Uptake of Al,Ca, and P in black spruce seedlings: Effect of organic versus inorganic al in nutrient solutions.

Two-year old black spruce seedlings (Picea mariana Mill.] B.S.P.) of greenhouse-grown paper-pot stock were subjected to chemically well-characterized nutrient solutions for 28 days to assess the elemental uptake (A1,P,Ca) of these plants in response to organic versus inorganic Al in the rooting medium (pH=3.0; 0 ≤ total Al ≤ 48 mg L^?1). Oxalate additions to the nutrient solutions (0 ≤ Ox ≤ 2.4 mmol) served as organic Al-complexing agent. The results indicated that the plants took up Al in proportion to the Al concentration of the rooting medium, with Al uptake from the Al-Ox treatments somewhat more extensive than the Al uptake from the inorganic Al treatments. Furthermore, root Al ? shoot Al for both cases. The pattern of P uptake was similar to that of Al uptake but for the roots only, i.e. root P was proportional to root Al.Increased root P was not associated with increased shoot P. Calcium content of the roots was slightly reduced with increased inorganic and organic Al, but increased strongly with increasing oxalate in the rooting medium.