Atmospheric PAN Concentrations and Foliar Injury to Petunia Indicator Plants in Tokyo

This study was conducted to clarify the relationship between peroxyacetyl nitrate (PAN) pollution and plant response basing on visible foliar injury observed in the field-grown petunia, Petunia hybrida _VILM. The visible injury on ‘White ensign’ petunia, a PAN sensitive variety, and atmospheric PAN concentrations were recorded almost every day at Yurakucho from April to November from 1976 to 1983. PAN injury to petunia leaves appeared 15 times in 1976 and 4-6 times in other years. Foliar injury to petunia occurred by less than 10% when the plants were exposed to atmospheric PAN at less than 6 ppb daily maximum concentration or at less than 30 ppb·h daily dose. The percentage of injury occurrence increased with an increase in daily maximum concentration or daily dose. However, the correlation between daily PAN level and percentage of foliar injury was not significantly.<BR>To investigate the distribution of atmospheric PAN, a field survey using petunia (‘White ensign’, PAN-sensitive variety and ‘Blue ensign’, PAN-tolerant variety) as indicator plants, was conducted at 5 locations (Ohme, Yohga, Shakujii, Yurakucho, and Adachi) in Tokyo from 1982 to 1983. Injury to ‘White ensign’ petunia was recognized every month at more than one location among five petunia monitoring stations from May to October during two years. Generally, the monthly cumulative foliar injury per plant to both sensitive and tolerant petunia in the west (Ohme, Yohga, and Shakujii) of Tokyo was considerably greater than at the east (Adachi) of Tokyo. The monthly cumulative foliar injury to ‘Blue ensign’ was almost half of those to ‘White ensign’. The results of this field survey using petunia revealed that PAN pollution occurred all over the Tokyo during late spring and autumn.