膨润土对镉胁迫下水稻幼苗生理生化特性的影响

摘要

A pot experiment was conducted to explore effects of bentonite on physiological and biochemical characteristics , such as chlorophyll content, shoot biomass, SOD and POD activities, and MDA content of rice seedlings growing in Cd contaminated soil. Results show that the amendment of bentonite increased the content of chlorophyll in leaves of the rice seedlings and promoted growth and development of the seedlings. The dry biomass of rice shoots increased with rising bentonite application rate. In the soil contaminated only with Cd, SOD activity remained almost unchanged in leaves of the rice seedlings, but did significantly in roots of the plants, SOD lowered with rising Cd concentration in the soil ( P < 0. 05 ) , and application of bentonite increased SOD activity in the roots as a whole. However, POD activities in leaves and roots of the plants rose sharply first and then declined with the increase in Cd concentration in the soil treated only with Cd. Application of bentonite reduced POD activity in leaves of the plants. However, the application of 5 -50 g · kg bentonite significantly increased POD activity in roots of the rice seedlings, by 13.2% - 22.4% , 4.9% - 9.5% , 44. 8% -80. 6% , and 6.9% -49. 6% , respectively, over that in the control. MDA contents in leaves and roots of the plants rose with rising Cd concentration and were 139. 0% and 158. 1% higher, respectively than that in control. Application of bentonite significantly lowered MDA contents in the rice, and weakened the effect of membrane lipid peroxidation. To sum up, application of bentonite can effectively alleviate Cd toxicity to rice seedlings, thus it can be used as an approach to the remediation of Cd contaminated soils.%为了探讨膨润土钝化修复镉(Cd)污染土壤对水稻幼苗生理生化特性的响应,通过盆栽试验研究了膨润土对Cd胁迫下水稻幼苗地上部生物量,叶片叶绿素含量,SOD、POD活性以及MDA含量的影响.结果表明,膨润土在不同程度上提高了水稻幼苗叶片叶绿素含量,促进了水稻幼苗的生长和发育,地上部生物量随膨润土投加量的增加而增大.单一Cd污染土壤中,水稻幼苗叶片SOD活性变化不明显,而幼苗根系SOD活性随Cd浓度的增加而显著降低(P＜0.05),投加膨润土后整体上提高了根系SOD活性.单一Cd污染土壤中,水稻幼苗叶片和根系POD活性随Cd浓度的增加而均呈现先应激性升高然后降低的变化趋势,投加膨润土后叶片POD活性有所降低,而5 ～50 g·kg-1膨润土处理显著提高根系POD活性(P＜0.05),比未投加膨润土处理分别增加13.2％ ～22.4％、4.9％ ～9.5％、44.8％～80.6％和6.9％～49.6％.单一Cd污染土壤中,水稻幼苗叶片和根系MDA含量随着Cd浓度的升高而升高,与无Cd胁迫对照相比,分别增加139.0％和158.1％；投加膨润土处理水稻幼苗MDA含量显著降低,膜脂过氧化作用明显减弱.因此,膨润土能有效缓解Cd胁迫对水稻幼苗的毒害作用,可用于Cd污染土壤的钝化修复.