Sulfur Accumulation and Development of Injury-Symptom in Plants Which Absorbed Sulfur Dioxide from the Atmosphere

Abstract

Plants highly sensitive to sulfur dioxide, namely, rush and buckwheat, were exposed to sulfur dioxide gas of three different concentrations for 30 or 50 days. In any given gas concentration, both plants accumlated sulfur by absorbing sulfur dioxide, with the advance of the exposing period. In rush, the sulfur content at the time of showing injury-tip-burn-symptom of 3% length caused by exposure to 0.26, 0.13, and 0.065ppm gas were about 0.4, 0.8, and 0.9%, respectively. In buckwheat, the sulfur content at the time of appearance of injury-lesion on leaves caused by exposure to 0.26, 0.13, and 0.065ppm gas were about 0.6, 0.75, and 1.2%, respectively. Control plants not treated with gas always maintained about 0.2% sulfur level.
Thus, the lower the gas concentration, the higher was the level of sulfur in the plant for liminal appearance of injury-symptom. In the plants which were exposed to sulfur dioxide gas of lower concentration, the sulfur absorbed by the plant seemed to be transformed to less toxic compounds, such as cystine and methionine, but this hypothesis was disproved by the analysis of amino acids in the plants.