Biofortification of lettuce (Lactuca sativa L.) with iodine: the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce grown in water culture.
BACKGROUND
Iodine is an essential trace element for humans. Two billion individuals have insufficient iodine intake. Biofortification of vegetables with iodine offers an excellent opportunity to increase iodine intake by humans. The main aim was to study the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce, grown in water culture.


RESULTS
In both a winter and summer trial, dose rates of 0, 13, 39, 65, and 90 or 129 microg iodine L(-1), applied as iodate (IO(3)(-)) or iodide (I(-)), did not affect plant biomass, produce quality or water uptake. Increases in iodine concentration significantly enhanced iodine content in the plant. Iodine contents in plant tissue were up to five times higher with I(-) than with IO(3)(-). Iodine was mainly distributed to the outer leaves. The highest iodide dose rates in both trials resulted in 653 and 764 microg iodine kg(-1) total leaf fresh weight.


CONCLUSIONS
Biofortification of lettuce with iodine is easily applicable in a hydroponic growing system, both with I(-) and IO(3)(-). I(-) was more effective than IO(3)(-). Fifty grams of iodine-biofortified lettuce would provide, respectively, 22% and 25% of the recommended daily allowance of iodine for adolescents and adults.
Voogt
Wim
W
Wageningen University and Research-Greenhouse Horticulture, 2665 MV Bleiswijk, the Netherlands. Wim.Voogt@wur.nl
Holwerda
Harmen T
HT
Khodabaks
Rashied
R
D018533:Biomass; D018556:Crops, Agricultural; D003677:Deficiency Diseases / Q000517:prevention & control; D004553:Electric Conductivity; D005527:Food, Fortified / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D018527:Hydroponics / Q000379:methods; D007452:Iodates / Q000493:pharmacokinetics; D007455:Iodine / Q000737:chemistry* / Q000172:deficiency / Q000493:pharmacokinetics*; D018545:Lactuca / Q000254:growth & development* / Q000378:metabolism*; D009994:Osmolar Concentration; D018515:Plant Leaves / Q000737:chemistry; D017680:Potassium Compounds / Q000493:pharmacokinetics; D011193:Potassium Iodide / Q000493:pharmacokinetics; D011786:Quality Control; D012621:Seasons; D013997:Time Factors; D014018:Tissue Distribution; D014867:Water / Q000032:analysis
D007452:Iodates; D017680:Potassium Compounds; D014867:Water; D011193:Potassium Iodide; D007455:Iodine; C039693:potassium iodate