Physiological responses of photosynthetic and respiratory rates of some leafy vegetables to Spent engine oil contamination

Abstract

Indiscriminate disposal of Spent engine oil (SEO) is a threat to food security in Nigeria. Therefore, this study evaluated effects of SEO on photosynthetic and respiratory rates of Telfairia occidentalis, Corchorus olitorius and Amaranthus hybridus leaves. The experiment was laid using a complete randomized design with five replicates. The vegetables were sprayed with 20, 40, 60, 80 and 100 mgL-1 SEO. Water served as control. Respiratory and photosynthetic rates of leaves of the vegetables were determined 2, 3, 4, 5 and 6 weeks after treatments. Data were analyzed using Statistical Analysis System. Means were separated using Duncan’s Multiple Range Test at 5%. Respiratory rates (6.3 x10-5) were significantly higher (p<0.05) in T. occidentalis treated with 100 mg L-1 compared with lower concentrations of the SEO. Also, significant reduction (6.9 x10-5) was recorded in the photosynthetic rates of T. occidentalis treated with 100 mg L-1 while photosynthetic rate (11.4 x10-5) of T. occidentalis showed significant increase. Furthermore, 100 mg L-1 produced significant increase (5.6 x10-5) in the respiratory rates of C. olitorius while photosynthetic rate (5.7 x10-5) showed significant decrease in C. olitorius treated with lower concentrations of the oil. Respiratory rate (7.7 x10-5) showed significant increase in A. hybridus treated with 100 mg L-1 while photosynthetic rate of the vegetables treated with 100 mg L-1 SEO revealed significant reduction (5.1 x10-5). In conclusion 100 mg L-1 SEO had negative effects on respiration and photosynthetic rates of leaves of vegetables therefore the vegetables should not be cultivated in oil contaminated land area.