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Wheat (Triticum aestivum L.) cultivation in cadmium (Cd) polluted soil is a core concern to food quality and food security all over the world. Cadmium toxicity is mainly associated with a Cd influx from contaminated soils to human via grain consumption. Organic amendments are widely used for Cd immobilization and enhancement in plant growth, but the residual effects of these amendments are mostly unknown. The present study addressed the long-term effects of organic amendments in contaminated soils by evaluating their residual effects on 3rd crop (wheat) in the sequence. Initially six organic amendments viz. rice husk biochar (RHB), wheat-straw biochar (WSB), cotton-stick biochar (CSB), poultry manure (PM), press mud (PrMd) and farm manure (FM) were applied once at a rate of 2% in Cd (50 mg kg -1 ) contaminated soil with wheat-rice rotation. After the harvest of wheat and rice crops, wheat (Var. Galaxy) was again grown in the same pots. Results revealed that plants grown under Cd stress (without any amendment) contain more tissue (root, shoot and grain) and soil AB-DTPA extractable Cd. The soil amended with RHB has shown lowest AB-DTPA extractable Cd (69% lower than control). Similarly, RHB application has significantly reduced wheat root, shoot and grain Cd concentrations compared to control and other amendments. Results have confirmed the effectiveness of RHB residual contents as an active amendment for restriction of Cd in non-bioavailable pool of soil and better growth and yield of wheat., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Cadmium (Cd) phytoremediation potential and its accumulation in edible and nonedible plant tissues is the function of various biochemical processes taking place inside plants. This study assessed the impact of organic ligands on Cd phyto uptake and different biophysiochemical processes of Spinacia oleracea L., and associated health hazards. Plants were exposed to Cd alone and chelated with citric acid (CA) and ethylenediaminetetraacetic acid (EDTA). Results revealed that the effect of Cd on lipid peroxidation, H 2 O 2 production and pigment contents varied greatly with its applied level and the type of organic ligand. Moreover, the effect was more prominent in root tissues than leaf tissues and for high concentrations of Cd and organic ligands. Cadmium accumulation increased by 90 and 74% in roots and leaves, respectively, with increasing Cd levels (25-100 µM). Cadmium exposure at high levels caused lipid peroxidation in roots only. Application of both CA and EDTA slightly diminished Cd toxicity with respect to pigment contents, lipid peroxidation and hydrogen peroxide (H 2 O 2 ) contents. Hazard quotient (HQ) of Cd was <1.00 for all the treatments. Under nonlinear effect of treatments, multivariate analysis can be an effective tool to trace overall effects/trends.

Cadmium (Cd) stress is a serious concern in agricultural soils worldwide whereas little is known about the impact of farmyard manure (FYM) alone or combined with limestone, lignite and biochar on Cd concentrations in plants. Wheat was grown in Cd-contaminated field amended with control (T 1 ), FYM @ 0.1% (T 2 ), FYM + limestone @ 0.05% each (T 3 ), FYM + lignite @ 0.05% each (T 4 ), FYM + biochar @ 0.05% each (T 5 ) and subsequent rice was grown without additional use of amendments. Soil application of amendments increased straw and grain yield and thousand grain weight being maximum in FYM + limestone treatment. Wheat and rice straw yield increased by 19% and 10% in T 3 than control respectively. Photosynthetic pigments increased with the supply of amendments than control. Amendments decreased Cd concentration, total Cd uptake in straw and grains and Cd harvest index of both crops and the maximum reduction in these parameters was recorded with where FYM + limestone (T 3 ). Cd concentration in wheat and rice straw decreased by 78.5% and 65% in T 3 than control, respectively. The highest benefit to cost ratio was obtained in FYM + limestone (T 3 ). Ammonium bicarbonate - diethylenetriamine penta acetic acid (AB-DTPA) extractable Cd of the post-harvest soil reduced whereas Cd immobilization index and soil pH increased with the supply of all treatments than control being maximum in T 3. The present study revealed that field management with FYM + limestone increased plant yield and reduced Cd concentrations in grains., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Despite significant recent advancement in research, biogeochemical behavior of heavy metals with respect to their applied form is still topical. Moreover, metal toxicity to plants may vary with their stage of development/maturity. Therefore, this study for the first time evaluated the influence of ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) on cadmium (Cd) accumulation and toxicity to germinating and young pea seedlings as well as in younger and older leaves. The experimental setup of current study consisted of two separate studies. The first study was performed on germinating seedlings grown in a Cd-contaminated sand media. Pea seeds were treated with two levels of Cd (Cd-25 and Cd-100) alone and combined with different levels of EDTA and CA. The second study was carried out in hydroponic solution. The influence of organic amendments on Cd accumulation and toxicity to pea plants was evaluated by determining Cd contents in pea seedlings, H 2 O 2 contents, chlorophyll contents and lipid peroxidation in younger and older leaves. Cadmium stress caused overproduction of H 2 O 2 in roots and leaves of pea seedlings. Cadmium-induced overproduction of H 2 O 2 caused a decrease in the pigment contents and increased lipid peroxidation. Application of EDTA at higher levels (81 and 200µM) increased Cd accumulation by pea plants. However, CA did not affect Cd accumulation by pea. Both EDTA and CA increased Cd-induced H 2 O 2 production and lipid peroxidation. Younger pea leaves showed more sensitivity to Cd stress compared to older leaves. Similarly, Cd toxicity was more pronounced in germinating seedlings than young seedlings. Moreover, Pearson correlation and principal component analysis (PCA) showed very interesting correlations between treatments and stress responses of germination and young seedlings as well as younger and older leaves. Based on multivariate analysis, it is proposed that the Cd toxicity to pea plants greatly vary with its growth stage and the maturity of organs (younger or older leaves)., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Cadmium (Cd) toxicity is a widespread problem in crops grown on contaminated soils, and little information is available on the role of inorganic amendments in Cd immobilization, uptake, and tolerance in crops especially under filed conditions. The effect of three amendments, monoammonium phosphate (MAP), gypsum, and elemental sulfur (S), on Cd immobilization in soil and uptake in wheat and rice plants, under rotation, were investigated under field conditions receiving raw city effluent since >20 years and contaminated with Cd. Three levels of each treatment, 0.2, 0.4, and 0.8% by weight, were applied at the start of the experiment, and wheat was sown in the field. After wheat harvesting, rice was sown in the same field without application of amendments. Both crops were harvested at physiological maturity, and data regarding grain yield, straw biomass, Cd concentrations, and uptake in grain and straw, and bioavailable Cd in soil and soil pH were recorded. Both MAP and gypsum application increased grain yield and biomass of wheat and rice, while S application did not increase the yield of both crops. MAP and gypsum amendments decreased gain and straw Cd concentrations and uptake in both crops, while S application increased Cd concentrations in these parts which were correlated with soil bioavailable Cd. We conclude that MAP and gypsum amendments could be used to decrease Cd uptake by plants receiving raw city effluents, and gypsum might be a better amendment for in situ immobilization of Cd due to its low cost and frequent availability.

