Effects of sulfur dioxide on water relations of hybrid poplar foliage and bark

Abstract

Hybrid poplar cuttings were exposed to 0.25 ppm SO2 for 72 h/week for 14 consecutive weeks in 1979. In 1980, a second set of cuttings was exposed to 0.12 ppm SO2 for 72 h/week for 6 consecutive weeks. Foliar and bark water potential, osmotic potential, and the pressure component, as well as leaf conductance, were determined during or following exposure and compared with data from unexposed control plants. Leaf conductance was stimulated during 72-h exposures to 0.25 ppm SO2. Six 72 h/week exposures to 0.12 ppm SO2 had no effect on conductance, but induced changes in foliar water potential and osmotic potential.