INFLUENCE OF ALUMINUM AND NITROGEN ON UPTAKE AND DISTRIBUTION OF MINERALS IN BEECH ROOTS (FAGUS-SYLVATICA)

Beech seedlings (Fagus sylvatica L. provenance Vastra Torup) were grown in nutrient solution at low pH (4.2) and exposed to AlCl3 and different concentrations of nitrogen. The effects of AlCl3 and nitrogen on uptake of Ca2+ (Ca-45) and H2PO4- (P-32) in roots of intact beech were studied. Crossections of roots were analyzed with respect to element concentrations, by use of Mikro-PIXE (particle induced X-ray emission). The distribution of Al, Ca, P, Mg, K, and S was analysed. The experiments were designed to evaluate the effects of aluminium on localization of elements in plant root tissue. Aluminium reduced the concentration of Ca in plants and increased that of K. High nitrogen levels in the solution further decreased the concentration of Ca in the roots. Aluminium (1.0 mM) effectively reduced the Ca2+ (Ca-45) uptake in short time experiments. Aluminium accumulated in high concentration (up to 500-mu-mol/g dry weight in areas of 30 x 30-mu-m2) on the root surface, epidermis and outer layers of cortex. Corresponding areas had an extremely low Ca concentration (ca 5-mu-mol/g dry weight) which could be harmful for regulation of mineral uptake and development of roots. It is concluded that the calcium concentration in roots was reduced by aluminium. The combination with high nitrogen levels further reduced calcium changing the mineral balance which could result in deficiency conditions of calcium in the root.