Fluorine in 20 vegetable species and 25 lettuce cultivars grown on a contaminated field adjacent to a brick kiln.

Crops grown in areas contaminated by industrial and agricultural fluorine (F) have gained increasing attention, however F levels in different vegetables and lettuce cultivars are rarely reported. In situ-field experiment was designed to investigate the concentration, translocation, and health risks of F in 20 vegetable species and 25 lettuce cultivars. After the growth of 150 d for vegetables and 60 d for lettuce, F concentration (12.83-138.07 mg kg-1), translocation factor (0.16-6.32), and bio-concentration factor (1.90-13.73) varied significantly between vegetable species and lettuce cultivars. According to the hazard quotient values (based on the reference dose of F), all the vegetable species appears to pose no risk to human health, while 60% of the lettuce cultivars present potential health risks to children. Therefore, the limit value of F in vegetables for adults and children should be enacted in the future. Moreover, cabbage, green radish, spinach, leaf mustard, and Frisee lettuce (Huayu) were considered as a safe dietary product. These findings contributed to the safe cultivation of vegetables and the control of fluorosis in the areas contaminated by industrial and agricultural activities.

Soil properties drive the bacterial community to cadmium contamination in the rhizosphere of two contrasting wheat (Triticum aestivum L.) genotypes.

Cadmium (Cd) bioavailability in the rhizosphere makes an important difference in grain Cd accumulation in wheat. Here, pot experiments combined with 16S rRNA gene sequencing were conducted to compare the Cd bioavailability and bacterial community in the rhizosphere of two wheat (Triticum aestivum L.) genotypes, a low-Cd-accumulating genotype in grains (LT) and a high-Cd-accumulating genotype in grains (HT), grown on four different soils with Cd contamination. Results showed that there was non-significant difference in total Cd concentration among four soils. However, except for black soil, DTPA-Cd concentrations in HT rhizospheres were higher than those of LT in fluvisol, paddy soil and purple soil. Results of 16S rRNA gene sequencing showed that soil type (52.7%) was the strongest determinant of root-associated community, while there were still some differences in rhizosphere bacterial community composition between two wheat genotypes. Taxa specifically colonized in HT rhizosphere (Acidobacteria, Gemmatimonadetes, Bacteroidetes and Deltaproteobacteria) could participate in metal activation, whereas LT rhizosphere was highly enriched by plant growth-promoting taxa. In addition, PICRUSt2 analysis also predicted high relative abundances of imputed functional profiles related to membrane transport and amino acid metabolism in HT rhizosphere. These results revealed that the rhizosphere bacterial community may be an important factor regulating Cd uptake and accumulation in wheat and indicated that the high Cd-accumulating cultivar might improve Cd bioavailability in the rhizosphere by recruiting taxa related to Cd activation, thus promoting Cd uptake and accumulation.

Cadmium phytoextraction through Brassica juncea L. under different consortia of plant growth-promoting bacteria from different ecological niches.

Combined bioaugmentation inoculants composed of two or more plant growth-promoting bacteria (PGPB) were more effective than single inoculants for plant growth and cadmium (Cd) removal in contaminated soils. However, the principles of consortia construction still need to be discovered. Here, a pot experiment with Cd natural polluted soil was conducted and PGPB consortia with different ecological niches from hyperaccumulator Sedum alfredii Hance were used to compare their effects and mechanisms on plant growth condition, Cd phytoextraction efficiency, soil enzymatic activities, and rhizospheric bacterial community of Brassica juncea L. The results showed that both rhizospheric and endophytic PGPB consortia inoculants promoted plant growth (6.9%-22.1%), facilitated Cd uptake (230.0%-350.0%) of oilseed rape, increased Cd phytoextraction efficiency (343.0%-441.0%), and enhanced soil Cd removal rates (92.0%-144.0%). PGPB consortia inoculants also enhanced soil microbial carbon by 22.2%-50.5%, activated the activities of soil urease and sucrase by 74.7%-158.4% and 8.4%-61.3%, respectively. Simultaneously, PGPB consortia inoculants increased the relative abundance of Flavobacterium, Rhodanobacter, Kosakonia, Pseudomonas and Paraburkholderia at the genus level, which may be beneficial to plant growth promotion and bacterial phytopathogen biocontrol. Although the four PGPB consortia inoculants promoted oilseed growth, amplified Cd phytoextraction, and changed bacterial community structure in rhizosphere soil, their original ecological niches were not a decisive factor for the efficiency of PGPB consortia. therefore, the results enriched the present knowledge regarding the significant roles of PGPB consortia as bioaugmentation agents and preliminarily explored construction principles of effective bioaugmentation inoculants, which will provide insights into the microbial responses to combined inoculation in the Cd-contaminated soils.

