Biofortification of Forage Peas with Combined Application of Selenium and Zinc Under Mediterranean Conditions

Agronomic biofortification can be used to alleviate the deficient intake of selenium (Se) and zinc (Zn) by livestock. These two essential micronutrients for human and animals play an important role in many physiological functions and biological processes. The aim of the present study was to evaluate the suitability of forage peas, crop with an increasing importance as plant protein source, to be biofortified with a combined treatment of Zn (as ZnSO4-7H2O) and Se (as Na2SeO4). A 2-year field experiment was established in southern Spain under semiarid Mediterranean conditions, by following a split-split-plot design. The study year (2017/2018, 2018/2019) was considered the main-plot factor, soil Zn application (50 kg Zn ha−1, nil Zn) as a subplot factor, and foliar application (nil, 10 g Se ha−1, 8 kg Zn ha−1, 10 g Se ha−1 + 8 kg Zn ha−1) as a sub-subplot factor. The combined application of 50-kg soil Zn ha−1 and the foliar application of 10 g Se ha−1 + 8 kg Zn ha−1 was the most effective treatment to increase the concentration in forage of Zn and Se, 4-fold and 5-fold, respectively, as well as the Zn bioavailability, forage yield (close to 30%), and crude protein (~ 8%). Thus, forage peas could be considered a very suitable crop to be included in biofortification programs under Mediterranean conditions with Zn and Se as target minerals.