Growth and mitotic chromosomes of soybean (Glycine max L. Merril) plants as affected by spent engine oil in sandy-loam soils

Soybean (Glycine max L. Merril) is one of the most nutritionally valuable legumes in Africa. However, spent automobile engine oil is always  disposed indiscriminately on lands and water bodies in Nigeria, which pollutes both terrestrial and aquatic ecosystems, with adverse  effects on crop growth and productivity. This study investigated the effects of spent engine oil (SEO) polluted soils on growth parameters  and mitotic chromosomes of soybean. Two soybean varieties (TGX-1448-2E and local) were planted in pots filled with sandy-loam soil treated with 0, 0.1, 0.4 and 0.7% v/w SEO concentrations, in 2 × 4 factorial experiment laid in a completely randomized design with six  replications. Data were collected at weekly intervals for four weeks on growth parameters (plant height, number of leaves, leaf width and  leaf length) and chromosomal aberration. Data were subjected to ANOVA and means separated with LSD. Among the treatments, seed  germination rate was significantly higher in TGX-1448-2E (95.0 ± 0.0-96.0 ± 0.7%) than local variety (70.0 ± 0.7-71.0 ± 0.7%). Both 0.4 and  0.7% SEO caused significant (p ≤ 0.01) reductions in plant height, number of leaves, leaf length and leaf width whereas, 0.1% did not  reduce growth parameters. Treatments 0.4 and 0.7% SEO caused high chromosomal aberrations in soybean as they reduced  chromosome numbers (from 40.0 to 23%), cell division, mitotic index (70.0 to 20.8%) and produced 31.7% abnormal cells. Abnormalities  such as bridges, laggards and chromosome stickiness occurred. This study shows that 0.4-0.7% SEO polluted soils is phytotoxic to  soybeans.