Effect of Different Crude Oil Fractions on Growth and Oxidative Stress Parameters of Maize Radicle

Abstract

This study investigated the effect of different crude oil fractions (whole crude WC, water soluble fraction WSF, water insoluble fraction WIF and soil from a crude oil contaminated site, Ubeji) at different percentages of soil contamination (2, 5 and 10%) on growth (percentage seedling emergence, plant height, leaf number, leaf area, root length and radicle length) and oxidative stress (catalase (CAT), superoxide dismutase (SOD), peroxidase (POX) and malondialdehyde (MDA) concentrations) parameters in maize radicle. A total of 330 bags containing 500g of soil were used for this study. 30 bags containing sandy loam soil served as control, 270 bags of sandy loam soil were mixed with different crude oil fractions to give 2%, 5% and 10% contamination, while 30 bags containing 500g of soil were collected from a crude oil contaminated site in Ubeji, south-south, Nigeria. The maize grown in these soils was harvested after 7, 14 and 21 days of seedling emergence and assessed for growth and oxidative stress parameters. Descriptive statistics and analysis of variance were employed to statistically analyse data that were obtained. The growth parameters in maize, including percentage seedling emergence, leaf number, leaf area, root length etc, significantly (P<.01) reduced as percentage contamination increased. Maize grown in soil contaminated with 10% WIF and the Ubeji soil produced the greatest reduction in growth parameters. Oxidative stress assessed by measuring maize radicle CAT, SOD, POX and MDA levels, revealed a percentage contamination dependent alteration of these parameters implying the presence of oxidative stress. The results of this study have again shown the deleterious effects of crude oil contamination on plant growth. Efforts to intensify effective cleanup of crude oil contaminated sites must be given top priority.