BHARDWAJ, S.K.WALIA, KASHISH2017-05-092017-05-092014http://krishikosh.egranth.ac.in/handle/1/5810010817ABSTRACT The present investigation entitled “Studies on air pollution tolerance index of trees growing in the industrial area of Solan district of Himachal Pradesh”was conducted during 2013-2014 in the industrial area of Baddi in Solan district of Himachal Pradesh. In order to select the site and study the vegetation distribution pattern, the survey of the region was conducted. Keeping in view the distribution of industries in the region five distances were selected from the central location of the industrial cluster namely: 0-100 m, 100-200 m, 200-400 m, 400-800m, > 800m. In order to select non polluted site as control the distance of more than 800m with less transportation, development and low industrial activity was considered. Three tree species namely Azadirachta indica, Dalbergia sissoo and Leucaene leucocephala of uniform age, size, spread and common in occurrence on all the five distances were selected for the study. In order to study tolerance and sensitivity of trees to air pollution Air Pollution Tolerance Index (APTI) of selected tree species was computed based on leaf physiological and biochemical parameters (ascorbic acid, chlorophyll, pH and relative water content). Dust accumulation on the leaves was recorded during (Rainy, Winter and Summer) season. The leaf dust load was also analyzed for heavy metal content. In total there were 45 treatment combinations which were replicated four times in Randomised Block Design (Factorial). The APTI of selected trees ranged from 8.60-14.98.The order of tolerance of selected tree species was A .indica (13.08) >L .leucocephal > (11.61) D.sissoo(10.68). Highest APTI was noticed in rainy followed by winter and summer season. The trend of APTI for trees growing at different sites was 0-100>100-200>200-400>400-800>800. The relatively higher APTI value of A.indica as compared to other species indicated its tolerance to pollution in industrial area.The dust load on leaves of selected tree species varied from 0.001- 0.085 g m -2 The dust accumulation on the leaves was found maximum 0.045g m -2 in L. leucocephala and minimum 0.018 g m -2 in A. indica, which followed the order of L. leucocephala>D. sissoo>A. indicaand season wise maximum in winter followed by summer and minimum in Rainy. The general trend of dust accumulation at different distances was 0-100>100-200>200-400>400-800>800(control). The dust load of all the species growing at different distances from the industrial area contained significant concentration of heavy metalslike Cd (0.008 – 1.332), Cu (0.040 – 0.980), Fe (6.483 – 25.153), Hg (0.094 – 3.275), Mn (3.503 – 15.085), Ni (2.983 – 93.685), Pb (0.170 – 24.615) and Zn (1.693 – 5.8900 mg kg -2 .The concentration of Cd (1.332 mg kg -1 ), Hg (3.275 mg kg -1 ) and Fe (25.153 mg kg -1 ) in leaf dust load of selected tree species was above t he normal permissible limit prescribed for soil.ennullThesis