Iodine Agronomic Biofortification of Cabbage (Brassica oleracea var. capitata) and Cowpea (Vigna unguiculata L.) Is Effective under Farmer Field Conditions

Abstract

Iodine (I) is an essential micronutrient, which plays a critical role in human metabolism.However, its concentration is known to be low in most soils, making it deficient in crops. With most Iagronomic biofortification studies conducted under controlled environments, limited informationcurrently exists on this approach of enriching I deficient crops under farmer field conditions. Two-yearfield experiments were conducted in 2017 and 2018 to examine efficacy of cowpea and cabbage in theuptake of foliar applied potassium iodide (KI) and potassium iodate (KIO3), each with 0, 5, 10, and15 kg I ha−1under farmer field conditions. Results indicate that KI was 34% more efficient than KIO3.Iodine concentration increased with application rate. In cabbage, the lowest I concentration (8.2 mgkg−1) was registered at 5 kg I ha−1with KIO3while the highest was 109.1 mg kg−1at 15 kg I ha−1with KI. Cowpea registered the lowest I concentration of 531.5 mg kg−1at 5 kg I ha−1with KIO3while the highest (5854.2 mg kg−1) was registered at 15 kg I ha−1with KI. Therefore, cowpea andcabbage can be effectively biofortified through foliar application of both KI and KIO3under farmerfield conditions.