Cadmium Accumulation and Distribution in Tagetes erecta L. Affected by Major Mineral Nutrition

An experiment was conducted under hydroponic culture conditions to determine effects of nitrogen (N), phosphorus (P) and sulfur (S) deficiency on Tagetes erecta L. growth, cadmium (Cd) accumulation and chemical forms. Seedlings of similar age and size were pre-cultured in either N-, P-, or S-deficient nutrition solution for 12 days before exposure to 0.1 mg Cd L^-1 (nonphytotoxic). The control group had normal nutrient supply before and during Cd exposure. The plants were harvested after 15 days´ exposure to Cd. Plant growth was inhibited by nutrient deficiencies. Cd appeared to accumulate preferentially in the youngest leaves with nutrient deficiencies, and leaf Cd concentrations were lower than that of control for N- and P-deficiency but the S-deficiency treatment had higher leaf Cd accumulation. P deficiency increased Cd concentrations in stems and roots by 24 and 123 mg kg^-1 (DW), respectively. Different organs contained Cd in different chemical forms, as determined by selective extraction reagents. In leaves, the Cd forms extracted by 2% acetic acid and 1M NaCl were predominant. In stems, the Cd forms extracted by1M NaCl were predominant. In roots, Cd extractable by 80% ethanol was the primary chemical form except in the P-deficiency treatment, where it was by 1M NaCl. The results suggested that nutrient deficiencies did not significantly affect the chemical forms of Cd in plant tissues except the forms in roots of the P-deficiency treatment plants, but the deficiencies obviously affected Cd distribution among plant tissues. The study indicates that Cd accumulation in plants tissues is closely related to provision of nutrition to the tissues.