Effects of petroleum contamination on some of physiological indexes of alfalfa

In order to understand the phytoremediation mechanism of alfalfa (Medicago sativa) in petoleum contaminated soil, a variety Yuedongzhixing of alfalfa and soil contaminated with varying petroleum concentration were used for pot experiments. Treatments of the experiments were included non contaminated soil (CL0), non contaminated soil with 2 500 (CL1)，5 000 (CL2) and 7 500 (CL3) mg/kg of petroleum, respectively. Results from this study showed that pertoleum contaminated soil inhibited alfalfa growth significantly; so that plant height, leaf numbers, the dry matter acucumulation of aerial parts and roots of alfalfa decreased significantly with increasing of petroleum contamination in soil compared with non contaminated soil. Soluble protein, starch and malondialdehyde (MDA) contents in leaves of alfalfa increased firstly at low petroleum contamination, and then decreased with the increasing of petroleum contamination in soil. The soluble protein content in leaves declined at petroleum contamination above 7 500 mg/kg in soil at very beginning. The starch and MDA contents reached the highest level with the petroleum contamination at 5 000 and 2 500 mg/kg in soil, respectively. Chlorophyll content in leaves of alfalfa treated with different concentration of petroleum increased differently compared with non contaminated soil.