Cadmium accumulation in and tolerance of rice (Oryza sativa L.) varieties with different rates of radial oxygen loss

Cadmium (Cd) uptake and tolerance were investigated among 20 rice cultivars based on a field experiment (1.2 mg Cd kg−1 in soil) and a soil pot trial (control, 100 mg Cd kg−1), and rates of radial oxygen loss (ROL) were measured under a deoxygenated solution. Significant differences were found among the cultivars in: (1) brown rice Cd concentrations (0.11–0.29 mg kg−1) in a field soil, (2) grain Cd tolerance (34–113%) and concentrations (2.1–6.5 mg kg−1) in a pot trial, and (3) rates of ROL (15–31 mmol O2 kg−1 root d.w. h−1). Target hazard quotients were calculated for the field experiment to assess potential Cd risk. Significant negative relationships were found between rates of ROL and concentrations of Cd in brown rice or straw under field and greenhouse conditions, indicating that rice cultivars with higher rates of ROL had higher capacities for limiting the transfer of Cd to rice and straw.

► There are significant differences in brown rice Cd concentrations and rates of ROL among the rice cultivars.
► The rates of ROL are significantly correlated with concentrations of Cd in brown rice.
► Rice cultivars with higher rates of ROL have higher capacities for limiting the transfer of Cd to rice and straw.