Physiological responses of Ulmus minor Mill. to ozone, carbon monoxide, and nitrogen dioxide in regions with different levels of atmospheric pollutants in Iran

The present study was aimed to investigate the physiological responses of the leaves of Ulmus minor to air pollutants such as ozone, carbon monoxide, and nitrogen dioxide to verify the ability of this species to resistant the air pollutants. The leaves of Ulmus minor Mill. were collected from one location (Chaloos) in the Mazandaran province with lower air pollution and three locations in the Tehran province (Tajrish, Park Laleh, and Park Shahr) with higher air pollutions. The leaves were randomly collected from the middle part of the crowns in each sampling location with five replications and the growth and physiological characters were measured. The climate factors of the sampling locations were also evaluated. The results showed that dry matter, protein, chlorophyll a, anthocyanin, and activity of the peroxidase enzyme in the plants grown in Park Shahr with higher amount of air pollutants was almost 35, 50, 30, 50, and 40 percent higher than those of the plants grown in Chaloos with the lower amount of air pollutants, respectively. The number and intensity of peroxidase isoenzyme bands were significantly higher in the leaves of plants collected from the locations in Tehran province. However, the prominent role of rainfall on the physiological responses of Ulmus minor cannot be ignored. It seems that Ulmus minor is a resistant tree to air pollutants and it might be considered as a biological filter in removing gaseous pollutants in areas like Tehran city to improve air quality.