THE EFFECTS OF AIR POLLUTION ON PLANT GROWTH WITH SPECIAL REFERENCE TO SULPHUR DIOXIDE. III. GROWTH STUDIES WITH LOLIUM MULTIFLORUM LAM. AND DACTYLIS GLOMERATA L.

Abstract

Summary Lolium multiflorum cv. S22 and Dactylis glomerata cv. S143 were grown in a sealed glass chamber, force‐ventilated with ambient SO2‐polluted air and the yields compared with those of control plants grown in a second chamber receiving filtered air, free of SO2 and particulates. Shoot dry weight of both species was reduced by 30 to 40 % after 8 to 10 weeks in unfiltered air containing mean SO2 concentrations of 50 to 90 μg m−3, growth reductions being readily detectable after 3 weeks from transplanting seedlings to the chambers. The productivity of L. multiflorum was only marginally depressed (c. 10 %) by late summer SO2 levels in the range 10 to 50 μg m−3. It is suggested that grass plants may be particularly susceptible to SO2 pollution during the early growth phase following germination when aerodynamic resistance is low and relative growth rate maximal. The possibility that environmental factors other than SO2 pollution contributed to the inhibitory effect of the unfiltered air treatment is discussed.