Combined biofortification of soilless grown lettuce with iodine, selenium and zinc and its effect on essential and non-essential elemental composition

Zinc (Zn), iodine (I) and selenium (Se) deficiencies are the most common nutritional disorders for humans in the world. Biofortification is a process of increasing vitamin and mineral concentrations and mineral bioavailability in the edible parts of plants. Zinc is essential for plants and humans, but I and Se are not essential for plants and both have important roles in human nutrition. The main purpose of the study was to determine the combined biofortification of soilless grown lettuce with I, Se and Zn and through the introduction of these elements at the rates of 150, 20 and 50 mu M, respectively into nutrient solution. Besides, I, Se and Zn concentrations; other essential and non-essential element concentrations of the lettuce plants were also determined. The results revealed the increased Se and Zn concentrations significantly (p < 0.05) in leaves but I concentrations did not improved with the applied levels of these elements. Combined biofortification with I-Se-Zn had no significant effect on the concentrations of P, K, Ca, Mg, Na, Al, Cl, Mo, Cu, Cd, Rb, Sr, Cr, Zr, Nb, Ta, Th, Ga, Sn, Sb, whereas; S, Si, Ba, La, Pb, Bi and Ti increased and Fe, Mn, Co, Ni and Br decreased. Since the composition of soilless growing environments is very different from soils, in biofortification studies with non-essential elements, their effects on essential and non-essential elements must be evaluated.