## 3 Biofortification of Crops
### Crop Breeding and Genetic Modification as Biofortification Tool  
Biofortification using crop breeding involves the science of improving micronutrient content of staple crops, using the conventional breeding methods and current biotechnology [32]. Crops are bred and genetically modified to improve absorption capacity and nutrient content. Plant breeding methods, which tend to enhance the micronutrient content of various cereals, legumes and tubers, exist. Biofortification by breeding has several advantages as a policy: it leads to development of staples consumed daily and ardently caters for the poor. Again, these developed varieties can be used over time, thus reducing cost and making it sustainable.  
In conventional breeding, crops such as legumes and cereals with high micronutrient content are selected, purified and multiplied [33]. Then, newly improved food crops of varying nutritional contents can be conventionally developed and isolated from the varieties of the same plant. Breeding of crops is principally committed to increasing micronutrients and vitamin A content in the common food crops [34]. Crops produced through conventional breeding have gained more acceptance than those from gene modification. Collection of such high nutrient rich varieties has been on the increase since the 1960s in seed banks. According to [PERSON] et al. [13], orange fleshed sweet potato (OFSP) and quality protein maize have been well accepted and can be seen as interesting examples of conventionally bred biofortified crops. Iron beans and zinc rice are other examples. It is obvious that not all micronutrients can be enhanced in crops through conventional breeding. As a result, this necessitates the role of genetic nutrient modification in nutrient enhancement.  
Genetic engineering of crops has facilitated modification of crops in unique ways and is a tool for addressing global agricultural challenges. Improved knowledge of DNA led to speedy advancement of agricultural biotechnology as a field. Agricultural biotechnology uses modern biology techniques to alter living beings or their components for cogent purpose in crops. As a result, it permits infusion of genes from the wild. Such cannot be done using conventional breeding. The overall objective of nutritional genetic modification is to integrate high micronutrient traits in already proven highest-yielding varieties [13]. This will motivate farmers to cultivate that new variety. [PERSON] et al. reported that improving the Fe, Zn, and Se content of crops by utilizing the plant genetic makeup and applying biotechnological process could solve nutritional inadequacies in human foods; unfortunately, it is an expensive approach and involves a lot of time [35]. However, once these crop varieties are obtained, no more resources are invested and generations yet unborn will benefit from them. In soil low or lacking in these essential micronutrients, it becomes difficult for the crops to obtain enough micronutrients, which makes agronomic biofortification using fertilizers essential.  
Although plant breeding is the most practiced sustainable method in fortification [24; 36; 37], development of new genotypes enriched with micronutrient is a long-time venture [38]. In addition, available micronutrient in the soil limits the effectiveness of new genotypes in increasing micronutrient content [39; 40]. Moreover, these genetically-modified micronutrient-rich crops may not be adopted by many. Consequent upon these limitations, agronomic biofortification is an alternative mechanism to increase micronutrients content in staples to overcome the limitations accruing from crop breeding biofortification technique.