Evaluation of air pollution tolerance index of certain plant species grown alongside Parwanoo to Solan National Highway-22 in Himachal Pradesh, India
The study examined the Air Pollution Tolerance Index (APTI) of selected plant species growing along national highway-22 from Parwanoo to Solan, falling in Solan district of Himachal Pradesh, India. Four species namely Grewiaoptiva, Toonaciliata, Melia azedarach and Woodfordia floribunda of uniform size, age, spread and common in occurrence on both sides of the highway are selected. Leaf samples were collected from selected spe-cies and used to estimate four physiological and biochemical parameters, namely; leaf relative water content (RWC), ascorbic acid content (AA), total leaf chlorophyll (TChl) and leaf extract pH were used to compute the APTI values. The trend of APTI recorded for various species was Melia azedarach (18.37) >Grewiaoptiva(8.77) >Woodfordia floribunda (7.43) >Toonaciliata(6.82). The APTI also varied with seasons of the year. The highest APTI was noticed in rainy followed by winter and summer season. The study indicated Melia azedarach as most tolerant and Toonaciliataas most sensitive species to air pollution.