Anatomical and physiological changes in Iris pumila leaves in the unpolluted and polluted environment

Abstract

Plants are capable of sensing various types of stress and plant stomata, as well as photosynthetic pigments may play an important role in response to altered environmental conditions in order to maintain optimal photosynthetic efficiency, carbon uptake and water metabolism. In this survey, we estimated the stomatal density and photosynthetic pigments concentration of Iris pumila leaves as an indicator of antropogenically induced stress (traffic pollution). Leaf samples were taken from one unpolluted site – Deliblato sands (natural protected area), and one polluted site (along the main road Belgrade-Novi Sad), where replicas of the clones selected in the unpolluted site were previously transplanted. We measured anatomical (Stomatal density) and physiological traits (Chlorophyll a (Chla), Chlorophyll b (Chlb), Carotenoid (C) and Total chlorophyll (ChlT) concentration, the ratio of Chlorophyll a to Chlorophyll b, and the ratio of Chlorophyll a to Carotenoids). Estimated parameters differed significantly between studied sites. We detected statistically significant increase in stomatal density in polluted sites. Chla, Chlb and C concentrations, as well as ChlT and Chla/C showed significantly lower values in a polluted environment. Cha/b ratio showed significantly higher values in plants originating from the polluted habitat. We can conclude that there was a decrease in photosynthetic pigments in polluted habitat, as well as change of Chla/C ratio in favor of carotenoids that serve as photo protective pigments. All these conclusions confirm that stomatal density and concentration of relevant pigments can serve as a stress indicator in this protected species.