Nutritional biofortification of lettuce in response to iron- and zinc-enriched nutrient management techniques

Micronutrient deficiencies are a growing global public health concern. Iron (Fe) and zinc (Zn) deficiencies are the most prevalent nutritional disorders affecting human populations. Agronomic biofortification has emerged as a practical and scalable strategy to enhance the micronutrient density of food crops. In this context, the present study evaluated the effectiveness of three Fe- and Zn-enriched nutrient management techniques, (i) seed nutripriming, (ii) growth medium application, and (iii) foliar application, on biomass production, mineral accumulation, and nutritional quality of lettuce (Lactuca sativa L.). Fe and Zn were supplied as FeSO4 and ZnSO4, respectively, in two independent experiments. Results indicated that foliar application was the most effective method for increasing Fe and Zn concentrations in lettuce leaves. Seed nutripriming significantly enhanced photosynthetic pigments, particularly chlorophylls and carotenoids, under both Fe and Zn treatments. Ascorbic acid content increased significantly with foliar Fe application, whereas Zn application via the growth medium resulted in higher ascorbic acid levels. Additionally, foliar Zn application significantly improved antioxidant capacity compared to other treatments. However, other nutritional attributes, including total polyphenols and macronutrient (nitrogen and phosphorus) concentrations, were not significantly influenced by the Fe- and Zn-based nutrient management approaches. Overall, the findings suggest that foliar application is a promising strategy for Fe and Zn biofortification in lettuce, while seed nutripriming may improve specific quality traits related to photosynthetic pigments.