Iodine biofortification impacts the nutraceutical compounds content and agronomic characteristics of lettuce (Lactuca sativa L.)

Currently, agronomic biofortification through foliar fertilization is an effective process for correcting micronutrient deficiencies in the population in a sustained manner. Some studies have shown that iodine has a positive effect on crop metabolism and development, as well as on the absorption of this element and its buildup in the edible organs of the vegetable, mitigating the problem of iodine deficiency in the population. In this work, the response of potassium iodide (KI) on lettuce plants (Lactuca sativa L.) produced in a hydroponic system (NFT) was evaluated using a completely randomized design. Five treatments, one control, and five replicates per treatment (control, 5, 10, 15, 20, 25 µmol L-1). The morphological variables, chlorophyll content, phytochemicals, and mineral concentration were quantified. The results show that the dose of 20 µmol L-1 of (KI) increases compared to the control treatment in the morphological variables, including plant height (41.83%), leaf length (41.30%), leaf width (45.45%), crown diameter (29.79%), number of leaves, root fresh weight (99.58%), and dry matter (77.7%). At concentrations of 20 µmolL-1 of (KI), chlorophyll showed better results (43.5%) than the control. At doses of 15 and 20 µmolL-1 of (KI), phytochemical variables showed increases in phenols (56.5%), flavonoids (31.8%), antioxidant capacity (5.5%), and vitamin C (3.33%) compared to the control. Iodine concentration increased with higher doses, showing the maximum concentration at 25 µmol L-1 of (KI) (48.04%) compared to the control. Doses of 20 µmolL-1 of (KI) increased the accumulation of certain minerals (N, P, Ca+2, Mg+2, Cu, Mn, Na) (7.7 to 35.7%) compared to the control. In contrast, higher doses of 15 µmolL-1 of (KI) caused antagonism, decreasing the concentration of Fe and Zn. The application of adequate doses of iodine is a good alternative for biofortification.