Tissue Zn Concentrations Research Articles

Effect of excess zinc and arbuscular mycorrhizal fungus on bioproduction and trace element nutrition of Tomato (Solanum lycopersicum L. cv. Micro-Tom)

ABSTRACTThe effect of excess Zn and arbuscular mycorrhizal (AM) fungus on bioproduction and trace element nutrition were investigated in tomato. In a completely randomized factorial design, the experimental treatments – Zn addition at 0 (normal) and 300 (excess) mg Zn kg−1 soil, and AM inoculation (non-AM and Rhizophagus irregularis) – were set up in a growth chamber for 10 weeks. Generally, AM effects on the available Zn, Mn, Cu, and Fe in the rhizosphere soil were in tandem with the effects in host tissues. Under normal Zn condition, AM enhanced Cu availability in the rhizosphere, optimized the Cu:Zn balance in shoots, and increased the host biomass production. Excess Zn reduced mycorrhizal colonization in AM plants and the total plant biomass in both AM and non-AM plants. Although AM decreased the Zn concentrations in soil and host tissues under excess Zn, the distortions in host TE balance were not significantly ameliorated by the fungus. While Zn in fruit was within the safety threshold, Mn deficiency in the fruit was observed under excess Zn, alongside increased root-to-fruit Fe and Cu translocations. Mycorrhizal reductions in soil and tissue Mn concentrations were considered a minus in terms of probable symbiont amelioration of Mn:Zn in-balance under excess Zn. Additional microbe(s) that can enhance Mn homeostasis might be helpful in tomato under elevated soil Zn.

Uptake of As, Cd, Cu, Fe, Mn, Pb, and Zn in pasture grasses on three metal contaminated soils from Montana

Successful phytoremediation contaminated mine land soils require the identification of plant species that with wide-spread adaptation to multiple ecological sites that exclude or uptake heavy metals of interest. This study observed metal uptake of arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), magnesium (Mn), lead (Pb) and zinc (Zn) in forage (mg kg-1 DM) of alfalfa and nine other dryland and irrigates grass species when grown on soil from Clarks Fork, Cabbage Gulch, and Keating mine sites in Montana. On the Clarks Fork soil, increased tissue concentrations of As, Cd, Cu, and Zn; were greater than observed in normal plant tissue. However, bio-concentration factors (BCF) were 1 in crested wheatgrass, intermediate wheatgrass, meadow and smooth brome grasses, Russian wildrye, tall wheatgrass, orchardgrass, and tall fescue suggest that these species have the ability to uptake Cd particularly on soils with pH levels of 5.01 and 4.26 found Cabbage Gulch and Keating soils compared to more basic Clarks Fork soil. Observed BCF >1 in Hycrest II crested wheatgrass, AI intermediate wheatgrass, Regar and Cache meadow bromegrass, Manchar smooth bromegrass, NewHy RS-hybrid wheatgrass, Bozoisky II Russian wildrye Alkar tall wheatgrass, Paiute and UTDG-101 orchardgrass, and Fawn tall fescue for Mn accumulation warrants further investigation as another option Mn phytoextraction. Only RS-H RS-hybrid wheatgrass had a Zn BCF >1 and may be a candidate for Zn accumulation.

Effects of Zinc Oxide Nanoparticles on Performance, Egg Quality, Tissue Zinc Content, Bone Parameters, and Antioxidative Status in Laying Hens.

