Iodine Biofortification of Crops

Abstract

The biofortification of crops with iodine consists of a set of techniques that allow obtaining plant foods with concentrations of iodine that partially or entirely provide the daily intake requirements for humans. Iodine is transferred from plants to humans through the trophic chain, which is why we seek to biofortify the crops as part of the strategy to ensure adequate consumption of this element. The concentration of iodine in food depends primarily on the ability of plants to absorb and accumulate it, as well as the capacity of soil and water to provide it in bioavailable forms for plants. In many soils, the low concentration of bioavailable iodine is the result of intrinsic geological factors, although in other cases it results from edaphic fixation. These edaphic factors that modify the bioavailability of iodine are well known, pH and ORP, organic matter, minerals of colloids, and microbial activity. Although almost all of these factors are or can be part of routine agronomic management, little is known about their proper combinations to increase the bioavailability of iodine that is fixed in agricultural soils. All of the experimental reports on biofortification refer to the contribution of exogenous iodine in mainly inorganic (KI and KIO₃) and some organic (kelp and iodinated organic acids) forms both in soil crops and in soilless production systems. The ideal situation would be for exogenous applications to be used mostly for crops in soilless systems, whereas for the crops in soil, the exogenous applications were a complement to agronomic management that promoted the bioavailability of iodine in the soil solution. As iodine is not an element qualified as essential for plants, the extension of its use among agricultural producers will not be simple, unless it ensures some utilitarian facet of iodine, which could be its antioxidant capacity and potential inducer of tolerance to stress.