Zinc is one of the essential elements necessary for the normal growth and development of humans and plants. Zinc is an essential element required for metabolic activities of 300 enzymes of body, and also requires for DNA synthesis, protein synthesis and cell division, these enzymes played an important role in metabolism of carbohydrates, proteins and fat. Zinc is very essential element for growth of tissues, healing of wounds, maintenance of connective tissues, functioning of immune system, mineralization of bones, blood clotting and sperm production. Zinc is crucial for humans to taste and smell things properly, and it also favours normal growth and development during pregnancy, childhood, and adolescence.
Zinc is necessary for healthy skin, zinc based solutions are being used as to treat acne, cold sores and hot burns. Zinc plays a role in activation of brain areas that receive and process information from sensors of taste and smell. Zinc influences the appetite and taste performance. Zinc abnormalities also exist in mood disorder patients. Zinc is very effective in reducing fatigue, mood swings and changes in appetite. Zinc has interaction with other chemicals to transfer message to sensory brain center, increasing memory and thinking skills.
Zinc is required in small quantity for human health even a small deficiency of zinc is disaster for human health. Zinc is very important for pregnant women and fetus. It is estimated that 82 per cent pregnant women of world have diets low in zinc contents and both woman and fetus suffer the effects of zinc deficiency. About two billion peoples in developing countries are facing the problem of zinc deficiency.
Zinc deficiency causes various types of irregularities in human like growth retardation, loss of appetite and impaired humans. While severe kind of zinc deficiencies cause irregularities like loss of hairs, diarrhea, and delay in sexual maturation, hypogonadism in males and eye and skin lesions. In children zinc deficiencies increase the infection, time duration, Severity and incidence of diarrhea leads to the death of 800,000 children worldwide per year. Zinc deficiency effects the maternal by showing various consequences like low birth weight, spontaneous abortion and pregnancy related toxemia.
Symptoms of zinc deficiency in humans (clockwise from top left): dermatitis, retarded mental growth, acne and white spots on nails
In Pakistan 40 per cent mothers and every third child is suffering from Zn deficiency. Zinc, iron and vitamin A deficiencies have been reported by the World Health Organization in peoples of developing countries. Zinc deficiency in humans is the fifth major cause of disease and deaths in these countries. Black et al. (2008) reported that every year 500,000 children under 5 years of age died due to Zn and Fe deficiencies. Zinc and Fe deficiencies together with vitamin A deficiency have been identified as the top priority global issue to be addressed to achieve a rapid and significant return for humanity and global stability.
Zinc is very essential micronutrient for healthier growth and reproduction of humans, animals and plants. Zinc deficiency is a worldwide problem in agriculture soils; more than 50 per cent of cereal growing soils are being low in plant available zinc content. Soils of Pakistan are calcareous and alkaline in nature. Such kind of soils mostly have less amount of available micronutrients to plants, such as zinc. Zinc deficiency is a common problem in cereals growing on calcareous soils.
Zinc deficiency may occur due to diets inadequate in bioavailable zinc. In Pakistan zinc deficiency is a wide spread problem in different crops including wheat (Triticum aestivum L.). Zinc fertilizer application is recommended for different crops; however, its use is limited to rice, citrus and potato. In Pakistan the applied doses of zinc are less than the crop requirement, i.e., 2-5 kg Zn ha-1. Therefore, crop production and grain Zn concentration remains below. As a result when humans will take the food lower in Zn that will cause zinc deficiency in them. In human beings zinc deficiency can be occur due to two reasons: deficiency can be occur due to consumption of food lower in zinc contents or due to unavailable forms of zinc, deficiency can also be occur due to diseases or genetic malfunctions that impairs intestinal absorption and enhance the loss of zinc through intestine.
Biofortification is a technique (Plant breeding or Agronomic) to increase grain micronutrient concentration. Breeding technique is costly and it requires long term effort and resources. Agronomic technique to increase grain nutrient concentration is quick solution to address the problem. In this technique fertilizers can be applied to plants through different application methods to increase grain nutrient concentration. Agronomic techniques may provide quick solution to this problem and it involves micronutrients application either by seed priming, soil application and foliar application to enhance the concentration level of these important micronutrients in food crops. Biofortified foods have high micronutrient concentration as compared to non biofortified foods. The crops that are mostly subjected to biofortification include wheat, rice, maize, beans, sweet potatoes and pearl millet.
Fertilizer application method is very important to make nutrient availability to the plants. Different methods of zinc application are used in different areas; the success of any fertilizer application method depends on soil, money and social factors. Fertilizer application through soil application is very easy but it requires more application cost and involves high chances of nutrient losses by leaching and fixation. Soil application of zinc is less effective on increasing grain zinc concentration, while foliar application of zinc is extra ordinary method for increasing grain zinc concentration. By optimizing the timing and the solute concentration of foliar Zn application, wheat grain Zn concentration could be further increased, not only in whole grain but also in the endosperm.
By adopting agronomic biofortication method we can reduce zinc deficiency in humans in short interval of time and can solve zinc deficiency problem in humans.
The authors are from the Department of Agronomy University of Agriculture Faisalabad; and Institute of Agricultural Sciences University of Punjab, Lahore.