The objective of this study was to observe the effects of dietary supplementation with zinc oxide nanoparticles (ZnO-NPs) on performance, egg quality, tissue Zn content, bone parameters, superoxide dismutase activity (SOD), and egg malondialdehyde (MDA) content in laying hens. A total of 288 laying hens at 64weeks of age were randomly assigned to 4 treatments, 6 replicates, with 12 birds each. Experimental diets included the based diet (without Zn supplementation), and basal diet supplemented with 40, 80, and 120mg Zn/kg from ZnO-NPs. Feed intake and egg mass were significantly higher in the 40 and 80 ZnO-NPs groups than the other groups. The birds in the 80 ZnO-NPs group had significantly higher egg product than the 120 ZnO-NPs and control groups. Egg shell thickness and shell strength significantly increased in the 40 and 80 ZnO-NPs groups. Moreover, Haugh unit significantly improved in the groups supplemented with ZnO-NPs, compared to the control group. Bone-breaking strength was significantly greater in the 80 ZnO-NPs group than the 120 ZnO-NPs and control groups. Also, ash weight was significantly greater in the 40 and 80 ZnO-NPs groups than the control group. There were significant differences among the groups in the Zn content in plasma, tibia, liver, pancreas, and egg. Relative to the control group, ZnO-NPs supplementation significantly increased the activities of SOD in the liver, pancreas, and plasma. The MDA content in egg was significantly reduced in the groups supplemented with ZnO-NPs. In conclusion, this study demonstrates that ZnO-NPs as dietary supplementation can improve the performance of laying hens, and levels of 40 to 80 ZnO-NPs are the optimal concentrations.

Environmental status of the NE Adriatic Sea, Istria, Croatia: Insights from mussel Mytilus galloprovincialis condition indices, stable isotopes and metal(loid)s

The environmental status of the marine environment in the NE Adriatic Sea was assessed, using as a bioindicator species the Mediterranean mussel Mytilus galloprovincialis Lamarck, 1819. Samples were collected seasonally from mariculture sites and from major Istrian ports between the years 2010 and 2013. The condition indices of mussels ranged from 13.3 to 20.9% at mariculture sites and from 14.3 to 23.3% at port locations. The seasonally δ13CDIC values of seawater varied between −10.9 to 0.7‰. Pollution by sewage sludge (based on δ15N values) was confirmed only in two ports. Tissue concentrations of Mn, Co, Ni, Cu, Zn, Se, Cd, and Pb were significantly higher in the tissue of the mussels collected from the ports (polluted sites). Arsenobetaine was the major As compound present in the samples and there was no significant difference in the levels of total As in mussel tissues from mariculture and port sites.

Liver tissue trace element levels in HepB patients and the relationship of these elements with histological injury in the liver and with clinical parameters

AimIn this study, the relationship of liver tissue trace element concentrations with hepatitis B disease and the effects of several environmental factors were analysed. MethodThe liver tissue concentrations of Al, Fe, Cd, Mn, Cr, Cu, Pb, Ni, Zn, Ag, and Co were evaluated in 92 patients with hepatitis B using the Inductively Coupled Plasma − Mass Spectrometry (ICP/MS) method in the analyses. The patients were divided into the following two groups: low-high Ishak histologic activity index (HAI) (0–6: Low Histologic Activity, 7–18: High Histologic Activity) and low-high fibrosis (FS) (Fibrosis 1,1,2 and Fibrosis 3,4,5,6). The metal levels were compared between the groups. ResultsThe Cd concentration was found to be statistically higher in the group with low HAI scores (p=0.019). The hepatic Cu concentration was found to be higher in women than in men (p=0.046). The hepatic Fe concentration was found to be higher in the group with increased FS compared to the group with decreased FS (p=0.033). Cd was found to be higher in patients who worked in positions involving exposure to heavy metals and in individuals with an ALT level above 40 IU/L (p=0.008). Several correlations have been found between the hepatic tissue metal levels in our study. In a linear regression analysis, Fe and Zn were found to be correlated with the fibrosis scores (p=<0.001 and p=0.029), and Cu was correlated with HAI (p=0.023). In the linear regression model, Ni (p=0.018) and Cr (p=0.011) were correlated with gender. There was a correlation between the hepatic Fe level and the location where hepatitis B patients were living (village/city) (p=0.001), frequency of fish consumption (p=0.045) and smoking (p=0.018) according to the linear regression analysis. Using a logistic regression analysis, Cr (p=0.029), Ni (p=0.031) and Pb (p=0.027) were found to be correlated with smoking habit, and Zn (p=0.010), Ag (p=0.026), Cd (p=0.007) and Al (p=0.005) were correlated with fish consumption. ConclusionThe liver tissue trace element levels are correlated with disease activity and histologic damage in patients with HepB disease. Additionally, smoking, the environment in which the patient works and the amount of fish consumption affect the accumulation of trace elements in the liver.

