Effect of nitrogen fertiliser applications on cadmium concentrations in durum wheat (Triticum turgidum) grain

The effect of different rates of nitrogen (N) fertiliser application on cadmium (Cd) concentrations in the grain of two durum wheat (Triticum turgidum L.) cultivars was investigated at three different field trial sites in Canterbury, New Zealand. The mean Cd concentration in this study was 66 mug kg(-1) fresh weight (FW), which is 30% below the maximum level (ML). Uptake of Cd was higher in 'CRDW 17' compared with 'Waitohi' at all three sites. Also increasing amounts of calcium ammonium nitrate (CAN) fertiliser increased the Cd concentration in durum wheat grain at all three sites. Wheat grain Cd concentrations were not found to be related to any measured soil properties. Grain Cd concentrations were in most instances positively correlated with total biological yield (TBY). This response may be the result of the combined effects of fertiliser salts on ionic composition of the soil solution, and increased root interception and enhanced mass flow of Cd related to increased TBYs. The evidence suggests that it is TBY rather than grain yield that is more important with regards to Cd uptake in durum wheat.