印度芥菜和蜈蚣草对外源汞胁迫的生理生化响应

土壤汞污染是当前全球环境问题之一,研究植物对土壤中汞的吸收积累及生理生化响应特征,其结果对于贵州土壤汞污染治理具有重要意义.以印度芥菜和蜈蚣草为试验材料,研究施加不同浓度(0、0.5、5、15 mmol/L)外源汞(HgCl2)条件下,两种幼苗汞积累及生理生化响应特征.结果表明:外加0.5 mmol/L汞溶液培养7d后,印度芥菜的叶面积为1.91 cm2,显著高于其他处理;CAT活性和MDA含量随着处理汞浓度升高而升高,当外加15 mmol/L汞后,两者均达到最大值,此时植株地上部分汞含量也达到最大值11 537.8 mg/kg;相反SOD活性呈下降的趋势;在外加5、15 mmol/L汞溶液培养7d后,地上部分汞含量分别为10 141.8、11 537.8 mg/kg,显著高于CK,当培养延长至14d后,积累的汞含量相对培养7d后有所下降.对蜈蚣草而言,外加5 mmol/L汞培养7d后,地下鲜重显著增加;同时,地上部分汞含量达到最大值(1 241.870 mg/kg);延长培养时间后,地上和地下部分汞含量迅速增加;随着处理汞浓度和茎内汞含量的增加,CAT活性和SOD活性逐渐降低,而MDA在培养初期增加,后期降低.研究表明,印度芥菜和蜈蚣草可作为土壤汞污染的修复植物,印度芥菜地上吸收的汞高于蜈蚣草,但蜈蚣草更容易忍受土壤汞胁迫.

Physiological and biochemical responses to exogenous mercury stress in Brassica juncea and Eremochloa ciliaris

Soil polluted by mercury is one of the most important environmental problems in the world. The paper mainly studied the absorption and accumulation of mercury and physiological and biochemical responses characteristics for plants in the polluted soil located in mercury production areas in Guizhou province. Brassica juncea and Eremochloa ciliaris seedlings were planted in soil containing different concentration (0, 0.5, 5, 15mmol/L) mercury (HgCl2), and physiological and biochemical responses characteristics and mercury accumulation of them were investigated. For B. juncea, the leaf area was 1.91 cm2 at 0.5 mmol/L of Hg for 7 days and was significantly higher than other treatments. CAT activities and MDA contents increased and SOD activities decreased with the increase of mercury concentration in the soil and the highest value of CAT and MDA was observed at 15 mmol/L of Hg. Meanwhile, mercury contents were the highest in the aerial parts (11 537.8 mg/kg). After 7 days of treatment at 5 and 15 mmol/L of Hg, mercury content in the aerial parts were 10 141.8 mg/kg and 11 537.8 mg/kg, respectively, were significantly higher than those of other treatments. When the treated time were delayed for 14 days, mercury content accumulated in the plants were lower than that for 7 days. For E. ciliaris, fresh weight in underground part increased significantly for 7 days at 5 mmol/L of Hg. At the same time,mercury content in aerial part had the highest value (1 241.870 mg/kg). Mercury content increased rapidly with delaying of cultural time. CAT and SOD activities decreased with the increase of mercury concentration in soil. MDA content increased at the beginning of treatment and declined later. B.juncea and E. ciliaris could be recommended as a plant to remediate polluted soil located in Guizhou province.The accumulated mercury of aerial part in B. juncea was higher than that in E. ciliaris. While E. ciliaris had more tolerance to mercury stress.