The dual benefit of arbuscular mycorrhizal fungi under soil zinc deficiency and toxicity: linking plant physiology and gene expression

Colonisation of roots by arbuscular mycorrhizal fungi (AMF) can increase plant biomass and nutrition under soil zinc (Zn) deficiency and toxicity conditions, but the genes and transporters involved in these processes are unknown. The aim here was to determine whether there is a ZIP (Zrt-, Irt-like protein) transporter gene that is differentially-regulated by mycorrhizal colonisation that may be involved in mycorrhizal Zn uptake. We grew Medicago truncatula plants at soil Zn concentrations ranging from deficient to toxic, with and without inoculation of the AMF Rhizophagus irregularis, and measured plant dry weight, shoot nutrient concentrations and the expression of phosphate, aquaporin and ZIP genes in the roots. At low and high soil Zn concentrations, there were positive biomass responses to AMF colonisation. Furthermore, at low soil Zn concentrations, MtZIP6 was highly up-regulated in the mycorrhizal plants. With increasing soil Zn concentration, expression of the AMF-induced phosphate transporter gene MtPT4 increased, and mycorrhizal colonisation was maintained. We have identified two different mechanisms by which AMF colonisation can increase plant biomass under low and high Zn stress: first, up-regulation of MtZIP6 at low soil Zn to supplement Zn uptake from the rhizosphere; and second, persistence of mycorrhizal colonisation and expression of MtPT4, which at high Zn could promote increased plant biomass and reduced tissue Zn concentration.

Effect of mycorrhizal inoculation on metal accumulation by poplar leaves at phytomanaged sites

Phytotechnologies for the management of lands contaminated with potentially toxic elements (PTEs) are considered as gentle alternatives to conventional remediation techniques. During the last few years, phytotechnologies have progressively shifted to phytomanagement, a concept that includes the valorization of the plant biomass produced on the contaminated site. This study aimed at evaluating the mid-term effect of ecto- and endomycorrhizal inoculation on the reduction of PTE mobility in soils and foliar accumulation by two poplar clones, Skado (Populus trichocarpa x P. maximowiczii) and I-214 (P. deltoides x P. nigra), dedicated to bioenergy purposes. The effects of inoculation were investigated in two large scale trials of 1ha each. Poplars grown on highly contaminated soils accumulated excessive Cd and Zn in leaves compared with those planted on less contaminated soils, and the I-214 clone generally accumulated less PTEs than the Skado clone. Interestingly, the filtering capacity of mycorrhizal fungi was significant for Zn, Cu, Pb and Cr in Skado leaves only at the most contaminated areas after two growing seasons. These foliar concentrations were not correlated with Ca(NO3)2-extractable concentrations in soils, suggesting that mycorrhizal fungi limited PTE translocation from roots to leaves without impacting PTE mobility in soils. Therefore, the reduction of PTE accumulation in poplar leaves may be optimized by selecting appropriate combinations of cultivars and inocula at specific PTE levels and soil conditions. Because Cd and Zn may pose a risk after leaf abscission and wood harvest, further research is needed to efficiently reduce Cd and Zn concentrations in poplar tissues. Otherwise, the phytomanagement of metal contaminated sites with poplars should include options to safely manage both leaves and wood.

The Effects of Nitrogen Addition on the Uptake and Allocation of Macro- and Micronutrients in Bothriochloa ischaemum on Loess Plateau in China.

