grain Zn concentration (12.2%), relative to the control (no Cd, no Zn, and no biochar). This treatment also decreased the Cd concentrations in straw (7.1%) and grain (95.6%). The sole application of Zn or biochar improved wheat productivity and grain Zn concentration and deceased grain Cd concentration under Cd stress, but more improvements resulted from the combined application of Zn and biochar. Plants grown from seed with high Zn were better able to tolerate Cd stress than the plants raised from seeds with medium and low Zn levels.

Grafting Alleviates Cadmium Toxicity and Reduces Its Absorption by Tomato

A pot experiment was conducted to determine whether the grafting could improve growth and reduce cadmium (Cd) accumulation of tomato planted in Cd-contaminated soil. ‘Zhongyanhong 6’ (common tomato) and ‘Hongyu F1’ (cherry tomato) were grafted onto two varieties of wild eggplant (Solanum torvum and Totosga) and three varieties of tomato (‘Dalishengen’, ‘Banzhen18’, and ‘Guozhen 1’) rootstocks, respectively, and then transplanted in 10 mg kg−1 Cd-contaminated soil for 3 months. The results indicate that except for Totosga, grafting onto other rootstocks resulted in decreased growth and biomass of ‘Zhongyanhong 6’, but grafting increased growth and biomass of ‘Hongyu F1’, especially wild eggplant. Compared with un-grafted, grafting on ‘Guozhen’, Solanum torvum, and Totosga enhanced weight and size of two types of tomato fruits under Cd stress, but only S. torvum improved soluble sugar content and soluble solids of tomato fruits. The Cd content in plants and fruits of ‘HongyuF1’ grafted on five rootstocks was reduced, and only grafted on ‘Banzhen18’, Solanum torvum, and Totosga reduced Cd content in plants and fruits of ‘Zhongyanhong6’, especially two kinds of wild eggplant rootstocks had the most significant reduction in Cd content. Therefore, grafting on different rootstocks had different impacts on two types of tomato under Cd stress, and wild eggplant especially S. torvum is relatively better rootstock for both types of tomato.

Synergistic effect of silicon and selenium on the alleviation of cadmium toxicity in rice plants

Silicon (Si) and selenium (Se), two beneficial elements that alleviate cadmium (Cd) toxicity, are important for agricultural production and human health. However, the effects and related mechanisms of Si-Se interaction on Cd toxicity alleviation are still poorly understood. Herein, a hydroponic experiment was employed to evaluate the effects of Si and Se alone and together, on the growth, Cd content, and biochemical parameters of Cd-treated rice plants. The results revealed that both Si and Se can effectively alleviate Cd toxicity, and a strong synergistic effect of Si and Se was observed. Simultaneous use of Si and Se significantly promoted rice plant growth, decreased malondialdehyde (MDA) content in both the roots and shoots, and reduced Cd translocation factor leading to a significant 73.2 % decrease in shoot Cd content. Additionally, Si-Se interaction increased glutathione (GSH) content, phytochelatin (PC) content and Cd distribution in root cell walls and organelles. Furthermore, the relative expression of OsHMA2 was down-regulated, while those of OsNramp1 and OsMHA3 were up-regulated. The above findings suggest that synergistic effect of Si and Se on Cd toxicity amelioration occurs mainly via regulating gene expression, sequestering Cd in the root cell walls and organelles, and reducing Cd transfer to the shoots.

Phytoavailability-based threshold values for cadmium in soil for safer crop production

The phytoavailability of heavy metals in soils is important for both food safety and environmental management. Hence soil metal phytoavailability threshold values need to be established based on a firm scientific basis. In this study, optimal Cd phytoavailability threshold values, were determined for bean, rice and sesame cultivated in 100 soils varying widely in soil chemical characteristics by comparing the soil Cd phytoavailability obtained using three commonly used extraction procedures. Subsequently, the transfer functions derived in this study, were used to establish soil Cd phytoavailability threshold value standard limits for each specific crop. In addition, independent experimental data were used to supplement the obtained soil phytoavailable Cd threshold value for rice. Soil phytoavailable Cd concentrations extracted by 1 M NH4NO3, 0.05 M EDTA and Mehlich3 solutions were each more significantly correlated with plant Cd concentrations than total soil Cd concentrations. Thus, the soil Cd phytoavailability threshold values proposed in this study provide a more effective means of ensuring safer agricultural food production. Therefore, it is recommended that current agricultural soil heavy metal management policy; which is based on total concentrations; should be changed to embrace soil metal phytoavailability for safer agricultural food production.

Evaluation of inorganic contaminants emitted from automobiles and dynamics in soil, dust, and vegetations from major highways in Pakistan.

The deposition of toxic metals in the ecosystem contributes to the exposure and bioaccumulation of metals in the food chain, thus affecting human health. This study aimed to access the distribution of metal pollution emitted from automobiles in the dust, soil, and plant samples collected from the roadsides of national highways. Furthermore, metals were also determined in fuels and vehicular emissions. High contents of Pb, Cd, Cr, Cu, Fe, Mn, and Zn were found in roadsides as compared to control (35km away from roads). The comparison among plants indicated that Calotropis procera and Rumex dentatus contained significantly higher metals than other plants. The concentrations of Pb, Cd, Cr, and Fe in plants were above the safe limits of the WHO/FAO. Significant and positive correlations were found between Cr, Cu, Fe, Pb, and Zn in the dust and soil samples and Cd and Cr in dust and plants. According to the results of the PCA analysis, all metals formed the first two components explaining 89.5% of the total variance. The source of these metals was attributed to automobile exhaust and dust depositions. The findings of the present study suggest that roadside plants are heavily infested with heavy metals due to vehicular smoke pollution, so the consumption of vegetation facing vehicular pollution may lead to certain physiological disorders and diseases. Graphical abstract.