We conducted a pot experiment to evaluate the potential for soil- and foliar-applied silicon (Si), alone and in combination, to a Cd-contaminated soil in order to evaluate the effects on such amendments on the Cd translocation from soil to wheat root, shoot and grains. Five treatments were used, T1) control with no external factor added, T2 received only Cd, while T3–T5 treatments received Cd in combination with soil, foliar and soil plus foliar applied Si. Except control (T1), soil was contaminated with Cd at 10 mg kg−1 in all the treatments and 1% solution of Si as an amendment was used for soil and/or foliar application or their combination. Overall, while Si application improved both plant growth and yield in Cd-contaminated soil. Control and combined soil- and foliar-applied Si in Cd contaminated treatments showed equally positive (2.5%) increase in plant height over Cd contaminated treatment. Grain yield was also highest in the treatment receiving Cd plus soil-applied Si (29%) followed by control (26%). It was concluded that Si can alleviate Cd toxicity in wheat irrespective of whether the Si was soil-applied or applied via a foliar method, but soil applied Si proved the best in this regard. Novelty statement Immobilization of metals i.e., cadmium (Cd) with soil-applied amendments like biomaterials and organic manure to decrease Cd concentration in plants have already been widely investigated. Silicon (Si) is a cheap in-organic and readily available element in the nature and also used for the same purpose. It can be applied both in soil as well as by foliar and soil + foliar application to decrease the metals concentration in soil and plants. However, comparative effectiveness of these three methods have not been checked simultaneously. In this study, we have studied the comparative effectiveness of Si application to soil, foliar and their combination (soil + foliar) to decrease Cd concentration during wheat crop. [ABSTRACT FROM AUTHOR]

We compared acetic, ascorbic, and oxalic acids with ethylenediaminetetraacetic acid (EDTA) to enhance phytoextraction of nickel (Ni), manganese (Mn), zinc (Zn), copper (Cu), cadmium (Cd), and lead (Pb) by maize. Except ascorbic acid, acids significantly (P< 0.05) decreased shoot dry weight with maximum (5.60 g pot−1) recorded with ascorbic acid and minimum with oxalic acid (4.06 g pot−1). Maximum ammonium bicarbonate–diethylenetriaminepenta acetic acid (AB-DTPA)–extractable nickel (19.94 mg kg−1) was recorded with EDTA and it was minimum (10.57 mg kg−1) with oxalic acid. The EDTA significantly (P< 0.05) increased AB-DTPA-extractable lead while other acids decreased it. Except acetic acid, other acids significantly (P< 0.05) increased Ni and Zn concentration in shoots with maximum Ni (9.22 mg kg−1) and Zn (37.40 mg kg−1) with EDTA. [ABSTRACT FROM AUTHOR]

In developing countries, farmers use effluent as a source of irrigation and nutrients and the government takes this practice as a viable option for disposal. Sewage samples have hazardous electrical conductivities (EC), sodium adsorption ratios (SARs), and residual sodium carbonate (RSC) for irrigation, but metals were close to upper permissible limits. The EC of saturated soil paste extract (ECe) ranged from 2.18 to 4.02 dS m–1 and soil SAR 7.72 to 16.00 in soils 0.2 m deep. Average cadmium (Cd), nickel (Ni), lead (Pb), zinc (Zn), and copper (Cu) in soils ranged from 0.02 to 0.13, 0.00 to 4.45, 2.27 to 4.57, 0.71 to 13.76, and 3.17 to 10.37 mg kg–1, respectively. Plants acquired metal contents greater than in raw sewage or soils. The wide biodiversity regarding metals in shoots of natural and planted vegetation that receives raw sewage is of practical significance. It seems imperative to study under controlled conditions various plants' metal tolerance and mechanisms of metal partitioning among plant parts. [ABSTRACT FROM AUTHOR]