UPTAKE AND ACCUMULATION OF RADIOCESIUM BY MYCORRHIZAL AND NONMYCORRHIZAL HEATHER PLANTS

Short-term uptake of Cs-137 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 500-mu-M) 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.