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Chronic effects of SO/sub 2/ on western wheatgrass in a Montana grassland

Book ·
OSTI ID:5003967
The effects of three different concentrations of chronic sulfur dioxide fumigations on western wheatgrass (Agropyron smithii Rydb.) in a Montana grassland were studied. Treatments consisted of continuous fumigation with SO/sub 2/ throughout two growing seasons at 30 day median concentrations of 0 pphm (control), 2 pphm (low treatment), 5 pphm (medium treatment), and 10 pphm (high treatment). The response of western wheatgrass was examined at three levels of organization: organ (leaf), organism (plant), and community. Forty western wheatgrass plants were collected from each treatment in June, July, August, and September 1975 and May, June, July, and August 1976. It was concluded that SO/sub 2/ fumigation stimulated leaf growth. This stimulation was reflected by greater numbers of leaves per individual western wheatgrass plant rather than larger leaves. Increased leaf number appeared to be directly related to both time and concentration of SO/sub 2/ exposure (dosage response). Two hypotheses were advanced as plausible explanations for stimulation of leaf production. The first was based on the assumption SO/sub 2/ directly stimulated growth while the second suggested stimulation was an indirect effect of SO/sub 2/. No abnormal lesions on leaf surfaces were evident which could be attributed to SO/sub 2/ treatment. However, an increase in leaf necrosis was concluded to have occurred with increasing SO/sub 2/ treatment. It was concluded that aboveground net primary production was not significantly altered because of SO/sub 2/ treatment for either western wheatgrass or the entire community.
OSTI ID:
5003967
Country of Publication:
United States
Language:
English