PHYTOREMEDIATION POTENTIALS OF PENNISETUM PURPUREUM AND Leuceana Leucocephala AMENDED WITH ORGANO-MINERAL FERTILIZER AND BRASSINOLIDE FOR SELECTED HEAVY METALS REMOVAL FROM CRUDE OIL CONTAMINATED SOIL

Soil and water pollution due to oil exploration activities has become a key environmental challenge in Nigeria’s Niger Delta region. Phytoremediation is an environmentally friendly approach in managing soil pollution. This study aimed to evaluate the potential of some native plant species for phytoremediation of heavy metals in crude oil-polluted soils. Two native plant species (Pennisetum purpureum and Leuceana leucocephala were studied under field condition with four levels of crude oil pollution (0, 2.5, 5.0 and 7.5 % (w/w), organo-mineral fertilizer (5 t/ha) and Brassinolide (250 ml per plant) using a Randomized Complete Block Design with three replications. Results obtained showed that there was a significant (p<0.05) increased in the absorption of heavy metals by the plants after 6 months of pollution. The plants partitioned more heavy metals (Pb, Ni, Cd) to the roots and stem than the leaf. Pennisetum purpureum had the highest absorption efficiency of 79.8 %, followed by Leaceana leucocephala (61.0 %), against (41.0 %) in non-amended soils and (38.6 %) in non-vegetated soil. The possible reasons for the high uptake of heavy metals by these two plants were due to such mechanisms as phytoextraction (metal accumulation in plants), application of organomineral fertilizer and brassinolide increased metal mobility in the soil, thus facilitating the remediation by both plants. Therefore, P. purpureum and L. leucocephala have good potential to bi-accumulate heavy metals from crude oil-polluted soils and are recommended.