Comparison of Iodide, Iodate, and Iodine-Chitosan Complexes for the Biofortification of Lettuce

Iodine is an essential trace nutrient for humans; its deficit can affect motor and cognitive development. Biofortifying crops with iodine is a way of promoting the adequate intake of this element. The uses of chitosan-iodine complexes for crop biofortification have not been previously studied. The present work evaluated the effects of KIO3 and KI salts, chitosan-KIO3 complex (Cs-KIO3), and chitosan-KI complex (Cs-KI) application on lettuce, with a chitosan-only treatment as a control and water as the absolute control. Each treatment involved the application of 0, 5, and 25 mg I kg−1 soil applied before transplanting or 25 mg I kg−1 soil applied as split doses of 12.5 mg kg−1, once immediately before transplanting and the second application 15 days later. Single application of Cs-KIO3 at 5 and 25 mg I kg−1 increased lettuce biomass while the split-dose application (SDA) of Cs-KI (25 mg I kg−1) led to a decrease in biomass. Maximum accumulation of iodine in lettuce was observed after the application of KIO3 (25 mg I kg−1) in two parts. This study shows that the use of chitosan complexes, especially Cs-KIO3, may be a viable alternative for crop biofortification with iodine without affecting crop yields.