Mineral composition of two Brazilian corn cultivars as a function of cadmium in the nutrient solution1

Abstract

Plants from the Brazilian corn (Zea mays L.) cultivars CMS 54 and BR 473 were grown in nutrient solutions with 0.0, 0.05, 0.1, 0.5, and 1.0 mg cadmium (Cd) L‐1 for a ten day period. The experiment was a completely randomized block design with the treatments arranged in a 2×5×3 factorial, two corn cultivars, five Cd rates, and three replications. The influence of the Cd rates on the nutritional status of the corn plants was studied. Samples from roots and shoots were analyzed for their Cd, phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and copper (Cu) contents. At rates above 0.5 mg Cd L‐1, there was an influence of exogenous Cd on the elemental composition of the plants. It seems that with rates above 0.5 mg Cd L‐1, the influence of Cd on the P status of the shoots took place in the CMS 54 but not in the BR 473 cultivar. Similar results for K, Ca, Mg, and S were found. There was competition between the Cd and Zn ions at the absorption sites in the plant roots. Copper translocation from roots to shoots was diminished as the Cd rates increased in the nutrient solution. Iron and Zn contents in the shoots of the BR 473 plants diminished less than in shoots of the CMS 54 plants as compared to the shoots of plants grown without Cd. A differential response of the CMS 54 and BR 473 cultivare as related to the elemental composition of the shoots is evident.