cultivar were found in antioxidative enzymes, such as SOD and CAT, but not in stomatal conductance (gs). There-
fore, it can be concluded that antioxidative enzymes rather than gs or antioxidants are responsible for the differ-
ential responses to E-O3 among cultivars. These findings provide important information for the development of
accurate modeling O3 effects on crops, especially with respect to the developmental stage when O3 damage to
photosynthesis becomes manifest