The pot soil maintained 70% of the total water-holding field capacity for 15 days equilibration. Then, three uniform size root systems of giant reed were transplanted into each pot and cultivated in a greenhouse with a daily 14 h photoperiod and 10 h dark period, with day/night temperature of 30 °C/20 °C, and relative humidity of 60%. Two weeks before harvesting, AA, CA and EDTA at the concentrations of 0, 1.25, 2.5 and 5.0 mmol/kg soil were added to the remaining pots, respectively (Table 3). Each treatment was four replicates.