Response of growth and antioxidant protection system of Caragana korshinskii to oil-contaminated soil

This study aimed to investigate oil-contaminated tolerance and mechanism of Caragana korshinskii.Growth indexes,activities of superoxide dismutase(SOD),catalase(CAT),ascorbate peroxidase(APX) and glutathione reductase(GR) and contents of ascorbic acid(AsA),reduced glutathione(GSH),carotenoid(Car) and hydrogen peroxide (H2O2) of annual C.korshinskii seedlings were determined.Pot experiments with 5 treatments were arranged which included 0,5,10,15 and 20 g oil per kilogram of dry soil.The results showed that the effects of 5 g·kg-1 treatment on the growth of C.korshinskii were not significant.However,the treatment of 10~20 g·kg-1 significantly decreased the growth of C.korshinskii (P0.05).Under different treatments,SOD,GPX,GR,AsA and GSH played very important role in antioxidant protection for all of the treatments.However,the activity of CAT was inhibited for a long time and Car was obvious degradated.H2O2 accumulation under 5 and 10 g·kg-1 treatment were not significant different with control.H2O2 accumulated significantly under 15 and 20 g·kg-1 treatments.In general,during the whole period of oil contamination,the synergy between SOD and CAT weakened.Under high oil concentrations treatments (15 and 20 g·kg-1),the synergy of APX,GR,AsA and GSH strengthened,and Halliwell-AsAda cycle started efficiently.Oil-contaminated tolerance threshold of C.korshinskii might be 10 g·kg-1 treatments.