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The remediation of heavy metals contaminated soils is increasingly a global problem with serious implications for human health. This study aimed to evaluate the in-situ remediation performance of multi element contaminated soil by the electrokinetic. To achieve this, the effects of chelating agents (water, ethylenediamine tetraacetic acid (EDTA), diethylenetriamine pentaacetic acid (DTPA)), potential gradient (0, 1, and 2 V cm− 1), and position of soil in electrokinetic cell on metals fractions and metals removal were investigated. The results revealed that the electric potential difference and application of EDTA or DTPA electrolyte generally enhanced heavy metals removal efficiency and for Ni and Pb the interactions effects of these factors were significantly positive. Results showed that Ni, Zn, Cd, and Pb removal efficiency is highest with DTPA, DTPA, EDTA and EDTA electrolytes, respectively. In particular, the usage of electric current remarkably shifted the soil-metal bonds from stable (residual) to a less stable (mobile and mobilisable) fraction. The optimum electric current for the removal of Zn, Cd, and Ni was 1, 1, and 2 V cm− 1, respectively, which removed 44, 47 and 41% of the average of these heavy metals in soil, respectively. Results of present study demonstrated that removal efficiency was highly metal-dependent; and the order of metals removal was Cd > Ni > Zn > Pb.

Copper (Cu) is an essential micronutrient that both deficient and excess concentration of this element can cause damages to plants. A greenhouse trial was conducted to investigate the effectiveness...

Irrigation of plants by contaminated water with metals is very common in countries facing freshwater scarcity. To enhance plant growth via improved absorption of essential metals including Zn from ...

The present study was conducted to evaluate the effectiveness of an innovative electro-bio-chemical approach, in the phytoremediation of multi-elements polluted soil. A 3×4 factorial greenhouse trial was conducted with four levels of amendments (without amendment, chemical amendment, nitrilotriacetic acid (NTA), biological amendment (Thiobacillus), and both) and three levels of electrical current (0, 1, and 2 V cm−1). Ryegrass seeds were sown in a soil polluted with Pb, Cd, Zn, and Ni. Two months after planting, roots and shoots were harvested. Dry matter yield was measured in harvested parts, and the contents of metals in different parts of ryegrass were determined. Application of electric current (1 V cm−1) increased mean root and shoot dry weights of ryegrass and consequently increased Ni, Zn, Pb, and Cd uptake in ryegrass root and shoot. Application of 2 V cm−1 electric current increased Pb shoot uptake but decreased root dry weight, Cd and Zn root and shoot uptake, and also Pb root uptake. Although the addition of NTA and/or inoculation of Thiobacillus enhanced metal uptakes, co-application of these two treatments caused higher enhancement in metal uptakes by ryegrass. Plant position (anode vs cathode) had no considerable effect on most parameters measured. Mean Ni and Cd uptakes were higher in plants grown in anode position. Overall, the highest root and shoot dry weight, metal uptake, phytoextraction efficiency, uptake efficiency, and translocation factor especially for Pb were observed following the triple usage of 1 V cm−1 electric current along with application of chemical and biological treatments. The main conclusion derived from these observations is that the proposed electro-bio-chemical approach is highly influential in the phytoremediation of multi-elements polluted soil.

Immobilisation is an effective technique in the remediation of heavy metals polluted soils. A laboratory experiment was conducted to clarify the kinetics of Zn and Cd release using citric, oxalic, ...

