Morphological Responses of Chromolaena odorata, Axonopus compressus and Aspilia africana Grown in Used Engine Oil Polluted Soil

Background and Objective:The resultant effect of indiscriminate disposal of spent engine oil is a trending issue in most developing countries of the world.Contamination of agricultural soil by spent engine oil may alter soil physicochemistry and subsequently reduce crop production.The study was carried out to ascertain the morphological responses of Chromolaena odorata, Axonopus compressus and Aspilia africana grown in used engine polluted oil-polluted soil.Materials and Methods: Equal volume of pre-sieved soil (20 kg) was filled in polythene bags and arranged at 0.5 m spacing between polybags and 1 m between replications and perforated at the base to avoid water logging.Concentrations of spent engine oil spiked included 0, 4, 8, 12 and 16% (v/w) and which was allowed to stabilize for 2 weeks to simulate the condition of a natural spill.Parameters recorded at 2 weeks intervals were: Plant height, number of leaves per plant, fresh weight and root number.Results: A dose-dependent decrease in plant height, number of leaves per plant, fresh weight and root number.The mean growth parameters of the control (0%) were significantly higher than that of plants exposed with 4, 8, 12 and 16% concentration of spent engine oil at p<0.05%.The trend in a marked reduction of growth parameters was as follows: A. compressus > C. odorata > A. africana.Conclusion: Although spent engine oil affected the growth parameters measured, the plant species were able to tolerate and grow in various concentrations.This underscores the need to further probe Chromolaena odorata, Axonopus compressus and Aspilia africana as possible plant species for remediation of used engine oil-polluted soil in the tropics.