The effects of nitrogen (N) addition on the macro- and micronutrient concentrations, storage, and allocation of Bothriochloa ischaemum (L.) Keng, a native forage plant on the Loess Plateau in China remain unclear. We studied the effects of N addition at 0 (CK), 2.5 (N1), 5.0 (N2), and 10.0 (N3) g N m-2 y-1. N addition significantly decreased the available copper (Cu), zinc (Zn), and total Cu concentration, but significantly increased the available iron concentration in the soil. Cu, manganese (Mn), and sodium (Na) concentrations in aboveground tissues and potassium (K), magnesium, and Zn concentrations in belowground tissues significantly increased with N addition. Calcium (Ca) concentrations in belowground tissues decreased significantly. The ratios of above- to belowground Ca, Cu, Zn, and Mn significantly increased with N addition. The maximum ratios appeared at N2 for Cu, Zn, and Mn. The aboveground, belowground, and total biomass storage of studied nutrients significantly changed with N addition, and most attained maximum values under N2 treatment. The storage ratios of above- to belowground Cu, Zn, Mn, and Na attained maximum values at N2. We conclude that N addition significantly, but differentially influence the macro- and micronutrient concentrations and storage in B. ischaemum. B. ischaemum allocated and accumulated increased macro- and micronutrients to its aboveground tissues and exhibited high total storage when the amount of N addition reached 5 g N m-2 y-1.

Effect of dietary organic zinc sources on growth performance, incidence of diarrhoea, serum and tissue zinc concentrations, and intestinal morphology in growing rabbits

&lt;p&gt;This study was conducted to evaluate the effect of dietary organic zinc (Zn) sources on growth performance, the incidence of diarrhoea, serum and tissue Zn concentration, and intestinal morphology in growing rabbits. A total of 120 New Zealand White rabbits aged 35 d and with an initial body weight of 755±15 g, were randomly divided into 4 treatment groups for a 49 d feeding trial. Dietary treatments were designed with different Zn supplements as follows: (1) Control group: 80 mg/kg Zn as ZnSO&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;; (2) ZnLA group: 80 mg/kg Zn as Zn lactate; (3) ZnMet group: 80 mg/kg Zn as Zn methionine; (4) ZnGly group: 80 mg/kg Zn as Zn glycine. The results showed that, when compared with rabbits fed ZnSO&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;, supplementation with ZnLA improved (P&amp;lt;0.05) growth performance and led to a lower (P&amp;lt;0.01) incidence of diarrhoea. ZnLA supplement increased the liver Zn concentration (58.97 vs. 46.59 mg/g; P&amp;lt;0.05) compared with rabbits fed ZnSO&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;. Supplementing with ZnLA increased duodenum villi height (681.63 vs. 587.14 μm, P&amp;lt;0.05) and decreased duodenum crypt depth (141.69 vs. 168.91 μm; P&amp;lt;0.05) when compared to that of the control group. However, experimental results obtained ZnMet and ZnGly supplementation were no significantly different to ZnSO&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;, except that feeding ZnMet led to higher (P&amp;lt;0.05) Zn concentrations in serum and liver than rabbits fed ZnSO&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;. The results indicated that supplementation with 80 mg/kg Zn as ZnLA could improve growth performance, increase liver Zn concentration and enhance duodenum morphology, while reducing the incidence of diarrhoea in growing rabbits.&lt;/p&gt;

Concentration of Zinc, Copper, Iron, Calcium, and Magnesium in the Serum, Tissues, and Urine of Streptozotocin-Induced Mild Diabetic Rat Model.

