Effects of Genotype and Sewage Sludge on Cadmium Concentration in Lettuce Leaf Tissue

Leaf Cd concentrations were determined for 60 commercial cultivars and USDA plant introductions of noncrisphead lettuce ( Lactuca sativa L.). This 2-year study evaluated each genotype in field plots receiving an industrial sludge, a municipal sludge, or no sludge amendment. Genotype and sludge treatment had significant effects on leaf Cd concentration. Although the genotype x year interaction was also significant, the Cd concentrations of some cultivars (‘Waldmann’s Green’ and ‘Summer Queen’) were consistently low while others (PI 278080, PI 167148, and ‘Citation’) were consistently high. Plots amended with the industrial sludge had the highest total and available Cd levels, and plants grown on these plots had the highest leaf Cd concentrations, ranging from 3.1 to 11.9 μg·g −1 . Leaf Cd concentrations from plants grown on the municipal sludge-amended plots ranged from 1.4 to 5.5 μg·g −1 and from 1.2 to 2.5 μg·g −1 for the control plots.