Air Pollution Tolerance Index of Tree Sepcies Growing in Traffic Area of Madurai, Tamil Nadu

Air pollutant from vehicles affect tree by injuring and killing them, and by adversely affecting physiological processes so as to decrease growth without necessarily causing visible symptoms of injury. In the present study, the four leaf parameters such as pH, relative water content, total chlorophyll and ascorbic acid for the five tree species such as Peltophorum ferrugineum, Pongamia glabra, Polyalthia longifolia, Tectona grandis and Ailanthus excelsa in three different sampling stations such as residential area, commercial cum heavy traffic area and less traffic area has been monitored. The air pollution tolerance index (APTI) has been evaluated, incorporating the biochemical parameters to categorize the plants as sensitive or resistant to air pollutants. The analysis of the parameters show that all the four parameters are high in the residential area compared to the sampling stations exposed to automobile exhaust. It reveals that the air pollutants from the vehicles enter the plants through the natural opening usually stomata and react within leaf tissues. They do not cause tissue death but inhibit leaf function.