Plant growth–promoting bacteria (PGPB) inhabiting the phyllosphere improve the growth and yield of plants by producing natural growth regulators. The objectives of this study were to identify and characterize the indigenous PGPB of maize phyllosphere and to evaluate their ability to improve growth and nutritional status of maize (Zea mays L.). The bacteria were isolated from phyllosphere of maize in the fields located at different geographical locations and screened for various plant growth–promoting (PGP) traits. The most promising PGPB were identified by 16S rRNA gene sequence analysis. A greenhouse experiment was carried out in a completely randomized design with the foliar application of 15 different bacterial treatments. It was found that members of genera Bacillus, Pseudomonas, Microbacterium, Stenotrophomonas, Enterobacter, Pseudarthrobacter, and Kocuria were the most dominant PGPB in maize phyllosphere. Foliar spray of M. arborescens, B. subtilis + S. maltophilia, S. maltophilia, B. megaterium, and E. hormaechei significantly increased the shoot dry weight by 10.40, 9.53, 8.86, 8.73, and 6.00% compared with the control, respectively. M. arborescens and S. maltophilia isolates with the ability to produce indole-3-acetic acid (IAA) had positive effects on dry weight of the shoot. E. hormaechei showed a marked nitrogenase activity, phosphate solubilization, and IAA production and was the most effective treatment in improving the uptake of most nutrients. The nitrogenase activity and IAA production were generally considered to be the most important PGP traits of the bacteria when applied via foliar spray. Overall, the findings presented in this study indicate that the foliar application of the leaf-colonizing PGPB enhanced the growth and nutritional status of maize.

Immobilisation is among efficient strategies in the remediation of heavy metals, including chromium (Cr)-polluted soils. A greenhouse trial was conducted to investigate the effectiveness of chitosa...

Understanding the processes crops use to detoxify heavy metals (HMs), are critical in crops production and environmental management. The role of organic acids (OAs) exudation as an external mechani...

Modification of biochar using chitosan and hematite made the biochar product more effective for hexavalent chromium (Cr (VI)) reduction in contaminated soils. Release experiment was conducted to ex...

Immobilization is an efficient method in the remediation of heavy metal-polluted soils. A greenhouse experiment is conducted to investigate the influence of fish scale powder, chitin, and chitosan on the growth and chemical composition of rice grown on a soil contaminated with Zn, Pb, Cd, and Ni. Results showed that the application of fish scale powder, chitin, and chitosan significantly increased root and shoot dry matter yield of rice, but decreased Pb phytoextraction efficiency. Further, the translocation factor of Ni decreased following the application of fish scale powder and chitosan. Application of fish scale powder decreased Ni, Cd, Zn, and Pb bioavailability in soil. The addition of chitosan reduced Ni and Pb concentration in rice shoots. Among different amendments, only the application of chitosan had a significant effect on the reduction of Zn content in rice root. Considering that the translocation factors were less than one in all treatments, it can be concluded that biostabilization of the studied metals has occurred. based on the obtained results fish scale derivatives including fish scale powder and chitosan play an important role in the removal of heavy metals due to having suitable functional groups. Therefore, it can be deduced that due to the economic feasibility, environmentally friendly, and high metal removal capability of chitosan and fish scale powder, these two amendments are highly recommendable to be applied in multi-metal polluted soils for increasing metals removal and hence decreasing their phytotoxicity.

Iron (Fe) deficiency is common when grain crops are grown in calcareous soils. The study was conducted to determine if the DTPA-extractable Fe concentration and Fe uptake of sorghum and cor...

Although crude oil contamination is a constraint for crop production, some plants can develop under crude oil contaminated conditions by utilizing crude oil as nutrients after decomposition. A gree...

In order to study the effect of water deficit stress (WDS), plant growth promoting rhizobacteria (PGPR)-enriched and non-enriched vermicompost tea(VT) and vermiwash(V) on the growth and nutrients u...

Veterinary antibiotics can enter the environment especially agricultural soils via animal manure application in which Sulfadiazine (SDZ) is considered as one of the most used antibiotic. After soil application, it may be transported into subsurface water. The sorption behavior of SDZ is not only influenced by the soil type but also by soil organic matters as well. Hence, an experiment was executed aimed to study sorption/desorption processes of SDZ under experimental conditions in three various soils treated by different bio fertilizers including rice husk compost (RHC), rice husk biochar (RHB) and Micrococcus yunnanensis (My) bacterium. Sorption/desorption data of soils with and without bio-fertilizers were well fitted with Freundlich model (R² = 0.97). Results showed that bio-amended soils had higher values of kd sorption ranged from 1.16 to 52.4 without and with bio-fertilizers application respectively, proposing low sorption of SDZ with substantial risk of leaching without bio-fertilizers application. Also for the desorption cycle values of Kd increased from 1.03 to 39.1 without and with bio-fertilizers application, respectively. Furthermore, there was a hysteresis effect using organic matter. As a result of bio-fertilizers application, a significant value of SDZ was strongly adsorbed on the soil particles which was not desorb through desorption process.

