Influence of ozone on white ash (Fraxinus americans L. )

Book · Thu Jan 01 04:00:00 EST 1970

OSTI ID:6426315

Wilhour, R G

Scattered stippling of the upper leaf surface was the most common symptom of injury to white ash (Fraxinus americana L.) seedlings exposed to 10 and 25 pphm ozone for various time intervals; in fewer cases stipples were confined to specific areas of the leaf. Bifacial necrosis and tissue collapse were less common symptoms. Seedlings 1-year old were sensitive to 10 pphm ozone for 0.5 hr or 25 pphm for 1 hr. A direct relationship was present between sensitivity and exposure time to 25 pphm ozone for exposures of 1 to 5 hr; sensitivity remained relatively constant at longer exposures up to 8 hr. Temperature and relative humidity had a profound influence on the sensitivity of seedlings to ozone. Seedlings treated with a high temperature before or after exposure were more sensitive than those treated at a lower temperature. In contrast, seedlings exposed to ozone at a low temperature were more sensitive than those exposed at a higher temperature. The response to relative humidity treatments was more uniform. White ash seedlings were sensitive to 25 pphm ozone during the 15-week period of the growing season examined. Sensitivity increased initially with age, but after a maximum level of sensitivity was reached it remained relatively constant for the duration of the growing season. Cotyledons and primary and secondary leaves appeared to respond to ozone in a similar manner. There were essentially no significant differences in the response to ozone of leaves with respect to leaf position; however, the middle-aged leaves were generally most sensitive. 48 references, 15 figures.

• OSTI ID: 6426315
• Country of Publication: United States
• Language: English

Related Subjects

560303* -- Chemicals Metabolism & Toxicology-- Plants-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AGE DEPENDENCE
AIR POLLUTION
DATA
DOSE-RESPONSE RELATIONSHIPS
EXPERIMENTAL DATA
HUMIDITY
INFORMATION
LEAVES
NECROSIS
NUMERICAL DATA
OZONE
PATHOLOGICAL CHANGES
PLANTS
POLLUTION
SEEDLINGS
SENSITIVITY
TEMPERATURE DEPENDENCE
TOXICITY
TREES