Search

The prevalence of inorganic pollutants in the environment, including heavy metals (HMs), necessitates a sustainable and cost-effective solution to mitigate their impacts on the environment and living organisms. The present research aimed to assess the phytoextraction capability of spinach (Spinach oleracea L.), under the combined effects of ascorbic acid (AA) and microwave (MW) irradiation amendments, cultivated using surgical processing wastewater. In a preliminary study, spinach seeds were exposed to MW radiations at 2.45 GHz for different durations (15, 30, 45, 60, and 90 seconds). Maximum germination was observed after the 30 seconds of radiation exposure. Healthy spinach seeds treated with MW radiations for 30 s were cultivated in the sand for two weeks, after which juvenile plants were transferred to a hydroponic system. Surgical industry wastewater in different concentrations (25 %, 50 %, 75 %, 100 %) and AA (10 mM) were provided to both MW-treated and untreated plants. The results revealed that MW-treatment significantly enhanced the plant growth, biomass, antioxidant enzyme activities and photosynthetic pigments, while untreated plants exhibited increased reactive oxygen species (ROS) and electrolyte leakage (EL) compared with their controls. The addition of AA to both MW-treated and untreated plants improved their antioxidative defense capacity under HMs-induced stress. MW-treated spinach plants, under AA application, demonstrated relatively higher concentrations and accumulation of HMs including lead (Pb), cadmium (Cd) and nickel (Ni). Specifically, MW-treated plants with AA amendment showed a significant increase in Pb concentration by 188 % in leaves, Cd by 98 %, and Ni by 102 % in roots. Additionally, the accumulation of Ni increased by 174 % in leaves, Cd by 168 % in roots, and Pb by 185 % in the stem of spinach plant tissues compared to MW-untreated plants. These findings suggested that combining AA with MW irradiation of seeds could be a beneficial strategy for increasing the phytoextraction of HMs from wastewater and improving overall plant health undergoing HMs stress. [Display omitted] • Low level microwave (MW) radiations increased seed germination and growth of spinach. • Surgical industrial wastewater differentially affected the growth of MW treated and untreated spinach. • Ni, Cd and Pb concentrations increased in spinach with increasing concentrations of surgical wastewaters. • Ascorbic acid improved the physiology and biochemistry of MW treated and untreated spinach. • Ascorbic acid increased Ni, Cd and Pb accumulation in both MW treated and untreated spinach grown under wastewater. [ABSTRACT FROM AUTHOR]

Soil contamination with heavy metals is threatening the food security around the globe. Chromium (Cr) contamination results in poor quality and reduction in yield of crops. The present research was performed to figure out the Cr toxicity in sunflower and the ameliorative role of 5-aminolevulinic acid (ALA) as a plant growth regulator. The sunflower (FH-614) was grown under increasing concentration of Cr (0, 5, 10 and 20 mg kg −1 ) alone and/or in combination with 5-ALA (0, 10 and 20 mg L −1 ). Results showed that Cr suppressed the overall growth, biomass, gas exchange attributes and chlorophyll content of sunflower plants. Moreover, lower levels of Cr (5 and 10 mg kg −1 ) increased the production of reactive oxygen species (ROS) and electrolyte leakage (EL) along with the activities of antioxidant enzymes i.e., superoxide dismutase (SOD), guaiacole peroxidase (POD), ascorbate (APX), catalase (CAT). But at higher concentration of Cr (20 mg kg −1 ), the activities of these enzymes presented a declining trend. However, the addition of 5-ALA significantly alleviated the Cr-induced toxicity in sunflower plant and enhanced the plant growth and biomass parameters along with increased chlorophyll content, gas exchange attributes, soluble proteins and soil plant analysis development (SPAD) values by scavenging the ROS and lowering down the EL. The 5-ALA also enhanced the activities of antioxidant enzymes at all levels of Cr. The increase in Cr concentration in all plant parts such as leaf, root and stem was directly proportional to the Cr concentration in soil. The application of 5-ALA further enhanced the uptake of Cr and its concentration in the plants. To understand this variation in response of plants to 5-ALA, detailed studies are required on plant biochemistry and genetic modifications. [ABSTRACT FROM AUTHOR]

