The effects of aluminium and Paxillus involutus Fr. on the growth of Norway spruce [Picea abies (L.) Karst.]

Norway spruce [ Picea aides (L.) Karst.] seed lots were obtained from populations growing on an acid soil in the Black Forest, West Germany (acid), and a calcareous soil in the Schwabische Alb, West Germany (calc). Seedlings were grown in sterile perlite culture containing 0–6 mM aluminium. Hypocotyl extension was inhibited by aluminium in the calcareous seedlings, hut not in the acidic seedlings. In a longer term experiment acidic and calcareous plants were grown for 10 weeks in perlite. Some of the tubes were inoculated with the fungus Paxillus involutus Fr. (designated F +) and some were not (F -). Aluminium sulphate solutions were then added to the tubes to raise the aluminium concentrations to 0–6 mM. Plants were harvested after a further 10 weeks. Fungus was associated with the roots in F+ plants, but mycorrhizas did not form. Growth of acid(F -) was somewhat stimulated by aluminium treatment, but that of calc(F -) was greatly reduced, and the plants were chlorotic. The presence of a rhizospherie fungus (F +) enhanced the growth of the calcareous plants, but had little effect on the acidic plants. Shoot analyses suggested that the greater aluminium sensitivity of the calcareous plants involves an inability to exclude aluminium or to maintain normal levels of calcium and magnesium uptake in its presence. The presence of rhizospheric fungi reduced the effects of aluminium.