Abstract
Three mineral elements, barium (Ba), strontium (Sr) and molybdenum (Mo), were simultaneously incorporated into lettuce (Lactuca sativa L.) grown in hydroponics as markers for certifying vegetable provenance. When lettuce was cultivated in nutrient solutions with combinations of the three elements at various concentrations, the concentrations of these elements in the top of lettuce were increased with increase in the concentration of each element in nutrient solutions without absorption interference of these elements with each other. These element concentrations in tops were statistically evaluated by canonical discriminant analysis, then eight treatments prepared using combinations of these elements at various concentrations in nutrient solutions were obviously distinguished from each other: i.e., the probability of miss judgment was zero and the rate of correctness of judgment was 100%. Therefore, eight different labels can be incorporated into lettuce using combinations of these elements. Amounts of the three elements contained in 470 g (the value to be consumed daily recommended by the Ministry of Health, Labor and Welfare of Japan) of fresh plants grown thus manner were lower than those of Acceptable Daily Intake or Tolerated Daily Intake for the respective elements. These findings suggest that a digital marking system by introducing mineral elements into lettuce grown in hydroponics can be of practical use for certifying its source.
