INVERSTIGATION INTO THE EFFECTS OF AUTOMOBILE POLLUTANTS ON GROWTH AND METAL CONTENTS OF SOME ROADSIDE PLANTS

The phenology of Astonia scholaris, Pongamia pinnata, Cassia siamea and peltophorum pterocarpum was significantly (p<0.05) affected in the Karachi city polluted environment. Plants were more affected to pollutants at Gulshan-e-Iqbal, Nazimabad, Shahrah-e-Faisal and M.A Jinnah Roadm as compared to Karachi University Campus. Leaf length, width and area of A. Scholaris were found lowest in summer at M.A Jinnah Road, as compared to Shahrah-e-Faisal, Nazimabad, Gulshan-e-Iqbal and Karachi University Campus, respectively. Leaf length and area of P. pinnata were Significantly (p<0.05) reduced in autumn at the highly polluted sites of M.A Jinnah Road as compared to Karachi University Campus. Leaf width and area of C.siamea were significantly (P<0.05) reduced in autumn at the highly polluted sites of M.A Jinnah Road, as compared to Karachi University Campus. Leaf length of P. pterocarpum was also found significantly (P<0.05) reduced at M.A Jannah Road in winter as compared to other less polluted sites of the city.\ud \ud Autoemission showed toxic effect on seed germination and seedling growth of plants. The seeds of P.Ptercarpum and C. siamea collected from the trees growing along the busy roads of the city showed low percentage of germination. Seedling dry weight of the plants also decreased significantly (P0.05). In pot experiments, the seed germination and seedling growth of C. siamea was badly affected in seeds collected from the polluted areas of the city as compared to Karachi University Campus.\ud \ud Lead and cadmium treatment produced toxic effects on seed germination and seedling growth of Peltophorum pterocarpum and Leucaenal leucocephala. Root length of L leucocephala and P. pterocarpum was significantly (P<0.05) reduced at 50 ppm treatment of lead. The treatment of Pb at 25 ppm suppressed the seedling dry weight of P. pterocarpum. Cadmium treatment of 50 ppm produced significant (p