M.Z. Iqbal - Department of Botany, University of Karachi, Karachi-75270, Pakistan
M Athar - California Department of Food and Agriculture, 3288 Meadowview Road, Sacramento, CA 95832, USA

The effect of automobile pollution was determined on chlorophyll content of four different tree species viz. Azadirachta indica L., Conocarpus erectus L., Guiacum officinale L. and Eucalyptus sp. growing along the roads of the city. Significant changes in the level of chlorophyll a , chlorophyll b and total chlorophyll a+b were found in the leaves of four tree species (A. indica, C. erectus, G.officinale and Eucalyptus sp.) collected from polluted sites (Airport, Malir Halt, Quaidabad) as compared to control site (Karachi University Campus). Lowest concentration of chlorophyll a , chlorophyll b and chlorophyll a+b was recorded in the leaf samples of all tree species collected from Quaidabad site when compared with the leaf samples collected from control site. The highest levels of chlorophyll pigment were recorded in all tree species leave samples collected from Karachi University Campus. Similarly, betterlevels of chlorophyll a , chlorophyll b and total chlorophyll a+b was observed in all tree species growing at Airport site as compared to plants growing at Malir Halt and Quaidabad sites. This study clearly indicated that the vehicular activities induced air pollution problem and affected on the level of chlorophyll pigments in trees which were exposed to road side pollution.

Automobiles; Chlorophyll pigment content; Road side pollution; Urban trees