Phytoremediation is a promising technique to clean up toxic heavy metals including lead (Pb). A greenhouse trial was conducted to evaluate the effectiveness of citric, succinic, malonic and oxalic ...

A greenhouse study was conducted as a completely randomised design in a factorial arrangement to assess how inoculation of AMF (arbuscular mycorrhizal fungus) and application of EDTA (ethyl...

Annually, a huge amount of shrimp waste (SW) is produced worldwide. Application of SW as an organic fertilizer may cause environmental concern; therefore, conversion of SW to shrimp waste biochar (SWB) along with arbuscular mycorrhizal fungus (AMF) (Funneliformis mosseae) may improve its properties and could be used as a valuable source of nutrients in agriculture. A greenhouse experiment was conducted to evaluate the influence of SW and SWB levels and AMF on corn growth, macronutrient uptake, and antioxidant enzymes under salinity stress. Conservation of SW to SWB by pyrolysis almost eliminated SW foul smell and drastically decreased its electrical conductivity (EC). Shoot and root dry weights of corn plants significantly decreased at the highest salinity level. Corn growth was significantly higher in both levels of SWB (1% and 2%) compared to 1% SW and application of 2% SW-killed corn plants 20 days after emergence. Addition of SWB increased phosphorus and nitrogen uptakes compared to SW-amended pots. Activities of antioxidant enzymes in corn shoot were affected by salinity, and SW and SWB applications were highest in 2% SWB-amended pots compared to the control treatment. Inoculation of AMF enhanced growth parameters in corn plants. Corn growth parameters including phosphorus uptake in co-application of SWB- and AMF-treated plants were higher compared to those of SW- and/or AMF-amended pots.

A 12-week incubation experiment was conducted to determine the pattern and rate of N mineralized from organic materials. Treatments consisted of sheep manure (SM), cattle manure (CM), poultry manur...

This study was conducted to investigate the effect of pyrolysis temperature on chemical properties of poultry manure (PM) biochar over the range of 200–500°C. Chemical properties of biochar produce...

In order to study the effect of plant growth promoting rhizobacteria (PGPR), Azolla compost and Azolla biochar on some soil quality indicators and rosemary growth, a greenhouse experiment w...

The fate of antibiotics and their effects on plant growth may be changed by the application of fertilizers. The present study was carried out to investigate the effect of sulfadiazine (SDZ), rice husk compost (RHC), rice husk biochar (RHB), and mycorrhiza (MR) on the growth attributes of Iranian Echium amoenum Fisch & C.A. Mey. A greenhouse experiment as a completely randomized design with six treatments of bio/organic-fertilizers (no bio-fertilizer (NF), RHB, RHC, MR, RHB + MR, and RHC + MR) and three levels of SDZ application (0, 100, and 200 mg kg−1) was performed for 7 months with three replicates. Shoot and root SDZ concentrations were determined using high-pressure liquid chromatography–diode array detection (HPLC–DAD) instrumentation. The results revealed that the application of RHC, RHB, and MR had a significant impact on the reduction of the toxicity effects of SDZ on plant properties. The lowest values of growth parameters belonged to the 200 mg kg−1 of SDZ with no bio-fertilizers, while the highest growth parameters were observed in the treatments of RHB + MR, and RHC + MR with no SDZ application. Also, chlorophyll pigments content was affected by used treatments and the lowest rates of chlorophyll a (4.24), chlorophyll b (2.99), and carotenoids (2.88) were related to the 200 mg kg−1 of SDZ with no biofertilizers application. The co-application of bio-fertilizers and SDZ (at both levels of 100 and 200 mg kg−1) decreased SDZ uptake by both shoot and root in comparison with the control. The same results were obtained with macro (NPK) and micro (Fe, Zn, Cu, and Mn) nutrients uptake by the shoot in which the lowest values of nutrients uptake were observed in treatment of 200 mg kg−1 of SDZ with no bio-fertilizers. Furthermore, in the case of the effect of the used treatments on root colonization, the results showed that the lowest value (7.26%) belonged to the 200 mg kg−1 application of SDZ with no bio-fertilizers. Generally, this study demonstrated that bio-fertilizers could be considered as an effective strategy in controlling the negative effects of antibiotics on the growth properties and nutrients status of the plants grown in such contaminated soils.

