|Keywords (Extracted from title, table of contents and abstract of thesis)
soil of industrial areas, plants, korangi, landhi, vegetation, abutilon, amaranthus-prosopis, salsola, abutilon indicum, corchorus trilocularis, corchorus, prosopis juliflora, heavy metals
Phytosociological studies were carried in the vicinity of Korangi and Landhi industrial areas of Karachi. The vegetation was herbaceous, shrubs and predominantly disturbed in nature. Fifteen plant communities based on the composition, structure and distribution of species were recognized. Highest number of species was recorded in Abutilon and Amaranthus-Prosopis communities whereas, Salsola community had lowest number of species. Importance value index of all the species were calculated and eleven leading dominant species were recognized in the study area. Abutilon indicum, Corchorus trilocularis, Corchorus depress us and Prosopis juliflora were found in most of the communities. Abutilon indicum had strong association with Corchorus spp, Prosopis juliflora and Tribulus terrestris while, P. juliflora was the most dominant species at Karachi University.
A relationship between soil characteristics and plant communities of the industrial areas of Korangi and Landhi was studied. In most of the plant communities, coarse sand (41%), water holding capacity (29%), organic matter (1.5%), soluble salts (9.9%), and available sulfate (279 µg-g) were moderate while, the level of pH (8.2) and CaC03 (21.7%) were high. The soil had moderate amount of ferric (7.062 µg-g) , copper (1.062 µg-g) and zinc (1.031 µg-g) in most of the plant communities whereas, lead (0.016 µg-g) and chromium (0.664 µg-g) were low. In most of the dominant species, the soil characters were similar, as mentioned in the plant communities.
Highest amount of coarse sand (88%), calcium carbonate (36.5%) and chromium (6.899 µg-g) were found in soil of One Tech Rubber Factory whereas, water holding capacity (40%), available sulfate (608 µg-g) and copper (0.074 µg-g) were high in soil of One Tech Ply Board Factory as compared to other soil types. Khan Towel Factory and Tanveer Garment Factory soils had comparatively higher soluble salts (14.0%) and zinc (0.090 µg-g) , respectively, than other soil types.
In seed germination and plant growth experiments, some of the species like Albizia lebbeck (L.) Benth., Leucaena leucocephala (Lam.) de-Wit, Thespesia populnea (L.) Soland. ex Correa, Peltophorum pterocarpum (DC.) Baker ex K. Heyne., Azadirachta indica (L.) A. Juss. and Prosopis juliflora Swartz were chosen. Many growth variables of A. lebbeck were reduced in soil extract of One Tech Rubber Factory whereas, the growth of P. juliflora (Karachi University seeds) was decreased in soil extract of One Tech Ply Board Factory. Tanveer Garment Factory soil extract caused reduction in many growth variables of L. leucocephala and T. populnea as compared to other soil extracts.
A. lebbeck and P. pterocarpum were also grown in soils of different industries. The growth of these plants was reduced in soil of One Tech Rubber Factory than other soils whereas, Tanveer Garment Factory soil caused reduction in many growth variables of L. leucocephala than other soil types. A. indica and P. juliflora (Karachi University seeds) were greatly reduced in soil of Khan Towel Factory as compared to other soils. The growth was enhanced in L. leucocephala, T. populnea, P. pterocarpum, A. indica and P. juliflora (Korangi and Landhi industrial areas seeds) in soil of One Tech Ply Board Factory than other soils. 75% soils of Khan Towel and One Tech Ply Board Factories caused reduction in the growth of A. lebbeck as compared to 25 and 50% factories soils. While, the growth of L. leucocephala was reduced in 75% soil of Khan Towel Factory and 50% soils of other factories.
Highest amount of ferric (66.427 µg-g) and copper (0.211 µg-g) were recorded in plants of L. leucocephala when grown in soil of One Tech Rubber Factory as compared to other soils. While, comparatively higher amount of . chromium (0.015 µg-g) was found in L. leucocephala when grown in soil of One Tech Ply Board Factory than other soil types. The foliage of P. juliflora accumulated high amounts of ferric (1.348 µg-g) and copper (0.017 µg-g) at Tanveer Garment Factory. Ferric (1.440 µg-g) and lead (0.015 µg-g) were high in the foliage of A. indicum at Tanveer Garment Factory. The level of zinc (0.018 µg-g) and chromium (0.212 µg-g) were highest in the foliage of A. indicum whereas, the level of copper (0.083 µg-g) and chromium (9.893 µg-g) were highest in the foliage of S. holosericea at Khan Towel Factory. High levels of ferric (1.718 µg-g) and lead (0.088 µg-g) were accumulated in S. holosericea at One Tech Ply Board Factory than other sites.
In this investigation, it is concluded that the soil of the industrial areas of Korangi and Landhi is injurious for plant growth. However, if soils of industrial areas are mixed with garden soil, the plants showed enhancement in their growth form.