Impact of crude oil-polluted soil on germination and development of Abelmoschus caillei (A. Chev.) Stevels seedlings

Abstract

Crude oil pollution poses a major problem in many countries of the world, especially in oil-rich nations where it negatively impacts agricultural production. Abelmoschus caillei (A. Chev.) Stevels (West African okra), a vital vegetable prized for its high fibre and mineral contents, is widely cultivated in oil-producing regions of Nigeria, yet its response to crude oil-contaminated soil remains poorly understood. The present study examines the effects of crude oil-polluted soil on the germination and seedling development in West African okra, Abelmoschus caillei (A. Chev.) Stevels. Five crude oil-contaminated soil treatments denoted as T₁, T₂, T₃, T₄ and T₅ (with 0.1%, 0.5%, 1.0%, 2.5% and 5% v/w crude oil to dried sandy-loam soil) and uncontaminated (control) soil were set up, with each replicated three times. Ten viable seeds of A. caillei were planted into the treatment pots in a screen house and observed for germination, growth, chlorophyll content, and biomass of the seedlings. The results showed that seedling emergences started at 6 days after sowing in the crude oil treatments and the control, but the % germination decreased in T₂ to T₅ (with <0.5% crude oil) by 3.3-13.7%. Plant height was markedly reduced under high contamination, with T₅ having the least at 2 WAS (4.00 cm) and 4 WAS (6.76 cm) compared with the control (12.08 cm). Leaf production declined from 3.42 in T₁ to 2.16 in T₅. Chlorophyll a decreased significantly in T₅ (6.85 mg g⁻¹) from T₁ (10.87 mg g⁻¹). Fresh weight was significantly highest in T₁ (7.39 g) and lowest in T₅ (3.01 g). Overall, crude oil contamination adversely affected the germination, growth and pigment development of A. caillei, although mild contamination elicited a transient stimulatory response.