Effectiveness of Enriching Lettuce with Iodine Using 5-iodosalicylic and 3,5-diiodosalicylic Acids and the Chemical Composition of Plants Depending on the Type of Soil in a Pot Experiment

Iodine is a beneficial element for humans, animals and plants. This study was a comparison of the effectiveness of iodosalicylate uptake by lettuce. The experiment included two sub-blocks: organic soil and mineral soil with the addition of the same fertigation of plants (8 times every 7 days) with 10 µM solutions (100 mL/per one plant/one application) of potassium iodate (KIO), salicylic acid (SA) alone or together with KIO, 5-iodosalicylic acid (5-ISA) or 3,5-diiodosalicylic acid (3,5-diISA). None of the tested iodine compounds negatively affected the yield of lettuce. When growing plants on mineral soil, plants accumulated more iodine in the leaves than plants grown on peat substrate. The use of 5-ISA allowed for achieving better efficiency of plant biofortification in iodine than the application of KIO and 3,5-diISA. The type of soil significantly modified the chemical composition of lettuce.