Cadmium phytoextraction from loam soil in tropical southern China by Sorghum bicolor

The cadmium (Cd) uptake characteristics by Sorghum bicolor cv. Nengsi 2# and Cowley from the acidic sandy loam soil (pH = 6.1) during the entire growth period (100 days) were investigated in pot outdoors in a tropical district of southern China, Hainan Island. The Cd-spiked levels in soil were set as 3 and 15 mg/kg. Correspondingly, the available Cd levels in soil extracted by Mehlich III solution were 2.71 and 9.41 mg/kg, respectively. Basically, two varieties in a full growth period (100 days) did not show a significant difference in their growth and Cd uptake. Under high Cd stress, the plant growth was inhibited and its biomass weight and height decreased by 38.7-51.5% and 27.6-28.5%, respectively. However, S. bicolor showed higher bioaccumulation capability of Cd from soil to plant [bioconcentration factor (BCF)>4], and higher transfer capability of Cd from roots to shoots [translocation factor (TF)>1] under high Cd stress; Cd contents in the roots, stems, and leaves of S. bicolor reached 43.79-46.07, 63.28-70.60, and 63.10-66.06 mg/kg, respectively. S. bicolor exhibited the potential phytoextraction capability for low or moderate Cd-contamination in acidic sandy loam soil.