Agronomic approaches for improving the micronutrient density in edible portions of field crops

Increased micronutrient density in grain destined for human consumption may alleviate micronutrient deficiencies (Fe, Zn, Cu, and I) in human populations around the world. The review of literature indicates that fertilization with inorganic and organic forms of micronutrients has a potential to increase their concentrations in grain. The most effective fertilization could be via soil (for Zn and, to some extent, Cu), foliarly (for Fe) and by adding fertilizers to the irrigation water (for iodine). Care should be exercised not to overfertilize crops with micronutrients because of consequent toxicity and losses in quality and quantity of grain yield. Effectiveness of various agricultural measures in increasing micronutrient density depends on soil type, crop, cultivar, rotation, and environmental and other factors, thus necessitating development of a specific set of measures for individual regions. Agricultural measures would need to be supplemented with appropriate changes in the milling technology to ascertain that increased micronutrient concentrations in some grain parts are passed into the food chain. (C) 1999 Elsevier Science B.V. All rights reserved.