Influence of a mycorrhizal fungus and mineral fertilizer on the performance of Costus lucanusianus under crude oil contaminated soil

Abstract

Considering the detrimental effects of crude oil pollution on plants, and its implications on food security and environmental safety, it becomes imperative to screen for plants with strong tolerance to crude oil contaminated soil. This study was conducted to assess the influence of arbuscular mycorrhizal fungus (AM) and a mineral fertilizer (NPK 15 15 15 grade), on the performance of African spiral ginger (Costus lucanusianus) plant, under crude oil contaminated soil. About 10 kg of sterilized soil was contaminated with Bonny light crude oil at different concentrations of; 0, 200, 300 and 500 ml/ pot. Moreover, a fertilizer (i.e. NPK) was applied at three different levels (0, 0.7 and 1.2 g/ pot) to the crude oil contaminated soil in the pots, and then inoculated with arbuscular mycorrhizal (AM) fungus; consisting of 20 g of Glomus clarum. After that, Costus lucanusianus was planted in the pot soil by stem cuttings. Results of this greenhouse assay involving; the residual total petroleum hydrocarbon (TPH) content of the soil, plant height, number of leaves, fresh and dry weights, percent of mycorrhizal root colonization, and fungal total colony count, were collected at 4, 8 and 12 weeks after planting (WAP). Current results showed that mycorrhizal inoculation and fertilizer application enhanced the tolerance and growth of C. lucanusianus plant to the crude oil contaminated soil. Mycorrhizal inoculation and NPK fertilizer application at 1.2 g/ pot recorded higher and significantly (p <0.05) different plant height, number of leaves, fresh and dry weights of C. lucanusianus. The TPH degradation and removal was higher in soil inoculated with AM, compared to non AM inoculated control treatments. Similarly, NPK fertilizer application also resulted in lower residual TPH content in the crude oil contaminated soil, compared to the control. Combined AM colonization and NPK fertilizer application resulted in improved physiological parameters of the C. lucanusianus plant.