Two common bean (Phaseolus vulgaris L.) cultivars, Carioca and IAPAR-14, were grown in a nutrient solution in the presence of 0,1,2, and 4 mg/L of nickel (Ni). Both cultivars developed symptoms of toxicity in the roots and tops., but especially in the leaves. Dry matter was reduced by the higher Ni levels. The IAPAR-14 cultivar, however, was more tolerant than the Carioca cultivar to Ni. Yield decreased as Ni levels in the solutions were increased. There was no seed production at the 4 mg/L Ni concentration for either of the two cultivars. A 50% reduction in leaf chlorophyll was observed when 4 mg/L Ni was supplied. Mineral analysis of several plant parts showed a build up of Ni concentration in the roots which was accompanied by higher iron (Fe) concentrations. Increasing Ni supply resulted in no significant changes in the concentrations of calcium (Ca), magnesium (Mg), manganese (Mn), and zinc (Zn) in the tissue. The levels of nitrogen (N), phosphorus (P), potasium (K), copper (Cu), and Ni, however, increased, as a consequence either of either the dilution effect, interaction in absorption, or both. No explanation can be given for the observed differential tolerance.
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