Iodine deficiency disorders (IDD) in sub-Saharan African countries are related to low dietary I intake and generally combatted through salt iodisation. Agronomic biofortification of food crops may be an alternative approach. This study assessed the effectiveness of I biofortification of green vegetables (Brassica napus L and Amaranthus retroflexus L.) grown in tropical soils with contrasting chemistry and fertility. Application rates of 0, 5 and 10 kg ha⁻¹ I applied to foliage or soil were assessed. Leaves were harvested fortnightly for ~ 2 months after I application before a second crop was grown to assess the availability of residual soil I. A separate experiment was used to investigate storage of I within the plants. Iodine concentration and uptake in sequential harvests showed a sharp drop within 28 days of I application in all soil types for all I application levels and methods. This rapid decline likely reflects I fixation in the soil. Iodine biofortification increased I uptake and concentration in the vegetables to a level useful for increasing dietary I intake and could be a feasible way to reduce IDD in tropical regions. However, biofortification of green vegetables which are subject to multiple harvests requires repeated I applications.

撒哈拉以南非洲国家的碘缺乏病 (IDD) 与膳食I摄入量低有关，通常通过食盐加碘来防治。粮食作物的农艺生物强化可能是一种替代方法。本研究评估了生长在具有不同化学和肥力的热带土壤中的绿色蔬菜（ Brassica napus L 和Amaranthus retroflexus L.）的I生物强化效果。评估了施用于叶子或土壤的 0、5和 10 kg ha ^-1 I的施用率。在I施用后的约 2 个月内每两周收获一次叶子，然后再种植第二次作物以评估残留土壤I的可用性 . 使用单独的实验来研究I在植物中的储存。在所有I施用水平和方法的所有土壤类型中， I施用后 28 天内，连续收获中的碘浓度和摄取量都急剧下降。这种快速下降可能反映了土壤中的I固定。碘生物强化将蔬菜中的I摄取和浓度提高到有助于增加膳食I摄入的水平，并且可能是减少热带地区 IDD 的可行方法。然而，多次收获的绿色蔬菜的生物强化需要重复I应用。