The urban air pollution is a major environmental concern, particularly in the developing countries and in their major cities. Therefore, the present study was mainly aimed to study the effect of air pollution on the morphological characteristics of leaf of 13 common plant species viz., Elaeagnus angustifolia L., Eucalyptus tereticornis L., Ficus carica L., Fraxinus excelsior L., Melia azadirach L., Morus alba L., Morus nigra L., Pistacia vera L., Prunus armeniaca L., Punica granatum L., Robinia pseudo acacia L., Rosa indica L. and Vitis vinifera L. grown in the urban (polluted site) and peri-urban (non-polluted) sites of Quetta. Results showed that all plant species exhibited significant (p<0.05) reduction at polluted site in their leaf length, width, area and petiole length when compared with the same plant species of non-polluted site. These plant species also showed significant variation in the growth of morphological parameters from season to season. Results also showed that the overall reduction % in leaf length, width, area and length of petiole during different seasons at polluted sites with respect to those of non-polluted sites were found maximum during summer (33.91, 36.61, 37.08 and 46.17 %), followed by autumn and lowest was recorded during spring season (28.39, 23.50. 32.49 and 26.34 %), respectively. Results also deciphered that minimum decrease in leaf length (19.86%), leaf width (17.81%), leaf area (22.66%) and petiole length (02.56%) was observed in Vitis vinefera L., Pistacia vera L., Ficus carica L. and Pistacia vera L. Whereas, maximum decrease 72.59, 50.58, 57.98 and 65.48% for the same attributes were noted in Punica granatum L., Elaeagnus angustifolia L., Rosa indica L. and Eucalyptus tereticornis L., respectively. Results further indicated that as the plants get ages, the reduction % of various leaf attributes of polluted plants also increased as compared with non-polluted plant species. This could be mainly due to maximum exposure of plants to air pollutants come from various auto emission sources.
