DOES SO2 FUMIGATION CHANGE THE CHEMICAL DEFENSE OF WOODY-PLANTS - THEEFFECT OF SHORT-TERM SO2 FUMIGATION ON THE METABOLISM OF DECIDUOUS SALIX MYRSINIFOLIA PLANTS

The effect of a moderate increase in atmospheric sulphur dioxide on th e production of phenolic secondary chemicals, soluble sugars and phyto mass distribution within plants was investigated in six willow (Salix myrsinifolia Salisb.) clones. The plants were cultivated for 3 weeks u nder 0.11 ppm of SO2 (300 mu g m(-3)). The production of salicin and c hlorogenic acid was significantly reduced under increased SO2. However , salicortin, 2'-O-acetylsalicortin, (+)-catechin and two unknown phen olics did not show any clear trend. The increase in SO2 did not affect the glucose, fructose and sucrose contents. The final weight of the S O2-treatment plants was significantly greater than that of the control plants: the leaf, stem and root phytomass was from 14 to 48% greater under increased SO2. All the clones showed the same trend, although th ere was a significant variation in phytomass production. Our results i ndicate, although not consistently that even a short-term exposure of enhanced atmospheric SO2 may change moderately the accumulation patter n of willow phenolics.