Nicht reproduzierbar: Versuchsergebnisse zur synergistischen Wirkung von Xeno?strogenen

Ohne Zusammenfassung     

Ozon: Bioindikation von Photooxidantien mit Bel W3-Tabak

Results of an ozone-biomonitoring program performed from May to October 1994 at five different stations on exposed Bel W3 tobacco plants in the southwest of Germany (region of Trier) are presented. No linear dose-response relationship could be deduced between ambient ozone concentration and leaf necroses. Gas-exchange rates of tobacco plants during typical summer days would have to be determined to evaluate the stomatal uptake of photo-oxidant gases. Nevertheless, monitoring with the aid of Bel W3 tobacco plants permits an evaluation of qualitative differences in the ambient ozone concentrations. More severe leaf damage were clearly related to periods with higher radiation and was consequently found more frequently in sites located at higher altitudes. Microclimatic differences, however, may also be responsible in part for the ozone-related leaf damage seen at these sites. For this reason, only general conclusions concerning the relative levels of pollution can be deduced from biomonitoring studies using the reactivity of the indicator plant, which strongly restricts the reliability of such field studies. Pigment levels and leaf patterns in tobacco plants which still demonstrate no necrosis cannot be used as early ozone indicators.