| Description |
This study is concerned with the effects that low levels of sulfur dioxide exhibit to plants exposed to the pollutant over long periods of time. Alfalfa, clover, and bluegrass were grown together in simplified plant communities in a number of pots placed in plexiglass chambers. In the two experiments the plants were fumigated three hours a day at sulfur dioxide concentrations averaging below 0.5 ppm for a total of 24 days. The s02 levels within the fumigation chambers were tested daily using the West-Gaeke method of analysis. At the end of the experiments, which ran a total of 28 days each, the plants were harvested at soil-level and fresh and dry weights determined. All fumigated. plants were examined closely for signs of injury, but only the clover and alfalfa sustained visible damage. Analysis of data revealed no significant difference in yield between fumigated and control plants, even though there was an estimated 20 % of the alfalfa and clover leaf surface damaged. Likewise it was found that the fumigated and control communities did not differ significantly with respect to their species composition. It has been suggested that the plants rely on energy sources stored in the seed until they produce leaflets, at which time the plants turn to photosynthesis as their energy source. During photo synthesis sulfur dioxide is absorbed into leaf tissue, and that which cannot be used in metabolism accumulates within the leaf. Such accumulation leads to leaf injury; however, even with visible leaf injury the results of these experiments indicated that S02 does not significantly effect the plants or the community structure during the first month of development. |
