Effects of pretreatment with low ozone concentrations on ozone injury to bean and mint

Acute ozone injury to bean (an ozone-sensitive species) is reduced more than 50% by pretreatment with a low level of ozone (0.02 μl/liter), as compared with pretreatment in ozone-free air. In contrast, mint (an ozone-tolerant species) demonstrates a synergism of low and injurious doses. The reduction in susceptibility of bean is accompanied by a long-term effect of low ozone levels on stomatal conductance.