SPENT ENGINE OIL MEDIATED OXIDATIVE STRESS IN COWPEA (Vigna unguiculata) SEEDLINGS

Spent engine oil mediated oxidative stress in cowpea ( V unguiculata (L) Walp ) seedlings was studied. The results indicated that exposure spent engine oil caused a significant ( P< 0.05 ) increase in xanthine oxidase activitiy in the leaves of 8 day old cowpea seedling at 0.25%,0.5% 1.5% and 2.0% oil in soil relative to control. Similarly, there was a significant ( P <0.05 ) increase in the activity of the enzyme at 0.25% 0.5% 1.0%, 1.5% and 2.0% compare to the control in the stem of 12day old seedling. Moreover, a non uniform response was observed for the activity of catalase in the leaves of 8 day old seedlings. There was a significant decrease (P < 0.05) in the activity of catalase at 0.5%, 1.5% and 2.0% relative to the control. This is against the significant ( P < 0.05) increase in the activity of the enzyme at 1.0% oil in soil. On the whole, the data presented seem to suggest that exposure to spent engine oil can induce oxidative stress in plants.