Effect of Ozone and Ozonated 1-hexene on Respiration and Photosynthesis of Leaves.

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Abstract
Respiration and photo-synthesis were determined using the differences in CO, concentration (measured by an infrared analyzer) of incoming and outgoing air streams from an enclosed attached leaf. Treatment of Pinto bean leaves with either ozone or ozonated hexene gas at oxidant concentrations from 0.5-7.7 ppm caused a rise in the respiration rate up to more than 4 times that of untreated control leaves. Plant responses to the 2 gases were similar. The rate of photosynthesis of treated bean leaves was less than that of controls. Both the amounts of stimulation of respiration and the inhibition of photosynthesis were directly related to the development of visible injury symptoms in certain tissues of the leaves. No stimulation of respiration or inhibition of photosynthesis occurred unless visible injury developed. However, ozone (16 ppm) caused a rise in respiration rate of Valencia orange leaves with no concomitant development of visible injury. Treatment with ozonated hexene at concentrations eliciting changes in respiration and photosynthesis in bean leaves caused no change in these processes in citrus leaves. A comparison of ozone and ozonated hexene-treated bean leaves showed that the respiratory quotients were not different from that of the control leaves.