Zinc (Zn) and iron (Fe) deficiencies are well-documented public health issue affecting nearly half of the world population. Developing countries are among the worst affected from Zn and Fe deficiencies which result in number of serious health complications, such as impairments in brain function and mental development, high susceptibility to deadly infectious disease and high risk for anemia. Recent reports indicate that, for example, Zn deficiency is responsible for death of nearly 450 000 children under 5-years old, annually. Very low concentrations and poor bioavailability of Zn and Fe in the commonly consumed foods seem to be the main reason for widespread occurrence of micronutrient deficiencies in human populations. Cereal-based foods are most commonly consumed foods and contribute up to 75 % of the daily calorie intake in the rural parts of the developing countries. Zinc and Fe deficiencies are also common micronutrient deficiencies in agricultural soils limiting both crop production and nutritional quality

Breeding new cereal genotypes with high genetic capacity for grain accumulation of micronutrients is widely accepted and most sustainable solution to the problem. There are impressive progresses in breeding new genotypes for high micronutrient density. However, the breeding approach is a long-term process and may be affected from very low chemical solubility of Zn and Fe in soils due to high pH and low organic matter. Agronomy-related approaches offer short-term and complementary solutions to the Zn and Fe deficiency in human health and crop production. Soil amendments contributing to solubility of Zn and Fe in soil solution, cereal-legume intercropping systems, and soil and foliar application of micronutrient-containing fertilizers are well-documented agronomic tools which contribute to root uptake, shoot and grain accumulation of Fe and Zn.

Fertilizer strategy is a simple and effective agronomic practice to contribute grain concentrations of micronutrients. Increasing number of evidence is available showing that soil and especially foliar application of Zn fertilizers results in impressive enhancements in grain Zn concentration. In contrast, soil and foliar application of Fe fertilizers is not effective in increasing grain Fe concentration. In wheat, foliar application of ZnSO4 at later growth stages seems to be more effective in enhancing grain Zn concentration than the application at earlier growth stages. Late foliar application of Zn is also effective in higher accumulation of Zn in the endosperm part of grains compared to earlier application. Enrichment of commonly soil-applied fertilizers like urea with Zn seems to be also very helpful strategy in improving grain Zn concentration. Recently published results indicate that soil and/or foliar application of nitrogen fertilizers improve both root uptake and grain accumulation of Fe and Zn.

The results available indicate high potential of agronomic approaches for improving grain Zn and Fe concentrations. Agronomic practices mentioned are simple and easily applicable in many target countries with high incidence of micronutrient deficiencies. Combination of agronomic practices with breeding approach will ensure the plants to maximize grain accumulation of micronutrients. This paper will also summarize the results of a recently initiated global zinc fertilizer project in 10 countries under HarvestPlus program (www.harvestzinc.org).

Iron (Fe) toxicity is a widespread nutrient disorder and limit to grain yield in lowland rice. As it is, however, sometimes associated with deficiency of other nutrients, Fe toxicity might be also managed and alleviated by applications of concerned nutrients such as potassium (K) and zinc (Zn). However, the information on this topic available in literature is very limited, especially in the case of Zn. The objective of this study was to evaluate the effects of soil and foliar Zn applications on severity of Fe toxicity and grain concentrations of Zn in rice grown on a Fe-toxic soil in Laos under field conditions. Soil Zn applications have been realized in 2 forms: 1.5 % Zn-containing KCl (KCl-Zn) and ZnSO4. The results with soil Zn applications showed that plant growth at early growth stage was increased by both forms of Zn applications which in turn contributed to final grain yield. The increases in grain yield resulted from the KCl-Zn and ZnSO4 applications were similar and were around 35 % compared to the control treatment without any Zn application. Leaf Zn concentrations were also increased by Zn applications while Fe concentrations tended to decrease. In a separate experiment soil and foliar applications of ZnSO4 were examined for their effectiveness in affecting plant Zn concentration. Soil Zn application was not affective in increasing grain Zn concentration, but foliar-applied Zn increased Zn concentration of brown rice up to 34 %. This study suggested that Zn fertilizer strategy is a promising approach to contribute to both grain yield and grain Zn concentrations in rice under Fe toxic soil conditions.

Wheat is an important staple food crop for human consumption. Developing minerals-enriched cereals is the most promising and cost-effective approach for diminishing malnutrition. Wild emmer wheat [Triticum turgidum ssp. dicoccoides (Körn.) Thell.], the progenitor of domesticated wheats, offers a valuable allelic repertoire for economically important traits, including grain mineral concentrations. Twenty two wild emmer wheat accessions, representing a wide range of drought resistance capacity, as well as two durum wheat cultivars, were examined under two contrasting irrigation regimes (well-watered control and water-limited) for grain yield, total biomass production and grain Zn, Fe and protein concentrations. The obtained results demonstrated the presence of a large genetic diversity for grain protein and mineral nutrient concentrations in wild emmer germplasm and about two-fold greater values as compared with domesticated wheat. A strong positive association between GPC, Zn and Fe, and no association between any of these three variables and yield was noted. The genetic basis of grain mineral concentrations was further dissected using a population of 152 recombinant inbred lines, derived from a cross between durum wheat (cv. Langdon) and wild emmer (acc. G18-16). A total of 82 QTLs were mapped for 10 minerals. There was significant positive correlation between GPC, Zn and Fe, which was supported by a significant overlap between QTLs, suggesting a common physiological-genetic control of these compounds. The identified genetic resources and QTLs may facilitate the use of wild alleles for improvement of grain protein and mineral concentrations in elite wheat cultivars.

Localization of iron (Fe), zinc (Zn), and protein was studied in a set of spelt (Triticum aestivum ssp. spelta) genotypes selected for low (i.e. ~12 %) or high (i.e. ~25 %) grain protein concentration. Following instrumental analysis for Fe, Zn and protein, spelt seeds were longitudinally excised and stained with specific dyes for assessment of Fe, Zn, and protein localization. For Fe and Zn staining, pre-defined methods with Perls’ Prussian blue and dithizone were applied whereas protein staining was performed by a modified Bradford reagent. Following staining, seed surfaces were examined by light reflectance microscopy and photographed to (i) examine the localization of Fe, Zn and protein and (ii) visually compare the variations in color intensity with the concentration data obtained by instrumental analysis of seeds with contrasting protein concentration. The applied staining method revealed that Fe localization was limited to scutellum and aleuron; however Zn and protein was localized in the whole germ and the aleuron as well. It was concluded that the staining methods applied for protein and Fe localization can also be used for mass screening of spelt genotypes for high seed protein and Fe concentration. The role of seed proteins as a sink for Fe and Zn in the spelt seed is discussed.