Effects of SO2 and NO2 on the photosynthetic efficiency and catalase antioxidative enzyme activity in Betula pendula Roth

Abstract

Air pollution in urban environment is one of the major stressors for vegetation. The aim of the present study was to investigate the levels of sulfur dioxide (SO2) and nitrogen dioxide (NO2) in the air in Belgrade and Smederevo and their effects on photosynthetic efficiency and catalase enzyme activity of Betula pendula Roth. It was found that SO2 and NO2 concentrations increased from June to October at both studied sites but did not exceed the limits set by the national regulation. NO2 concentrations above the limits were measured only in October in Belgrade. It was also found that the values of the parameter of photosynthetic efficiency (Fv/Fm) were within the optimal range determined for deciduous trees, except in June in Belgrade, indicating that birch has optimal photosynthetic efficiency. Average catalase activity increased during the course of season at both sites. The lowest enzyme activity was measured in June in Belgrade and the highest in October in Smederevo. It was be concluded that under the given environmental conditions, the birch trees show no signs of damage and that the basic physiological processes are running at an optimal level. The increase in photosynthetic efficiency and catalase activity in birch leaves in the second part of the season could represent some kind of adaptation mechanism that allows it to survive under unfavorable environmental conditions.