Cadmium accumulation in rice straws and derived biochars as affected by metal exposure, soil types and rice genotypes.

Straw residues, as one of the conservation farming practices, are being strongly encouraged in China, including some cadmium-polluted areas. Nowadays, a portion of this plant residue is promoted to be removed for reducing excess metal(loid) in the soil and to be used for bioenergy production. Nevertheless, the possible influences of contaminated straw or the burial of its derived biochars on Cd accumulation in soil and data based on health risk assessment associated with different status and extent of soil contamination were relatively unknown. Thus it is important to provide a more systematical understanding of contaminated straw burial at specific contamination zones, which may provide useful guidance for straw utilization. In this study, we harvested two genotypes of rice straw from 6 contaminated levels among three soil types to comprehensively study the total Cd contents in straws and its derived biochars and correlate the sets of straw characteristics and Cd contents in three different contamination zones. The total Cd concentration in straws grew at a steady rate relatively with increasing soil Cd contamination levels, compared to those in biochars which performed more fluctuate due to the strong burning. According to correlational analyses, three-way ANOVA showed that the moisture, ash, volatile and fixed carbon were all significantly affected by straw CdTotal contents (p < 0.001). Such relationships were attributed to guide straw removal portions for gasification. Meanwhile, there was a significant correlation between straw Cd concentration and soil types (p < 0.001), confirming that it might be worth determining soil remediation by straw removal according to site-specific farmland conditions. This work will help to assess efforts toward predicting Cd concentration in the paddy soils related to kinds of contamination status and would also give useful guidance to make sustainable management strategies for crop straws in polluted regions.Novelty statement This work provided data on how much rice straw is needed to remove to ensure the minimal amount to control soil contamination and reduce costs according to site-specific conditions and soil Cd contamination status. It also explains the correlations between straw characteristics related to bioenergy use and soil conditions which would give guidance to balance using crop straw for increased bioenergy production and the need to also protect, preserve, and enhance soil resources.

Organic/inorganic amendments for the remediation of a red paddy soil artificially contaminated with different cadmium levels: Leaching, speciation, and phytoavailability tests.

In the present study, the viability of using manure (M), lime (L), and sepiolite (S) alone and in combinations (M/L, M/S, and M/L/S) was evaluated for the remediation of a red paddy soil artificially contaminated with three levels of cadmium (Cd- 0.6, 1, and 2 mg kg-1 soil). Experiments were performed in columns (to evaluate Cd leaching) and pots by growing rice plants (to study Cd accumulation in plants). Before their application, the tested amendments were thoroughly characterized using SEM, EDS and FT-IR spectroscopy. The leaching experiment indicates that the application of L or M/L significantly improved the pH of soil leachate collected at different time intervals. However, the use of M/L/S was found better in decreasing the Cd contents in collected leachate. The use of M/L efficiently decreased the DTPA metal extraction (0.19, 0.41, and 0.55 mg kg-1) as compared to the CK (0.35, 0.63, and 1.13 mg kg-1, respectively). The Cd speciation results depicted a 33% decrease in exchangeable Cd with M/L/S treatment when compared with control (55%). Moreover, the M/L/S treatment was more efficient in lowering the Cd phytoavailability and subsequent accumulation in rice grains (0.05, 0.09, and 0.08 mg kg-1). These findings demonstrate that the use of composite amendments is categorically effective as an in-situ remediation tool to decrease Cd leaching and availability in diverse contaminations.

Variations in phytoremediation potential and phytoavailability of heavy metals in different Salix genotypes subjected to seasonal flooding.

