Accumulation and Translocation of Essential and Nonessential Elements by Tomato Plants (Solanum lycopersicum) Cultivated in Open-Air Plots under Organic or Conventional Farming Techniques

Accumulation of livestock manure-derived heavy metals in the Hexi Corridor oasis agricultural alkaline soil and bioavailability to Chinese cabbage (Brassica pekinensis L.) after 4-year continuous application

Hexi Corridor is one of the most important base of vegetable producing areas in China. Livestock manure (LM) applied to agricultural field could lead to soil heavy metal (HM) pollution. Previous studies have focused on HM pollution following LM application in acidic polluted soils; however, fewer studies have been conducted in alkaline unpolluted soils. A 4-year field vegetable production experiment was conducted using pig manure (PM) and chicken manure (CM) at five application rates (0, 15, 30, 45, and 60 t ha-1) to elucidate potential risks of HMs in an alkaline unpolluted soil in the Hexi Corridor oasis agricultural area and HM uptake by Chinese cabbage. The results showed that LM application caused a significant build-up of Cu, Zn, Pb, Cd, and Ni content in topsoil by 30.6-99.7%, 11.4-51.7%, 1.4-31.3%, 5.6-44.9%, 14%-40.8%, respectively. The Cd, Cu, Zn could potentially exceed the soil threshold in next 8-65 years after 15-60 t ha-1 LM application. Under LM treatment, the soil DTPA-extractable Cu, Zn, Fe, the acid-extractable fraction of Cu, Zn, Fe, Cd, Ni, and the Oxidable fraction of Cu, Zn, Fe, Mn, Cd, Ni significantly increased, but the DTPA-extractable Pb, Cd, the acid-extractable fraction of Pb, and the reducible fraction of Cd significantly decreased. Cu and Zn could migrate to the deeper soil and relatively increase in DTPA-extracted Cu, Zn were found in 20-40 cm soil depth after LM application. The pH and SOM could influence the bioavailability of HMs in soil. The bioaccumulation factor and transfer factor (TF) values were <1 except Mn (TF > 1). HMs in leaf did not approach the threshold for HM toxicity due to the "dilution effect". Recommend the type of manure was the PM and the annual PM application rate was 30 t ha-1 to ensure a 20-year period of clean production in alkaline unpolluted Fluvo-aqiuc vegetable soils.

Quality and Nutritional Parameters of Food in Agri-Food Production Systems

Organic farming is a production system that avoids or largely excludes the use of synthetic agricultural inputs such as pesticides, growth regulators, highly soluble mineral fertilisers, supplements, preservatives, flavouring, aromatic substances and genetically modified organisms, and their products. This system aims to maintain and increase soil fertility and quality, and relies on systems such as crop rotation, polyculture, intercropping, ecosystem management, covering crops, legumes, organic and bio-fertilisers, mechanical cultivation and biological control methods. The present review summarises and evaluates research comparing the quality of traditionally, organically and conventionally produced foods. In some cases, although the results of the studies contradict each other, organically grown in vegetables, especially berries and fruits are slightly higher dry matter, minerals such as P, Ca, Mg, Fe and Zn, vitamin C, sugars, carotenoids, antioxidant activity, phenolic and flavonoid compounds. In addition, their sensory properties are more pleasant. The nutritional content, quality and safety of organic foods are acceptable if the recent trends are reviewed, tested and verified. Therefore, the aim of this review is to compile, describe and update scientific evidence and data on the quality, safety, bioactive compounds and nutritional and phytochemical quality of foods in traditional and organic fruit, vegetable and cereal production systems.

