Uptake and accumulation of radiocaesium by mycorrhizal and non-mycorrhizal heather plants

Short-term uptake of 137Cs by heather (Calluna vulgaris L.) was measured using radiolabelled liquid media and plants grown from shoot cuttings. Uptake by mycorrhizal plants was compared with uptake by non-mycorrhizal plants, and the effects of different external Cs and K concentrations were determined. At each time point during the 3 h experimental period the content (and hence also the apparent influx) of the mycorrhizal plants in each treatment was found to be lower than that of the non-mycorrhizal plants. An increase of 100-fold in the total external Cs concentration (from 5 to 500μM) gave between a 35-fold and 96-fold increase in initial influx of Cs. A similar change in external K concentration, however, had little effect on Cs influx. Root-shoot transfer of Cs over the 3 h uptake period was slight; in most cases more than 90% of the radiocaesium remained in the root. The final shoot:root Cs ratio was higher in mycorrhizal than in non-mycorrhizal plants, suggesting that in mycorrhizal plants, despite their lower overall accumulation during the first 3 h, a higher proportion of the Cs taken up is translocated to the shoot.