The Accumulation Kinetics of Phytolacca americana Accumulating Cadmium in Soil and Its Response to Fertilization

Greenhouse pot-culture experiments with different concentration and fertilization treatments were carried out to study the kinetics of cadmium (Cd) accumulation in Phytolacca americana and the effect of ammonium sulfate(NH₄)₂SO₄ and urea (CH₄N₂O) as nitrogen fertilizer and potassium chloride (KCl) as potassium fertilizer on plant growth and Cd accumulation in P. americana. When the Cd concentration in soil was 10 mg·kg^-1, P. americana showed the highest bioaccumulation factor (BCF, 10.37) and transfer factor (TF, 2.78). The highest accumulation rate (21.1 μg·d^-1) and uptake rate constant(0.21±0.01) d^-1 were found during the period of 15 days to 30 days. The absorption rate constant decreases with the increasing exposure time:k_{u, 15 d}(0.35±0.02) d^-1 > k_{u, 30 d}(0.21±0.01) d^-1 > k_{u, 60 d}0.11±0.01) d^-1 > k_{u, 90 d}(0.09±0.01) d^-1. When the (NH₄)₂SO₄ and CH₄N₂O concentration was 400 mg·kg^-1 as nitrogen fertilizer, it increased by 183.6% and 142.3% Cd content in the shoots of P. americana, about 165.3% and 150.4% biomass and about 478.7% and 337.3% Cd accumulation in tissues of P. americana respectively. Although KCl could significantly increase Cd concentrations by 264.4% when KCl concentration was 600 mg·kg^-1, it could only increase by about 1.4% biomass of P. americana which resulting in the Cd accumulation in tissues of P. americana treated by potassium fertilizer to be lower than treated by nitrogen fertilizer.