Zinc and iron agronomic biofortification of selected Brassicaceae microgreens

Authors: DI GIOIA, FRANCESCO - State College Of Pennsylvania; PETROPOULOS, SPYRIDON - University Of Thessaly; OZORES, HAMPTON - University Of Florida; MORGAN, KELLY - University Of Florida; Rosskopf, Erin

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2019
Publication Date: 10/25/2019
Citation: Di Gioia, F., Petropoulos, S., Ozores, H., Morgan, K., Rosskopf, E.N. 2019. Zinc and iron agronomic biofortification of selected Brassicaceae microgreens. Agronomy Journal. https://doi.org/10.3390/agronomy9110677.
DOI: https://doi.org/10.3390/agronomy9110677

Interpretive Summary: Insufficient or suboptimal dietary intake of iron (Fe) and zinc (Zn) represent a latent health issue affecting a large proportion of the global population, particularly among young children and women living in poor regions at high risk of malnutrition. Agronomic crop biofortification, which consists in increasing the accumulation of target nutrients in edible plant tissues through fertilization or other eliciting factors, has been proposed as a short-term approach to develop functional staple crops and vegetables to address micronutrient deficiency. Microgreens are a relatively new class of crops that are considered to have great potential due to their nutrient density and ability to grow in small space, making them ideal for urban horticulture. The ability to increase their nutritional value through growth with high nutrient solutions make them an ideal crop for biofortification. A study was conducted to determine if microgreen content of iron and zinc could be increased by growing with solutions high in these minerals. Three species of Brassicaceae microgreens were grown in solutions containing increasing amounts of iron and zinc. Each species had a different response to increased levels but the highest level of applied iron caused phytotoxicity in all three species. No impact on yield resulted from any applied levels of zinc. All zinc and lower concentrations of iron resulted in significant increases in accumulation of these minerals in all three species, with increases in red cabbage microgreens being the greatest. Brassicaceae microgreens are a good target for biofortification for zinc and iron. Further research is needed to assess the potential for biofortification of other microgreens species and investigate the micronutrient bioavailability and the potential presence of antinutritional factors in zinc and iron biofortified microgreens.

Technical Abstract: Insufficient or suboptimal dietary intake of iron (Fe) and zinc (Zn) represent a latent health issue affecting a large proportion of the global population, particularly among young children and women living in poor regions at high risk of malnutrition. Agronomic crop biofortification, which consists in increasing the accumulation of target nutrients in edible plant tissues through fertilization or other eliciting factors, has been proposed as a short-term approach to develop functional staple crops and vegetables to address micronutrient deficiency. The aim of the presented study was to evaluate the potential for biofortification of Brassicaceae microgreens through Zn and Fe enrichment. Two experiments were conducted to investigate the effect of nutrient solutions supplemented with zinc sulfate (Exp-1; 0, 5, 10, 20 mg L-1) and iron sulfate (Exp-2; 0, 10, 20, 40 mg L-1) on the growth, yield, and mineral concentration of three microgreen species (arugula, red cabbage, and red mustard). Zn and Fe accumulation in all three species increased according to a quadratic model with increasing level of Zn and Fe, respectively. However, significant interactions were observed between Zn or Fe level and the species examined, suggesting that the response to Zn and Fe enrichment was genotype specific. The highest level of Zn and Fe supplied through the nutrient solution resulted in toxic accumulation of Zn and Fe, respectively, and in the case of Fe was phytotoxic for all three species, whereas Zn had no effects on yield. The application of Zn at 5 and 10 mg L-1 resulted in an increase in Zn concentration compared to the untreated control ranging from 75% to 281%; while solutions enriched with Fe at 10 and 20 mg L-1 increased Fe shoot concentration from 64% in arugula up to 278% in red cabbage. In conclusion, the tested Brassicaceae species grown in soilless systems are a good target to produce high quality Zn and Fe biofortified microgreens through the simple manipulation of nutrient solution composition. Further research is needed to assess the potential for biofortification of other microgreens species and investigate the micronutrient bioavailability and the potential presence of antinutritional factors in Zn and Fe biofortified microgreens.