Paper Title
Effect of Pollution on Relative Water Content in Temperate Species Growing along National Highway 5 in Himachal Pradesh

Abstract
Exposure of evergreen plants to air pollutants creates many changes in physiological and biochemical parameters. High water content in plants ensures the maintenance of the physiological balance under stresses such as air pollution, and the relative water content (RWC) is usually associated with the protoplasmic permeability of cells, which is involved in the loss of water and dissolved nutrients in plants, resulting in senescence of leaves. RWC has been found to vary with air pollution. In the present study, the species-wise variation in relative water content of commonly growing plant species along the National Highway 5 was studied and it was observed that RWC varied significantly in different species. Maximum RWC was observed in case of Hypericum oblongifolium while the least was observed in Quercus leucotrichophora. The distancewise variation in relative water content of species growing along the National Highway 5 revealed that distance from the National Highway had significant effect on RWC. Maximum RWC was observed in case of Hypericum oblongifolium (84.83%) at the distance >100 m while minimum RWC was observed in case of Quercus leucotrichophora (64.79%) at the distance 0-5 m from the National Highway. RWC was found to be highest at the distance >100 m from the National Highway in all the species except Grevillea robusta; the difference, however, was not significant. Since Grevillea robusta showed an increase in RWC with increase in pollution, it can thus be suggested for growing along the highways for green belt development. Keywords - Pollution, Relative Water Content, Temperate species