According to the recommendations of the World Health Organization (WHO), due to the increased risk of cardiovascular disease, the daily consumption of table salt should be reduced. To avoid the health consequences of iodine deficiency, it is necessary to include alternative food sources of this trace element in the human diet. One of the most effective ways of improving nutrition is the biofortification of crops with minerals and vitamins. The purpose of this study was to determine the influence of iodine biofortification (potassium iodate/KIO₃/, 5-iodosalicylic acid/5-ISA/and 3.5-diiodosalicylic acid/3.5-diISA/) on the chemical composition of lettuce (Lactuca sativa L. capitata) cv. ‘Melodion’. Plants were cultivated in a hydroponic system NFT (Nutrient Film Technique). We compared the effect of iodine fertilization on the basic chemical composition, fatty acid profile, macro- and micronutrients, content of sugars, nitrogenous compounds, chlorides, and iodine compounds. The results obtained in this research indicate that the application of iodine compounds has an influence on changes of concentration of iodine and other compounds in the treated samples. In lettuce, the main fatty acid was linolenic acid; however, fertilization with iodine did not affect the fatty acid profile in plants, except for concentrations of myristic and arachidic acids. We also found that iodine fortification has positive effects on concentrations of some micro- and micronutrients. Moreover, the application of 3.5-diISA decreased the concentration of nitrates as compared to control and other treatments. Therefore, it may be postulated that the production of lettuce fortified with iodosalicylates is worthy of consideration due to the fact that it may be a good source of iodine and other compounds in the human diet.

In marine algae, vanadium (V) regulates the cellular uptake of iodine (I) and its volatilization as I₂, the processes catalyzed by vanadium-dependent haloperoxidases (vHPO). Relationships between I and vanadium V in higher plants, including crop plants, have not yet been described. Little is known about the possibility of the synthesis of plant-derived thyroid hormone analogs (PDTHA) in crop plants. The activity of vHPO in crop plants as well as the uptake and metabolism of iodosalicylates in lettuce have not yet been studied. This studyaimed to determine the effect of V on the uptake and accumulation of various forms of I, the metabolism of iodosalicylates and iodobenzoates and, finally, on the accumulation of T3 (triiodothyronine—as example of PDTHA) in plants. Lettuce (Lactuca sativa L. var. capitata ‘Melodion’ cv.) cultivation in a hydroponic NutrientFilm Technique (NFT) system was conducted with the introduction of 0 (control), 0.05, 0.1, 0.2, and 0.4 µM V doses of ammonium metavanadate (NH₄VO₃) in four independent experiments. No iodine treatment was applied in Experiment No. 1, while iodine compounds were applied at a dose of 10 µM (based on our own previous research) as KIO₃, 5-iodosalicylic acid (5-ISA) and 3,5-diiodosalicylic acid (3,5-diISA) in Experiment Nos. 2, 3 and 4, respectively. When lettuce was grown at trace amount of I in the nutrient solution, increasing doses of V contributed to the increase of (a) I content in roots, (b) I uptake by whole lettuce plants (leaves + roots), and (c) vHPO activity in leaves (for doses 0.05–0.20 µM V). Vanadium was mainly found in roots where the content of this element increased proportionally to its dose. The content of V in leaves was not modified by V introduced into the nutrient solution. We found that5-ISA, 3,5-diISA and T3 were naturally synthesized in lettuce and its content increased when 5-ISA, 3,5-diISA were applied. Quantitative changes in the accumulation of organic metabolites (iodosalicylates and iodobenzoates) accumulation were observed, along with increased T3 synthesis, with its content in leaves exceeding the level of individual iodosalicylates and iodobenzoates. The content of T3 was not affected by V fertilization. It was concluded that iodosalicylates may participate in the biosynthesis pathway of T3—and probably of other PDTHA compounds.

