研究了0~12 mg·L^-1羧基化多壁碳纳米管（MWCNTs-COOH）单一及其与10 μmol·L^-1镉（Cd）复合处理对水稻（Oryza sativa Linn.）品种‘Y两优900’（‘Y Liangyou 900’）幼苗叶片生理指标及H2O2定位的影响。结果表明：随着MWCNTs-COOH质量浓度提高，MWCNTs-COOH单一处理组水稻幼苗叶片叶绿素含量呈逐渐降低的趋势，超氧化物歧化酶（SOD）活性和过氧化物酶（POD）活性呈先升高后降低的趋势，丙二醛（MDA）含量和O2产生速率呈逐渐升高的趋势。6和3 mg·L^-1 MWCNTs-COOH单一处理组的SOD和POD活性分别达到最大值，显著高于0 mg·L-1 MWCNTs-COOH（CK1）组；1.5、3、6和12 mg·L^-1 MWCNTs-COOH单一处理组的MDA含量和O2产生速率均高于CK1组。随着MWCNTs-COOH质量浓度提高，MWCNTs-COOH-Cd复合处理组水稻幼苗叶片叶绿素含量和SOD活性呈逐渐降低的趋势，POD活性呈“降低—显著升高—降低”的趋势，MDA含量呈逐渐升高的趋势，O2产生速率呈先降低后升高的趋势。同一质量浓度MWCNTs-COOH-Cd复合处理组的叶绿素含量和SOD活性均低于MWCNTs-COOH单一处理组，而MDA含量和O2产生速率均高于MWCNTs-COOH单一处理组。12 mg·L^-1 MWCNTs-COOH-10 μmol·L^-1 Cd复合处理组水稻幼苗叶片褐色斑点面积最大、颜色最深。上述研究结果显示：高质量浓度MWCNTs-COOH单一和MWCNTs-COOH-Cd复合处理均对水稻幼苗叶片产生毒性效应，MWCNTs-COOH-Cd复合处理对水稻幼苗叶片具有明显的协同抑制效应，致使毒性显著增强。

 Effects of single carboxylated multi-walled carbon nanotubes （MWCNTs-COOH） at 0-12 mg·L^-1 and their combined treatments with 10 μmol·L^-1  cadmium （Cd） on physiological indexes and H2O2 localization of leaves of seedlings of cultivar ‘Y Liangyou 900’ of Oryza sativa Linn. were studied. The results show that with enhancing of mass concentration of MWCNTs-COOH， chlorophyll content in leaves of O. sativa seedlings decreases gradually， activities of superoxide dismutase （SOD） and peroxidase （POD） increase first and then decrease， while malondialdehyde （MDA） content and O2 generation rate increase gradually in single MWCNTs-COOH treatment group. Activities of SOD and POD in single treatment group of 6 and 3 mg·L^-1 MWCNTs-COOH reach the maximum value， respectively， which are significantly higher than those in 0 mg·L^-1 MWCNTs-COOH （CK1） group. MDA content and O2 generation rate are higher in single treatment group of 1.5， 3， 6 and 12 mg·L^-1 MWCNTs-COOH than in CK1 group. With enhancing of mass concentration of MWCNTs-COOH， chlorophyll content and SOD activity of leaves of O. sativa seedlings decrease gradually， POD activity appears the trend of “decreasing-increasing significantly-decreasing”， MDA content increases gradually， and O2 generation rate decreases first and then increases in combined MWCNTs-COOH-Cd treatment group. Chlorophyll content and SOD activity are lower and MDA content and O2 generation rate are higher in combined MWCNTs-COOH-Cd treatment groups than those in single MWCNTs-COOH treatment groups with the same mass concentration. The area of brown spots on leaves of O. sativa seedlings in combined treatment group of 12 mg·L-1 MWCNTs-COOH-10 μmol·L^-1 Cd is the largest， and its color is the deepest. It is indicated that both single MWCNTs-COOH and combined MWCNTs-COOH-Cd treatments with high mass concentration have toxic effects on leaves of O. sativa seedlings， and combined MWCNTs-COOH-Cd treatment has an obvious synergistic inhibitory effect on leaves of O. sativa seedlings， resulting in toxicity significantly enhancing.