Abstract
Field experiments were carried out in 2007 and 2008 growing seasons at the Delta State University,
Asaba Campus Teaching and Research Farm to screen six cultivars of cowpea (IT80D- 699, IT82 (e-18),
IT84S- 2246- 4, TVx3236, IT90K–277-2 and IT870- 941- 1) for adaptation to soil contaminated with spent
engine oil. 0 (control), 25, 50, 75 and 100 ml of the oil served as the treatments. The experiment was
arranged in a randomized complete block design with four replications. The results showed that
cowpea cultivars grown in 25 ml of spent engine oil gave consistently significant higher (P 0.05)
values than the control and the other treatments (50, 75 and 100 ml) of the spent oil in terms of plant
height, leaf area, number of leaves, stem diameter, days to 50% flowering, number of nodes on main
stem, number of branches, and number and length of peduncles. The results also showed that as from
the 50 ml of oil application to soil, all the traits examined showed significant reductions (P ³ 0.05) when
compared to their controls, however, TVx3226 and IT84S – 2246-4 were higher in performance whereas,
IT890.699 and IT870- 941-, showed the lowest inhibitory effect. The study also showed a build up of
heavy metals in oil-impacted soil. The current study has demonstrated that spent engine oil has a
highly significant effect of reducing the growth characteristics of the six cultivars of cowpea examined
with the TVx3236 and the IT84S- 2246- 4 showing some levels of tolerance hence, they can be
recommended to farmers in oil impacted areas.
Key words: Screening, cowpea cultivars, adaptation, spent engine oil.
