The sensitivity of Abelmoschus esculentus to ozone (O3) was assessed in plants exposed during four days, six hours/day, to filtered air (AF) and to AF plus 80 ppb of O3 (AF+O3) into fumigation chambers, by determining visible leaf symptoms and changes on gas exchange and on antioxidants. Visible symptoms were daily evaluated. Gas exchange and antioxidants (ascorbic acid and superoxide dismutase) were analyzed at the end of the experiment. All plants from AF+O3 treatment showed leaf injury, characterized by interveinal reddish punctuations on the adaxial surfaces. In average, 15% of leaf injury index and 62% of severity were estimated. Net photosynthesis, stomatal conductance, transpiration rate, ascorbic acid level and superoxide dismutase activity were significantly reduced in those plants, compared to measurements performed in plants exposed to AF only. The results suggest that Abelmoschus esculentus is sensitive to ozone, showing low levels of antixidative defenses and physiological distubances.
Abelmoschus esculentus; antioxidants; gas exchange; ozone; visible foliar symptoms
