VIEW ARTICLE

Physiology and Biochemistry

The Influence of Exposure Temperature and Relative Humidity on the Response of Pinto Bean Foliage to Sulfur Dioxide. D. L. Rist, Former graduate student, Department of Plant Pathology and Center for Air Environment Studies, The Pennsylvania State University, University Park, PA 16802, Current address of senior author: Department of Plant Pathology, Cornell University, Ithaca, NY 14853; D. D. Davis, associate professor, Department of Plant Pathology and Center for Air Environment Studies, The Pennsylvania State University, University Park, PA 16802. Phytopathology 69:231-235. Accepted for publication 10 August 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-231.

When 20-day-old pinto bean plants (Phaseolus vulgaris ‘Pinto 111’) were exposed to 0.9 ppm sulfur dioxide (SO₂) the amount of trifoliolate leaf injury induced by SO₂ generally was greater at 32 C than at either 13 or 21 C, and greater at 80% relative humidity (RH) than at 40 and 60% RH. However, injury was less following exposures at 32 C for 1 hr and 21 C for 1 and 2 hr than that caused by equivalent exposures at 13 C. Stomatal conductance increased significantly with increased temperature and RH. Stomatal conductance of trifoliolate leaves from plants exposed to SO₂ was less than that of exposed control plants. The foliar content of SO₂, evaluated after exposures at 21 and 32 C, generally was greater at the higher temperatures.