Effects of ozone and Phytophthora citricola on non-structural carbohydrates of European beech (Fagus sylvatica) saplings

A lysimeter study was performed to monitor long term effects of chronic ozone enrichment on saplings of European beech (Fagus sylvatica L). After 3 years of ozone exposure a root infection with Phytophthora citricola Swada was established in the fourth year to study the interaction between elevated ozone and the root infection on the carbon budget of beech saplings. By using quantitative PCR no differences in root infection with P. citricola were observed between the ozone treatments. In contrast to the first 3 years of ozone exposure, sucrose and starch concentrations in leaves were diminished in ozone treated plants in the fourth year. The root infection reduced sucrose concentrations in leaves. Starch reserves of the heterotrophic biomass were not affected by any treatments. Thus 4 years of ozone exposure and 1 year of P. citricola root infection had only limited effect on carbohydrate metabolism in beech saplings.