White cabbage, Brassica oleracea, plants and artificial leaves covered with B. oleracea epicuticular wax were exposed to α-pinene and α-pinene oxidation products formed through the oxidation of α-pinene by ozone (O₃) and hydroxyl (OH) radicals. O₃ and OH-induced oxidation of α-pinene led to the formation of oxygenated volatile organic compounds (OVOCs) and secondary organic aerosol particles (SOA), referred to together as oxidation products (OP). Exposure of cabbage plants to O₃ and OH-induced α-pinene OP led to the deposition and re-emission of gas-phase OP by exposed cabbage plants. In a series of 2-choice bioassays, the specialist cruciferous herbivore, Plutella xylostella adults deposited less eggs on artificial leaves exposed to α-pinene OP than on control plants exposed to clean filtered air. P. xylostella larvae did not show a specific feeding preference when offered leaves from different exposure treatments. However, the generalist Indian stick insect, Carausius morosus, fed more on control filtered air-exposed plants than on those exposed to α-pinene OP. Taken together, our results show that exposure to α-pinene oxidation products affects VOC emissions of B. oleracea and alters P. xylostella oviposition and C. morosus feeding responses.

The perennial evergreen woody shrub, Rhododendron tomentosum, confers associational resistance against herbivory and oviposition on neighbouring plants through passive adsorption of some of its constitutively emitted volatile organic compounds (VOCs). The adsorption process is dependent on transport of VOCs in the air. In polluted atmospheres, the VOCs may be degraded and adsorption impeded. We studied the effect of elevated ozone regimes on the adsorption of R. tomentosum volatiles to white cabbage, Brassica oleracea, and the oviposition of the specialist herbivore Plutella xylostella on the exposed plants. We found evidence for adsorption and re-emission of R. tomentosum volatiles by B. oleracea plants. Ozone changed the blend of R. tomentosum volatiles and reduced the amount of R. tomentosum volatiles recovered from B. oleracea plants. However, plants exposed to R. tomentosum volatiles received fewer P. xylostella eggs than control plants exposed to filtered air irrespective of whether R. tomentosum volatiles mixed with ozone. Ozone disrupts a volatile mediated passive plant-to-plant interaction by degrading some compounds and reducing the quantity available for adsorption by neighbouring plants. The change, however, did not affect the deterrence of oviposition by P. xylostella, suggesting that aromatic companion plants of Brassica crops may confer pest-deterring properties even in ozone-polluted environments.

Many pharmaceutical and personal care products (PPCPs) and endocrine-disrupting chemicals (EDCs) are present in reclaimed water, leading to concerns of human health risks from the consumption of food crops irrigated with reclaimed water. This study evaluated the potential for plant uptake and accumulation of four commonly occurring PPCP/EDCs, i.e., bisphenol A (BPA), diclofenac sodium (DCL), naproxen (NPX), and 4-nonylphenol (NP), by lettuce (Lactuca sativa) and collards (Brassica oleracea) in hydroponic culture, using 14C-labeled compounds. In both plant species, plant accumulation followed the order of BPA > NP > DCL > NPX and accumulation in roots was much greater than in leaves and stems. Concentrations of 14C-PPCP/EDCs in plant tissues ranged from 0.22 ± 0.03 to 927 ± 213 ng/g, but nearly all 14C-residue was non-extractable. PPCP/EDCs, particularly BPA and NP, were also extensively transformed in the nutrient solution. Dietary uptake of these PPCP/EDCs by humans was predicted to be negligible.

Interest in selenium pollution and remediation technology has escalated during the past two decades. Although not known to be essential for plants, selenium is essential but could be toxic for humans and animals, depending on its concentration. A major selenium controversy in the 1980's emerged in California when the general public and scientific community became aware of selenium's potential as an environmental contaminant. After extensive research on several strategies to reduce loads of mobile Se for entering the agricultural ecosystem a plant-based technology, defined as 'phytoremediation' received increasing recognition, as a low-cost environmentally friendly approach for managing soluble Se in the soil and water environment. Successful long-term field remediation of Se by plants is, however, dependent upon acceptance and widespread use by growers, who are also concerned about potential commercial value from using the plant-based technology. Obtaining products with economic value from plants used in the cleanup of soil would certainly be an additional benefit to phytoremediation, which could help sustain its long-term use.

