Plant water status influences ozone sensitivity of bean plants

Studies were conducted in a controlled environment chamber to determine the association between plant water status and ozone sensitivity. Bean plants were subjected to various water stress regimes for 4 to 10 days using a semipermeable membrane system which controlled plant water status and then exposed to ozone. Ozone sensitivity was measured using stress ethylene which was highly correlated with foliar injury. Plant water stress decreased plant sensitivity to ozone; complete protection was attained within 1 to 3 days depending on the level of water stress. When water stress was removed, the plants regained ozone sensitivity equal to nonwater stressed plants within 6 days. The decreased ozone sensitivity was associated with only a small changes in leaf water potential. The reduced sensitivity following water stress was apparently associated with a decreased leaf conductance reducing ozone uptake.