. Iron and zinc
deficiencies in human nutrition are widespread in developing Asian and African
countries where cereal grains are the staple food. Effects are therefore
underway to develop cereal genotypes with grains denser in Fe and Zn by
traditional plant breeding or using genetic engineering techniques. This
approach requires a long period and adequate funds. However, the products of
genetic engineering are not well accepted in many countries. Also, there is a trade-off
between yield and grain biofortification. Agronomic biofortification offers to
achieve this without sacrificing on yield and with no problem of product
acceptance. From the viewpoint of biofortification, foliar application has been
reported to be better than the soil application of Fe and Zn, and for this
purpose, chelated Fe and Zn fertilizers are better. When soil applied, water
soluble sources of Zn are better. Soil application of Fe is not recommended.
Agronomic biofortification depends upon management practices (tillage, water
management, nutrient interactions), soil factors (amounts present, pH,
mechanisms of Zn fixation other than pH), and plant factors (root
characteristics, excretion of phytosiderophores and organic acids by roots, Zn
utilization at the cellular level, translocation within plant and mechanisms of
Zn accumulation in grain). Genetic and agronomic biofortification are
complementary to each other. Once the genotypes having denser grains are
developed, they will have to be adequately fertilized with Fe and Zn. - Seemore at:
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