A Quantitative Analysis of the Relationships between SO₂ or NO₂ Sorption and Their Acute Effects on Plant Leaves Using Image Instrumentation

Abstract

We have reported on a method for evaluating the distributions of stomatal resistance to water vapor diffusion and SO₂or NO₂sorption on a leaf, using a thermal infrared image instrumentation system. In the present paper, we examined quantitatively the relation-ships between the acute effects, such as stomatal response and visible injury, of SO₂or NO₂on a leaf and gas sorption, using the image instrumentation method. The results obtained were as follows.
1) There was a tendency for stomata to close during SO₂or NO₂exposure. However, the behavior varied randomly at different sites on a leaf. The differences in stomatal response at local sites were not dependent on those in integrated SO₂or NO₂sorption for 60 minutes exposure. These results suggest that there are differences in the stomatal sensitivity to SO₂or NO₂at local sites on a leaf.
2) There was a tendency for visible injury to occur at sites where the integrated SO₂or NO₂sorption was over a threshold value. Injured leaves were generally separated into two areas, a healthy area and an injured one. It was seen that the characteristic visible injuries were caused by differences in boundary layer and stomatal resistances at local sites governing the gas sorption.