The accumulation of cadmium in poplar trees during three consecutive years

Abstract A three-year pot experiment was designed to investigate cadmium (Cd) accumulation in the various parts of poplar ( Populus deltoides Bartr. cv. ‘Lux’ I-69/55) by setting up 5 Cd application treatments (0, 5, 20, 50, and 100 mg/kg dry soil). The results showed that poplar exhibited a high tolerance to Cd stress, with Cd uptake significantly increasing across all plant parts as soil Cd levels rose. In general, leaves exhibited the highest Cd concentration while stems had the lowest. An upward increase trend of the accumulation of Cd in the aboveground parts from the base wood, along the stem to the branch, until the leaves, as well as a radially outward increase of Cd from the wood near the pith, to the wood near the bark, and finally to the bark, were observed. Over the three successive years, poplar trees exhibited a generally increasing extraction ability in terms of Cd concentration and the bioconcentration factor (BCF) in their aboveground parts, attributed to the enhanced leaf transpiration and conducting tissue development. The BCFs of various parts of poplar ranged from 0.09 to 6.30, following the trend of leaf > bark > branch > root > stem.