Copper and bacterial diversity in soil enhance paeonol accumulation in cortex moutan of Paeonia suffruticosa ‘Fengdan’

The effects of environmental factors on the paeonol accumulation in cortex moutan of herbal Paeonia suffruticosa cv. Fengdan were investigated. Cortex moutan of ‘Fengdan’ and the corresponding soil samples were collected from Tongling (Anhui Province, China). A pot experiment was also conducted to investigate the responses of plant growth and paeonol concentrations to copper (Cu) supply. The paeonol and Cu concentrations in cortex moutan samples, the basic soil properties and soil’s bacterial diversity were analyzed. The results showed that moderate levels of Cu in the soil enhanced the paeonol concentration in the cortex moutan. Moreover, the paeonol concentration was related significantly to soil bacterial diversity. The results of the pot experiment showed that increasing Cu supply from 63 to 263 mg·kg−1 did not produce any significant effect on the dry weight of ‘Fengdan’ cortex moutan, duramen, and total plant. Increasing Cu supply significantly increased the concentrations of paeonol in cortex moutan and duramen; but at 263 mg·kg−1 Cu there was a slight decline in their concentrations than those obtained at 156 mg·kg−1 Cu. In all treatments, the concentrations of paeonol were much higher in the cortex moutan than those in the duramen. Due to its ecological benefits, ‘Fengdan’ can be planted in soil contaminated with moderate Cu.