Studies of Air Pollutant Sorption by Plants (I) Relation between local SO2 sorption and acute visible leaf injury

• Published in: Journal of Agricultural Meteorology Vol. 34; no. 2; pp. 51 - 58
• Main Authors: OMASA, Kenji, ABO, Fumiaki
• Format: Journal Article
• Language: English; Japanese
• Published: The Society of Agricultural Meteorology of Japan 15.09.1978
• ISSN: 0021-8588; 1881-0136
• DOI: 10.2480/agrmet.34.51

In order to investigate the relation between the gaseous pollutant sorption into the leaves and the power of resistance to the air pollution, the local SO2 sorption into the leaf in relation to the degree of acute visible leaf injury was examined in an environmental control chamber. The results were obtained as follows. (1) An equation for the relation between Q/w′ and Pas was obtained as Q/w′≅1.8×10-3Pas, where w′ was transpiration rate per unit difference in water vapor pressures at leaf and in the air, Q was SO2 sorption rate and Pas was atmospheric SO2 concentration. The result agrees with the equation which is obtained by a model, Q/w′=(kw/kskr)(Pas-Pls) with Pls=0 volppm and kr=1.53, where Pls is SO2 concentration at gas-liquid interface in leaf, kr is the ratio of SO2 diffusive resistance to water vapor diffusive resistance, kw is a constant, 1.06×106mmHg·cm3/g, and ks is a constant, 3.95×108volppm·cm3/g. (2) Relation between leaf air temperature and transpiration rate was obtained as a linear equation during SO2 fumigation in the chamber, in which light intensity, air temperature, humidity, wind velocity and SO2 concentration were kept at constants, and the regression coefficient was -5.8×105cm2·s·°C/g. According to the results, the local transpiration rate which indicates the stomatal aperture is able to be estimated by measuring leaf temperature, and the SO2 sorption rate can be estimated from obtained diffusive resistances. (3) The degree of visible injury in a local area of the leaf to SO2 fumigation had a correlation with the local changes of leaf temperature, that is, the slower the rise of leaf temperature in a local area was, the greater the degree of injury in the local area was. According to the results of (1) and (2), the rise of leaf temperature means a decrease of transpiration rate, stomatal closure and a decrease of SO2 sorption rate. Therefore, the major cause of differences in the degree of visible injury seems to be the differences in SO2 sorption rate at different sites in the leaf.