ASSESSMENT OF PHYTOTOXIC EFFECT OF SPENT ENGINE OIL ON GERMINATION AND EARLY SEEDLING GROWTH OF SOME LEGUMES IN IMO STATE, SOUTHEASTERN NIGERIA.Author(s): JOHNPAUL AZORJI
Seed germination is considered the most crucial stage for seedling development, growth and yield of plant species and success at this stage is dependent on nutrient status of the growth medium. This study was carried out to assess the toxicity of spent engine oil on six leguminous plant species (TVu-10343, TVu-10366, TVu-13606, TGm-504, TGm-570 and TGm-547) under laboratory condition. Bioassay endpoints used were final germination percentage (FGP), germination index (GI), seedling vigour index (SVI), shoot and root lengths, fresh and dry weights in the phytotoxic assessment with 0%(control), 3%, 6% and 9% spent engine oil and monitored for 14 days after sowing (DAS). The experiment was arranged in a completely randomized design with three replicates each. The analyzed data showed that all the parameters assayed were significantly (p<0.05) different among the accessions which was dose dependent. Significant difference (p<0.05) was also observed in the rates at which the different plant speciessurvived in the different treatments. The inhibitory effect of the contaminant increased with increase in contaminant level relative to the control. Pearson correlation analysis revealed positive and highly significant association among final germination percentage, germination index, seedling vigour index, shoot and root lengths, and fresh and dry weights respectively. The Pearsonâ€™s correlation analysis revealed positive and significant association among final germination percentage, shoot and root length and shoot and root weight respectively. The correlation between FGP and GI; FGP and SVI were significantly negative (r = -0.134; -0.371 (P < 0.001) indicating that the germination index and seedling vigor index were delayed with decrease in germination percentage. Although all the varieties showed appreciable level of tolerance to the various levels of spent engine oil, ranking of the accessions based on tolerance to contaminant level were: TVu-10366>TVu-10343>TGM-504>TVu-13605>TGM-570>TGM547.VarietiesTVu-10366, TVu-10343 and TGM-504are recommended to be used in the reclamation of spent engine polluted sites.