Iodine is an essential trace element in the human diet because it is involved in the
synthesis of thyroid hormones. Iodine deficiency affects over 2.2 billion people worldwide,
making it a significant challenge to find plant-based sources of iodine that meet
the recommended daily intake of this trace element. In this study, cabbage plants
were cultivated in a hydroponic system containing iodine at concentrations ranging
from 0.01 to 1.0 mg/L in the form of potassium iodide or potassium iodate. During
the experiments, plant physiological parameters, biomass production, and concentration
changes of iodine and selected microelements in different plant parts were investigated.
In addition, the oxidation state of the accumulated iodine in root samples was determined.
Results showed that iodine addition had no effect on photosynthetic efficiency and
chlorophyll content. Iodide treatment did not considerably stimulate biomass production
but iodate treatment increased it at concentrations less than 0.5 mg/L. Increasing
iodine concentrations in the nutrient solutions increased iodine content in all plant
parts; however, the iodide treatment was 2–7 times more efficient than the iodate
treatment. It was concluded, that iodide addition was more favourable on the target
element accumulation, however, it should be highlighted that application of this chemical
form in nutrient solution decreased the concetrations of selected micoelement concentration
comparing with the control plants. It was established that iodate was reduced to iodide
during its uptake in cabbage roots, which means that independently from the oxidation
number of iodine (+ 5, − 1) applied in the nutrient solutions, the reduced form of
target element was transported to the aerial and edible tissues.
