Ozone toxicity to sugar maple
Sugar maples exposed to ozone under laboratory and field conditions were less sensitive to ozone than Pinto bean seedlings. The threshold level for visible injury to maple foliage after short exposures was 20 to 30 pphm for 2 hr. Extended intermittent doses as low as 10 pphm at 2 hr day for 14 days caused slight injury. Trees treated in the field were injured by ozone only slightly less than potted trees treated under artificial conditions, but understory saplings in the shade were not injured by a high dose. There was great tree-to-tree variability in sensitivity. Ozone caused disruption and collapse of palisade parenchyma cells and adaxial flecks in the vein islet tissue; bifacial scorch developed following exposure to higher doses. Immature leaves were not injured by high doses. Ozone caused leaf abscission only after severe injury by the higher doses. It sometimes induced chlorosis on field trees but never caused twig dieback. Total lipids in some ozone-injured cells were reduced, but no gross changes in the lignin, cellulose, pectic, or starch constituents of the cells were detected. There was no evidence of natural ozone damage to trees when the external and histologic symptoms induced experimentally were compared with those observed on sugar maples growing in urban and roadside environments. It is concluded that ozone is not an important causal factor in the etiology of sugar maple dieback.
- Research Organization:
- Brooklyn Botanic Garden, Ossining, NY
- OSTI ID:
- 5262463
- Journal Information:
- Phytopathology; (United States), Vol. 59:10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MAPLES
INJURIES
OZONE
SENSITIVITY
TOXICITY
AGE DEPENDENCE
AIR POLLUTION
BIOLOGICAL VARIABILITY
CELLULOSE
DOSE-RESPONSE RELATIONSHIPS
LIGNIN
LIPIDS
PLANT CELLS
PLANT DISEASES
PLANT GROWTH
SYMPTOMS
CARBOHYDRATES
GROWTH
ORGANIC COMPOUNDS
PLANTS
POLLUTION
POLYSACCHARIDES
SACCHARIDES
TREES
560303* - Chemicals Metabolism & Toxicology- Plants- (-1987)