Cd Concentration In Edible Parts Research Articles

Positive effects of applying endophytic bacteria in eggplant-Sedum intercropping system on Cd phytoremediation and vegetable production in cadmium polluted greenhouse

The combination of intercropping and phytoremediation in the remediation of cadmium contaminated soil is an emerging model in recent years, but the results of previous studies are inconsistent. In the field experiment, eggplant was intercropped with hyperaccumulator Sedum alfredii Hance (inoculated or not inoculated with endophytic bacteria) to study the effects of intercropping on vegetable safety production, phytoremediation efficiency of hyperaccumulator and variation of soil available nutrients. The results showed that the intercropping treatment had a negative effect on the growth of eggplant and Sedum, but endophyte SaMR12 alleviated the inhibition of intercropping on plant growth. Intercropping treatment increases the Cd concentration in edible part of eggplant to 1.34 mg/kg compared with eggplant monoculture (1.19 mg/kg). While the application of SaMR12 reduces the Cd concentration of eggplant fruit to 0.95 mg/kg and significantly promotes the Cd uptake by Sedum. What's more surprising is that compared with eggplant monocropping, the content of soil available nitrogen, phosphorus and potassium in the treatment of intercropping with inoculated Sedum increased significantly. And according to the correlation analysis of various indexes of plants and soil, the Cd content of eggplant is negatively correlated with the available phosphorus and potassium in the soil, while the Cd content of Sedum is positively correlated with it, which suggested that the application of phosphorus and potassium fertilizers in this experimental site was beneficial to reduce Cd content in eggplant and improve Cd phytoextraction of Sedum. Therefore, in the daily production of moderately Cd-contaminated soil, intercropping eggplant with Sedum inoculated with endophytic bacteria is an excellent Phytoextraction Coupled with Agro-safe-production (PCA) pattern.

Lower cadmium accumulation and higher antioxidative capacity in edible parts of Brassica campestris L. seedlings applied with glutathione under cadmium toxicity.

Glutathione (GSH) is involved in not only plant developmental processes but also plantresponses to abiotic stresses. A hydroponic experiment was performed to explore the protective roles of exogenous GSH in mitigating cadmium (Cd) stress in Brassica campestris L. seedlings by analyzing the morphological and physiological parameters. Results showed that Cd caused severe growth inhibition and Cd accumulation. However, application of GSH significantly mitigated toxic symptoms induced by Cd, including the improvement of the photosynthesis-, plant growth-, and root morphology-related parameters in seedlings under Cd stress. These responses were associated with a striking increase in activities of representative antioxidative enzymes and contents of corresponding non-enzymatic antioxidants. In vivo imaging of O2.- and H2O2, and the detection of lipid peroxidation further demonstrated that increased ability by GSH for Brassica campestris L. seedlings to endure Cd stress was consistent with a striking elevation of ratios of reduced to oxidized glutathione (GSH/GSSG) and ascorbic acid to dehydroascorbic acid (AsA/DHA). Additionally, GSH application increased Cd retained in roots, thus significantly decreased its translocation from root to shoot, ultimately decreased Cd accumulation in shoots. Taken together, our results proved evidence for GSH in ameliorating Cd toxicity via reducing Cd accumulation in shoots and increasing oxidation resistance. Accordingly, application of GSH could be a high-efficiency and promising strategy to decrease Cd concentration in edible parts of Brassica campestris L. in agricultural production.

Relationships between Cd concentrations in different vegetables and those in arable soils, and food safety evaluation of vegetables in Taiwan

The cadmium (Cd) accumulation capacity of various vegetables and the relationship between Cd concentrations in edible parts of vegetables and those in soils were assessed by conducting field experiments at Cd-contaminated sites in northern and central Taiwan. In addition, to thoroughly assess Cd concentrations in vegetables and to understand the food safety of vegetables in Taiwan, 2257 paired vegetable and surface soil samples were collected from major vegetable production areas for Cd concentration analysis. According to the bioconcentration factors calculated, the Cd accumulation capacity varied considerably among the vegetable species tested, and the order of the five vegetables with the highest capacities is peanut (Arachis hypogaea L.) > amaranth (Amaranthus tricolor L.) > spinach (Spinacia oleraceae L.) > gynura (Gynura bicolor DC.) > okra (Hibiscus esculentus L.), whereas the order of the five vegetables with the lowest capacities is bitter gourd (Momordica charantia L.) < cucumber (Cucumis sativus L.) < asparagus bean (Vigna unguiculata (L.) Walp. ssp. sesquipedalis (L.) Verdc.) < snap bean (Phaseolus vulgaris L.) < sponge gourd (Luffa cylindrica Roem.). We derived 29 soil–plant transfer models of Cd for individual vegetable species based on available pools of the Cd, manganese (Mn), zinc (Zn), copper (Cu) and iron (Fe) concentrations; soil pH; and cation exchange capacity (CEC). According to the derived models, the available Cd, Mn and Zn concentrations, and pH, served as the main factors affecting Cd concentrations in the edible parts of vegetables, whereas the CEC and available Cu and Fe concentrations are less important factors. The data of previous studies and those of this study from major vegetable production areas, including 30 vegetable crops, were used to evaluate the safety of vegetables in Taiwan. The results indicated that the percentage of vegetables with Cd concentrations exceeding the regulatory concentration was 0.54%; therefore, the food safety concern is low. However, 9.8, 1.0, 0.9 and 0.6% of amaranth, cabbage (Brassica oleracea L. Capitata Group), Chinese cabbage (Brassica pekinensis Skeels.) and carrot (Daucus carota L.), respectively, had Cd concentrations in the edible parts exceeding the regulatory concentration. Particular attention should be paid when planning production areas for these vegetables. We recommend cultivating peanuts in fields with a soil Cd concentration < 0.33 mg kg−1. The bioconcentration factors and soil–plant transfer models derived in this study might serve as assessment tools for planning farming areas for these vegetables.