The present study aimed to investigate, in the streptozotocin-induced mild diabetic rat model, the zinc (Zn), copper (Cu), iron (Fe), calcium (Ca), and magnesium (Mg) concentration in serum, liver, and kidney tissues, and urine samples from adult Wistar rats treated neonatally with streptozotocin (STZ). Diabetes was induced by subcutaneous administration of streptozotocin (100mg/Kg) in female Wistar rats of 2days old (STZ, n=10). Control group (CG, n=10) received only sodium-citrate buffer. The mineral concentrations were measured by atomic absorption spectrophotometry. The validity and accuracy were checked by conventional methods. STZ neonatal injection successfully leaded to mild diabetes in the adult rats. Serum concentrations of Zn, Cu, Fe, Ca, and Mg showed no changes (p>0.05) due to diabetes. The Zn, Fe, Ca, and Mg concentrations in liver and kidney tissues were not different (p>0.05) between STZ and CG. The mean values of Cu were higher (p<0.05) in liver and kidney samples from STZ as compared to CG. Urine minerals concentrations (Zn, Cu, Fe and Ca) in STZ-rats group were lower (p<0.05) than CG. However, the content of all evaluated minerals in the excreted urine were higher (p<0.01) in STZ-rats during a 24h collection period. Urinary excretion of Zn, Cu, Fe, Ca, and Mg was strongly correlated with urinary volume during the 24h period (r>0.7; p<0.001). Observed changes in mineral metabolism of STZ-induced mild diabetes model could be due to the endocrine imbalance associated with the diabetic condition.

Soil-applied ZnEDTA: Vegetative Growth, Nut Production, and Nutrient Acquisition of Immature Pecan Trees Grown in an Alkaline, Calcareous Soil

A field study was conducted to evaluate efficacy of soil-applied zinc (Zn) fertilizer on young pecan [Carya illinoinensis (Wangenh.) K. Koch] trees growing in alkaline, calcareous soils. Chelated Zn ethylenediaminetetraacetic acid (ZnEDTA) was applied at rates of 0, 2.2, or 4.4 kg·ha−1 of Zn via injection into irrigation water (fertigation) in microsprinkler irrigated ‘Western’ and ‘Wichita’ trees. Over the 5-year duration of the study, leaf Zn levels were increased from 22 to 35 µg·g−1 in the highest rate of ZnEDTA treatment compared with 7 to 14 µg·g−1 in unfertilized trees. Zn concentrations in shoot and root tissues were also elevated in Zn-treated trees. Zn treatments largely eliminated visible Zn deficiency symptoms, and increased trunk diameter growth compared with untreated trees. Nut yield (in the third through fifth seasons) were also increased as a result of Zn fertilization. No additional benefit in terms of trunk diameter growth or nut yield was observed by adding a higher rate of Zn (4.4 kg·ha−1) vs. the lower rate (2.2 kg·ha−1). ‘Western’ and ‘Wichita’ trees responded similarly to Zn fertigation.

Biochemical and molecular mechanisms associated with Zn deficiency tolerance and signaling in rice (Oryza sativa L.)

ABSTRACTIn this study, zinc (Zn) deficiency caused a significant reduction in growth parameters and tissue Zn concentrations in BRRI 33 (sensitive) but not in Pokkali (tolerant). The increase of proton extrusion in both genotypes under high pH suggests that it gets triggered as a common consequence of reducing pH and solubilization of Zn. Real-time PCR showed pronounced upregulation of OsZIP4, OsDMAS1, OsNAS2 and OsPCS1 in Zn-deficient roots of Pokkali, and to a lesser extent in BRRI 33 only for OsZIP4 and OsPCS1. This suggests that OsDMAS1, OsNAS2 and OsPCS1 functions as secondary consequences leading to higher chelation and uptake of Zn under Zn deficiency in Pokkali. Further, a major increase in CAT, POD, SOD, GR and key metabolites suggests that high antioxidant defense plays a critical role in Zn deficiency tolerance in Pokkali. Further, Pokkali self-grafts and plants having Pokkali rootstock combined with BRRI 33 scion showed no significant decline in plant height, root dry matter and Zn concentration along with upregulation of Zn transporters (OsZIP4 and OsIRT1) under Zn deficiency, suggesting that signal driving mechanisms for Zn deficiency tolerance mechanisms are generated in the root and Zn-inefficient BRRI 33 is not capable of producing signals or sensing them.

