Influence of N, P, K nutrient levels on Pb uptake ability of hyperaccumulators

In the greenhouse experiment, 3 varieties of hypertolerant plants: L.Amaranthus tricolor , Sophora japonica and Bidens maximowicziana were grown at different levels of nitrogen(0,0.06,0.12,0.18,0.24,0.30 g/kg), phosphorous(0,0.06,0.12,0.18,0.24,0.30 g/kg), and potassium(0,0.08,0.16,0.24,0.32,0.40 g/kg) to study their performance with regard to lead uptake ability, while the other two-element levels were 0.12 g/kg and soil lead was 800 mg/kg. The results show that N, P, K level had significant effect on plant total lead translocation. The ratio of maximum to minimum value for Bidens maximowicziana,L.Amaranthus tricolor and Sophora japonica were 11.6,10.6,11.9, respectively. But the influence of three elements were not uniform. A little amount of nitrogen and potassium can increase the dry weights of plant, advance the lead uptake of hyperaccumulators, but with the increasing of nitrogen and potassium concentration, the lead uptake of the plants dropped, and dry weights decrease constantly. The little different effect between nitrogen and potassium on lead uptake was that the restraint of the former was more significant than the latter. Additionally, the phosphorus applied to the soil can decrease the lead uptake of the hyperaccumulators dramatically. The conclusion of the research was that if using the plans on the purpose of phytoremediating the lead polluted soil, the total lead translocation can be increased by regulating the soil N, P, K level.