Climate-related flooding poses a potential challenge to phytoremediation of metal polluted areas. In the present study, uptake, translocation and accumulation of heavy metals (Cd, Zn and Cu), and their phytoavailability in six flood-tolerant Salix genotypes were investigated under simulated seasonal flooding conditions (non-flooding conditions were kept as the control). Plants were cultivated in a greenhouse with open windows using the soil polluted with Cd, Zn and Cu for 110 days. All the control (non-flooded) genotypes did not exhibit visible toxic symptoms, whereas the flooded genotypes showed leaf chlorosis and developed both lenticels and adventitious roots. Biomass production and metal accumulation in tissues varied with Salix genotypes. The flooded genotypes dramatically decreased aerial biomass production compared with corresponding non-flooded genotypes. All the control Salix genotypes showed relatively high accumulation for Cd, Zn and Cu in aerial parts due to high EDTA-extractable metals in the rhizosphere, exhibiting phytoextraction features. In contrast, the flooded genotypes drastically decreased uptake, translocation, accumulation, and extraction capacities for Cd, Zn and Cu in aerial parts, differing with genotypes, and tended to phyto-stabilize them in roots, especially Cu. This study indicated that flooding is a leading factor on phytoremediation efficiency for contaminated sites with willows.

The endophytic bacterium Sphingomonas SaMR12 alleviates Cd stress in oilseed rape through regulation of the GSH-AsA cycle and antioxidative enzymes.

BACKGROUND: Microbes isolated from hyperaccumulating plants have been reported to be effective in achieving higher phytoextraction efficiency. The plant growth-promoting bacteria (PGPB) SaMR12 from the cadmium (Cd)/zinc hyperaccumulator Sedum alfredii Hance could promote the growth of a non-host plant, oilseed rape, under Cd stress. However, the effect of SaMR12 on Brasscia juncea antioxidative response under Cd exposure was still unclear. RESULTS: A hydroponic experiment was conducted to study the effects of Sphingomonas SaMR12 on its non-host plant Brassica juncea (L.) Czern. under four different Cd treatments. The results showed that SaMR12 could colonize and aggregate in the roots and then move to the shoots. SaMR12 inoculation promoted plant growth by up to 71% in aboveground biomass and 81% in root biomass over that of the non-inoculated plants. SaMR12-inoculated plants significantly enhanced root Cd accumulation in the 10 and 20 µM Cd treatments, with 1.72- and 0.86-fold increases, respectively, over that of the non-inoculated plants. SaMR12 inoculation not only decreased shoot hydrogen peroxide (H2O2) content by up to 38% and malondialdehyde (MDA) content by up to 60% but also reduced proline content by 7-30% in shoots and 17-32% in roots compared to the levels in non-inoculated plants. Additionally, SaMR12 inoculation promoted the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) and facilitated the relative gene expression levels of dehydroascorbate reductase (DHAR) and glutathione reductase (GR) involved in the glutathione (GSH)-ascorbic acid (AsA) cycle. CONCLUSIONS: The results demonstrated that, under Cd stress, SaMR12 inoculation could activate the antioxidative response of B. juncea by decreasing the concentrations of H2O2, MDA and proline, increasing the activities of antioxidative enzymes, and regulating the GSH-AsA cycle. These results provide a theoretical foundation for the potential application of hyperaccumulator endophytic bacteria as remediating agents to improve heavy metal tolerance within non-host plant species, which could further improve phytoextraction efficiency.

Genetic and physiological regulation of folate in pak choi (Brassica rapa subsp. Chinensis) germplasm.

Folates are one of the essential micronutrients for all living organisms. Due to inadequate dietary intake, folate deficiency remains prevalent in humans. Genetically diverse germplasms can potentially be used as parents in breeding programs and also for understanding the folate regulatory network. Therefore, we investigated the natural genetic diversity of folates and their physiological regulation in pak choi (Brassica rapa subsp. Chinensis) germplasm. The total folate concentration ranged from 52.7 µg 100 gFW-1 to 166.9 µg 100 gFW-1, with 3.2-fold variation. The main folate vitamer was represented by 5-CH3-H4folate, with 4.5-fold variation. The activities of GTP cyclohydrolase I and aminodeoxy chorismate synthase, the first step of folate synthesis, were high in high folate accessions and low in low folate accessions. Analysis of the transcription levels of 11 genes associated with folate metabolism demonstrated that the difference in folate concentrations may be primarily controlled at the post-transcriptional level. A general correlation between total folate and their precursors was observed. Folate diversity and chlorophyll content were tightly regulated through the methyl cycle. The diverse genetic variation in pak choi germplasm indicated the great genetic potential to integrate breeding programs for folate biofortification and unravel the physiological basis of folate homeostasis in planta.

Study amino acid contents, plant growth variables and cell ultrastructural changes induced by cadmium stress between two contrasting cadmium accumulating cultivars of Brassica rapa ssp. chinensis L. (pak choi).

