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Pak. J. Bot., 42(4): 2565-2578, 2010. |
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Updated: 09-12-10 |
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THE ROLE OF MICRONUTRIENTS IN CROP PRODUCTION AND HUMAN HEALTH
MUHAMMAD IMTIAZ1*, ABDUL RASHID2, PARVEZ KHAN, M.Y. MEMON AND M. ASLAM
Abstract:
The soils in Pakistan across 22 Mha cultivated area are predominantly
alluvial and loessal, alkaline in pH, calcareous and low in organic
matter. These factors are mainly responsible for nutrient fixation in
soil and low availability to plants. Zinc (Zn) deficiency in Pakistan
was the first micronutrient disorder recognised in early 1970s as a
cause of hadda disease in rice. After identification of Zn
deficiency, extensive research has been carried out during last four
decades on micronutrient deficiencies in soils and their drastic effects
on crops. Subsequently, field-scale deficiencies of zinc (Zn) boron (B)
and iron (Fe) have been established in many field and horticultural
crops. The most widespread deficiency is of Zn as 70 % of the soils of
Pakistan are Zn deficient and observed in rice, wheat, cotton, maize,
sunflower, sugarcane, brassica, potato and in many other crops along
with citrus and deciduous fruits. Boron deficiency is another major
nutritional disorder which severely affects rice, cotton, wheat,
sugarbeet, peanut, citrus and deciduous fruits. The third field-scale
disorder is Fe chlorosis which has been exhibited in peanut, chickpea,
cotton, citrus, ornamentals and many tree species. Copper (Cu) and
manganese (Mn) deficiencies are of localized occurrence. The mineral
elements like Zn, Fe and Cu are as crucial for human health as organic
compounds such as carbohydrates, fats, protein and vitamins. The daily
dietary intake of young adult ranges from 10-60 mg for Fe, 2-3 mg for Cu
and 15 mg for Zn. Intake less than these values can cause slow
physiological processes. These micronutrients deficiencies in soil are
not only hampering the crop productivity but also are deteriorating
produce quality. High consumption of cereal based foods with low
contents of micronutrients is causing health hazards in humans. The
contents of micronutrients in food can be elevated either by
supplementation, fortification or by agricultural strategies i.e.,
biofortification and application of micronutrients containing
fertilizers. Food fortification and supplementation are too expensive,
not practical to be applied on large scale and not easily accessible to
poor masses. The development of micronutrient efficient genotypes can be
a successive tool to overcome the micronutrient disorders in soil and
for improvement in human health. However, the harvesting of
micronutrient enriched grains from field would mine out more
micronutrients. The cultivation of these genotypes can be integrated
with the application of micronutrients containing fertilizers. Addition
of such fertilizers will not only correct the deficiencies but also
improve the fruit size and quality of crops. In general, 2-5 kg Zn ha-1
may be adequate for improved crop production, however, soil applied Fe
is generally ineffective except for Fe-sequestrine. Repeated sprays of
Ferrous sulphate (FeSO4) or chelated Fe cure the chlorosis
and improve the quality of food stuff. However, despite being highly
cost effective, currently micronutrient use is negligible.
1Soil Science Division, Nuclear Institute of Agriculture, Tando Jam, Sindh, Pakistan 2Pakistan Atomic Energy Commission, HQ, Islamabad, Pakistan. *Corresponding author E-mail: drimtiaz64@yahoo.com |
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