Soil-application of Zinc-EDTA Increases Leaf Photosynthesis of Immature ‘Wichita’ Pecan Trees

Zinc deficiency is common in pecan (Carya illinoinensis) grown in alkaline, calcareous soils. Zinc (Zn)-deficient pecan leaves exhibit interveinal chlorosis, decreased leaf thickness, and reduced photosynthetic capacity. Low photosynthesis (Pn) contributes to restricted vegetative growth, flowering, and fruiting of Zn-deficient pecan trees. Our objectives were to measure effects of soil-applied ethylenediaminetetraacetic acid (EDTA)-chelated Zn fertilizer on gas exchange of immature ‘Wichita’ pecan and characterize the relationship between leaf Zn concentration and Pn. The study orchard had alkaline and calcareous soils and was planted in Spring 2011. Zinc was applied throughout each growing season as Zn EDTA through microsprinklers at rates of 0 (Control), 2.2, or 4.4 kg·ha−1 Zn. Leaf gas exchange and SPAD were measured on one occasion in the 2012 growing season, four in 2013, and five in 2014. Soil Zn-EDTA applications significantly increased the leaf tissue Zn concentration throughout the study. On all measurement occasions, net Pn was significantly increased by soil-applied Zn EDTA compared with the control, but Pn was not different between the two soil-applied Zn-EDTA treatments. Leaf Pn in midseason did not increase at leaf tissue Zn concentrations above 14–22 mg·kg−1. Leaf SPAD consistently followed a similar pattern to Pn. Soil Zn-EDTA application increased leaf stomatal conductance (gS) compared with the Control early through midseason but not after August. Intercellular CO2 concentration was significantly lower for Zn-EDTA-treated trees than the Control even on dates when there was no significant difference in gs, which suggests that soil application of Zn-EDTA alleviated nonstomatal limitations to Pn caused by Zn deficiency.

Growth and volatile compounds of Martianthus leucocephalus exposed to heavy metal stress

ABSTRACT: Martianthus leucocephalus is found in the semi-arid Northeast of Brazil and has high pharmacological potential due to the production of volatile compounds. This study aimed to evaluate the Cd (15, 30, 45 and 60µmol L-1), Cu (30, 60, 90 and 120µmol L-1) and Zn (150, 300, 450 and 600µmol L-1) levels on the growth of this species and its volatile compounds production. Apical cuttings were placed in plastic trays containing 6.0L nutrient solution, and after rooting, they were submitted to Cd, Cu and Zn treatments for 15 days. All the metals evaluated reduced the succulence and growth of all parts of M. leucocephalus . This effect was accompanied by the increase of Cd, Cu and Zn concentrations in all plant tissues. Volatile compounds content produced by M. leucocephalus was increased only by Zn (86%).

An Optimal Dietary Zinc Level of Brown-Egg Laying Hens Fed a Corn-Soybean Meal Diet.

An experiment was conducted to estimate the optimal dietary zinc (Zn) level of brown-egg laying hens fed a corn-soybean meal diet from 20 to 40weeks of age. A total of 120 20-week-old Beijing Red commercial laying hens were randomly allotted by bodyweight to one of five treatments with six replicates of four birds each in a completely randomized design, and fed a Zn-unsupplemented corn-soybean meal basal diet containing 27.95mg Zn/kg by analysis and the basal diets supplemented with 30, 60, 90, or 120mg Zn/kg as Zn sulfate (reagent grade ZnSO4·7H2O) for a duration of 20weeks. Laying performance, egg quality, tissue Zn concentrations, and activities of serum alkaline phosphatase (AKP), and liver copper-Zn superoxide dismutase (CuZnSOD) were measured. Regression analyses were performed to estimate an optimal dietary Zn level whenever a significant quadratic response (P<0.05) was observed. Tibia Zn concentration (P=0.002) and serum AKP activity (P=0.010) showed significant quadratic responses to dietary supplemental Zn levels. The estimates of dietary Zn requirements for brown-egg laying hens from 20 to 40weeks of age were 71.95 and 64.63mg/kg for tibia Zn concentration and serum AKP activity, respectively. The results from this study indicate that the tibia Zn might be a more suitable and reliable parameter for Zn requirement estimation, and the optimal dietary Zn level would be about 72mg/kg for brown-egg laying hens fed a corn-soybean meal diet from 20 to 40weeks of age.

