Impact of Agronomic Biofortification with Zinc on the Nutrient Content, Bioactive Compounds, and Antioxidant Capacity of Cowpea Bean (Vigna unguiculata L. Walpers)

David López-Morales,Rodolfo Osorio-Osorio,Pablo Preciado-Rangel,César Márquez-Quiroz,Esteban Sánchez-Chávez,Efraín De La Cruz-Lázaro

doi:10.3390/agronomy10101460

Abstract

Zinc intake deficiency is a public health problem and increasing the nutrient’s content in the edible parts of plants can help mitigate it. The objective of this work was to determine the effect of the edaphic and foliar application of zinc sulphate on the nutrient content, bioactive compounds, and antioxidant capacity of cowpea beans (Vigna unguiculata L. Walpers). A sample of 100 grains was taken, and the length, width, thickness, weight, ash content, fat, humidity, fibers, carbohydrates, protein, energy, macro- and micro- nutrients, total phenols, flavonoids, anthocyanins, and antioxidant capacity were determined. The 0.250 g edaphic-12.5 mM foliar dose produced grains of a greater weight and size. All of the edaphic and foliar doses increased the grain zinc content, and the highest value was found with the 0.125 g edaphic-50.0 mM foliar dose. The total phenols increased with 12.5 g of edaphic zinc, while phenols, flavonoids, and the antioxidant capacity increased with 50.0 mM foliar zinc. The edaphic and foliar application of zinc sulphate increased the grain weight and size, zinc content, total phenols, and antioxidant capacity. Therefore, edaphic and foliar zinc biofortification enriches this nutrient in cowpea grains, and could reduce micronutrient malnutrition in the urban and rural communities of Mexico.

Highlights

Pulses are the primary group of food legumes consumed in developing countries, and the second most important group of plants as a source of carbohydrates, proteins, amino acids, fibers, vitamins and phytochemicals [1]
The weight of 100 grains was higher than the 11 g reported [37]; it was within the range reported for zinc biofortified cowpea beans
The largest grain sizes were obtained with the application of 0.250 g edaphic in combination with 12.5 mM foliar doses, while the highest fat, carbohydrate, and protein contents were found with the 0.250 g edaphic dose

Summary

Introduction

Pulses are the primary group of food legumes consumed in developing countries, and the second most important group of plants as a source of carbohydrates, proteins, amino acids, fibers, vitamins and phytochemicals [1]. Walpers) is a legume and belongs to the family Fabaceae, tribe Phaseolae, genus Vigna, and section Catiang. It is a herbaceous annual crop, mostly grown in the dry agroecologies of the tropics in Latin America, Africa, and South Asia [2]. It is characterized by having significant contents of proteins, carbohydrates, fibers, vitamins, and nutrients, with a low-fat content and bioactive compounds, such as phenols and polyamines [3].These characteristics make cowpea potentially important to the human diet from a nutritional perspective. The content of zinc in the grains is often suboptimal, especially when produced in soils deficient in microelements [4]

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Discussion

Conclusion