UPTAKE OF MG-24 BY EXCISED PINE ROOTS - A PRELIMINARY-STUDY

Uptake of Mg-24 by excised roots of Pinus sylvestris L. during up to 4 h long incubations in 99.9 atom % Mg-24 (50 mu M) was measured by ICP -MS. A rapid initial uptake phase (30 min) was followed by a slower up take. This was interpreted as a shift from a phase dominated by satura ble ion exchange (free space uptake), to a non-saturable phase, during which the rate of uptake was 0.077+/-0.0.012 mu mol Mg g(-1) (d.wt.) h(-1). The metabolic uncoupler DNP (2,4-dinitrophenol) at 50 mu M decr eased the Mg uptake rate by 35% only, but the effect of DNP was signif icant (p<0.01). Several problems related to a high variability in the experimental material were encountered, and further refinement of this approach in studies of plant Mg uptake is suggested.