Net photosynthesis, dark respiration and susceptibility to air pollution of 20 European provenances of scots pine Pinus sylvestris L.

One-year-old seedlings of Pinus sylvestris L., representing 20 European provenances of the species from Sweden, USSR, Poland, GDR, FRG, Belgium, France, Hungary, Yugoslavia and Turkey, were subjected to the action of SO₂ (0·75 μl litre⁻¹ ×5 days, 6 h daily). The sensitivity of two-year-old seedlings of the same provenances were also studied under field conditions near an SO₂ and fluoride source. In both experiments there were statistically significant differences in the extent of needle injury between individual populations. Northern provenances (Sweden, USSR) and those from the south (Yugoslavia, Turkey) showed less sensitivity than provenances from the central part of the specie's range. A substantial agreement was found between the extent of necrosis under laboratory conditions and in the field (r = 0·44, significant at α = 0·1). A comparison of the net photosynthesis of control plants with needle necrosis under both treatment conditions has shown that there is a positive significant correlation.