A greenhouse pot experiment was conducted in Agrinion, Greece, in 2009, using a Randomized Block Design. Treated Municipal Wastewater (TMWW) in five levels was applied to Brassica oleracea var. Capitata (cabbage) in four replications. The experiment aimed at investigating the effect of TMWW on: (a) the interrelationships of cabbage plant parts (roots, stems, leaves, and heads) heavy metal content, with the respective dry matter yield. (b) The relationship between each individual soil bioavailable diethylenetriaminepentaacetic acid (DTPA extractable) heavy metal, with the dry matter (dm) yield of the abovementioned cabbage plant parts. The heavy metals of cabbage plant parts dry matter were significantly related negatively and statistically with the respective dry matter yield. Similarly, the soil available DTPA-extractable heavy metals were generally negatively affecting the dry matter yield of roots, stems, leaves, and heads. Conversely, Co, Cr, and Cd were found to be positively associated with the dry matter yield increase of the aforementioned plant parts. This effect was indirect, probably being due to contribution in essential elements by the synergistic interactions of these heavy metals with plant nutrients, such as Ca, Mg, Fe, and Mn.

Leaching of trace metals and greenhouse plant growth (Collard greens; Brassica oleracea var. acephala) response studies were conducted in two types of soils with contrasting characteristics amended with varying rates (0 to 24.70 Mg ha⁻¹) of poultry litter (PL) or 1:1 mixture of PL and fly ash (FA). Leaching of Cr, Zn, Cd, Cu, and Pb from soils amended with PL or PL + FA (1:1) increased with increasing rates of amendment. Leaching losses were greater from coarse-textured soil compared to that from medium-textured soil. Crop performance study indicated that growth as well as trace elements concentrations increased with increasing rates of amendments only up to 12.35 Mg ha⁻¹. Trace element concentrations in plant parts were greater in plants grown in Candler fine sand (CFS) compared to that grown in Ogeechee loamy sand (OLS). Trace element concentrations were greater in the above ground plant parts (leaf and stem) than those in roots. This study demonstrated beneficial effects of PL or mixture of PL + FA amendments to soils at rates not exceeding 4.94 Mg ha⁻¹. Further field studies are recommended to evaluate the long-term impact of using poultry litter and fly ash on plant growth and tissue trace metal concentration as well as environmental impact.

Cadmium is a cumulative, chronic toxicant in humans for which the main exposure pathway is via plant foods. Cadmium-tolerant plants may be used to create healthier food products, provided that the tolerance is associated with the exclusion of Cd from the edible portion of the plant. An earlier study identified the cabbage (Brassica oleracea L.) variety, Pluto, as relatively Cd tolerant. We exposed the roots of intact, 4-week-old seedlings of Pluto to Cd (control ∼1 mg L⁻¹ treatment 500 μg L⁻¹) for 4 weeks in flowing nutrient solutions and observed plant responses. Exposure began when leaf 3 started to emerge, plants were harvested after 4 weeks of Cd exposure and the high Cd treatment affected all measured parameters. The elongation rate of leaves 4–8, but not the duration of elongation was reduced; consequently, individual leaf area was also reduced (P < 0.001) and total leaf area and dry weight were approximately halved. A/C ᵢ curves immediately before harvest showed that Cd depressed the photosynthetic capacity of the last fully expanded leaf (leaf 5). Despite such large impairments of the source and sink capacities, specific leaf weight and the partitioning of photosynthate between roots, stems and leaves were unaffected (P > 0.1). Phytochelatins (PCs) and glutathione (GSH) were present in the roots even at the lowest Cd concentration in the nutrient medium, i.e. ∼1 μg Cd L⁻¹, which would not be considered contaminated if it were a soil solution. The Cd concentration in these roots was unexpectedly high (5 mg kg⁻¹ DW) and the molar ratio of –SH (in PCs plus GSH) to Cd was large (>100:1). In these control plants, the Cd concentration in the leaves was 1.1 mg kg⁻¹ DW, and PCs were undetectable. For the high Cd treatment, the concentration of Cd in roots exceeded 680 mg kg⁻¹ DW and the molar –SH to Cd ratio fell to ∼1.5:1. For these plants, Cd flooded into the leaves (107 mg kg⁻¹ DW) where it probably induced synthesis of PCs, and the molar –SH to Cd ratio was ∼3:1. Nonetheless, this was insufficient to sequester all the Cd, as evidenced by the toxic effects on photosynthesis and growth noted above. Lastly, Cd accumulation in the leaves was associated with lowered concentrations of some trace elements, such as Zn, a combination of traits that is highly undesirable in food plants.