Phyto-Availability of Potentially Toxic Metals in &lt;i&gt;Curcubita ficifolia&lt;/i&gt; Grown on Contaminated and Non-Contaminated Soils

In order to estimate plant available fraction of metals in two soil samples-contaminated soil (A) and non-contaminated soil (B), a vegetable crop, Curcubita ficifolia was grown on both soil samples. The matured leaf was harvested and analyzed for its metal concentration after three (3) months of growth. The soil samples were collected before and after planting, digested with acid and analyzed to determine the pseudo total metal concentration and quantification was done using atomic absorption spectroscopy (AAS). To correlate metal accumulation by the vegetable with potential bioavailability of metals in soils, sequential extraction (SE) using the modified BCR technique was performed on the soils. Soil sample B was used for quality control. It was observed that each metal differed considerably in uptake. And the C. ficifolia cultivated on soil sample A had tissue concentrations of Zn, Mn and Cu as follows: 39.6mgkg-1, 18.3mgkg-1and 26.3mgkg-1 respectively. Also, C. ficifolia cultivated on soil sample B had a lower absorption of Zn, Mn and Cu with concentrations of 10.21mgkg-1, 9.11mgkg-1, and 7.6mgkg-1 respectively. Results of sequential extraction showed that Zn for soil sample A, and Fe for sample B were mostly present in the acid exchangeable and reducible fractions where these metals were mostly taken up.

Phyto-Availability of Potentially Toxic Metals in &lt;i&gt;Curcubita ficifolia&lt;/i&gt; Grown on Contaminated and Non-Contaminated Soils

In order to estimate plant available fraction of metals in two soil samples-contaminated soil (A) and non-contaminated soil (B), a vegetable crop,Curcubita ficifoliawas grown on both soil samples. The matured leaf was harvested and analyzed for its metal concentration after three (3) months of growth. The soil samples were collected before and after planting, digested with acid and analyzed to determine the pseudo total metal concentration and quantification was done using atomic absorption spectroscopy (AAS). To correlate metal accumulation by the vegetable with potential bioavailability of metals in soils, sequential extraction (SE) using the modified BCR technique was performed on the soils. Soil sample B was used for quality control. It was observed that each metal differed considerably in uptake. And theC. ficifoliacultivated on soil sample A had tissue concentrations of Zn, Mn and Cu as follows: 39.6mgkg-1, 18.3mgkg-1and 26.3mgkg-1respectively. Also,C. ficifoliacultivated on soil sample B had a lower absorption of Zn, Mn and Cu with concentrations of 10.21mgkg-1, 9.11mgkg-1, and 7.6mgkg-1respectively. Results of sequential extraction showed that Zn for soil sample A, and Fe for sample B were mostly present in the acid exchangeable and reducible fractions where these metals were mostly taken up.

In situ stabilization of heavy metals in multiple-metal contaminated paddy soil using different steel slag-based silicon fertilizer.