Growing environmental concern regarding multi elements-contaminated soils reveals the necessity of paying more attention to environmentally friendly remediation techniques such as phytoremediation. A large number of factors influences phytoremediation of potentially toxic elements (PTEs) and investigation on a variety of these factors need appropriate statistical approaches such as “Taguchi optimization” which effectively decreases time and cost of experiments. In the present study, based on the Taguchi optimization method, the effects of several biological (plant type and mycorrhizal fungi (AMF)) and chemical (chelating agents, surfactants and organic acids) factors, on the phytoremediation of soils contaminated with zinc (Zn), lead (Pb), cadmium (Cd) and nickel (Ni) were investigated. The goal was to find out the most effective factors as well as the best level for each factor. The values of dry weights in roots and aerial parts of the studied plants were in orders of maize > sorghum > sunflower and sorghum > maize > sunflower, respectively. AMF was the main factor in increasing dry weight of shoots. Inoculation of AMF caused increases in root and shoot uptake of some PTEs. Results showed that phytoremediation of PTEs is element-dependent; as Zn showed the highest translocation factor (TF) and bioconcentration factor (BCF) values, while Ni showed the lowest ones and the intermediate values belonged to Pb and Cd. These results show the diverse distribution of elements in plant parts, as Zn and Ni were mostly accumulated in shoot and root, respectively. Although different factors caused impacts on phytoremediation criteria, the role of plant type in the phytoremediation of PTEs was at the first rank. Mean TF of PTEs in sunflower was 6.3 times that of maize. Sunflower showed high TF value for the four elements and translocated most of the PTEs from root to the aerial parts demonstrating phytoextraction as the main mechanism in this plant. Maize and sorghum, however, showed low TF and accumulated most of PTEs in their roots revealing phytostabilization as the main mechanism. In general, it can be concluded that plant type was the most influential factor in the phytoremediation of PTEs followed by EDTA and AMF. Taguchi optimization revealed the appropriateness and significance of different chemical and biological treatments on phytoremediation criteria of different elements.

Assisted phytoremediation has been widely used for decontamination of potentially toxic elements contaminated soils. A greenhouse experiment was conducted to evaluate the effectiveness of different...

Zinc (Zn) is an essential micronutrient for crop growth. This metal can be found in chemical forms or fractions in the soil. The objective of this study was to investigate the distribution of Zn in special chemical forms using the sequential extraction method after treating eight calcareous soils by zinc sulfate and municipal solid waste (MSW) compost. Zn was separated in seven defined forms as exchangeable (Ex), carbonate (Car), organic (Om), manganese oxide bound (MnOX), amorphous iron oxide bound (FeAOX), crystalline iron oxide bound (FeCOX), and residual (Res). According to the results, the mean concentrations of Zn in chemical forms in untreated soils from higher to lower were 31.84, 8.13, 2.64, 2.57, 0.45, 0.39, and 0.16 mg kg−1 for the Res, FeCOX, Car, FeAOX, Om, MnOX, and Ex forms, respectively. The total applied Zn to the studied soils from both the sources of zinc sulfate and MSW compost after incubation for 30 days was converted to chemical forms in the following order: Car > Res > FeCO...

A greenhouse experiment was conducted with a factorial arrangement in a completely randomized design with three replications. Treatments consisted of two levels of plant growth promoting rhizobacteria (PGPR) (Pseudomonas fluorescens) (with and without inoculation), two levels of vermicompost (0 and 1% w/w), and four phosphate (P) sources (control, rock phosphate powder (RP), tricalcium phosphate (TCP), and triple super phosphate (SP) at 25 mg P kg⁻¹ level). Co-application of PGPR and RP in non-vermicompost treatments significantly increased shoot fresh weight, shoot dry matter yield, shoot P uptake, soil Ca₂-P concentration, but it significantly decreased soil Ca₈-P and Ca₁₀-P concentrations. The maximum shoot P uptake was obtained in combined application of RP with vermicompost which had no significant difference with the co-application of SP with vermicompost in bacterial and non-bacterial treatments. There was a negative correlation coefficient between shoot P concentration and chemical forms of phosphorus. It may be concluded that application of biofertilizers changed the chemical forms of inorganic phosphorus and increased P uptake by plant.