Selenium (Se) uptake by plants depends on its form and salicylic acid (SA) can increase the efficiency of plant biofortification in Se. This study investigated the effects of selenite (Na₂SeO₃) and selenomethionine (SeMet) applied individually or together with SA on a total content of Se, Se speciation forms, yield and content of sugars and ascorbic acid of lettuce, as well as activity of selenocysteine methyltransferase (smt) and methionine methyltransferase (mmt) genes of the Se metabolic pathway. Lettuce was grown in the nutrient film technique (NFT) system. Se and SA were used at doses of 0.5 and 10.0 mg dm⁻³ of the nutrient solution, respectively. The treatments were: 1. control, 2. Na₂SeO₃, 3. Na₂SeO₃ + SA, 4. SeMet, 5. SeMet + SA, 6. SA. Se was accumulated more in the roots than the leaves. SeMet was more effective in biofortification than Na₂SeO₃. SA enhanced Se uptake, especially organic Se. Plants supplied with SeMet alone or SeMet + SA accumulated in their leaves mainly SeMet and methylselenocysteine (MeSeCys), while those treated with Na₂SeO₃ or Na₂SeO₃ + SA accumulated MeSeCys and selenite (SeO₃⁻²). The roots showed no expression of smt, while the expression of two mmt genes was independent of either Se or SA. The leaves of plants supplied with Na₂SeO₃ demonstrated the strongest expression of mmt and smt.

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 (KIO₃), salicylic acid (SA) alone or together with KIO₃, 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 KIO₃ and 3,5-diISA. The type of soil significantly modified the chemical composition of lettuce.

The process of uptake and translocation of non-organic iodine (I) ions, I^– and IO₃^–, has been relatively well-described in literature. The situation is different for low-molecular-weight organic aromatic I compounds, as data on their uptake or metabolic pathway is only fragmentary. The aim of this study was to determine the process of uptake, transport, and metabolism of I applied to lettuce plants by fertigation as KIO₃, KIO₃ + salicylic acid (KIO₃+SA), and iodosalicylates, 5-iodosalicylic acid (5-ISA) and 3,5-diiodosalicylic acid (3,5-diISA), depending on whether additional fertilization with vanadium (V) was used. Each I compound was applied at a dose of 10 μM, SA at a dose of 10 μM, and V at a dose of 0.1 μM. Three independent 2-year-long experiments were carried out with lettuce; two with pot systems using a peat substrate and mineral soil and one with hydroponic lettuce. The effectiveness of I uptake and translocation from the roots to leaves was as follows: 5-ISA > 3,5-diISA > KIO₃. Iodosalicylates, 5-ISA and 3,5-diISA, were naturally synthesized in plants, similarly to other organic iodine metabolites, i.e., iodotyrosine, as well as plant-derived thyroid hormone analogs (PDTHA), triiodothyronine (T3) and thyroxine (T4). T3 and T4 were synthesized in roots with the participation of endogenous and exogenous 5-ISA and 3,5-diISA and then transported to leaves. The level of plant enrichment in I was safe for consumers. Several genes were shown to perform physiological functions, i.e., per64-like, samdmt, msams5, and cipk6.

This study evaluated rooting of Pennisetum ‘Vertigo’ cuttings and development and the nutritional status of rooted plants. Cuttings of Pennisetum ‘Vertigo’ rooted in a perlite or peat medium were treated with Goëmar Goteo biostimulator as follows: (1) soaking (2) watering (3) spraying (4) no Goteo applied (control). Then, 83.3–100% of cuttings formed adventitious roots. The, 100% rooting was obtained for plants in perlite when Goteo spraying or watering was used for plants rooted in peat only after Goteo watering application. Cuttings rooted in perlite had 30% more roots and they were longer than in peat. Goteo watering of cuttings affected root elongation in both peat and perlite. Neither rooting media nor biostimulator treatment affected root dry weight (DW). Rooting medium after 2 months of pot cultivation had no effect on biometric features of plants, but those grown from cuttings rooted in peat had a higher fresh weight (FW) compared to those rooted in perlite. Plants developed from Goteo-treated cuttings were higher compared to the control plants. Goteo watering during rooting stimulated the formation of new shoots in the greenhouse cultivation. Plants from cuttings rooted in perlite had more Fe and Cu in their leaves, especially when they were Goteo-watered. Goteo increased P content in plants derived from biostimulator-watered cuttings, and K in plants from cuttings soaked in Goteo and rooted in perlite.