The effects of tropospheric ozone on plant species: New perspectives

The effect of tropospheric ozone on the physiology of plants has been well established using physicochemical analysis and visual assessment. One of the main metabolic processes, in plants that is affected by ozone, is photosynthesis. This in turn affects a number of secondary processes required for the survival of plants. This study focused on two main aspects; the qualitative determination of damage through visual assessment and the quantification of damage through the determination of the content of chlorophyll and other quality parameters using spectrophotometric techniques in a number of plant species. Three distinct setups were considered, mainly rural, urban and semiurban, representing the topography of the islands of Malta and Gozo. It was observed that chlorosis was not the sole factor contributing to the yellowing of the leaves. Another important finding was the correlation between ozone levels (50.18-69.35 ppb) and the anthocyanin content (2.57-28.99 mg/kg) of leaves. From the three plant species that were extensively studied (Nerium oleander, Pinus halepensis and Schinus terebinthifolius), the N. oleander exhibited promising results as a bioindicator for ozone-induced damage. Due to the presence of this ornamental plant in rural and urban areas, it can be used by researchers and authorities as a tool for assessment of tropospheric ozone levels.