Interactive Effects of Cd and NaCl on Growth and Mineral Nutrition in Hordeum vulgare L. (Var. Raihane)

In this work, we investigated the combined effect of salt and cadmium on plant nutrition and Cd accumulation in the most cultivated barley variety in Tunisia, Raihane. Seedling were hydroponically subjected to four different treatment: the control without salt and Cd, 50mM NaCl alone, 10µM Cd alone and to the combination of Cd (10 µM) and NaCl (50 mM) during 1 month. At the harvest, plant growth, Cd content in shoots and roots and tissue nutrient concentrations in shoots(Ca, Fe, Mn and Zn) were measured. 50 mM NaCl alone does not significantly affected the morphology and the biomass of plants. However, when subjected to 10 µM Cd alone, plants of barley were less developed and produced low biomass as compared to control ones. NaCl addition to the Cd-treated plants further reduces the development and biomass production. With respect to nutrient acquisition results showed that NCl alone reduced Ca2+ and Fe2+ concentration in the shoots but not affected that of Zn and Mn. But Cd, applied alone or combined with NaCl disturbed all measured element concentration in the shoots. However, the addition of salt to the Cd-containing medium reduced significantly Cd accumulation in the roots and the shoots of plants. In conclusion, salt in the water irrigation is able to reduce Cd accumulation in this barley variety but it accentuated in the same time the toxic effect of this heavy metal in barley. View Article DOI: 10.47856/ijaast.2022.v09i10.00

Nodulation of Sinorhizobium meliloti originated from a mining soil alleviates Cd toxicity and increases Cd-phytoextraction in Medicago sativa L

Besides their role in nitrogen supply to the host plants as a result of symbiotic N fixation, the association between legumes and Rhizobium could be useful for the rehabilitation of metal-contaminated soils by phytoextraction. A major limitation presents the metal-sensitivity of the bacterial strains. The aim of this work was to explore the usefulness of Sinorhizobium meliloti originated from a mining site for Cd phytoextraction by Medicago sativa. Inoculated and non-inoculated plants were cultivated for 60 d on soils containing 50 and/or 100 mg Cd kgˉ¹ soil. The inoculation hindered the occurrence of Cd- induced toxicity symptoms that appeared in the shoots of non-inoculated plants. This positive effect of S. meliloti colonization was accompanied by an increase in biomass production and improved nutrient acquisition comparatively to non-inoculated plants. Nodulation enhanced Cd absorption by the roots and Cd translocation to the shoots. The increase of plant biomass concomitantly with the increase of Cd shoot concentration in inoculated plants led to higher potential of Cd-phytoextraction in these plants. In the presence of 50 mg Cd kgˉ¹ in the soil, the amounts of Cd extracted in the shoots were 58 and 178 μg plantˉ¹ in non-inoculated and inoculated plants, respectively. This study demonstrates that this association M. sativa-S. meliloti may be an efficient biological system to extract Cd from contaminated soils

EDTA-enhanced phytoremediation of lead-contaminated soil by the halophyte Sesuvium portulacastrum

The low bioavailability of Pb and low number of Pb-tolerant plant species represent an important limitation for Pb phytoextraction. It was recently suggested that halophyte plant species may be a promising material for this purpose, especially in polluted salt areas while Pb mobility may be improved by synthetic chelating agents. This study aims to evaluate Pb extraction by the halophyte Sesuvium portulacastrum in relation to the impact of EDTA application. Seedling were cultivated during 60 days on Pb artificially contaminated soil (200, 400, and 800 ppm Pb) in the presence or in the absence of EDTA (3 g kg-1 soil). Results showed that upon to 400 ppm, Pb had no impact on plant growth. However, exogenous Pb induce a decrease in shoot K+ while it increased shoot Mg2+ and had no impact on shoot Ca2+ concentrations. Lead concentration in the shoots increased with increasing external Pb doses reaching 1,390 ppm in the presence of 800 ppm lead in soil. EDTA addition had no effect on plant growth but strongly increased Pb accumulation in the shoot which increased from 1,390 ppm in the absence of EDTA to 3,772 ppm in EDTA-amended plants exposed to 800 ppm exogenous Pb. Both Pb absorption and translocation from roots to shoots were significantly enhanced by EDTA application, leading to an increase in the total amounts of extracted Pb per plant. These data suggest that S. portulacastrum is very promising species for decontamination of Pb2+-contaminated soil and that its phytoextraction potential was significantly enhanced by addition of EDTA to the polluted soil. © 2014 Springer-Verlag Berlin Heidelberg

Nodulation by Sinorhizobium meliloti originated from a mining soil alleviates Cd toxicity and increases Cd-phytoextraction in Medicago sativa L

Besides their role in nitrogen supply to the host plants as a result of symbiotic N fixation, the association between legumes and Rhizobium could be useful for the rehabilitation of metal-contaminated soils by phytoextraction. A major limitation presents the metal-sensitivity of the bacterial strains. The aim of this work was to explore the usefulness of Sinorhizobium meliloti originated from a mining site for Cd phytoextraction by Medicago sativa. Inoculated and non-inoculated plants were cultivated for 60 d on soils containing 50 and/or 100 mg Cd kg−1 soil. The inoculation hindered the occurrence of Cd- induced toxicity symptoms that appeared in the shoots of non-inoculated plants. This positive effect of S. meliloti colonization was accompanied by an increase in biomass production and improved nutrient acquisition comparatively to non-inoculated plants. Nodulation enhanced Cd absorption by the roots and Cd translocation to the shoots. The increase of plant biomass concomitantly with the increase of Cd shoot concentration in inoculated plants led to higher potential of Cd-phytoextraction in these plants. In the presence of 50 mg Cd kg−1 in the soil, the amounts of Cd extracted in the shoots were 58 and 178 μg plant−1 in non-inoculated and inoculated plants, respectively. This study demonstrates that this association M. sativa-S. meliloti may be an efficient biological system to extract Cd from contaminated soils. © 2015 Ghnaya, Mnassri, Ghabriche, Wali, Poschenrieder, Lutts and Abdelly

