Based on the results from our study with ‘Kazan F1’ cultivar, it is possible to assess to some extent the efficiency of iodine biofortification of carrot taking into consideration its influence on yield quality and storage potential of this crop. Increasing iodine content in carrot may be advisable due to a high level of β-carotene – a direct precursor of vitamin A that has been shown to have a positive effect on thyroid function (Zimmermann, 2007). Iodine application combined with plant fertilizer with relatively high doses of nitrogen (100 kg N ha−1 applied pre-sowing and as a top dressing in the form of calcium nitrate and ammonium sulphate) did, however, decrease the quality of carrot yield evaluated at harvest. As far as storage potential is concerned, the lowest value was noted for carrots grown with KI without N. Analysis of our results suggests there is a need to develop independent methods of iodine biofortification for carrots intended for (a) consumption and/or processing directly after harvest or (b) long-term storage. The combination of iodine biofortification programmes with appropriate crop fertilization with mineral nutrients should also be taken into account. Furthermore, it seems reasonable to employ plant-breeding techniques to select cultivars characterised by increased iodine accumulation without decreased yield quality and storage potential.
Basing on conducted research it can be proposed that for the cultivation of carrot biofortified with iodine, KI form of this element should be applied rather than KIO3 (also when combined with nitrogen fertilization) due to a significantly more deleterious effect of iodates on carrot quality after harvest. In the production of carrot for long-term storage of roots high doses of nitrogen fertilizers need to be avoided (particularly in the form of calcium nitrate) when applied together with iodine in order to prevent increased losses of root weight or the decrease in its quality.