Steel slag has been widely used as amendment and silicon fertilizer to alleviate the mobility and bioavailability of heavy metals in soil. The objective of this study was to evaluate the influence of particle size, composition, and application rate of slag on metal immobilization in acidic soil, metals uptake by rice and rice growth. The results indicated that application of slag increased soil pH, plant-available silicon concentrations in soil, and decreased the bioavailability of metals compared with control treatment, whereas pulverous slag (S1) was more effective than granular slag (S2 and S3). The acid-extractable fraction of Cd in the spiked soil was significantly decreased with application of S1 at rates of 1 and 3%, acid-extractable fractions of Cu and Zn were decreased when treated at 3%. Use of S1 at both rates resulted in significantly lower Cd, Cu, and Zn concentrations in rice tissues than in controls by 82.6-92.9, 88.4-95.6, and 67.4-81.4%, respectively. However, use of pulverous slag at 1% significantly promotes rice growth, restricted rice growth when treated at 3%. Thus, the results explained that reduced particle size and suitable application rate of slag could be beneficial to rice growth and metals stabilization.

Corn Injury from Foliar Zinc Application Does Not Affect Grain Yield

Zinc deficiency symptoms have been observed on corn (Zea mays L.) grown on coarse‐textured, high‐pH soils in the Mississippi Delta. To correct deficiencies, many corn producers apply foliar Zn. Corn injury from foliar Zn application has been observed; however, it is not clear whether foliar Zn injury affects grain yield. Also, little information currently exists about the ability of foliar Zn sources to increase corn tissue Zn concentration. Therefore, the purpose of this study was to determine the effect of Zn source and Zn application rate on foliar injury, tissue Zn concentration, and grain yield in corn. Zinc‐citrate, Zn–ethylenediaminetetraacetic acid (EDTA), and ZnSO4 were applied to corn at 0.56, 1.12, and 2.24 kg Zn ha−1 at V4. Corn injury was evaluated 3, 6, and 9 d after application, and tissue Zn concentration was determined 2 wk after Zn application. Grain yield was determined at harvest. Zinc‐citrate imparted the greatest injury at all application rates, followed by ZnSO4 and Zn‐EDTA. Injury generally increased as Zn application rate increased. The 0.56 kg Zn ha−1 rate resulted in similar tissue Zn content across all Zn sources. Zinc‐citrate and ZnSO4 application resulted greater tissue Zn content than Zn‐EDTA at 1.12 and 2.24 kg Zn ha−1 rates. Despite high levels of foliar injury observed for some Zn sources and rates, no differences in grain yield were observed. Citrate‐Zn application to corn caused more foliar injury than EDTA‐Zn and Zinc sulfate. Citrate‐Zn resulted in highest corn tissue Zn concentrations. Corn injury from foliar Zn application did not affect grain yield.

Assessment of Trace Element Accumulation by Earthworms in an Orchard Soil Remediation Study Using Soil Amendments

This study assessed potential bioaccumulation of various trace elements in grasses and earthworms as a consequence of soil incorporation of organic amendments for in situ remediation of an orchard field soil contaminated with organochlorine and Pb pesticide residues. In this experiment, four organic amendments of differing total organic carbon content and quality (two types of composted manure, composted biosolids, and biochar) were added to a contaminated orchard field soil, planted with two types of grasses, and tested for their ability to reduce bioaccumulation of organochlorine pesticides and metals in earthworms. The experiment was carried out in 4-L soil microcosms in a controlled environment for 90 days. After 45 days of orchardgrass or perennial ryegrass growth, Lumbricus terrestris L. were introduced to the microcosms and exposed to the experimental soils for 45 days before the experiment was ended. Total trace element concentrations in the added organic amendments were below recommended safe levels and their phytoavailablity and earthworm availability remained low during a 90-day bioremediation study. At the end of the experiment, total tissue concentrations of Cu, Cd, Mn, Pb, and Zn in earthworms and grasses were below recommended safe levels. Total concentrations of Pb in test soil were similar to maximum background levels of Pb recorded in soils in the Eastern USA (100 mg kg−1 d.w.) because of previous application of orchard pesticides. Addition of aged dairy manure compost and presence of grasses was effective in reducing the accumulation of soil-derived Pb in earthworms, thus reducing the risk of soil Pb entry into wildlife food chains.