Cadmium (Cd) is an inauspicious abiotic traction that not only influences crop productivity and its growth parameters, but also has adverse effects on human health if these crops are consumed. Among crops, leafy vegetables which are the good source of mineral and vitamins accumulate more Cd than other vegetables. It is thus important to study photosynthetic variables, amino acid composition, and ultrastructural localization of Cd differences in response to Cd accumulation between two low and high Cd accumulating Brassica rapa ssp. chinensis L. (pak choi) cultivars, differing in Cd accumulation ability. Elevated Cd concentrations significantly lowered plant growth rate, biomass, leaf gas exchange and concentrations of amino acids collated to respective controls of both cultivars. Electron microscopy indicated that the impact of high Cd level on ultrastructure of leaf cells was associated to affecting cell functionalities, i.e. irregular cell wall, withdrawal of cell membrane, and chloroplast structure which has negative impact on photosynthetic activities, thus causing considerable plant growth suppression. Damage in root cells were observed in the form of enlargement of vacuole. The energy dispersive micro X-ray spectroscopy of both cultivars leaves indicated that cellular structure exhibited exudates of Cd-dense material. Ultrastructural damages and phytotoxicity were more pronounced in high accumulator cultivar as compared to the low accumulator cultivar. These findings are useful in determining the mechanisms of differential Cd-tolerance among cultivars with different Cd tolerance abilities at cellular level.

Adsorption of Cd and Pb in contaminated gleysol by composite treatment of sepiolite, organic manure and lime in field and batch experiments.

Contamination of arable land with trace metals is a global environmental issue which has serious consequences on human health and food security. Present study evaluates the adsorption of cadmium (Cd) and lead (Pb) by using different quantities of composite of sepiolite, organic manure and lime (SOL) at field and laboratory scale (batch experiments). Characterization of SOL by SEM, EDS and FTIR spectroscopy revealed the presence of elemental and functional groups (hydroxyl, C⋯H and -COOH groups) on its surface. The field experiment was performed in a paddy field of gleysol having moderate contamination of Cd and Pb (0.64 mg kg-1 and 53.44 mg kg-1). Here, different rates of SOL (0.25, 0.5, 1, 1.5 and 2% w/w) were applied by growing low and high Cd accumulator rice cultivars. Application of SOL at 2% w/w showed considerable efficiency to increase soil pH (up to 19%) and to reduce available Cd (42-66%) and Pb (22-55%) as compared to the control. Moreover, its application reduced metal contents in roots, shoots and grains of rice by 31%, 36% and 72% (for Cd) and 41%, 81% and 84% (for Pb), respectively in low accumulator cultivar. Further, the batch sorption experiment was performed to evaluate the adsorption capacity of SOL in a wide range of contamination. Obtained sorption data was better fitted to the Langmuir equation. Our results highlight the strong efficiency of composite treatment for an enhanced in-situ metal immobilization under field and lab conditions. Further, applied treatments greatly reduced the metal contents in rice grains. In a nut shell, application of SOL in a contaminated gleysol should be considered for soil remediation and safe food production.

Identification of high cadmium-accumulating oilseed sunflower (Helianthus annuus) cultivars for phytoremediation of an Oxisol and an Inceptisol.

Forty oilseed sunflower cultivars were screened in two soil types for phytoremediation of Cd coupled with maximum biomass yield and oil production. Several cultivars exhibited a significant difference in biomass and yield with enhanced uptake in shoots and low accumulation in roots from two Cd-contaminated soil types, an Oxisol and an Iceptisol. The Transfer Factor of Cd was >1 in several cultivars in both soil types, where as a significant difference in phytoextraction of Cd was observed in the Oxisol (acidic soil), greater than in the Inceptisol (alkaline soil). The results revealed that of the 40 cultivars, S9178, Huanong 667in the Oxisol and cvs. DW 667, HN 667, Huanong 667 and 668F1 in the Inceptisol showed a high biomass, better yield and enhanced accumulation of Cd in the shoots but a lesser accumulation in oil. The screened cultivar S 9178 produced the greatest amount of oil (55.6%) with 77% oleic acid, which makes it suitable for human consumption. Cultivar Huanong 667 was found to be the highest accumulating cultivar in both soil types. It is therefore suggested that some sunflower cultivars do exhibit phytoremediation potential together with agro-production potential.