Antioxidant Activities and Selenogene Transcription in the European Sea Bass (Dicentrarchus labrax) Liver Depend, in a Non-linear Manner, on the Se/Hg Molar Ratio of the Feeds

Feeding 3.9 and 6.7 mg Hg/kg (Se/Hg molar ratios of 0.8 and 0.4, respectively) for 14 days negatively affected Dicentrarchus labrax growth and total DNTB- and thioredoxin-reductase (TrxR) activities and the transcription of four redox genes (txn1, gpx1, txnrd3, and txnrd2) in the liver, but a diet with 0.5 mg Hg/kg (Se/Hg molar ratio 6.6) slightly increased both reductase activities and the transcription of txn1, gpx1, and txnrd2. Feeding 6.7 mg Hg/kg for 53 days downregulated the genes of the thioredoxin system (txn1, txnrd3, and txnrd2) but upregulated gpx1, confirming the previously proposed complementarity among the antioxidant systems. Substitution of 20% of the feed by thawed white fish (hake) slightly counteracted the negative effects of Hg. The effects were not statistically significant and were dependent, in a non-linear manner, on the Se/Hg molar ratio of the feed but not on its Hg concentration. These results stress the need to consider the Se/Hg molar ratio of the feed/food when evaluating the toxicity of Hg.

Study of the Unique Characteristics of Multi-Elements of the Wild Astragali Radix from Shanxi Province by Inductively Coupled Plasma Mass Spectrometry

BACKGROUND

Astragali Radix (AR) is widely used because of its dual use in medicine and food. Wild Astragali Radix from Hunyuan county of Shanxi Province in China is accepted as a geo-authentic medicine with high quality and good medicinal effects. Multi-elements of Astragali Radix partially reflect its efficacy and safety. However, there is no systemic research about the elemental analysis of geo-authentic Astragali Radix until now.

OBJECTIVE

In this paper, multi-elemental profiling of Astragali Radix from Gansu, Jilin, Inner Mongolia, Shaanxi and Shanxi provinces in China was implemented.

METHODS

A microwave digestion coupled with ICP-MS, principle component analysis and partial-least square-discriminate analysis were used for the analysis of unique elemental accumulation ability of Shanxi wild-type.

RESULTS

For 53 stably detected elements, the contents of most elements (Ba, Cs, Ga, La, Pr and so on) were significantly higher while some others (Cd, Cu, P, W and Zn) were significantly lower in wild Astragali Radix from Shanxi than those of the samples from Gansu, Jilin, Inner Mongolia, Shaanxi provinces and the cultivated samples from Shanxi. After binary logistic regression, combinational variable Ba-P was found to be a good marker to identify wild Astragali Radix of Shanxi Province from the samples with other origins, and the total positive prediction probability of the test samples from both market and their original field could reach 93.8% through external validation using the model.

CONCLUSIONS

Multi-elemental analysis coupled with PCA, PLS-DA, nonparametric analysis and binary logistic regression can be a good tool for the identification of wild Astragali Radix from Shanxi Province.

HIGHLIGHTS

An ICP-MS method was developed and validated for multi-elements. Fifty-three elements in Astragali Radix from differential origins were compared. The wild Astragali Radix from Shanxi had unique elemental characteristics. Combinational variable Ba-P is a good marker to identify wild-type from Shanxi.

Response of Horticultural Soil Microbiota to Different Fertilization Practices

Environmentally friendly agricultural production necessitates manipulation of microbe-plant interactions, requiring a better understanding of how farming practices influence soil microbiota. We studied the effect of conventional and organic treatment on soil bacterial richness, composition, and predicted functional potential. 16S rRNA sequencing was applied to soils from adjacent plots receiving either a synthetic or organic fertilizer, where two crops were grown within treatment, homogenizing for differences in soil properties, crop, and climate. Conventional fertilizer was associated with a decrease in soil pH, an accumulation of Ag, Mn, As, Fe, Co, Cd, and Ni; and an enrichment of ammonia oxidizers and xenobiotic compound degraders (e.g., Candidatus Nitrososphaera, Nitrospira, Bacillus, Pseudomonas). Soils receiving organic fertilization were enriched in Ti (crop biostimulant), N, and C cycling bacteria (denitrifiers, e.g., Azoarcus, Anaerolinea; methylotrophs, e.g., Methylocaldum, Methanosarcina), and disease-suppression (e.g., Myxococcales). Some predicted functions, such as glutathione metabolism, were slightly, but significantly enriched after a one-time manure application, suggesting the enhancement of sulfur regulation, nitrogen-fixing, and defense of environmental stressors. The study highlights that even a single application of organic fertilization is enough to originate a rapid shift in soil prokaryotes, responding to the differential substrate availability by promoting soil health, similar to recurrent applications.