Co-Planting Cd Contaminated Field Using Hyperaccumulator Solanum Nigrum L. Through Interplant with Low Accumulation Welsh Onion

Monoculture and intercrop of hyperaccumulator Solanum nigrum L. with low accumulation Welsh onion Renbentieganchongwang were conducted. The results showed that the remove ratio of S. nigrum to Cd was about 7% in intercrop plot when top soil (0–20 cm) Cd concentration was 0.45–0.62 mg kg−1, which did not significantly impact the yield of low accumulation Welsh onion compared to the monoculture. The consistency of remove ratio in practice and theory indicated the remediation of S. nigrum to Cd was significant. The Cd concentration and yield of Welsh onion were not affected by the growth of S. nigrum either in intercrop plot. The Cd concentration in edible parts of Welsh onion was available either. In short, inter-planting hyperaccumulator with low accumulation crop could normally remediate contaminated soil and produce crop (obtain economic benefit), which may be one practical pathway of phytoremediating heavy metal contaminated soil in the future.

High cadmium pollution risk on vegetable amaranth and a selection for pollution-safe cultivars to lower the risk

A pot experiment was carried out by growing 29 different genotypes (Amaranthus spp.) of vegetable amaranth under low- (0.12 mg·kg−1) and middle- (0.40 mg·kg−1) cadmium (Cd) exposure. The result showed that amaranth was vulnerable to cadmium (Cd) contamination in soil. Variations of Cd concentrations in both roots and edible parts among genotypes were significant (P<0.001) in both treatments. Cd concentrations in edible parts of the tested genotypes grown under low- and middle-Cd levels were significantly correlated (p<0.01), implying that Cdaccumulating property of amaranth is genotype-dependent. Differences in Cd chemical forms between cv. Nanxingdayemashixian (cv. Nan), a selected typical pollution-safe cultivar (Cd-PSC), and cv. Pennongjianyexian (cv. Pen), a selected typical non-Cd-PSC, under different Cd exposure conditions were compared. It was found that the alternation of Cd in FNaCl (Cd form extracted by 1 mol·L−1 NaCl) may be a key factor in regulating Cd accumulation of different amaranth genotypes and that the protein-binding Cd is considered to be associated with Cd translocation. The results indicated that amaranth is capable of enduring high level of Cd pollution when grown as vegetable crop, and accordingly, consuming vegetable amaranth would bring high health risk. Therefore, adopting Cd-PSC strategy would help reducing the risk of Cd pollution in amaranth. In this study, cv. Nan was identified as a Cd-PSC and recommended to be applied production practice.

Cadmium availability and accumulation by lettuce and rice

Among the toxic elements, Cd has received considerable attention in view of its association with a number of human health problems. The objectives of this study were to evaluate the Cd availability and accumulation in soil, transfer rate and toxicity in lettuce and rice plants grown in a Cd-contaminated Typic Hapludox. Two simultaneous greenhouse experiments with lettuce and rice test plants were conducted in a randomized complete block design with four replications. The treatments consisted of four Cd rates (CdCl2), 0.0; 1.3; 3.0 and 6.0 mg kg-1, based on the guidelines recommended by the Environmental Agency of the State of São Paulo, Brazil (Cetesb). Higher Cd rates increased extractable Cd (using Mehlich-3, Mehlich-1 and DTPA chemical extractants) and decreased lettuce and rice dry matter yields. However, no visual toxicity symptoms were observed in plants. Mehlich-1, Mehlich-3 and DTPA extractants were effective in predicting soil Cd availability as well as the Cd concentration and accumulation in plant parts. Cadmium concentration in rice remained below the threshold for human consumption established by Brazilian legislation. On the other hand, lettuce Cd concentration in edible parts exceeded the acceptable limit.