Evaluation of plant growth performance in Bioremediated petroleum contaminated soil in Rivers State, Nigeria

This study was carried out using complete randomized design to evaluate growth performance of Telfairia occidentalis (pumpkin) in certified  bioremediated petroleum contaminated soils obtained from Ogoniland in Rivers State, Nigeria. Four soil samples- a pristine soil and three  bioremediated soils of different ages (6 months, 12 months, and 18 months after bioremediation) were collected and transferred into plastic  buckets for the study. The physico-chemical characteristics of the soil samples were determined before planting 9 seeds of Telfairia occidentalis in the various soil samples contained in the buckets. Thereafter, seedling emergence vigour and final seedling emergence were determined for each set up. Plant growth indices such as plant height, root length, stem girth, leaf area, and chlorophyll content were also monitored bi-weekly for a period of 12 weeks (3 months). Experiments were conducted in both dry and wet seasons. Results indicated the presence of residual total petroleum hydrocarbons (TPH) in three bioremediated soil samples albeit at varied concentrations. However, TPH concentrations in soils were lower than the Department of Petroleum Resources (DPR) intervention limit. Seedling emergence occurred 11 days after planting. Telfairia occidentalis grown on pristine soil had the highest final percent seedling emergence in the dry season whereas, seeds sown in 18m-AB soil showed the highest final percent seedling emergence during the wet season. There were significant differences in the growth performances of Telfairia occidentalis grown on pristine soil and bioremediated soils (p<0.05) as plant growth was considerably hindered in bioremediated soils in both seasons. Best Telfairia occidentalis growth performance was obtained on pristine soil followed by bioremediated soil that had been left fallow for 18 months after intervention. Data from this study suggest that bioremediated petroleum contaminated sites may not be suitable for crop production even months after intervention due to residual hydrocarbon contaminants in soil. Keywords: bioremediated soil, petroleum, pumpkin, plant performanc