Interactions between cadmium and zinc in uptake, accumulation and bioavailability for Salix integra with respect to phytoremediation.

The willow (Salix spp.) is a potential accumulator of cadmium (Cd)/zinc (Zn), and the interaction between Cd and Zn is an important factor influencing their phytoextraction potentials. In this study, interactions between Cd and Zn in uptake, accumulation and bioavailability for Salix integra clone SI63 were investigated through nutrient solution and soil culture methods. The result of the soil culture showed that Cd had additive effects for Zn-caused biomass reduction. The result from nutrient solution indicated that added Zn showed antagonistic (low Cd level) or synergistic (moderate and high Cd levels) effects on shoot Cd accumulation and antagonistic effects on root Cd accumulation. Irrespective of nutrient solution or soil culture experiment, Cd addition always had antagonistic effects on Zn accumulation in both shoots and roots. Under Cd10Zn50 condition, the clone accumulated higher Cd and Zn concentrations (95 µg g-1 Cd and 165 µg g-1 Zn) in shoots. Cd slightly increased bioavailable Zn in the rhizosphere, and EDTA well predicted bioavailable Cd and Zn in the rhizosphere. Interactions of Cd-Zn markedly changed their respective phytoextraction potentials, especially for Zn. This result will provide a new insight into improving phytoextraction potentials of both Cd and Zn using willows through applying metal interactions.

Comparative assessment of Brassica pekinensis L. genotypes for phytoavoidation of nitrate, cadmium and lead in multi-pollutant field.

Information is needed for comparative assessment and agronomic practices for phytoavoidation in multi-pollutant field. A field study was conducted to explore 97 Brassica pekinensis L. genotypes with permissible limit of contaminants growing in a severely Cd, moderately nitrate and slightly Pb multi-polluted field. Thirteen genotypes, i.e. KGZY, CXQW, CAIB, JINL, JQIN, JFEN, WMQF, XLSH, TAIK, BJXS, JUKA, XYJQ and GQBW, were identified with permissible limit for nitrate, Cd and Pb based on their resistance to heavy metal and nitrate accumulation in leaves when grown in co-contaminated soils. Furthermore, the correlation between essential and toxic elements concentrations in plant of B. pekinensis were inconsistent. Generally speaking, application of increasing Ca, K and S fertilizers in appropriate forms and dosages tended to increase the yield and quality of B. pekinensis cultivated in multi-pollutant field.

Immobilization and sorption of Cd and Pb in contaminated stagnic anthrosols as amended with biochar and manure combined with inorganic additives.

The present study evaluated the efficiency of pre-selected composite amendments (CA-1: biochar-lime-sepiolite-zeolite and CA-2: manure-lime-sepiolite) for immobilization and sorption of Cd and Pb in field and batch sorption experiments. The field experiment was performed in a co-contaminated clay purple soil (stagnic anthrosols). Along with a control experiment (T1), CA-1 and CA-2 were tested at different rates including 750, 1500, 3000 and 6000 kg ha-1 by growing wheat as the test crop. The obtained results revealed that the highest dose of both composites (T5: 6000 kg ha-1 and T9: 6000 kg ha-1) increased the soil pH to 6.85 and 6.81, respectively as compared to the control (5.63). DTPA-extractable Cd and Pb contents decreased with composite treatments (T7 and T4) at harvest stage samples. Metal fractionation depicted that application of amendments decreased the exchangeable fraction at harvesting stage. Application of CA-2 and CA-1 (3000 kg ha-1) significantly increased the plant biomass (by 28% and 24%, respectively) and grain yield (by 26% and 22%, respectively) of wheat. Furthermore, batch sorption experiment results revealed that Langmuir adsorption model better fitted the sorption results with R2 values ranging between 0.99 and 0.91 for Cd and Pb, respectively. CA-1 and CA-2 exhibited the maximum adsorption capacity for Cd with no significant difference among treatments but Pb adsorption capacity was highest in CA-1 followed by CA-2 and control. The results of our experiments revealed that the application of organics combined with inorganic materials enhanced Cd and Pb immobilization and sorption, consequently reducing metals availability in laboratory and field conditions. Moreover, for field trials, application of the composite amendments at 3000 kg ha-1 emerged as the suitable treatment for tested wheat-grown area.

Assessment of sunflower germplasm for phytoremediation of lead-polluted soil and production of seed oil and seed meal for human and animal consumption.

