Comparison of Effects of Potassium Iodide and Iodosalicylates on the Antioxidant Potential and Iodine Accumulation in Young Tomato Plants

Abstract

Iodine (I) is classified as a beneficial element for plants. Until now, there have been only hypotheses regarding the uptakes of organic iodine compounds by plant roots. The purpose of our research was to compare the uptakes and effects of the application of the following mineral and organic iodine compounds on young tomato plants: KI, 5-iodosalicylic (5-ISA), and 3,5-diiodosalicylic (3,5-diISA) acids. An additional control combination included the treatment with salicylic acid (SA) alone. All compounds were introduced into the nutrient solution in 5, 10, 25, and 50 μM I concentrations. It was established that after the application of 5-ISA and 3,5-diISA, iodine is taken up to a smaller extent than from KI. The tested KI, 3,5-diISA, and 5-ISA doses had no negative impact on the growth and development of plants, apart from the reduction of shoot biomass after the application of 3,5-diISA in 10 and 25 µM I doses. All applied compounds, except for SA, caused a reduction of ascorbic acid (AA) content and increase of dehydroascorbic acid (DHA) content in leaves. A significant increase of APX activity was noted only for the highest doses of KI and 5-ISA. None of the iodine compounds, in most tested doses, have substantially increased the CAT and POX activities in tomato leaves. Application of KI decreased the levels of all analyzed sugars in tomato leaves. The effect of iodosalicylates on sugar content varied depending on the compound: when applied in the highest dose 5-ISA increased, while 3,5-diISA decreased the sugar accumulation in tomato plants. In all tested treatments, a reduction of SA content in leaves was noted. We conclude that organic iodine compounds, i.e., 3,5-diISA and 5-ISA, can be taken up by the roots of tomato plants at an early stage of development.

Chemical Composition of Lettuce (Lactuca sativa L.) Biofortified with Iodine by KIO3, 5-Iodo-, and 3.5-Diiodosalicylic Acid in a Hydroponic Cultivation

“…We found that the application of 5-ISA caused accumulation of a much higher content of iodine in plants than after KIO 3 and 3.5-diISA treatment. In a study conducted on tomato plants, the authors demonstrated that the absorption of iodine from the inorganic form (KI) is higher than iodine from iodosalicylates [63]. We showed that the application of iodosalicylates caused increased concentrations of these compounds in lettuce leaves.…”

Anti- and pro-oxidant potential of lettuce (Lactuca sativa L.) biofortified with iodine by KIO3, 5-iodo- and 3,5-diiodosalicylic acid in human gastrointestinal cancer cell lines

“…39 They also showed that the activity of POX in tomato leaves was dependent on the form and concentration of iodine. 39 A similar study was performed by Medrano-Macias et al, who also investigated antioxidant activity in tomato seedlings treated with iodide (I À ) and potassium iodate (IO 3 À ) at a dose of 1 mM daily and 100 mM twice per…”

Effect of Irrigation Water Containing Iodine on Plant Physiological Processes and Elemental Concentrations of Cabbage (Brassica oleracea L. var. capitata L.) and Tomato (Solanum lycopersicum L.) Cultivated in Different Soils

“…Studies focused on tomato plants reported a 45% or 70% decrease in the biomass production by applying solid fertilizer containing 150 mg KI/kg soil (pH = 5.91, OM = 4.09%, total iodine = 2.02 mg/kg) [6] or irrigation water having 760 mg/L iodide concentration [15]. When the iodine concentration applied for biofortification was considerably reduced to 6.3 mg I − /L or 1-5 mM, it was found that the biomass production of edible parts did not change significantly as compared to the control plants [26,50]. The differences between our experimental and literature data can be explained by the fact that the applied iodine concentrations in our experiments were considerably lower, and the treatment technologies were also different.…”