Authors:C. Galinha, M. Freitas, A. Pacheco, J. Coutinho, B. Maçãs, and A. Almeida
Selenium (Se) is an essential micronutrient for human health, but its deficiency may affect at least one billion people worldwide.
Plants and plant-derived products transfer the soil-uptaken Se to humans through the food chain, which is hardly enough when
soils have been always poor or already exhausted in bioavailable Se species. Other than agronomic approaches for enhancing
Se levels in cereals, such as soil and foliar supplements, seed enrichment may be viewed as an alternative Se-biofortification
technique. This study addresses the protocol for preparing Se-enriched wheat seeds, with the specific purpose of optimizing
the administration of Se to the seeds prior to sowing. The first step was to soak an amount of bread-wheat seeds in an active
Se solution, made with irradiated [Na2O4Se], and then monitoring 75Se in periodically-retrieved samples from that original amount. To avoid losing Se to soil (after sowing), and, especially,
to ensure that Se gets really absorbed into the seeds—and not just adsorbed onto them—the washing time of the seeds should
be optimized as well. This was carried out by washing Se-treated seeds several times, until no significant amount of the radiotracer
could be detected in the washing water. In what concerns the full optimization procedure, the overall results of the present
study point to an optimum time of 48 h for soaking and 24 h for washing.
An extensive investigation of elemental levels in cereals and their cultivation soils has been going on across the main production
areas of mainland Portugal, with a view to an eventual biofortification of major cultivars through agronomic practices. Cereals
are an obvious choice as primary vehicles for food-supplementation programs, especially in countries where they definitely
weigh in the dietary intake (like Portugal), and regions whose geographical and/or pedological features may account for nutrient
deficiencies in typical diets. Mature rye plants (Secale cereale L.; roots and grains) and local soils were collected in the summer of 2009 from two regions of northern Portugal, and put
through k0-standardized, instrumental neutron activation analysis (k0-INAA). Overall, the results (elemental concentrations, enrichment factors, transfer coefficients) seem to confirm an efficient
uptake of elements from soil and their translocation to the aerial parts of the plants, notably to the ones that really matter
in human nutrition (grains).