Biofortification with Micronutrients

Biofortification of Cereal and Legume Crops with Micronutrients

Ensuring global food and nutrition security, especially in developing countries, is a complex challenge due to numerous factors such as climate change, poverty, population growth, conflicts, and terrorism.

Iron, zinc, calcium, and magnesium are essential micronutrients that play a vital role in human health. Iron and zinc deficiencies are significant public health problems worldwide. Iron is crucial for cell division, differentiation, oxygen transport, and electron transfer. The prevalence of iron deficiency was four times higher in developing countries compared to developed countries, with infants, the elderly, and women, particularly during pregnancy, being the most affected groups. Zinc performs three functions: catalytic, structural, and regulatory. Its deficiency increases the risk of diarrhea, growth retardation, mortality, and childhood respiratory illness, and preterm birth during pregnancy. Its role has been central in the fight against COVID-19 due to its well-established role in human immunity. Calcium and magnesium are involved in many human health functions, and deficiency of either increases the risk of developing certain diseases.

To prevent micronutrient deficiencies, nutritionists recommend a balanced intake of nutrients from fruits, vegetables, root crops, tubers, cereals, and legumes. Biofortification is a process that involves increasing the nutrient content of crops by introducing essential micronutrients during the growth process. This is considered a sustainable strategy to address micronutrient deficiencies by enhancing the levels of key vitamins and minerals in selected crops. Biofortification of crops has been made possible through genetic and agronomic approaches.

The overall goal of agronomic biofortification is to increase the nutrient density of crop yields. 

Specifically, the objectives of biofortification are: 

– to develop a stable process for enriching crops with micronutrients; 

– to maintain or improve crop yields for farmers and product characteristics for consumers while improving the micronutrient content of crop products.

Biofortification of Cereal and Legume Crops with Micronutrients

Agronomic biofortification works by:

– supporting the overall soil condition;

– using appropriate agronomic practices;

– integrated use of soil and foliar fertilization.

Increased concentrations of nutrients in crops should be facilitated by:

– better uptake of nutrients from the soil,

– improved translocation of nutrients from leaves to grain,

– and enhanced sequestration of nutrients to the endosperm. 

Common agronomic approaches include fertilizer application, seed treatment, application of bioinoculants and/or plant growth-promoting bacteria, and crop rotation. 

Biofortification using fertilizers involves foliar application, soil application, and their combination, where foliar application is less costly (requires less fertilizer) and is more effective in terms of nutrient content in the grain. Additional application of fertilizers such as urea, diammonium phosphate, and potassium sulfate improves the uptake of micronutrients by the grain. 

Among agronomic methods of biofortification, foliar fertilization is the most widely used and beneficial, as it can significantly increase the micronutrient content in the edible parts of plants. Soluble forms of nutrients – nitrogen, phosphorus, potassium, sulfur, zinc, and iron – mixed in a working solution with water, with the addition of pesticides – insecticides, fungicides or herbicides, can be used for seed treatment before sowing or applied during the vegetation period of plants – at the growth and development stages of BBCH 31-39 – stem elongation and BBCH 71-79 – fruit and seed development. 

Although foliar fertilization for biofortification has several advantages, its full potential is not explored due to a lack of information. To develop effective and efficient foliar fertilization strategies, this knowledge gap needs to be addressed. More attention should be paid to the choice of medium and timing to improve the efficiency of nutrient use. 

One such way to induce micronutrients in grain is foliar fertilization. Foliar fertilization not only improves the nutritional value of grain but also helps to address the global problem of hidden hunger. Foliar fertilization usually delivers nutrients from leaves to grains in a form that is edible and absorbable by humans. 

Agronomic biofortification offers many options for cereal and legume crops, depending on the sources of nutrients, methods of application, rates, timing, and growth stages. 

Among the available options for agronomic biofortification of cereal and legume crops is the use of chemical sources of nutrients such as:

• ZnSO₄ for increased zinc uptake in plants,
• FeSO₄ and Fe-chelates for iron accumulation in edible parts of plants,
• MgSO₄ and MgCl₂ for increasing magnesium content,
• CO(NH₂)₂ (urea) and NPK for improving the mobility of micronutrients in the soil. 

Among the biofortification methods – seed coating, soil, foliar application or combination of methods. It was established by research that soil application is well suited for increasing yield, while foliar application proves to be effective for improving grain quality with promising indicators. 

Thus, the application of liquid fertilizers containing micronutrients essential for human nutrition for foliar fertilization of key crops will contribute not only to increasing their yield but also to increasing the concentration of important nutrients – iron, zinc, calcium and magnesium in edible parts of plants, which in turn will help to overcome the phenomenon of hidden hunger in the world and improve the health of the population through the consumption of high-quality plant products.