Urban market gardening in Africa is suffering from increasing environmental contamination due to sources of contamination as varied as traffic, industry, and agriculture practices. A field study was therefore conducted to determine the global influence of the polluted environment (atmosphere, soil, and irrigation waters) on vegetable quality in a large urban-farming area. For leafy vegetables collected in 15 ha of squatted land belonging to the international airport of Cotonou, total concentrations of metal(loid)s measured in consumed parts of Lactuca sativa L. and Brassica oleracea were 52.6–78.9, 0.02–0.3, 0.08–0.22, 12.7–20.3, 1.8–7.9, and 44.1–107.8 mg kg⁻¹for Pb, Cd, As, Sb, Cu, and Zn, respectively. Human gastric bioaccessibility of the metal(loid)s was measured, and the obtained values varied according to the considered metal(loid) and the plant species. The results identified values that are commonly found in non-polluted soils and roots associated with contaminated edible parts, raising the possibility of atmospheric contamination. Such a hypothesis is in agreement with values of magnetic susceptibility, since iron oxides and probably their associated metal(loid)s do not translocate from the roots toward the upper parts of the plants. (Bioaccessible) estimated dose intake ((B)EDI) and total (bioaccessible) target hazard quotient (Σ(B)THQ) were calculated to assess the health risk of consuming vegetables from this area. Pb and Sb were the major risk contributors. Taking the bioaccessible fractions into account, ΣBTHQ values were lower than ΣTHQ but were all still >1 for both males and females, leading to the conclusion that consuming these vegetables from this area is not risk-free.

Concentrations of chromium, copper, and lead were determined in soil and plant specimens collected from the area of coal power plant (CPP), A. Dimitrios, the largest CPP in Greece located on the eastern part of Ptolemais basin, Macedonia. Two cultivated plants (Brassica oleracea var. capitata L. and Zea mays L.) and two non-cultivated plants (Rumex acetosa L. and Verbascum phlomoides L.) were chosen. The mean heavy metal content in the soil is described in the descending order of Cr>Pb>Cu, while for the plant material, the order was Cr>Cu>Pb. Stations in the vicinity of the CPP showed a distinctly high load of Cr in the soil, whereas for the other metals, no such correlation has been noted. Unexpectedly, high levels of chromium and copper have been found in plant samples of the control station (Grevena) where there is no significant point source of air pollution by particulate matter. In general, roots revealed a higher metal concentration than that of the other plant organs. This is more obvious in B. oleracea var. capitata for all metals studied. Thus, B. oleracea var. capitata possesses the potential for phytoremediation of soils contaminated by metals since this plant is removable together with its roots from the contaminated soil. The most contaminated leaves showed a variation in surface roughness. In V. phlomoides the non-glandular, branched candelabrum-like trichomes on the leaf epidermis effectively trapped and retained a considerable number of particles. In contrast, the waxy cuticle of R. acetosa, which forms a smooth sheet over the epidermal cells, enabled the fast removal of particles by rain or wind. In the case of Z. mays, seeds accumulated the lowest amount of all metals.