Resistance of heather plants (Calluna vulgaris L.) to cesium toxicity

Experiments were carried out to determine uptake and distribution of 137Cs, and total isotopes of Cs and K in plants of heather (Calluna vulgaris) growing at two levels of CsCl: 0.03 and 0.3 mM. Levels of Cs and K were determined in soil and in parts of plants: roots, stem, leaves and flowers. Also calculated were: (i) transfer factor of Cs and K from soil to parts of plant and (ii) discrimination of K by Cs during the transport of Cs from roots to aboveground parts of plants, expressed as K/Cs discrimination factor. The results confirmed that heather plants are hyper-accumulators of cesium, because the accumulation of Cs in shoot was much greater than in roots. The K level in heather did not change at Cs concentrations as high as 8-fold Cs level in this plant. Heather plants seem to be relatively resistant to cesium toxicity at 0.3 mM of CsCl; the effect of exposure to CsCl at this concentration was exerted only on roots, without affecting leaves and flowers. These results supply new information on the interactions between Cs and K nutrition in plants; they also point to a possible role of heather in redistribution of the radiocesium pollution in the forest ecosystem.