01617naa a2200217 a 450000100080000000500110000800800410001902000220006010000200008224500950010226000090019752008570020665300220106365300190108565300180110470000250112270000230114770000220117070000170119277301900120916454082008-03-17       2007    bl uuuu     u00u1 u    #d  a978-7-302-15627-71 aCUNHA, K. P. V.  aBiogeochemistry of trace elementsbenvironmental protection, remediation and human health.  c2007  aDetermination of toxic concentration of metals in soils is needed to support legislations on soil pollution by trace metals. High concentrations of metals in plants are generally associated with visual symptoms of toxicity and anatomical alterations at cellular level. The work was carried out to determine the critical toxic concentration of cadmium (Cd) in an Ultisol cultivated with com (Zea mays L.) and its relation to toxicity symptoms. Plants were grown for 30 days in pots containing five rates of Cd (0, 1, 3, 5, 10 and 20 mg * kg -¹) added as CdCl2 solution. The critical concentration of Cd in soil, which caused a 30% reduction in dry matter production, was 10 mg * kg -¹. Chlorotic and coiled leaves were the most common visual symptoms of Cd toxicity. In creased lignification of the cell wall in several cell tissues was also observed.  aCadmium tolerance  aMetal toxicity  aTrace element1 aNASCIMENTO, C. W. A.1 aPIMENTEL, R. M. M.1 aACCIOLY, A. M. A.1 aSILVA, A. J.  tIn: ZHU, Y.; LEPP, N.; NAIDU, R. (Ed.). Biogeochemistry of trace elements: environmental protection, remediation and human health. Bei Jing: Tsinghua University Press, 2007. p. 160-161.