The simultaneous effect of soil-borne NaF and air pollutant SO on CO-uptake and pollutant accumulation.

Spruce cuttings were potted in quartz sand. One half was watered with tap water, the other with deionized water containing 100 ppm F as NaF, during winter till bud break. After flushing the plants were exposed continuously for five weeks (June/July) either to normal air or to air with 0.025 and 0.075 ppm SO, respectively. CO-uptake was measured in the laboratory (40,000 lux) with an IRGA.Even in the absence of visible symptoms of injury to last year's needles, root-applied fluoride did suppress CO-uptake significantly. Also the fumigation with 0.075 ppm SO caused a depression of CO-uptake, whereas 0.025 ppm SO remained without significant reaction within five weeks. Fluorides infiltrating through roots and airborne SO acting together may depress CO-uptake synergistically.Soil applied fluoride accumulated particularly in roots and twigs, whereas very little was found in the stem. The F-accumulation even increased with increasing SO-concentrations but was without effect on S-accumulation.