木薯和花生间作对Cd吸收及根区速效养分的影响

木薯（Manihot esculenta Crantz）是热带和亚热带广泛种植的大生物量能源植物，在污染土壤上具有较强的生物修复潜力，花生（Arachis hypogaea）对土壤Cd具有很强的富集能力.木薯与花生间作可充分利用光热水资源，具有良好的间作优势，是近年来我国南方红壤坡耕地生态种植模式.为了解木薯与花生间作对土壤Cd吸收及根区速效养分的影响，在重金属Cd污染的小区进行了木薯单作、花生单作、木薯与花生间作的比较试验.结果表明，木薯与花生间作的产量土地当量比（LER）大于1，土地利用率提高了87.0%.与木薯单作相比，间作下木薯茎和叶w（Cd）分别降低了12.24%和19.51%，二者呈显著性差异（P < 0.05），花生籽粒w（Cd）降低了35.38%，与单作花生差异显著（P < 0.05）.与单作下木薯和花生相比，花生、木薯总富集系数分别降低了16.32%、12.45%，间作系统对每hm2土地上Cd的富集量分别提高了10.72%、113.76%；间作下花生根区土壤w（速效氮）、w（速效磷）分别提高了18.85%、20.36%，木薯根区土壤w（速效氮）提高了21.00%，与单作下花生和木薯相比均呈显著性差异（P < 0.05）.研究显示，木薯与花生间作可提高土壤根区速效养分含量，促进作物生长，在提高作物生物量、降低作物各部位单位Cd含量的同时，可提高间作系统对土壤Cd的富集量，这种间作方式对实现两种能源植物生态修复及经济效益的整合具有重要意义. 

Effects of Cassava-Peanut Intercropping on the Absorption of Cadmium and Available Nutrient in Rhizosphere Soil

Cassava (Manihot esculenta Crantz) is an energy plant with large biomass and has great potential in bioremediation of contaminated soil. It is widely cultivated in the tropical and subtropical regions. Peanut (Arachis hypogaea) has great capability for enrichment of Cd in soil. The intercropping of cassava and peanut is a popular farming pattern in the slope land of southern China. It can make better use of light, heat as well as water resources, and hence have higher land use efficiency and higher yield. In order to understand its effects on absorption of Cd and on available nutrient in rhizosphere soil, three planting treatments were carried out in the field plot contaminated by Cd. The treatments included cassava monocropping (CM), peanut monocropping (PM), and cassava-peanut intercropping (CPI). The results showed that the land use ratio (LER) of CPI reached 1.87. Compared with monocropping, the content of Cd in stems and leaves of intercropped cassavas were significantly (P<0.05) reduced by 12.24% and 19.51%, respectively, while the content of Cd in the seeds of intercropped peanuts reduced significantly by 35.38% (P<0.05). The total enrichment coefficient of peanut was reduced by 16.32%, while it reduced by 12.45% in cassava. However, for the total accumulated amount of Cd per hectare in the treatment of CPI increased 10.72% compared with CM and 113.76% compared with PM. The available nitrogen and available phosphorus in rhizosphere soil of peanut in CPI were increased significantly (P<0.05) by 18.85% and 20.36% compared with PM, and the available nitrogen in rhizosphere soil of cassava were significantly increased by 21.00% (P<0.05) compared with CM. Therefore, CPI could increase soil available nutrient contents, promote crops growth, reduce Cd content in plants, and increase the total Cd phytoextraction from soil at the same time. This intercropping system can well realize both the ecology and economy benefits.