Phytoremediation is a valuable technology for mitigating soil contamination in agricultural lands, but phytoremediation without economic revenue is unfeasible for land owners and farmers. The use of crops with high biomass and bioenergy for phytoremediation is a unique strategy to derive supplementary benefits along with remediation activities. Sunflower (Helianthus annuus L.) is a high-biomass crop that can be used for the phytoremediation of polluted lands with additional advantages (biomass and oil). In this study, 40 germplasms of sunflower were screened in field conditions for phytoremediation with the possibility for oil and meal production. The study was carried out to the physiological maturity stage. All studied germplasms mopped up substantial concentrations of Pb, with maximum amounts in shoot > root > seed respectively. The phytoextraction efficiency of the germplasm was assessed in terms of the Transfer factor (TF), Metal removal efficiency (MRE) and Metal extraction ratio (MER). Among all assessed criteria, GP.8585 was found to be most appropriate for restoring moderately Pb-contaminated soil accompanied with providing high biomass and high yield production. The Pb content in the oil of GP.8585 was below the Food safety standard of China, with 59.5% oleic acid and 32.1% linoleic acid. Moreover, amino acid analysis in meal illustrated significant differences among essential and non-essential amino acids. Glutamic acid was found in the highest percentage (22.4%), whereas cysteine in the lowest percentage (1.3%). Therefore, its efficient phytoextraction ability and good quality edible oil and meal production makes GP.8585 the most convenient sunflower germplasm for phytoremediation of moderately Pb-contaminated soil, with fringe benefits to farmers and landowners.

Promotion of the root development and Zn uptake of Sedum alfredii was achieved by an endophytic bacterium Sasm05.

Endophyte-assisted phytoremediation has gained increasing attention. However, the interacting mechanisms of endophytes and metal hyperaccumulators are still not clear. An endophytic bacterium Pseudomonas fluorescens Sasm05 inoculation promoted Sedum alfredii Hance rooting and root development, in which the specific root length (SRL) and average number of root tips (ART) increased to 2.09- and 3.35-fold, respectively. Sasm05 inoculation promoted plant growth, increased the chlorophyll content, and elevated Zn uptake of plant at excess Zn supply. At 200 µM Zn treatment level, Sasm05 inoculation increased plant biomass and the chlorophyll content by more than 40%, and root Zn content by 40%. Furthermore, Sasm05 inoculation upregulated the expression of the Zn transporter SaIRT1 to 3.43-fold in the roots, while another transporter SaNramp1 expression was increased to 38.66-fold in the roots and 7.53-fold in the shoots. Time course study showed the best effects of Sasm05 on plant biomass and the chlorophyll content were detected at 30 d, while for Zn content at 3 d. These results firstly provided molecular evidences of endophytic bacteria in facilitating host plant Zn uptake, which will absolutely benefit the understanding of interacting mechanisms between hyperaccumulators and their endophytes.

Characterization of fava bean (Vicia faba L.) genotypes for phytoremediation of cadmium and lead co-contaminated soils coupled with agro-production.

The identification of high yield genotypes that are capable of accumulating multiple heavy metals in the non-edible parts (roots and shoots), but not in the edible parts (seeds) and have desired nutritional value is necessary for accomplishing phytoremediation coupled with agro-production. In this study, 17 fava bean genotypes were screened in two different field conditions to examine their phytoremediation potential in terms of uptake and translocation of Cd and Pb. Ten genotypes, LBAO, JNJX, DCAN, QXCJ, QIKM, LXYC, YDL6, RBCD, QPID and ZHW6 were found as the best accumulators for Cd and Pb with permissible limit of metals in seeds. The concentration of plant nutrients were genotype and soil type dependent and there was a significant correlation between these two factors. Furthermore, the three genotypes DCAN, LBAO and LXYC showed best performance in alluvial soil type while QPID, RBCD and LXYC were the best in red soil type. Genotype LXYC was similar for both soil types and appeared to be the best fit for phytoremediation coupled with agro-production for slightly or moderately Cd and Pb co-contaminated soil. Therefore, fava bean LXYC genotype is suggested as a potential candidate for phytoremediation of Cd/Pb co-contaminated soils coupled with agro-production.

Effects of CO2 application coupled with endophyte inoculation on rhizosphere characteristics and cadmium uptake by Sedum alfredii Hance in response to cadmium stress.

