Abstract

This study evaluated the eco-physiological responses of Picralima nitida seedlings grown in soils contaminated with different concentrations of spent lubricating oil (SLO). Morphological, physiological, and biochemical parameters were assessed across five treatments (T1-T5) vis 0L/ha, 3736.67L/ha, 7473.33 L/ha, 11210L/ha, 14946.67L/ha of spent lubricating oil in soil (uncontaminated, low, average, high and very high contamination) respectively. One year old seedlings of Picralima nitida were transplanted into soils treated with varying volumes of spent lubricating oil SLO: two weeks after the introduction of spent lubricating oil. Results indicated numerical differences in seedling height, collar diameter, leaf area, and chlorophyll content, with the control (T1) generally showing superior performance. However, analysis of variance (ANOVA) revealed no statistically significant differences across treatments. Despite this, trends indicate that increased SLO contamination negatively impacted photosynthesis and biomass allocation, with higher root-to-shoot ratios and reduced chlorophyll content observed at higher pollution levels. The findings suggest moderate tolerance of P. nitida at low SLO concentrations, but limited phytoremediation potential under severe contamination.

Keywords: Picralima nitida, Eco-physiologcal performance, Chlorophyll content, Phytoremediation, Petroleum pollution