土壤石油污染下柠条生长反应与抗氧化保护响应

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

为探讨柠条（Caragana korshinskii）对石油污染的耐受性及耐受机制,采用盆栽试验,于2012年7-9月测定了不同浓度石油污染（0、5、10、15和20g·kg-1,原油·干土-1）土壤中一年生柠条幼苗的生长指标、抗氧化指标及过氧化氢（H2O2）含量的动态变化。结果表明,石油浓度为5g·kg-1时,对柠条生长影响不显著,10-20g·kg-1时抑制柠条生长;超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、谷胱甘肽还原酶（GR）、抗坏血酸（AsA）和还原型谷胱甘肽（GSH）在土壤石油污染胁迫下发挥了重要的抗氧化保护作用,而过氧化物酶（CAT）活性长时间受抑制,类胡萝卜素（Car）也表现出明显的降解现象;石油浓度为5和10g·kg-1时,H2O2无显著积累,15和20g·kg-1时H2O2积累。总体上,整个土壤石油胁迫期间,SOD与CAT协同作用被削弱;石油在较高浓度（15和20g·kg-1）,APX、GR、AsA与GSH协同作用表现突出,Halliwell-AsAda循环高效启动;10g·kg-1浓度应是柠条对土壤石油污染的耐受阈值。

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 aseorbic 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 （P〈0.05）. 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· treatment were not significant different with control. H202 accumulated significantly under 15 and 20 g · kg· treatments. Ingeneral, 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.