Fertilizing Soil with Selenium Fertilizers: Impact on Concentration, Speciation, and Bioaccessibility of Selenium in Leek (Allium ampeloprasum)

Abstract

Leek was fertilized with sodium selenite (Na(2)SeO(3)) and sodium selenate (Na(2)SeO(4)) in a green house to assess the impact of selenium (Se) fertilization on Se uptake by the crop and its speciation in the crop. The bioaccessibility of Se in the Se-enriched leek was assessed using an in vitro extraction protocol mimicking the human gastrointestinal tract (stomach, small intestine, and colon). The lowest Se uptake was observed when Na(2)SeO(3) was used as a fertilizer, which results in a higher risk for Se accumulation in the soil on a longer term. When soil was amended with Na(2)SeO(4), 55 ± 5% of total Se in the leek occurred in an inorganic form, while only 21 ± 8% was inorganic when Na(2)SeO(3) was applied. Se-methylselenocysteine and selenomethione were the major organic species in both treatments. However, concentrations of Se-methylselenocysteine and γ-glutamyl-Se-methyl-selenocysteine, which were previously reported to induce positive health effects, were lower as compared to other Allium species. The majority of the Se in the leek was found to be bioaccessible in the stomach (around 60%) and small intestine (around 80%). However, a significant fraction also has good chances to reach the colon, where it seems to be taken up by the microbial community and may also induce positive health effects.

Selenium biofortification on garlic growth and other nutrients accumulation

“…Furthermore, we observed that Se content in garlic plants was increased thirty times by Se fertilization (Table 2). Similar results have been reported for other Allium plants like ramps, leek and onion where Se accumulation was also around 1000 µg g -1 (Montes- Bayón et al, 2002;Lavu et al, 2012;Schiavon & Pilon-Smits, 2017). For this reason, the Allium plants are considered as Se hyperaccumulaters and represent natural Se sources to humans.…”

“…Four doses were applied: 0, 5, 10 and 15 kg ha -1 of Se, with a random plot design and three replicates. The tested Se doses were similar to those reported in other studies about the Allium gender (Sharma et al, 2007;Domokos-Szabolcsy et al, 2011;Lavu et al, 2012). Three samplings were performed: at the beginning (September 2014:103-BBCH), mid-term (October 2014; 203-BBCH scale) and end (December 2014; 409-BBCH scale) of the growth cycle (Lopez-Bellido et al, 2016).…”

“…The fortification of different plants with Se has also been studied in order to obtain Se-enriched foods that have potential functionality to promote health. In fact, it is well established that vegetables derived from Allium and Brassica plant species, play an important role in Se supplementation because they have the ability of accumulating high amounts of Se even though Se is not a micronutrient for the plants, and hence, they could be used as natural dietary Se supplements (Lavu et al, 2012). Among these, garlic (Allium sativum) is highly important due to its multiple medicinal effects, for example, it reduces blood cholesterol levels and antiplatelet aggregation, produces anti-inflammatory activity and inhibits cholesterol synthesis (Burba, 2013).…”

Bioaccessibility of selenium after human ingestion in relation to its chemical species and compartmentalization in maize

“…The same trend is observed for seeds, usually consumed by human organisms, but results are here not significant. By contrast, working on Se oral bioaccessibility in leek (Allium ampeloprasum), Lavu et al (2012) highlighted that in the gastric phase, Se bioaccessibility was slightly higher when the leek was grown on selenite-enriched soil (63 %), as compared to selenate-enriched soil (56 %), although this difference is not significant. In our study, there is no significant difference in selenate bioaccessible fraction in function of the maize tissue, i.e., stems, leaves, or seeds.…”

Novel bioremediation processes for treatment of seleniferous soils and sediment

“…Therefore, it is considered as a high commercial value element. In agriculture, selenium has been applied as fertiliser in selenium deficient regions (Lavu et al, 2012) and has also been used to inhibit the formation of sulfate-mediated methylmercury in paddy fields, wherein amendment of selenium in soil leads to the formation of stable and non-toxic Hg-Se complex(es) . Being an essential element, selenium intake is recommended via food supplements in order to avoid deficiency in humans and animals (Rautiainen et al, 2016).…”