Effect of Selenium and Cadmium Additions to Soil on Their Concentrations in Lettuce and Wheat1

Abstract

AbstractIt has been reported that increasing selenium (Se) Concentration in nutrient solution decreased cadmium (Cd) concentration in plants grown in these solutions. In a greenhouse study, Se and Cd were added to Lima (Glossoboric Hapludalf, pH 7.3) and Mardin (Fragiochrept, pH 4.7) silt loam soils to investigate if a Se × Cd interaction could be used to lower Cd concentrations in plants grown on these soils. In a 3 × 3 factorial design, three replications of the following treatment were prepared 0, 2, and 4 µg Se/g soil added as Na2SeO3 and 0, 2, and 8 µg Cd/g soil added as CdCl2. The treatments were pipetted onto 100 g of soil. The soil was dried to a slightly moist state, aggregates were crushed, and the 100 g portion was blended into 2.9 kg of untreated soil for 15 min using a twinshell blender. All treatments received a blanket application of 58 µg/g soil each of N, P, and K. Additional N, P, and K was added before each new crop was planted. Lettuce (Lactuca sativa); ‘Black Seeded Simpson’, was grown on the lima soil before and after wheat (Triticum sp.), ‘Sheridad’. Only wheat was grown on the Mardin soil. After germination each crop was thinned to 3 plants/pot. In all crops, the concentration of an element added to the soil was correlated (P<l%) with that same element's concentration in the plant. In the first crop of lettuce, increased additions of Cd to soil reduced Se concentration in the plant from 1.3 to 0.8 µg Se/g and from 2.7 to 1.6 µg Se/g for the 2 and 4 µg Se/g soil treatments, respectively. Increasing soil Cd levels did not affect the Se concentration in the second lettuce crop. Selenium treatment did not affect Cd concentrations of lettuce in the first crop, but did reduce Cd concentrations in leaves of the second crop from 24 to 13 µg Cd/g and from 66 to 48 µg Cd/g for the 2 and 8 µg Cd/g soil treatments, respectively. The Se × Cd interaction was significant in both crops. In wheat, Cd reduced the concentration of Se in grain produced on the Lima soil 27% for the low‐Se and 227, for the high‐Se treatments, and in grain produced on the Mardin soil 33% for the low‐Se and 27% for the high‐Se treatments. Cadmium had little effect on the concentration of Se in the leaf and stem of the wheat, and Se had little effect on the Cd concentration in the aerial portion of wheat.