THE COMBINED EFFECT OF CO2, OZONE, AND DROUGHT ON THE RADICAL SCAVENGING SYSTEM OF YOUNG OAK TREES (QUERCUS-PETRAEA) - A PHYTOTHRON STUDY

In order to study the combined effects of CO2, ozone, and drought, we simulated in a controlled environment the climatic conditions of a Ger man oak stand with high ozone (daytime: 80 ppb, control: 20 ppb) durin g one vegetative period under a regime of low and high CO2 concentrati on (370 vs 720 ppm) and drought (4 weeks < -800 hPa). To investigate t he effects of CO2, ozone and drought on the radical scavenging system, we monitored the level of glutathione, ascorbate, and a-tocopherol. H owever, it is important that, under the regime of elevated CO2, the an tioxidative behaviour of glutathione and ascorbate appears to be maske d by their function as storage molecules for sulfur or carbon. (C)1998 Elsevier Science Ltd.