Soil and water contamination from heavy metals and metalloids is one of the most discussed and burning global issues due to its potential to cause the scarcity of healthy food and safe water. The scientific community is proposing a range of lab and field based physical, chemical and biological solutions to remedy metals and metalloids contaminated soils and water. The present study finds out a possibility of Chromium (Cr) extraction by sunflower from spiked soil under chelating role of citric acid (CA). The sunflower plants were grown under different concentrations of Cr (0, 5, 10 & 20 mg kg −1 ) and CA (0, 2.5 & 5 mM). Growth, biomass, gas exchange, photosynthesis, electrolyte leakage (EL), reactive oxygen species (ROS; malondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ) and the activities of antioxidant enzymes such as, superoxide dismutase (SOD), guaiacole values peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT) were measured. The results depicted a clear decline in plant height, root length, leaf area, number of leaves and flowers per plant along with fresh and dry biomass of all parts of plant with increasing concentration of Cr in soil. Similar reduction was observed in chlorophyll a and b, total chlorophyll, carotenoids, soluble protein, gas exchange attributes and SPAD. The increasing concentration of Cr also enhanced the Cr uptake and accumulation in plant roots, stem and leaves along with the production of ROS and EL. The activities of antioxidant enzymes increased with increasing Cr concentration from 0 to 10 mg, but decreased at 20 mg kg −1 soil. The CA application significantly alleviated Cr-induced inhibition of plant growth, biomass, photosynthesis, gas exchange, soluble proteins and SPAD value. Presence of CA also enhanced the activities of all antioxidant enzymes and reduced the production of ROS and EL. The chelating potential of CA increased the concentration and accumulation of Cr in plant roots, stem and leaves. It is concluded that the sunflower can be a potential candidate for the remediation of Cr under CA treatment, while the possibility may vary with genotype, Cr level and CA concentration. [ABSTRACT FROM AUTHOR]

The present study was aimed to evaluate the morphological, physiological and biochemical responses of Alternanthera Bettzickiana (Regel) G. Nicholson plant subjected to different levels of cadmium (Cd) and lead (Pb) (0, 0.5, 1.0 and 2.0 mM) stress. A. bettzickiana was able to accumulate Cd and Pb in different plant parts and total uptake of both metals was higher in shoots than roots. Plant growth, biomass and photosynthetic pigments increased with increasing metal concentrations, up to 1.0 mM, in soil and then decreased with higher metal levels. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) increased under lower metal levels (0.5 and 1.0 mM) while decreased at higher metal levels (2.0 mM). Leaf and root electrolyte leakage (EL), malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2 ) contents decreased at lower metal levels (≤1.0 mM) while increased at higher levels. The present study clearly signifies the potential of A. bettzickiana plant towards Cd and Pb tolerance and accumulation especially at lower metal levels. [ABSTRACT FROM AUTHOR]

Chromium (Cr) is one of the most phytotoxic metals in the agricultural soils and its concentration is continuously increasing mainly through anthropogenic activities. Little is known on the role of mannitol (M) on plant growth and physiology under metal stress. The aim of this study was to investigate the mechanism of growth amelioration and antioxidant enzyme activities in Cr-stressed wheat ( Triticum aestivum L. cv. Lasani 2008) by exogenously applied mannitol. For this, wheat seedlings were sown in pots containing soil or sand and subjected to increasing Cr concentration (0, 0.25 and 0.5 mM) in the form of of K 2 Cr 2 O 7 with and without foliar application of 100 mM mannitol. Plants were harvested after four months and data regarding growth characteristics, biomass, photosynthetic pigments, and antioxidant enzymes were recorded. Mannitol application increased plant biomass, photosynthetic pigments and antioxidant enzymes while decreased Cr uptake and accumulation in plants as compared to Cr treatments alone. In this study, we observed that M applied exogenously to Cr-stressed wheat plants, which normally cannot synthesize M, improved their Cr tolerance by increasing growth, photosynthetic pigments and enhancing activities of antioxidant enzymes and by decreasing Cr uptake and translocation in wheat plants. From this study, it can be concluded that M could be used to grow crops on marginally contaminated soils for which separate remediation techniques are time consuming and not cost effective. [ABSTRACT FROM AUTHOR]

