Sulphur dioxide and the growth of Pinus sylvestris.
Seedlings and young trees of Pinus sylvestris were grown in outdoor fumigation chambers at 5 and 150 mu g SO2/m3 (approx.). The higher SO2 concn. reduced growth in 2 experiments, by reducing net assimilation rate, but had no significant effect in a third experiment (with slowly growing trees). Stem and needle elongation were retarded by SO2 in a further experiment (started in the dormant season). The diffusive resistance of needles increased after SO2 treatment, but the rate of net photosynthesis was not affected. The increase in temp. and water vapour pressure deficit and decreased irradiance of the chamber environment make it difficult to extrapolate these results to field conditions.