Cadmium, Lead, Copper, Zinc, and Nickel in Lettuce and Dry Beans as Related to Mehlich-3 Extraction in Three Brazilian Latossols

ABSTRACT

Lettuce (Lactuca sativa L.) and dry beans (Phaseolus vulgaris L.) were grown in three Brazilian Red-Yellow Latossols (Oxisols) in greenhouse conditions with cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), and nickel (Ni) applied to soils in treatments arranged as a randomized complete block design. Plant metals were analyzed in lettuce shoots and dry beans roots, stems, leaves, and seeds. After plant growth, soil samples from the pots were extracted with Mehlich-3 (M-3) for metal availability evaluation. The release of Ni in the M-3 extraction was dependent on the soil exchangeable aluminum (Al^{3 +}). Mehlich-3 was efficient for determination of availability of Cd, Pb, Cu, Zn, and Ni for dry beans and availability of Cd and Ni for lettuce. The dry bean leaves Cd, Pb, Cu, Zn, and Ni were highly correlated with their recovering from soils with M-3. The same was observed for Cd and Ni in lettuce shoots and the M-3 recovered metals from soils.

Keywords:

• dry beans
• heavy metal extraction
• lettuce
• Mehlich-3
• metal availability

ACKNOWLEDGMENTS

JMNP thanks to CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for the academic scholarship. RLFF thanks to CNPq for the research financial support and the research fellowship.

Notes

^1/Walkley-Black (Defelipo and Ribeiro, 1981).

^2/Mehlich-1 (Defelipo and Ribeiro, 1981).

^3/KCl 1 mol/L (Defelipo and Ribeiro, 1981).

^4/Ca(OAc)₂ 0.5 mol/L, pH 7.0.

^5/Mehlich-3 (Mehlich, 1984).

^6/Pipet Method (EMBRAPA, 1997).

^7/ EMBRAPA (1997).

∗Control.

∗∗Significant at 5 and 1% probability levels, respectively.

∗∗Significant at the 1% probability level.