Effect of cultivar type and soil properties on cadmium concentrations in potatoes

Potatoes are a staple food in New Zealand and a contributing source of dietary cadmium (Cd), although there is little information nationally on the soil and plant factors that affect Cd concentrations in the crop. We measured Cd concentrations in 10 commercial potato cultivars grown in three field sites across New Zealand and assessed the soil factors that affect Cd concentrations. Cadmium concentrations in potato tubers ranged from 0.004 to 0.574 mg kg⁻¹ DW (0.001–0.113 mg kg⁻¹ FW), although overall Cd concentrations were lower than the maximum limit of 0.1 mg kg⁻¹ FW for human consumption. There were significant differences (2.8-fold) in Cd concentrations between potato cultivars, although these varied by site. No significant relationships were found between soil properties and Cd concentrations in potatoes. Management of Cd in potatoes is likely to be most effective by avoiding growing high-Cd-accumulating cultivars in soils with elevated Cd. Further studies could determine if other management factors such as irrigation or type and rates of fertiliser affect Cd concentrations in potatoes