Interaction of elevated CO2 and ozone concentrations and irrigation regimes on leaf anatomy and carbohydrate status of young oak (Quercus petraea) trees

Young sessile oak (Quercus petraea) trees were exposed for one vegetation p eriod in closed environmental chambers in a crossed factorial study on effe cts to varied CO2 concentrations, ozone concentrations and irrigation treat ments. Elevated CO2 concentrations (ambient + 350 mu mol mol(-1)) caused a significant increase in biomass production, alterations in leaf anatomy and chloroplast ultrastructure as well as an increase in leaf starch content, as compared to ambient CO2 concentrations. The effects of elevated O-3 conc entrations and drought stress were far less distinct. The leaf starch conte nt was influenced by CO2 and O-3 in a synergistic manner.