蚯蚓-菌根相互作用对土壤-植物系统中Cd迁移转化的影响

以灰化土(Aquods soil)为供试土壤,分别加入4种含量的Cd2 (0、5、10、20 mg·kg-1)模拟土壤污染,设置单独加8条蚯蚓(Pheretima sp.)、单独接种菌根(Inoculum Endorize-Mix2)、同时接种蚯蚓和菌根的3种处理,以不加蚯蚓和菌根为对照,各处理均种植黑麦草(Lolium multiflorum),研究蚯蚓、菌根相互作用对土壤-植物系统中Cd迁移转化的影响.结果表明:(1)菌根对土壤pH无明显影响,加蚯蚓可使土壤pH比对照约降低0.2,蚯蚓和菌根同时作用对土壤pH降低没有协同作用.(2)蚯蚓或菌根的加入均能显著增加土壤中可溶性有机碳(DOC)含量,蚯蚓的影响大于菌根,同时加入蚯蚓和接种菌根对土壤中DOC的增加有一定的拮抗作用.(3)蚯蚓活动增加了黑麦草根部Cd的积累,菌根则能促进Cd从黑麦草根部向地上部转移,二者具有促进Cd向地上部分转移的协同作用.(4)蚓粪和土壤中DTPA提取态Cd含量与黑麦草吸收Cd量呈显著相关(p＜0.01),而蚓粪中DTPA提取态Cd含量均显著高于土壤中的含量(p＜0.05).因此,蚓粪中有效态Cd是植物吸收Cd的重要供源.

Effect of earthworm-mycorrhiza interaction on transformation of Cd from soil to plant

The objective of this study was to investigate the effect of earthworms and arbuscular mycorrhiza (AM) on the Cd transfer from soil to plant. The Aquods soil, obtained from Laitiao Village, Hong Kong, was amended with Cd which Concentration is 5, 10 and 20 mg·kg^-1 , respectively. After two months amendment, the soil was inoculated with eight earthworms (Pheretima sp.) and arbuscular mycorrhiza (Inoculum Endorize-Mix2)separately, and in combiantions. Both blank and inoculated sample pots were received 15 pre-germinated ryegrass seeds (Lolium multiflorum). The results showed that(1)the soil pHdecreased by about 0.2 units with earthworms inoculation, while no soil pHchange was observed with mycorrhiza inoculation. The combination of earthworms and mycorrhiza inoculation was not able to reduce the soil pHto the same level as earthworms alone. (2)the concentration of dissolved organic carbon (DOC) in soil was significantly increased with earthworms and mycorrhiza inoculation, with the effect of earthworm outweighed that of mycorrhiza. The combination of earthworms and mycorrhiza inoculation did not significantly increase the DOCcompared with earthworms alone. (3) mycorrhiza inoculation significantly increased Cd concentration in shoot and root, however earthworm alone only significantly increased Cd concentration in root. Earthworms-mycorrhiza combination increased the Cd transfer from ryegrass root to shoot. (4) The concentration of DTPA-extractable Cd in earthworm cast or in soil was positively correlated with ryegrass uptake of Cd (p<0.01), and the concentration of DTPA-extractable Cd in earthworm cast was higher than that in soil (p<0.05). Therefore, the available Cd in earthworm cast was the important source of Cd uptake by plant.