Impacts of spent oil on growth potential of fluted pumpkin (Telfairia occidentalis) and soil biota

Abstract

Pollution is a key factor impacting the distribution and abundance of plants in nature. It has led to differential selection of plants in various regions of the world. One major source of pollution in Nigeria is inappropriate disposal of spent engine oil. Spent engine oil is inappropriately disposed in all regions of Nigeria and this activity calls for concerns due to its impacts on plants and soil biota. Therefore, this study evaluated the impacts of spent engine oil on growth potential of fluted pumpkin (T. occidentalis) and soil biota. Five seeds of T. occidentalis were planted in three replicates in soil polluted with spent engine oil at different concentrations (0, 10, 30, 50, 70 and 90 mL/kg). Seed germination, number of leaves and leaf area, stem height, dry weight of leaf, stem and root of the different setups were examined at intervals. Also, number of earthworms in the soil at the beginning and end of the experiment were counted. Results showed that 100% germination was obtained in control, 10 mL/kg and 30 mL/kg spent oil treated-soil while germination was inhibited at different levelsin all other contaminated soil. Additionally, germination was delayed in 50 mL/kg, 70 mL/kg and 90 mL/kg spent oil treated-soil, while number of leaves, leaf area, stem height and dry weight were significantly lower P<0.05 at 50 mL/kg, 70 mL/kg, and 90 mL/kg spent oil treated-soil when compared with control. The number of earthworm was highest in the control and 10 mL/kg treatment followed by a significant reduction in their number with increasing concentration of spent oil. Heavy metals in the soils increased with increase in concentration of spent oil. Consequently, the study showed that soil contaminated with above 10 mL/kg spent engine oil hinders growth of T. occidentalis as well as normal activity of soil biota.