This study was conducted to evaluate the effects of liquid organic fertilizers (LOFs) and soil moisture status on some biological and physical properties of postharvest soil of maize cultivation. For this purpose, a factorial greenhouse experiment was performed based on the completely randomized design with three replications. Treatments consisted of five levels of LOFs (control, vermicompost tea, vermiwash, plant growth-promoting rhizobacteria [PGPR] enriched vermicompost tea and PGPR enriched vermiwash) and three levels of soil moisture status (field capacity [FC], 0.8 FC and 0.6 FC). The results showed LOFs caused an increase of soil biological properties (soil microbial respiration, soil microbial biomass, dehydrogenase activity and the number of aerobic heterotrophic bacteria) and the improvement of soil physical condition. LOFs increased aggregate stability, hydrophobicity and total porosity, while decreased bulk density and soil penetration resistance. Increasing water stress levels reduced soil biological activity and made soil physical properties more unfavorable. In general, LOFs improved soil conditions by enhancing soil physical and biological properties and decreased the negative effects of water stress. In addition, results showed that LOFs enriched with PGPR could be more effective than non-enriched ones.

In order to study the effect of plant growth promoting rhizobacteria (PGPR), vermicompost and phosphate sources on the growth and nutrients uptake by lettuce, a greenhouse experiments was conducted...

Phytoremediation is an appropriate technology used to remove pollutants from environment components. A greenhouse trial was conducted to test the hypothesis that application of surfactant levels and inoculation with Pseudomonas fluorescens bacterium and/or Piriformospora indica fungus enhances the phytoremediation of cadmium (Cd). Maize seeds were sown in Cd-polluted soil, and after 2 months Cd status in plant tissues and Cd phytoremediation criteria was determined. Results showed that application of surfactant increased root and shoot dry weight. Mean Cd uptake in roots and shoots increased following the application of 2 and 4 mmol kg−1 Tween 80, respectively. Application of 2 mmol kg−1 Tween 80 increased mean Cd uptake efficiency, while application of 4 mmol kg−1 Tween 80 increased phytoextraction and translocation efficiencies. Inoculation with P. indica and P. fluorescens was mostly effective in increasing Cd uptake and Cd phytoextraction efficiency, respectively. Co-inoculation with P. indica and P. fluorescens had no superiority to application of each inoculant alone. Since most of the Cd remained in roots, phytostabilization is probably the main mechanism controlling Cd phytoremediation by maize. According to the results, application of Tween 80 and inoculation with P. indica and P. fluorescens effectively enhanced phytoremediation of Cd-contaminated soil by maize.

The response of arbuscular mycorrhizal fungi (AMF)-inoculated plants to environmental stresses including drought stress is a complex phenomenon that involves activation or modification of processes occurring at physiological, biochemical, and molecular levels. However, the information on the ionomic and biochemical responses of AMF-inoculated plants under drought stress is limited. This study aimed to investigate the effect of AM fungus Funneliformis mosseae on maize plant growth, uptake of nutrients, and antioxidant responses of the plant to water-deficit stress under greenhouse conditions in a sterilized calcareous soil(Typic Calcixerepts). The experiment was laid out in a two-factor experiment in a completely randomized design with four replicates. The experimental factors included three different water regimes (100%, 70%, and 50% field capacity (FC)) and AM fungus at two levels (inoculated with or without F. mosseae). Water-deficit stress reduced plant biomass, chlorophyll index, nutrients uptake (P, K, Ca, Mg, Fe, Zn, Mn and Cu in shoots and roots), root colonization but increased malondialdehyde content. Inoculation with F. mosseae had a positive effect on plant growth, chlorophyll index, and nutrients uptake. Activities of guaiacol peroxidase (12.4%), superoxide dismutase (6.5%), and catalase (21.6%) as well as total phenolic content (62.5%) were higher in mycorrhizal plants as compared to non-mycorrhizal plants at 50% FC level. Lipid peroxidation (36.6% and 39.4% at 70 and 50% FC levels, respectively) was higher in non-AM plants as compared to AM plants. Under non-stress conditions, growth and nutrients uptake of mycorrhizal plants were greater than non-mycorrhizal ones. In general, the results of this study indicated that inoculation with F. mosseae through the improvement of ionomic and biochemical status of the plant can mitigate the detrimental effects of water-deficit stress on maize plants. The results of this study also suggest that the shoot and root ionome could be a useful phenotype for understanding the complicated interaction between F. mosseae and maize plant by providing readouts indicative of the biochemical processes occurring in the roots and shoots.

