DOES OZONE STRESS CHANGE THE PRIMARY OR SECONDARY METABOLITES OF BIRCH (BETULA-PENDULA ROTH)

In field experiments three clones of two-year-old birch (Betula pendul a Roth.) were exposed for one growing season to an ozone concentration 1.2 times higher than ambient. At the end of August, leaf and stem ma terial was analyzed for a wide range of primary and secondary metaboli tes. Although most of these metabolites were not significantly affecte d by ozone exposure, ozone-treated leaves contained larger concentrati ons of total sugars and reduced amounts of the phenolic glucoside, deh ydrosalidroside. In the stems, greater amounts of catechin pentoside, hyperoside and papyriferic acid were found. The results indicated cons iderable inter- and intra-clonal variation in the production of phytoc hemicals in both leaves and stems.