Iodine and the Higher Plants

Iodine (I) is widely distributed in the biosphere in small concentrations. Iodide (I-) and iodate (IO3-) are the most important inorganic forms of I that can be found in the biosphere. Iodine is a necessary microelement for some marine algae and higher animals. Approximately 35% of the world’s population is insufficiently provided with I, which results in many health problems. Plants are an important source of I for humans, and the knowledge about the uptake, distribution, and accumulation of I in edible plant parts, as well as its effect on life processes and organic production of cultivated species is very important. The results of numerous studies indicate a favorable effect of I application on plant growth, tolerance to stress, and the antioxidant capacity of plants. In addition, its effects on photosynthesis, hydration, carbohydrate metabolism, respiration, and interaction with other elements are analyzed. At the same time, data are indicating that the application of I has no effect, moreover, it may act phytotoxically, especially at higher concentrations. Based on the current understanding of I impact on life processes and the organic production of higher plants, it can be considered a useful element. Plants can complete their life cycle without iodine, but it may have a stimulating effect on their growth under certain circumstances. Considering the importance of I for the health of the human population and higher animals, the application of I to increase its concentration in edible parts of grown plants using cultivation practices (biofortification of crops with I) is an important task for further research.