PHYSIOLOGICAL RESPONSES OF NORWAY SPRUCE TREES TO ELEVATED CO2 AND SO2

摘要

Young Norway spruce (Picea abies (L.) Karst.) trees were exposed to elevated CO2 (0.8 mL L(-1)), SO2 (0.06 mu L L(-1)), and elevated CO2 and SO2 (0.8 mL L(-1) and 0.06 mu L L(-1), respectively) for three months. Exposure to elevated CO2 resulted in an increased biomass production of the needles, while the pigment content was decreased. Exposure to SO2 hardly affected growth and pigment contents. Chlorophyll/carotenoid- and chlorophyll a/chlorophyll b-ratios were not affected by either CO2 or SO2. The epoxidation state of the xanthophyll-cycle was changed upon SO2-exposure, due to a higher zeaxanthin and a lower violaxanthin content. Chlorophyll fluorescence measurements showed F-v/F-m-ratios of 0.7 or higher for all needles, which indicated a healthy photosynthetic apparatus. Exposure to SO2 resulted in increased foliar contents of sulfate, total glutathione (reduced and oxidized form), cyst(e)ine, and a slightly more reduced redox state of glutathione. Exposure to elevated CO2 resulted in a slight decrease in glutathione contents, but it did not affect sulfate or cyst(e)ine contents of the spruce needles. Neither ascorbic acid content nor its redox state were affected by CO2 or SO2. The effects of CO2 and SO2 were independent from each other, since significant interactions CO(2)xSO(2) were not observed.