Pot-culture experiments were conducted to investigate the single effect of benzo[a]pyrene (B[a]P) and the
joint effect of metal–B[a]P on the growth of Tagetes patula and its uptake, accumulation and dissipation of
heavy metals and B[a]P. Results showed that the low concentration of B[a]P (≤10 mg kg−1) could facilitate
plant growth and resulted in an increase in biomass at the rate of 10.0–49.7% relative to the control. There
were significantly positive correlations between the concentrations of B[a]P accumulated in tissues of
the plants and soil B[a]P (P < 0.001). However, the occurrence of Cd, Cu and Pb had inhibitive effects on
plant growth and B[a]P uptake and accumulation on the whole. T. patula still exhibited a steady feature
of Cd-hyperaccumulator under combined contaminated soils. By contrast, the effectiveness of Cu and
Pb absorption in the plants was very weak. Plant-promoted biodegradation of B[a]P was the dominant
contribution, 79.2–92.4% and 78.2–92.9% of dissipation of B[a]P came from plant-biodegradation under
single B[a]P and metal–B[a]P contaminated soils, respectively. Therefore, T. patula might be useful for
phytoremediation of B[a]P and B[a]P–Cd contaminated sites