Comparative impact of CO2 application and endophyte inoculation was investigated on the growth, rhizosphere characteristics, and cadmium (Cd) absorption of two ecotypes of Sedum alfredii Hance in response to Cd stress under hydroponic or rhizo-box culture conditions. The results showed that both CO2 application and endophyte inoculation significantly (P < 0.05) promoted plant growth (fresh weight and dry weight), improved root morphological properties (SRL, SRA, SRV, ARD and RTN) and exudation (pH, TOC, TN, soluble sugar and organic acids), changed Cd uptake and distribution of both ecotypes of S. alfredii. Meanwhile soil total and DTPA extractable Cd in rhizo-box decreased by biofortification treatments. Superposition biofortification exhibits utmost improvement for the above mentioned parameters, and has potential for enhancing phytoremediation efficiency of hyperaccumulator and sustaining regular growth of non-hyperaccumulator in Cd contaminated soils.

Preincubation and vermicomposting of divergent biosolids exhibit vice versa multielements stoichiometry and earthworm physiology.

Sewage sludge and kitchen refuse are ubiquitously mounting wastes with high organic load, which if reprocessed they could salvage the environment. Reckoned with this certitude, an incubating study was initiated on sequential preincubation of sewage sludge with kitchen waste in 100:0, 70:30, 50:50, and 30:70 ratios for 16 days ensued by vermicomposting of 30 days using Eisenia fetida. Concentration of heavy metals (Cd, Cr, Cu, Mn, Pb, and Zn) in the biosolid mixtures increased during preincubation but reduced progressively through vermicomposting due to bioaccumulation of these metals in the earthworm tissues. Earthworm growth parameters data reflected that sewage sludge and kitchen waste mixture with 70:30 ratio increased the number of cocoons (10.6%), biomass (8.2%), growth rate (8.3%), reproduction rate (12.2%), and decreased their mean mortality rate (80.1%) as compared to that in sole sewage sludge (control). Results of chemical analysis and SEM/EDS imaging, showed that alkalinity, organic carbon, C/N ratio, organic matter and concentration of trace elements (Cd, Cr, Cu, Mn, Pb, and Zn) reduced while macronutrients (N, P, K, Ca and Mg) increased in the final vermicompost as compared to that in initial mixtures. The FT-IR analysis also revealed that various biochemical functional groups underwent biodegradation during combined preincubation-vermicomposting. Bioaccumulation factor (BAF) of all trace elements in the earthworm tissues was higher with 70:30 ratio of substrates, with the trend of Cd > Zn > Cu > Mn > Pb > Cr. Hence, this study concludes that combined preincubation-vermicomposting is the most efficient and ecofriendly technique for biodegradation, stabilization, and conversion of sewage sludge and kitchen waste into organic fertilizer. The nutrient rich vermicompost can be safely used as horticultural substrate and soil conditioner for efficient management of degraded soils. Finally, combined preincubation-vermicomposting is a sustainable system of recycling the sewage sludge along with kitchen waste.

Chromosome doubling of Sedum alfredii Hance: A novel approach for improving phytoremediation efficiency.

Sedum alfredii Hance is a cadmium (Cd)/zinc (Zn) hyperaccumulator native to China. However, its relatively low biomass restricted the large-scale application for heavy metal contamination remediation. The chromosome set doubling of S. alfredii in vitro was achieved by 0.1%-0.2% (W/V) colchicine treatment. The plant DNA ploidy was analyzed by flow cytometry and chromosome set doubling plants (CSD) were identified based on the obvious different sharp peak. A tissue culture experiment with different Cd treated levels and a field trial with natural polluted mined soil were conducted to study the effects of chromosome doubling on plant biomass and Cd accumulation in shoots. The results suggested that S. alfredii is a mixoploid. Compared with the wild type plants (WT), CSD exhibited typical "gigas" characteristics in morphology including stem thickness, root hair production, number of leaves and size of stoma guard cell. Fresh weight and dry weight of CSD were increased to 1.62-2.03-fold and 2.26-3.25-fold of WT. And Cd content of CSD showed a 17.49%-42.82% increase and 59% increase under tissue culture and field condition, accordingly. In addition, the TF and in BCF of CSD were 2.37- and 1.59-fold of WT, respectively. These results proved that it is feasible to promote phytoextraction efficiency of S. alfredii in Cd contaminated soils through chromosomal engineering, which provides a novel approach for hyperaccumulator application in phytoremediation.