Phytoremediation is a cleanup technology for the removal of contaminants from polluted soils. The influences of humic acid (HA) and four plant growth regulators, i.e. gibberellic acid, salicylic acid, 3-indoleacetic acid, and 6-benzylaminopurine on the phytoremediation of Pb by maize were investigated in a pot trial on a Pb-contaminated soil. Foliar spray of 6-benzylaminopurine and salicylic acid significantly increased mean root dry matter but none of growth regulators had a significant effect on that of shoot. Addition of HA decreased root dry matter and had no significant effect on that of shoots. Application of all growth regulators except gibberellic acid significantly increased root Pb uptake. Application of salicylic acid significantly increased mean uptake efficiency and shoot Pb concentration and uptake. Although addition of HA significantly increased mean phytoextraction and translocation efficiencies, these responses were mainly attributed to the role of HA in the reduction of both root...

This study was conducted to investigate the effects of poultry manure (PM) and its derived biochars on chemical properties of a calcareous soil. PM and biochars prepared at 200°C (B200), 300°C (B300) and 400°C (B400) were applied to a calcareous soil at 2% level (w/w) and incubated for 150 days. Selected soil chemical properties and phosphorous, potassium, iron, manganese, zinc and copper availability and recovery were determined at 1, 15, 45 and 150 days of incubation. Soil nutrients availability, organic carbon (OC), electrical conductivity (EC) and cation exchange capacity (CEC) increased by addition of all organic substances. Biochars prepared at higher temperatures were more effective in increasing soil OC with higher durability compared to other treatments. The addition of PM and B200 decreased soil pH, whereas B400 increased it. Although the highest soil EC was observed in B300- and B400-treated samples in the early stages of incubation, the rate of increase in soil EC was higher for PM- an...

In order to evaluate the effects of different levels of phosphorus (P) and boron (B) on yield, yield components, seed quality (protein and oil content) and P and B content of rapeseed (Brassica napus L.), a greenhouse experiment (aimed at removal of other environmental factors affecting growth parameters, which are not manageable in the field) was conducted. Treatments consisted of two cultivars of rapeseed (Talaye and Zarfam), three levels of P (0, 25 and 50 mg/kg) and three levels of B (0, 2 and 4 mg/kg) with three replications. Results revealed that significant differences were observed between the rapeseed cultivars in seed yield, plant height, number of siliques per plant, 1000-seed weight, and seed nitrogen (N), P and B content and oil concentration. Increasing the P level significantly increased dry weight of seeds, straw and roots yield, biological yield, plant height, number of siliques per plant, 1000-seed weight, protein yield, seed oil yield and seed oil content (p≤0.05). However, N concentration of seeds decreased by P application. Soil-applied B significantly increased B concentration and total uptake, and seed oil concentration in both rapeseed cultivars. There was a positive and significant correlation between seed yield and protein yield, number of siliques per plant and 1000-seed weight. Application of P and B fertilizers increased concentration and total uptake of P and B in the seeds of both rapeseed cultivars. There was synergistic interaction between P and B on most of the studied traits; but its significance was different in the two cultivars. It is advised to do the same research in the field with more P and B treatments and diverse rapeseed cultivars.

