Studies on the Mechanism of Injurious Effects of Toxic Gases on Crop Plants : III. On the degree of injuries and a kind of typical symptom of injuries caused by H2SO3 solution spray to rice plants

[摘要] Two kinds of typical symptoms of injuries caused by sulfur dioxide were observed on the leaf-blade and-sheath of paddy rice; the one was countless spots of brown color, and the other was lesions of white color, these symptoms being observed at the tip of the leaf-blade, interveinal and, sometimes, marginal part of the leaf-blade and-sheath. The former was presumed to appear when H2SO3-mist arised from combining SO2 with H2O in the air was absorbed from the surface of the leaf-blade and-sheath. In order to clarify an inference above-mentioned, the author's carried out this experiment by spraying rice plants with H2SO3 solution either in the daytime or at night. The results obtained were as follows: 1. Countless spots of brown color were identified as a typical symptom of injuries by H2SO3 solution spray either in the dayime or at night. No lesions of white color were observed in both treatments. 2. Destruction of chlorophyll in the leaf brought about a decrease of chlorophyll content almost in parallel with the concentration of SO2, afflicting severe damage to the 3rd and 4th leaves numbered downward from the uppermost leaf. 3. Chlorophyll content was in proportion to total dry weight of the plant. 4. Sulfur content of the leaf was higher in the plant sprayed with H2SO3 solution in the daytime than in the plant sprayed at night. A higher content of sulfur was observed in the 3rd and 4th leaves of the plant sprayed in the daytime and the 2nd and 3rd leaves of the plant sprayed at night.

[学科分类] 农业科学（综合）