RESULTS FROM THE UN ECE ICP-CROPS INDICATE THE EXTENT OF EXCEEDANCE OF THE CRITICAL LEVELS OF OZONE IN EUROPE/

The experiments of the United Nations/Economic Commission for Europe ( UN/ECE) International Cooperative Programme on effects of air pollutio n and other stresses on crops and non-wood plants (ICP-Crops) are desi gned to investigate the effects of ambient ozone pollution on crops an d non-wood plants. Each year, participants fi om approximately 17 Euro pean countries conduct a series of coordinated experiments to determin e which species develop visible injury following ozone episodes and wh ether the biomass or yield of sensitive species is reduced. In 1993, o zone injury was only seen at two thirds of sites but in 1994 injury wa s detected at almost all sites. This coincides with generally higher o zone concentrations measured in that year. Injury was seen on crops in cluding subterranean clover (Trifolium subterraneum L.), white clover (Trifolium repens L.), bran (Phaseolus vulgaris L.), tomato (Lycopersi con esculentum), soybean (Glycine mar), watermelon (Citrullus lanatus) and tobacco (Nicotiana tabacum L,.) at experimental sites and in some cases, in commercial fields. The application of ethylenediurea (EDU) to some crop species reduced the level of visible injury. At some site s, the yield of EDU-treated bean plants was greater than that of untre ated plants where the critical level of ozone for yield reduction was exceeded. Preliminary analysis of ozone concentrations in the days pre ceding injury indicated a sequential ozone concentration effect. The r esults art discussed in relation to Level I and Level II mapping of ex ceedance of the short- and long-term critical levels for ozone.