A greenhouse experiment was conducted to evaluate the effectiveness of arbuscular mycorrhizal (AM) fungi in phytoremediation of lead (Pb)-contaminated soil by vetiver grass. Experiment was a factorial arranged in a completely randomized design. Factors included four Pb levels (50, 200, 400, and 800 mg kg(-1)) as Pb (NO3)2, AM fungi at three levels (non mycorrhizal (NM) control, Rhizophagus intraradices, Glomus versiforme). Shoot and root dry weights (SDW and RDW) decreased as Pb levels increased. Mycorrhizal inoculation increased SDW and RDW compared to NM control. With mycorrhizal inoculation and increasing Pb levels, Pb uptake of shoot and root increased compared to those of NM control. Root colonization increased with mycorrhizal inoculation but decreased as Pb levels increased. Phosphorus concentration and uptake in shoot of plants inoculated with AM fungi was significantly higher than NM control at 200 and 800 mg Pb kg(-1). The Fe concentration, Fe and Mn uptake of shoot in plants inoculated with Rhizophagus intraradices in all levels of Pb were significantly higher than NM control. Mycorrhizal inoculation increased Pb extraction, uptake and translocation efficiencies. Lead translocation factor decreased as Pb levels increased; however inoculation with AM fungi increased Pb translocation.

Zinc deficiency and salinity stress often limits crop production in many calcareous soils. It has been suggested that root organic acids are a response of plants to both conditions. The aim of this hydroponic experiment was to investigate the effect of salinity on organic acids (malic, citric and acetic acids) release by roots in maize plant, under Zinc deficiency conditions. Treatments consisted of three zinc levels (0, 0.5 and 1 μM) and three salinity levels (0, 30 and 60 mM NaCl and CaCl2 in 1:1 ratio). Results showed that mean shoot and root dry matter yields significantly increased with increasing zinc concentration in nutrient solution, but increase in salinity levels significantly decreased mean shoot and root dry matter yields. Salinity had higher detrimental effect on maize shoot dry matter yield compared to those of zinc-deficiency treatments. By increasing zinc concentration and salinity levels in nutrient solution, the rate of malic, citric and acetic acids exudation decreased. The highest rate of malic, citric and acetic acids exudation was 6.61, 1.06 and 0.66 mg g RDW−1 respectively, that observed to the lowest level of zinc (Zinc0) and salinity (0 mM). The highest rate of zinc transport occurred at 60 mM salinity level which had the lowest rate of organic acids exudation. The rate of malic acid was significantly higher than citric acid (4 times higher) and acetic acic (15 times higher). In conclusion, it seems that zinc concentration in maize shoot control the release of root exudation of organic acids. However, it is not clear that the elevated organic acids release under saline condition is due to the lower zinc transport from root to shoot or higher roots membrane permeability or a combination of both mechanisms.

One of the fast responding methods of plants to fertilizer application is foliar application, which saves fertilizer consumption too. Foliar application of micronutrients is a useful method, especially when roots are unable to absorb necessary elements from soil. The amount of available iron (Fe) in calcareous soils, with high pH, is low for sensitive plants, such as sorghum, to Fe deficiency. To compare the effect of foliar application of different Fe sources on growth traits, concentration and uptake of nutrients in sorghum, a greenhouse experiment was conducted as a completely randomized design with three replications. Treatments consisted of three levels of Fe (0, 90 and 180 mg Fe/L) from three sources of Fe (Fe nano-chelate, Fe-EDDHA and FeSO4.7H2O). Results showed that application of all three sources of Fe increased shoot and root dry matter yield, plant height, leaf chlorophyll content, shoot Fe concentration and uptake as compared to control treatment. Foliar application of Fe reduced concentrations of P and Mn in shoot, but had no significant effect on root P, Mn and Fe concentrations. Concentration of Zn and Cu in shoot and root of sorghum was not affected by level of Fe application. Based on the results of this experiment, foliar application of FeSO4.7H2O compared to Fe-EDDHA and Fe nano-chelate can increase growth and improve some characteristics of sorghum plants under greenhouse conditions. This result is economically affordable as well.

