EFFECTS OF TROPOSPHERIC OZONE ON WHITE CLOVER PLANTS EXPOSED IN OPEN-TOP CHAMBERS OR PROTECTED BY THE ANTIOXIDANT ETHYLENE-DIUREA (EDU)

Tropospheric ozone concentration in a large part of Europe is high eno ugh to cause visible injury to sensitive plants and several crop speci es, In this paper the results are reported of a research carried out w ithin UNECEICP-Crops co-ordination in 1994. Effects of tropospheric oz one on vegetation in the Milan (Italy) experimental site are evaluated using white clover plants, Plants were exposed to the air and sprayed with water or ethylene-diurea (EDU) as antioxidant. Another set of pl ants were exposed in open-top chambers in filtered or unfiltered air. The data suggest that summertime ozone concentrations can be sufficien t to produce visible leaf injury to white clover plants of a sensitive cultivar. Moreover, data show a slight reduction in dry weight owing to ozone exposure; the loss is about 10% for water-treated plants vers us EDU-treated plants and 19.8% for exposure to unfiltered air compare d with filtered air at the final harvest.