Micronutrient enrichment of leguminous crops through agronomic biofortification: Strategies, challenges and future directions
Hidden hunger refers to micronutrient deficiencies affecting nearly two billion people globally, especially in regions dependent on calorie-rich but nutrient-poor staple diets. Legumes, termed as the "poor man's meat" for their high protein content and low cost, are critical for enhancing nutritional security in resource-limited communities. This review emphasises agronomic biofortification as a rapid, promising and versatile strategy for enhancing essential micronutrients, particularly iron (Fe), zinc (Zn) and selenium (Se), in legume grains. It discusses different agronomic strategies such as soil and foliar fertilisation, seed priming and biological interventions. Unlike conventional breeding and genetic methods, which require longer to develop, these agronomic techniques can increase nutrient density within a single cropping cycle. It also focuses on the scope of agronomic biofortification and addresses its challenges related to nutritional bioavailability, notably the inhibitory effect of anti-nutritional factors such as phytates and discusses strategies to enhance nutrient absorption through promoter compounds. Furthermore, emerging technologies such as nanotechnology and precision agriculture are recognised as promising innovations to enhance nutrient use efficiency (NUE) and ensure environmental sustainability. Overall, agronomic biofortification provides a sustainable pathway to combat micronutrient malnutrition and this approach requires integration with genetic advancements and supportive agricultural policies for its long-term success.