Controlled levels of pollutants were added for 103.5 h weakly,
clean air being given for the remaining 64.5 h.
The
concentration of each gas used during 103.5 h exposure was 0.11
ppm.
The treatments with concentrations calculated as weekly
means were (as follows) 0.068 ppm -> yields of Dactylis
glomerata and Poa pratensis were reduced.
Ashenden & Mansfield
1978
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