Biofortification of green bean (Phaseolus vulgaris L.) and lettuce (Lactuca sativa L.) with iodine in a plant-calcareous sandy soil system irrigated with water containing KI

Abstract

Uptake and translocation of iodine by green bean (Phaseolus vulgaris L.) and lettuce (Lactuca sativa L.) were investigated in a calcareous sandy soil-plant system. These plants were cultivated in calcareous sandy soil in presence of irrigation water with the iodine concentrations of 0.10, 0.25 and 0.50 mg/L. The growth of these plants was stimulated at the two lower iodine concentrations of 0.10 and 0.25 mg/L, but hampered at 0.50 mg/L. In lettuce the highest iodine dosage resulted in smaller leaf surface and higher number of leaves, nearly with the same biomass production. In the edible parts of green bean and lettuce plants irrigated with 0.25 mg/L iodine containing water, the iodine concentration levels amounted to 0.6 and 5.2 mg/kg dry weight (DW), respectively. In lettuce, the uptake and translocation of selected essential elements (P, Mg, Mn, Fe, Cu, Zn, B) were also stimulated (20-260%) by iodine treatment; however, in fresh bean pods this phenomenon was negligible. Considering the iodine level and moisture content of the fresh lettuce leaves and fresh bean pods, the consumption of 100 g fresh vegetable covers about 66%, 3% of the recommended dietary allowance (150 μg).