Stomatal closure during tobacco leaf desiccation as affected by ozone

The effect of acute ozone exposure on the stomatal conductance and leaf wat er content during rapid desiccation was examined in leaves of two tobacco c ultivars, ozone sensitive cv. BelW3 and ozone tolerant cv, Samsun. The rela tive rate of stomatal closure was constant during leaf desiccation in cv. S amsun but decreased in cv. BelW3 in both ozonated and control plants. Ozone exposure increased the relative rate of stomatal closure and transpiration rate (measured on the following day) in cv. Samsun, but reduced the respec tive parameters in cv, BelW3. As a result, the plants of ozone-sensitive cu ltivar, treated with ozone, lost more water during desiccation than control plants.