ENHANCEMENT OF CADMIUM EFFECTS ON GROWTH AND NUTRIENT COMPOSITION OF BIRCH (BETULA-PENDULA) BY BUTHIONINE SULFOXIMINE (BSO)

Binding of Cd to non-specific metal-binding peptides (phytochelatins) in birch roots has been suggested as an explanation for tolerance to C d toxicity in birch (Betula pendula), In the present study, the tolera nce of birch roots to Cd was further investigated by using buthionine sulphoximine (BSO) as an inhibitor of phytochelatin synthesis, Birch s eedlings, grown in nutrient solution at pH 4.2, were exposed to 0 or 2 mu M CdCl2 combined with 0 or 0.1 mM BSO for 6 d, Plant growth (fresh weight increase and shoot to root dry weight ratio) and the nutrient composition in fine roots, whole roots and shoots were determined, The effects of Cd on growth confirms the results of earlier studies on bi rch, suggesting a reduced shoot growth, but preserved or stimulated ro ot growth, When Cd and BSO were combined, overall plant growth was sev erely reduced, BSO was also shown to aggravate Cd-induced reductions o f root and shoot concentrations of K, Ca and Mg but to impede the accu mulation of Cd. The results suggest that phytochelatins participate in protecting the root against Cd interferences with growth, possibly by restricting Cd-induced changes in the nutrient composition of the pla nt.