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prerequisite for the calculation of the proportion of a legume's nitrogen derived from the atmosphere (%Ndfa) using the N natural abundance technique (NA) is the determination of the B value (δN value for a legume when completely dependent on N fixation for growth). With this objective, Kabuli-type chickpea seeds were inoculated with Mesorhizobium ciceri, strain ISC-6, and an indigenous strain mixture (ISM) from the Guadalquivir Valley (southern Spain); and mayor-equina-type faba bean seeds were inoculated with Rhizobium leguminosarum strain ISL-19. Both legumes were grown in perlite with an N-free nutrient solution and in a growth chamber; uninoculated plants were also grown under the same conditions. Samples of the inoculated plants were collected at full flowering and maturity, analyzing total N and N content of the nodules, root, shoot and seeds. The seeds sown and uninoculated plants at wilting were also analyzed. The uninoculated chickpea and faba bean plants showed strong N discrimination in the remobilization of reserve proteins from the cotyledons to the shoot. Only 52% of the N from the chickpea seed and 46% from the faba bean seed were translocated to the shoot. The B value for both inoculated species (−1.44‰ in chickpea and −1.33‰ in faba bean) demonstrated the existence of a significant isotopic discrimination of N in the fixation of atmospheric N. The B value did not show significant differences between full flowering and seed maturity for either species, which allowed field sampling to be performed for the calculation of %Ndfa between both growth stages. Each species presented different N discrimination for the different parts analyzed. In chickpea, strong discrimination was observed between the nodules (+3.11‰) and the rest of the plant (−1.67‰); this discrimination was less pronounced in faba bean and always with negative values between the underground parts (nodules and root, with a mean value of −0.75‰) and the shoot (−1.71‰). The B value obtained was −1.80‰ in chickpea and −1.71‰ in faba bean. However, given the importance of the amount of seed N in chickpea and faba bean, seed N contribution should be considered in the calculation of the B value using a mass balance model which considers 50% of this amount. In this case, the adjusted B values would increase to −2.05‰ and −1.89‰ in chickpea and faba bean, respectively. [ABSTRACT FROM AUTHOR]

Selenium (Se) has gone, in a few years, from being considered only a toxic element to attribute it remarkable benefits for the human health: from antioxidant and hormonal regulations of thyroid functions to established anti-carcinogen effects. The Se is an essential microelement for humans and livestock, but not for plants, which extract it from soil incidentally. Therefore the population Se status of a area ultimately depends on its presence in soil. In the last two decades have shown that the individual Se requirements are higher than the values referenced given for Official Organism, and that should be considered not only the direct effects of deficiency, but adequate to achieve optimal health through maximize/ optimize the Se-proteins. In Spain, the few studies on healthy people show low Se levels in blood. This fact is corroborated by the low Se concentration on the main food groups. The cereals, more specifically wheat and derivative products, is one of main groups that provide greater Se contribution to the diet. However, the wheat Se concentrations in Spain are low, partly explaining the low blood levels found in the Spanish population. It would need to involve the National Public Organizations to increase the number of studies of this subject, in order to elucidate the extent of Se deficiencies in Spanish population and to evaluate possible solutions., (Copyright © AULA MEDICA EDICIONES 2013. Published by AULA MEDICA. All rights reserved.)