To evaluate the effects of different levels of iron (Fe) (from Fe-nano-chelate and Fe-EDDHA sources) on growth parameters, concentration and absorption of Fe and some nutrients in cowpea (Vigna unguiculata) in a calcareous soil, a greenhouse experiment was conducted based on completely randomized design with three replications. Treatments consisted of four levels of Fe (0, 0.135, 0.270 and 0.405 mg Fe per kg soil as Fe-nano-chelate or Fe-EDDHA). The studied soil (Fine-loamy, carbonatic, thermic, Typic Calcixerepts) had a loam texture with low available Fe content. Results showed that application of both Fe fertilizers increased shoot dry-matter yield, root dry matter yield, number of pods per plant, weight of pods and seeds per plant, grain weight per pot, shoot Fe concentration and Fe uptake by cowpea as compared to control treatment. Some of the evaluated growth parameters at all levels of Fe from Fe-nanochelate source were higher than the Fe-EDDHA source and some were the same and had no significant difference. Application of both Fe-nano-chelate and Fe-EDDHA decreased phosphorus and manganese concentrations in shoots as compared to control treatment. Concentration of zinc and cooper in shoots was not significantly affected by the Fe level. In conclusion, lower rates of Fe-nano-chelate were required, as compared to Fe-EDDHA, to alleviate iron deficiency in cowpea grown in calcareous soils.

The effect of different kinds of amendments including coal fly ash (CFA), municipal solid waste compost (MSWC), rice husk biochars prepared at 300°C (B300) and 600°C (B600), zero valent iron (Fe°) and zero valent manganese (Mn°) were evaluated to determine their ability to stabilize lead (Pb) in Pb-spiked soil. The Pb-spiked soils were separately incubated with amendments at the rates of 2 and 5% (W/W) for 45 and 90 days at 25°C. The efficacy of amendments treatment was evaluated by desorption kinetic experiment and sequential extraction producer. According to the results, with increasing time, considerable changes in distribution of chemical forms of Pb occurred and carbonate-bound fraction significantly decreased, while amorphous Fe-bound fraction significantly increased. The applied treatments efficiently decreased the mobility factor of Pb compared to control treatment. Application of Mn°, Fe°, CFA, MSWC, and B600 in soils significantly decreased Pb desorption rate with respect to control treatment. B...

Lead (Pb) contamination of soils is a widespread problem. Mycorrhizal inoculation and synthetic chelators such as ethylenediaminetetraacetic acid (EDTA) may be useful for improving phytoremediation efficiency in Pb-contaminated soils. A greenhouse experiment was performed to study the influence of inoculation with arbuscular mycorrhizal fungus (AMF), Glomus mosseae, and addition of EDTA on phytoremediation of Pb by sunflowers (Helianthus annuus) in a calcareous soil. The experiment was a completely randomized design in a factorial arrangement with five levels of Pb, two levels of mycorrhizal treatments, and two levels of EDTA. Inoculation increased root colonization as Pb levels increased, but the addition of EDTA decreased it. Shoot and root dry matter yields increased by inoculation; however, they decreased with EDTA and Pb levels in co-application treatments. Pb concentration in shoots was significantly higher than that in roots, indicating a translocation factor greater than 1. Inoculation or...

A greenhouse experiment was conducted to study seed quality, micronutrient contents and translocations in rapeseed as affected by nitrogen and zinc fertilizers. In this study, two cultivars of rapeseed (Licord and Modena), three N levels (100, 200 and 300 mg kg−1) and three Zn levels (0, 5 and 10 mg kg−1) with three replications were used. As N and Zn fertilizers’ rates increased, seed protein content and seed, shoot and root yield increased. The highest seed protein was obtained at 300 mg N kg−1 plus 10 mg Zn kg−1 treatment. Seed oil content was significantly decreased or increased at higher N and Zn rates, respectively. Application of N significantly increased Zn, Fe and Cu concentrations in seed, shoot and root, while decreased that of Mn. As Zn rates increased, concentration of Fe in seed and that of Zn in seed, shoot and root of both cultivars increased; however, Fe concentration in root and shoot and Mn and Cu concentrations in seed, root and shoot decreased. The average translocation of micronutrie...