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

Abstract

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.

Do chronic aboveground O3 exposure and belowground pathogen stress affect growth and belowground biomass partitioning of juvenile beech trees (Fagus sylvatica L.)?

“…The decrease in root morphological parameters due to P. citricola infection in the 20-40 cm deep slice was contrasted by an increase in root biomass that was also observed between 60 and 100 cm depth. In the lower depths the higher biomass might compensate for the putative reduced resource uptake in the infested roots that was observed only down to 40 cm depth (Fleischmann et al 2009). …”

“…1). A suspension with zoospores of P. citricola was filled into three holes that were drilled nearby each tree down to 40 cm depth and the lysimeters were subsequently irrigated with 25 L of deionised water to allow zoospores to infect the roots (for details see Fleischmann et al 2009). Fig.…”

“…Beneath 80 cm depth a significantly enhanced fine root proportion on total roots was found in trees infected with P. citricola, even though infection was not present in roots at these depths (cf. Fleischmann et al 2009). …”

“…Under greenhouse conditions, beech seedlings sustained severe damage after P. citricola infection (Fleischmann et al 2002. The inoculation of the trees under otherwise natural conditions was only possible using the lysimeters as they provide containment that avoids an infection of the control trees (Fleischmann et al 2009;Winkler et al 2009). …”

Experimental setup of field lysimeters for studying effects of elevated ozone and below-ground pathogen infection on a plant-soil-system of juvenile beech (Fagus sylvatica L.)

“…A suspension with P. citricola zoospores was given into three 40 cm deep holes per tree at the easternmost (N4, S4) and westernmost (N1, S1) lysimeters ( Fig. 4) to avoid contamination of the "infection-control" lysimeters (for details see Fleischmann et al 2009). Subsequently each lysimeter was irrigated with 12.5 L of deionised water to allow infection of the roots by the zoospores and the same procedure was performed on the following day.…”