Use of organic acids for promoting heavy metals phytoextraction is gaining worldwide attention. The present study investigated the influence of citric acid (CA) in enhancing copper (Cu) uptake by Brassica napus L. seedlings. 6 Weeks old B. napus seedlings were exposed to different levels of copper (Cu, 0, 50 and 100 µM) alone or with CA (2.5 mM) in a nutrient medium for 40 days. Exposure to elevated Cu levels (50 and 100 µM) significantly reduced the growth, biomass production, chlorophyll content, gas exchange attributes and soluble proteins of B. napus seedlings. In addition, Cu toxicity increased the production of hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA) and electrolyte leakage (EL) in leaf and root tissues of B. napus . Activities of antioxidant enzymes such as guaiacol peroxidase (POD), superoxide dismutase (SOD), catalases (CAT), ascorbate peroxidase (APX) in root and shoot tissues of B. napus were increased in response to lower Cu concentration (50 µM) but increased under higher Cu concentration (100 µM). Addition of CA into nutrient medium significantly alleviated Cu toxicity effects on B. napus seedlings by improving photosynthetic capacity and ultimately plant growth. Increased activities of antioxidant enzymes in CA-treated plants seems to play a role in capturing of stress-induced reactive oxygen species as was evident from lower level of H 2 O 2 , MDA and EL in CA-treated plants. Increasing Cu concentration in the nutrient medium significantly increased Cu concentration in in B. napus tissues. Cu uptake was further increased by CA application. These results suggested that CA might be a useful strategy for increasing phytoextraction of Cu from contaminated soils. [ABSTRACT FROM AUTHOR]

In present era, heavy metal pollution is rapidly increasing which present many environmental problems. These heavy metals are mainly accumulated in soil and are transferred to food chain through plants grown on these soils. Silicon (Si) is the second most abundant element in the soil. It has been widely reported that Si can stimulate plant growth and alleviate various biotic and abiotic stresses, including heavy metal stress. Research to date has explored a number of mechanisms through which Si can alleviate heavy metal toxicity in plants at both plant and soil levels. Here we reviewed the mechanisms through which Si can alleviate heavy metal toxicity in plants. The key mechanisms evoked include reducing active heavy metal ions in growth media, reduced metal uptake and root-to-shoot translocation, chelation and stimulation of antioxidant systems in plants, complexation and co-precipitation of toxic metals with Si in different plant parts, compartmentation and structural alterations in plants and regulation of the expression of metal transport genes. However, these mechanisms might be associated with plant species, genotypes, metal elements, growth conditions, duration of the stress imposed and so on. Further research orientation is also discussed. [ABSTRACT FROM AUTHOR]

Phytoextraction is an environmentally friendly and a cost-effective strategy for remediation of heavy metal contaminated soils. However, lower bioavailability of some of the metals in polluted environments e.g. lead (Pb) is a major constraint of phytoextraction process that could be overcome by applying organic chelators. We conducted a glasshouse experiment to evaluate the role of citric acid (CA) in enhancing Pb phytoextraction. Brassica napus L. seedlings were grown in hydroponic media and exposed to various treatments of Pb (50 and 100 μM) as alone or in combination with CA (2.5 mM) for six weeks. Pb-induced damage in B. napus toxicity was evident from elevated levels of malondialdehyde (MDA) and H2O2 that significantly inhibited plant growth, biomass accumulation, leaf chlorophyll contents and gas exchange parameters. Alternatively, CA application to Pb-stressed B. napus plants arrested lipid membrane damage by limiting MDA and H2O2 production and by improving antioxidant enzyme activities. In addition, CA significantly increased the Pb accumulation in B. napus plants. The study concludes that CA has a potential to improve Pb phytoextraction without damaging plant growth. [ABSTRACT FROM AUTHOR]

Phytoextraction is an eco-friendly and cost-effective technique for removal of toxins, especially heavy metals and metalloids from contaminated soils by the roots of high biomass producing plant species with subsequent transport to aerial parts. Lower metal bioavailability often limits the phytoextraction. Organic chelators can help to improve this biological technique by increasing metal solubility. The aim of the present study was to investigate the possibility of improving the phytoextraction of Cd by the application of citric acid. For this purpose, plants were grown in hydroponics under controlled conditions. Results indicated that Cd supply significantly decreased the plant growth, biomass, pigments, photosynthetic characteristics and protein contents which were accompanied by a significant increase in Cd concentration, hydrogen peroxide (H2O2), electrolyte leakage, malondialdehyde (MDA) accumulation and decrease in antioxidant capacity. The effects were dose dependent with obvious effects at higher Cd concentration. Application of CA significantly enhanced Cd uptake and its accumulation in plant roots, stems and leaves. Citric acid alleviated Cd toxicity by increasing plant biomass and photosynthetic and growth parameters alone and in combination with Cd and by reducing oxidative stress as observed by reduction in MDA and H2O2 production and decreased electrolyte leakage induced by Cd stress. Application of CA also enhanced the antioxidant enzymes activity alone and under Cd stress. Thus, the data indicate that exogenous CA application can increase Cd uptake and minimize Cd stress in plants and may be beneficial in accelerating the phytoextraction of Cd through hyper-accumulating plants such as Brassica napus L. [Copyright &y& Elsevier]