© 1994 Heron Publishing—Victoria, Canada
Uptake and distribution of calcium and phosphorus in beech (Fagus sylvatica) as influenced by aluminum and nitrogen
Bengt Bengtsson, Håkan Asp and Paul Jensén
Department of Horticulture, Division of Root and Substrate Research, The Swedish University of Agricultural Sciences, Box
55, S-230 53 Alnarp, Sweden / Received September 15, 1992
Summary
We studied the effects of excess nitrogen added as nitrate (NO3–) or ammonium (NH4+), or both, on mineral nutrition and growth of beech (Fagus sylvatica L.) plants grown at pH 4.2 in Al-free nutrient solution or in solutions containing 0.1 or 1.0 mM AlCl3. A high external concentration of NH4+ increased the concentration of nitrogen in roots, stems and leaves. The root/shoot dry weight ratio was less in plants grown
in the presence of NH4+ than in plants grown in the presence of NO3–. The concentration of phosphorus in the roots was increased and the concentration of potassium in all parts of the plant
was decreased by NH4+. A high external concentration of NO3– caused a decrease in phosphorus concentrations of the root, stem and leaf. Uptake of 45Ca2+ by roots was reduced in the presence of high concentrations of NH4+ or NO3–, and a combination of high concentrations of nitrogen and aluminum further reduced the uptake of 45Ca2+. Uptake of phosphate (32P) and concentrations of phosphorus in root and shoot were increased when plants were grown in the presence of 0.1 mM Al.
Exposure to 1.0 mM Al, however, reduced the concentration of phosphorus in roots and shoots and the reduction was greater
when plants were grown in the presence of a high external NO3– concentration. Aluminum binds to roots, and plants grown in the presence of 1.0 mM Al had a slightly higher concentration
of aluminum in roots than plants grown in the presence of 0.1 mM Al, whereas the concentration of Al in the shoot was increased
2 to 3 times in plants exposed to 1.0 mm Al. Furthermore, the effects of 1.0 mM Al on uptake of other macronutrients were
quite different from the effects of 0.1 mM Al. We conclude that 0.1 mM Al facilitates uptake and transport of phosphorus in
beech and that between 0.1 and 1.0 mM Al there is a dramatic change in the effects of Al on uptake and transport of divalent
cations and phosphorus.
Keywords:
ammonium, growth, mineral distribution, mineral nutrition, nitrate.
