Assessment of air pollution tolerance index and anticipated performance index of a few local plant species available at the roadside for mitigation of air pollution and green belt development

Elevated level of atmospheric air pollution in urban areas has become a global problem nowadays due to the fact that air pollutants cause severe threat to human health. Plants grown along roadsides, while exposed to vehicular emissions, are considered effective structure for sinking of air pollutants and improving the air quality. Different plant species possess varied capabilities as well as biochemical constituents for their survival at polluted sites. Therefore, the air pollution tolerance index (APTI) and the anticipated (expected) performance index (API) have been found as efficient tools for evaluation and selection of appropriate plant species for polluted sites, especially, the heavy traffic areas. The present study was carried out to evaluate APTI and API of plants grown on roadsides of Batala city of Punjab (India). Among different plants species studied during present study, Ficus religiosa, Polyalthia longifolia, Bauhinia variegata, and Nerium oleander have shown the high APTI indicating that these plant species were tolerant while Acacia nilotica, Morus alba, and Ziziphus mauritiana were observed to be moderately tolerant and Ricinus communis as well as Cannabis sativa were observed to be sensitive plants species toward air pollution. The API values for different plant species varied from 43 to 80%. The maximum percentage API was observed for F. religiosa, anticipating that it was an excellent performer to air pollution while minimum API (%) was found to be for C. sativa indicating that it was a poor performer and thus could be used as bio-indicator plant species toward air pollution. The present study is of key significance because the obtained APTI and API values for plants studied can be used for classification and selection of suitable plant species for establishment of green belt along the roadside and polluted areas.