Photosynthetic efficiency and morphological damage symptoms of Juglans regia L. leaves in urban environment

Abstract

Urban areas and associated human activities have induced anthropogenic emissions of potentially toxic elements (PTEs), which can present risk to living organisms and ecosystems in case of enriched levels. To identify the concentrations of PTEs, and to assess their impact on researched plants, leaf and soil samples of Juglans regia L.(walnut) were collected from urban parks in Pancevo, Smederevo and Belgrade. Subsequently, concentrations of Cu, Mn, Sr and Zn, photosynthetic efficiency and morphological symptoms of damage were analyzed. The results obtained showed that Cu and Zn concentrations in Belgrade and Smederevo were above average values described for global soils, indicating their anthropogenic origin. The leaf analysis revealed deficient content of Cu and Zn in Pancevo, Cu and Mn in Smederevo and toxic Sr content at all sites. The Fv/Fm values in leaves of J. regia were lower than the empirically determined optimal values, indicating photoinhibition of PSII due to the accumulation of physiological and morphological leaf damages. Results of this study suggest that J. regia does not represent good selection for bioindication and/or biomonitoring of pollution in urban environments, except in case of Sr, where it can be used as a potential bioindicator.