Direct Correlation of Air-Polluting Ozone and Tobacco Weather Fleck

Abstract

Influxes of polluted air and attacks of tobacco weather fleck in southwestern Ontario were accurately forecast from the synoptic weather pattern and from considerations of mesoscale meteorological systems. However, the principal air pollutant, ozone, occurred daily at low concentrations that were often not followed by corresponding amounts of damage. This difficulty was largely removed by modification of the dose term with the coefficient of evaporation. The latter may empirically represent physiological and physical factors affecting gas exchange. A related downward flux of ozone might be important in determining the amount of ozone available for absorption. The threshold doses of air-polluting ozone and experimentally generated ozone were approximately the same.

Ozone Dose and Plant Injury

“…The exposure factor made a linear relation between data for ozone dose and injury to tobacco in the field (2), in accordance with a linear relationship described by Middleton (3).…”

Effects of Photochemical Air Pollution on Vegetation with Relation to the Air Quality Requirements

“…17 The experimentally fumigated plants were field grown in plots adjacent to those exposed to ambient air but were covered with a transparent polyethylene housing fitting over ten plants at a time. The air at the inlet of the chamber was carbon filtered to remove the atmospheric pollutants and then ozone concentrations were added equivalent to the ambient total oxidant levels.…”

Responses of Cucumber, Onion and Potato Cultivars to Ozone

“…(1964) also showed the importance of differences in cultivars to leaf injury caused by ozone. Cultivar differences in sensitivity to ozone have since been ieported foi a wide variety of crop plants, including cereals (sechler and Davis, 1964), onion (Engle et al, !2as), begonia (Leone and Brennan, 1969) Injury to field-grown tobacco has been observed at ozofle concentrations as low as 2 pphm (Macdowall et al, 1964), whereas much higher levels are required under controlled fumigations (Menser and Hodges, 1970). The low concentration effect in the fleld could be due to the synergistic effect produced by ozone with other air pollutants, particularly sulfur dioxide.…”

“…Ozone is estimated to be responsible for 85 to 90% of the total oxidizing potential of the polluted atmosphere of the Los Angeles and san Francisco Biy ut"as (Littman and Marynouski, 1956;Taylor, 1968), and has been identified as i causal factor in th_e foliar injury and yield depressions of several crop plants, particularly tobacco (Macdowall et al, 1964) and white beans (weav"t uoo Jackson, 196gi.…”