Polyamine and tyramine involvement in NaCl-induced improvement of Cd resistance in the halophyte Inula chritmoides L

The aim of the present work was to analyze the impact of salinity on the plant response to Cd toxicity in the Mediterranean halophyte species Inula crithmoides. For this purpose, cuttings were cultivated hydroponically during 21d in the presence of 0, 25 or 50 μM CdCl2 combined or not with 0, 100, 200 and 400 mM NaCl. The obtained data demonstrated that, in the absence of Cd, NaCl strongly increased plant growth (the maximal dry weight being observed at 100 mM) and enhanced the Na+/K+ ratio in the shoot. Cd alone strongly affected plant growth in this halophyte. However, in Cd-treated plants, NaCl protected Inula crithmoides from Cd toxicity and contributed to reduce Cd absorption and translocation. Small aliphatic polyamine (putrescine, spermidine, spermine) increased in response to both NaCl and CdCl2, the highest concentration in plants being observed when both agents are present in the medium. The recorded increase preferentially concerned the polyamine bound fraction, which might be related to their involvement in the protection of endogenous cellular structures. The aromatic monoamine tyramine also strongly increased in response to Cd toxicity and its putative role is discussed in relation to conjugation processes. Salinity and Cd increased ammonium/nitrate ratio in leaves and roots and the involvement of stress-induced modification of N nutrition on polyamine oversynthesis is also discussed

Comparative study of Cd tolerance and accumulation potential between Cakile maritima L. (halophyte) and Brassica juncea L.

In this work we evaluated Cd-phytoextraction ability of the halophyte Cakile maritima comparatively to the glycophyte Brassica juncea commonly recommended for phytoextraction. Seedlings were grown in nutrient solution added with 0–100 M Cd for 21 days. Cd impaired growth in B. juncea but had no significant impact on C. maritima. The halophyte C. maritima maintained also higher photosynthetic activity than the glycophyte B. juncea. Cd decreased leaf chlorophyll (Chl) and carotenoids concentrations as well as PSII efficiency (Fv/Fm, Fv/F0 and ˚PSII) in B. juncea while it increased intercellular CO2 concentration in this species. Shoot Cd content was higher in the halophyte C. maritima reaching 1365 g g−1dw at 100 M while it was 548 g g−1dw in B. juncea at the same dose. The translocation factor (TF) was higher for C. maritima than for B. juncea at all external Cd doses. It is concluded that the halophyte C. maritima could be considered as a promising plant material for Cd-phytoextraction.

Comparative study of Pb-phytoextraction potential in Sesuvium portulacastrum and Brassica juncea: Tolerance and accumulation

Lead phytoextraction from salty soils is a difficult task because this process needs the use of plants which are able to tolerate salt and accumulate Pb2+ within in their shoots. It has recently been suggested that salt-tolerant plants are more suitable for heavy metals extraction than salt-sensitive ones commonly used in this approach. The aim of this study was to investigate Pb-phytoextraction potential of the halophyte Sesuvium portulacastrum in comparison with Brassica juncea commonly used in Pb-phytoextraction. Seedlings of both species were exposed in nutrient solution to 0, 200, 400, 800 and 1000 μM Pb2+ for 21 days. Lead strongly inhibited growth in B. juncea but had no impact on S. portulacastrum. Exogenous Pb2+ reduced nutrients uptake mainly in B. juncea as compared to S. portulacastrum. Lead was preferentially accumulated in roots in both species. S. portulacastrum accumulated more Pb2+ in the shoot than B. juncea. Hence, the amounts of Pb2+ translocated at 1000 μM Pb2+ were 3400 μg g−1 DW and 2200 μg g−1 DW in S. portulacastrum and B. juncea, respectively. These results suggest that S. portulacastrum is more efficient to extract Pb2+ than B. juncea

Agricultural valorization of domestic sewage sludge: Impact on growth, photosynthesis, nutrition and toxic metal accumulation in Medicago sativa

One of the best alternative disposals of sludge sewage is through the soil-plant system as a fertilizer. Sludge sewage is both an environmentally and economically sound way of recycling nutrients which are beneficial for plant nutrition. A field experiment using four doses (100, 200, 300 and 400 t ha-1) of an urban sludge was carried out to study the effect of its application on growth, photosynthesis and ion accumulation in Medicago sativa (an important forage crop species) in order to check its usefulness as a safe fertilizer. Results showed a positive effect of the amendment on growth, CO2assimilation, stomatal conductance and transpiration rate as well as Ca, Mg and Fe acquisition, especially at 2001 ha-1. For metals accumulation, data showed that up to 300 t ha-1, sludge presented no risk of contamination. Hence, we suggest that, up to 3001 ha-1, this amendment is suitable for agriculture