【摘要】 探究在石灰性土壤中施用硅（Si）和硒（Se）对镉（Cd）胁迫下黄瓜幼苗光合作用和抗氧化酶系统的影响，为Si和Se在缓解Cd毒性方面的应用提供理论依据。采用盆栽试验，研究在Cd(5 mg/kg)胁迫下，单独或同时施用Si(300 mg/kg)、Se(2、4 mg/kg)对黄瓜幼苗生长、叶绿素含量、光合参数及抗氧化酶活性的影响。结果表明，Cd胁迫对黄瓜幼苗植株的生长、叶片光合作用以及抗氧化系统产生了明显的毒害作用。与空白对照相比，Cd处理下黄瓜叶片叶绿素含量、净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）显著降低，胞间CO2浓度（Ci）显著升高，过氧化物酶（POD）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性显著降低，丙二醛（MDA）含量显著增加。施用300 mg/kg Si或2、4 mg/kg Se均能有效缓解Cd毒害，促进黄瓜生长，显著提高黄瓜叶片叶绿素含量、Pn、Tr、Gs以及POD、SOD、CAT活性，降低Ci、MDA含量。同时施用Si和Se的作用效果比单施Si或Se更明显，施用300 mg/kg Si和2 mg/kg Se时作用效果最好，与单施Cd相比，黄瓜叶片Pn、Tr、Gs显著增加18.53%、42.67%、87.50%,Ci显著降低35.61%,POD、SOD、CAT活性显著提高87.65%、32.40%、23.58%,MDA含量显著降低42.68%。表明在石灰性土壤中施用Si和Se可有效缓解Cd对黄瓜的毒害，增强黄瓜叶片光合作用，提高抗氧化酶系统活性，且Si和Se同时施用具有一定的协同作用。更多还原

【Abstract】 To explore the effects of silicon(Si)and selenium(Se)on photosynthesis and antioxidant enzyme system of cucumber seedlings under cadmium(Cd)stress in calcareous soil,and provide a theoretical basis for the application of Si and Se in alleviating Cd toxicity,pot experiment was conducted to study the effects of single or simultaneous application of Si(300 mg/kg)and Se(2,4 mg/kg)on cucumber seedling growth,chlorophyll content,photosynthetic parameters and antioxidant enzyme activity under Cd(5 mg/kg)stress. The results showed that Cd stress had obvious toxic effects on plant growth,leaf photosynthesis and antioxidant enzyme activities in cucumber seedlings. Compared with blank control,the chlorophyll content,net photosynthetic rate(Pn),transpiration rate(Tr) and stomatal conductance(Gs)of cucumber leaves under Cd treatment were decreased significantly,the intercellular carbon dioxide concentration(Ci)increased significantly,the activities of peroxidase(POD),superoxide dismutase(SOD) and catalase(CAT) decreased significantly,while the content of malongizldehyde(MDA)increased significantly. Cd toxicity was alleviated under the application of 300 mg/kg Si or 2,4mg/kg Se,which could promote the growth of cucumber,increase the chlorophyll content and Pn,Tr,Gs and POD,SOD,CAT activities of cucumber leaves,and reduce the Ci and MDA content. The effect of simultaneous application of Si and Se was more obvious than that of single application of Si or Se,and the application of 300 mg/kg Si and 2 mg/kg Se had the best effect. Compared with single application of Cd,Pn,Tr and Gs of cucumber leaves significantly increased by 18. 53%,42. 67% and 87. 50%,respectively,Ci significantly decreased by 35. 61%,POD,SOD and CAT activities significantly increased by 87. 65%,32. 40% and 23. 58%,respectively,and MDA content significantly decreased by 42. 68%.The results show that applying Si and Se in calcareous soil can alleviate the toxicity of Cd to cucumber,enhance the photosynthesis of cucumber leaves and improve the activity of antioxidant enzyme system,and the simultaneous application of Si and Se has a certain synergistic effect.更多还原