Metabolic responses of plants differing in SO 2 sensitivity towards SO 2 fumigation

Abstract

To study the variations of plant response to sulphur dioxide, fumigation experiments were carried out with plants which have different sensitivities to SO 2. After SO 2 exposure it was obvious that the pea cultivar Späths Violetta (SV) is more sensitive to the pollutant than the pea cultivar Wunder von Kelvedon (WvK, Kelvedon Wonder). In comparison to SV, after 18 days of exposure, the less sensitive WvK showed increases in yield at lower SO 2 concentrations, sulphur accumulation in roots, and higher putrescine concentrations. After a short-term fumigation with 1·5 mg SO 2 m −3 differences between the cultivars could be recognised concerning the contents of sulphite and malondialdehyde and the activities of superoxide dismutase and peroxidase. In a fumigation experiment with deciduous trees, Tilia cordata was more sensitive to SO 2 than Populus nigra. This is revealed by the fresh/dry weight ratio, the sulphur content and the peroxidase activity. Besides that, the variations in susceptibility correlate with the results of a screening of the plants. Both SV and the sensitive Tilia cordata revealed lower buffering capacities for H + ions. Moreover, they showed a lower superoxide dismutase activity than the non-sensitive plants. These findings demonstrate that SO 2 tolerant plants have a more effective mechanism for the compensation of injurious reactions in metabolism than non-tolerant plants.