Antioxidative Systems in Spruce Clones Grown at High Altitudes

Antioxidative systems were studied in current-year needles of 15 different clones of four-year-old spruce trees (Picea abies (L.) Karst.) grown at three altitudes (800 m, 1150 m and 1750 m above sea level) and compared with those in mature spruce trees after life-time growth at these sites. In both mature spruce trees and clones antioxidative systems increased and chlorophyll decreased with increasing elevation. In general, the increase in antioxidative systems was less pronounced and chlorophyll reductions were higher in clones than in mature spruce trees. Ozone-tolerant clones did not display higher antioxidant contents and superoxide dismutase or guaiacol peroxidase activities than ozone sensitive clones. The maintenance of enhanced chlorophyll b contents in tolerant clones with increasing elevation suggests that stress compensation was associated with other factors than the antioxidants analysed.