Effects of Toxic Metals Cd, Ni and Pb on Matricaria Chamomilla L. Growth in a Laboratory Study

The paper presents a comparative bioaccumulation study between the growth of chamomile (Matricaria Chamomilla L.) exposed to toxic metals (Cd, Ni and Pb) and the growth of same plant species unexposed to metals. The soil was contaminated within three independent experiments with Cd, Ni and Pb at the intervention threshold value for sensitive use. Each of the toxic metal was added by watering the seeds, and subsequently the germinated plants. The experiments targeted the effects of soil pollution on the growth of chamomile during three months period. The results showed that in the first month of the study, all three metals accumulated in plants. After the seeds germination and plant growth, high Cd concentration in chamomile plants was detected. Moreover, Ni and Pb were detected in soil in the percentage of 96%. Overall, it was observed that chamomile plants were Cd accumulators at the tested concentrations of 6 mg/kg with no phytotoxic effects. Matricaria Chamomilla L. could be used in phytoremediation of polluted soils, with limitations of use for human consumption, except for the extracts.

Cataloging of Cd Allocation in Late Rice Cultivars Grown in Polluted Gleysol: Implications for Selection of Cultivars with Minimal Risk to Human Health

Cadmium (Cd) is a toxic trace metal that has polluted 20% of agricultural land in China where its concentration exceeds the standards for Chinese farmland. Plants are capable of accumulating Cd and other trace metals, but this capacity varies with species and cultivars within a species. Rice is a staple food consumed by half of the global population. In order to select safe late rice cultivars that are suitable late rice cultivars that can be cultivated in for growing in slightly contaminated soil, a two-year field experiment was conducted with 27 in the first year and 9 late rice cultivars in the second year. The results showed that plant Cd concentrations varied among the cultivars, with high magnitudes of variation occurred in straw and grains. Five genotypes including LR-12, LR-17, LR-24, LR-25 and LR-26 were identified as low accumulators for the first year while LR-15 and LR-17 were identified as promising cultivars based on Cd concentration in the polished rice grains (<0.02 mg kg−1 DW). In addition, these cultivars had favorable traits, including mineral nutrition and grain yield. Therefore, these genotypes should be considered for cultivation in slightly or moderately Cd contaminated soils.

Mitigating Cadmium Accumulation in Spinach and Onions by the Application of Silicon Fertilizer to Soil

ABSTRACTCadmium (Cd) is readily absorbed by plants and can accumulate to concentrations that exceed food standards. Testing strategies that can mitigate plant uptake of Cd are essential to help manage the risk to food quality. We measured whether applying silicon (Si) fertilizer to a soil contaminated with Cd from phosphate fertilizer could decrease Cd concentrations in spinach (Spinacia olearacea) and onion (Allium cepa). The application of Si (1000 and 2500 kg ha−1) increased spinach dry matter (DM) yield and Si concentrations but had no effect on plant Cd concentrations or uptake. Application of Si had no effect on DM yield or Si concentrations in onions, but there was a 45% decrease in Cd concentrations in the onion bulb. Application of Si had no effect on calcium nitrate-extractable Cd. The decrease in Cd concentrations in onions was likely related to Si restricting the movement of Cd from the root to the harvestable part of the plant. These findings indicate that Si may have some potential as a mitigation tool to decrease plant uptake of Cd. Further investigation is required to evaluate its effectiveness across different soil types and test the response of a wider range of crops under field conditions.

Interaction of Mn and Cd during their uptake in Celosia argentea differs between hydroponic and soil systems

Celosia argentea (Amaranthaceae) can accumulate both Cd and Mn. This study reveals the interactive effect and underlying mechanism of Cd and Mn during their uptake in this species. Plants were grown in hydroponic and soil media with different Cd and Mn treatments. The concentrations of Cd and Mn in plants and soil solutions were determined by ICP-MS. The real-time Cd2+ flux values into roots were measured with non-invasive micro-test technology. Manganese supply significantly decreased Cd bioaccumulation in C. argentea in hydroponic experiments. The mean net Cd2+ flux rates into roots decreased by 10.5% and 56.9% with the addition of 0.01 and 0.5 mM Mn2+, respectively. The Mn supply (1 mM) increased the Michaelis constant by 1.8-fold but did not significantly change the maximum uptake velocity of Cd. In soil culture experiments, Mn application significantly increased Cd bioaccumulation and Cd concentrations in soil solutions. The interactions of Cd and Mn in C. argentea differ between hydroponic and soil cultures. Mn inhibits Cd uptake in hydroponic experiments via competition in common transport systems. The enhancement effect of Mn on Cd uptake in soil systems is attributed to an increase of Cd in soil solutions by competitive adsorption.