Agronomic iodine biofortification of leafy vegetables grown in Vertisols, Oxisols and Alfisols

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 ofIbiofortification 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 similar to 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 ofIwithin the plants. Iodine concentration and uptake in sequential harvests showed a sharp drop within 28 days ofIapplication in all soil types for allIapplication levels and methods. This rapid decline likely reflectsIfixation in the soil. Iodine biofortification increasedIuptake and concentration in the vegetables to a level useful for increasing dietaryIintake 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.

Automated summary

This study assessed the effectiveness of iodine biofortification of green vegetables grown in tropical soils, showing that it increased iodine uptake and concentration in the vegetables, potentially reducing iodine deficiency disorders in the region. However, biofortification of green vegetables subject to multiple harvests requires repeated iodine applications.