Mechanism of Remediation of Cadmium-Contaminated Soil With Low-Energy Plant Snapdragon

In the process of remediation of contaminated soil, we should give full play to the role of low-energy plants and fully display the concept of modern energy-saving and environmental protection. Phytoremediation is an effective method to remediate cadmium-contaminated soil, and root exudates play an important part in this process. Here, the response of snapdragon in a pot-culture experiment under two concentrations of Cd (1.0 and 2.5 mg/kg) was evaluated. Snapdragon is a medicinal plant with low energy consumption, which has low requirements on environmental factors and strong resistance. The results showed that both Cd concentrations interfere with the uptake of B, P, Cu, Mn, Mo, and Zn by the soil. The results also showed that plant type and Cd stress can significantly change the concentrations and species of root exudates. The metabolic changes of root exudates revealed the active defense mechanism of plants to Cd stress: up-regulating of amino acids to sequester/exclude Cd, regulation of citric acid on chelation/complexation, and precipitation of cadmium ions. The application of snapdragon can effectively reduce energy consumption and gradually improve the utilization rate of vegetation, which promotes the degradation of cadmium pollutants in soil.

Nutrients and non-essential elements in edible crops following long-term mineral and compost fertilization of a Mediterranean agricultural soil

The effects of long-term soil fertilizations on nutrient and non-essential element concentrations in edible parts of three crops important in human diet were investigated repeating four treatments (biowaste compost, biowaste compost plus mineral nitrogen, mineral NPK, unfertilized control) for seven consecutive years (2007-2014). Fruits of Solanum lycopersicum cv San Marzano collected in 2011 and 2012, bulbs of Allium cepa cv Bianca di Pompei collected in 2012 and 2013, and bulbs of Foeniculum vulgare cv Orbit collected in 2014 were analyzed. Wide variations in element concentrations were observed along time and among species, with Ca, K, Mg, and Na higher in fennel bulbs and Cd, Cr, Mn, Ni, Pb, and Zn higher in tomato fruits, where Cd reached concentrations up to ninefold higher than the permitted values (EU Regulation n. 488/2014). Despite the enrichments in soil total Cu and available Cd, Fe, K, Mn, and Zn concentrations due to long-term fertilization with biowaste compost (alone or with mineral fertilizers), plants showed lower micronutrient and non-essential element concentrations in respect to those on unfertilized soils. Considering the potential toxicity for human beings of these mobile and persistent elements, the obtained findings reassure on the safe use of biowaste compost in agriculture. Overall, this study suggests the use of compost as the most advisable fertilization practice and highlights the need of multiple crops analysis in evaluating the effects of long-term soil fertilization on their chemical composition.

Assessment of trace metals in five most-consumed vegetables in the US: Conventional vs. organic

Metal concentrations (As, Cd, Pb, Cr, Ba, Co, Ni, Cu, and Zn) in conventional and organic produce were assessed, specifically, five most-consumed vegetables from the US including potato, lettuce, tomato, carrot and onion. They were from four representative supermarkets in a college town in Florida. All vegetables contained detectable metals, while As, Cd, Pb, Cr, and Ba are toxic metals, Co, Ni, Cu, and Zn are nutrients for humans. The mean concentrations of As, Cd, Pb, Cr and Ba in five vegetables were 7.86, 9.17, 12.1, 44.8 and 410 μg/kg for organic produce, slightly lower than conventional produce at 7.29, 15.3, 17.9, 46.3 and 423 μg/kg. The mean concentrations of Co, Ni, Cu, and Zn in five vegetables were 3.86, 58.5, 632, and 2528 μg/kg for organic produce, comparable to conventional produce at 5.94, 68.2, 577, and 2354 μg/kg. For toxic metals, the order followed tomato < lettuce < onion < carrot < potato, with root vegetables being the highest. All metals in vegetables were lower than the allowable concentrations by FAO/WHO. Health risks associated with vegetable consumption based on daily intake and non-carcinogenic risk based on hazard quotient were lower than allowable limits. For the five most-consumed vegetables in the US, metal contents in conventional produce were slightly greater than organic produce, especially for Cd and Pb.