Effect of Petroleum Crude Oil on Mineral Nutrient Elements, Soil Properties and Bacterial Biomass of the Rhizosphere of Jojoba (Simmondsia chinensis Link C.K. Schneid.)

This study elevated the effect of petroleum crude oil contaminated soil on the nutrient elements, soil
properties and bacterial biomass of the rhizosphere of Jojoba (Simmondsia chinensis Link C.K.
Schneid). Malondialdehyde (MDA) concentration increased in jojoba leaves when grown in petroleum
oil polluted soil especially at 2% and 3% crude oil. It was noted that, Na, Mg and Ca decreased while
K increased in shoots of jojoba. In roots Na and Ca increased however K and Mg decreased with
increasing crude oil concentration in the soil. Heavy metals, Cu, Mn, Cd and Pb increased in both
shoot and root with increasing crude oil concentration while, Zn decreased comparing with the control.
In soil, N and K decreased meanwhile Cu, Fe, Mn and Zn as well as organic matter increased with
increasing crude oil concentration. Soil was free from P while, the addition of inorganic fertilizers
improved P content. Bacterial account was significantly increased at the end of the experiment at 1%
and 2% crude oil especially after addition of inorganic fertilizers. The electric conductivity and MDA of
the leaves increased with increasing crude oil concentration. The addition of inorganic fertilizers to
crude oil contaminated soil decreased the electric conductivity and MDA comparing with crude oil
only. The observed changes in composition of mineral elements in jojoba plants in the present study
could be attributed to the cell injury and disruption in the cell membrane, heavy metal accumulation
and toxic nature of the petroleum oil. Also this study has demonstrated that soil contamination with
crude oil has a highly significant effect of reducing some mineral element composition of Jojoba
plants.