根际效应对大豆田土壤线虫群落组成及多样性的影响

根际作为重要的环境界面是植物与环境之间物质能量交换的场所,关于根际效应的研究已成为土壤生态学的新兴热点领域,然而有关大豆根际效应对土壤动物多样性影响的研究报道并不多见。在三江平原选择连续耕作15a的大豆田,对大豆根际区与非根际区土壤线虫群落结构组成进行了对比分析。结果表明:大豆根际区土壤线虫总数、辛普森多样性指数(Dom)显著高于非根际区,根际区的物种数(S)、物种丰富度指数(SR)显著低于非根际区。说明大豆根际效应增加土壤线虫的丰度,但降低了线虫群落结构的复杂性。大豆根际区植物寄生线虫(PP)、食真菌线虫(FF)和食细菌线虫(BF)数量显著高于非根际区,而PP类群的比例在根际区却显著低于非根际区。这一研究结果表明食微线虫(FF和BF)类群在大豆根际区的比例增加更显著。食真菌与食细菌线虫数量比值(F/B)指示大豆根际区细菌生物量相对高于真菌生物量。研究结果丰富了农田土壤线虫多样性的研究内容,并为我国东北大豆田线虫病害的防治及定制相应的农业管理措施提供参考。

Responses of soil nematode community composition and diversity to rhizosphere effects in a soybean field

The rhizosphere is an important interface for the exchange of materials and energy between the plant and the environment. As a result, research on investigating the rhizosphere effect has become an area of considerable interest in the field of soil ecology. However, research reports on responses of soil fauna to the rhizosphere effect of soybean are lacking. Soil nematode communities can provide important information about soil food web structure and function because they are the most abundant metazoan and ubiquitous in soil. In the present study, the soil nematode trophic composition, colonizer-persister (c-p) scale (1-5) group structure, functional structure index, as well as the diversity between the rhizosphere and non-rhizosphere areas of a soybean field were investigated. The aim of the present study was to understand the effect of rhizosphere effects on soil nematode community composition and diversity. Five plots of 10 m×10 m were selected in soybean field, which had been converted from marshland in the Sanjiang Plain of China, and continuously cultivated with soybean for 15 years. The soybean rhizosphere was collected by the Root-Shaking method, using a 2.5 cm diameter core, and sampling the soil range 0-10 cm in depth. The non-rhizosphere soil samples were collected at a depth of 10 cm. A total of 4021 nematodes were identified and classified into 12 families and 16 genera, and further divided into 4 trophic groups and 9 functional guilds. The abundance of Acrobeloides (Ba2), Aphelenchoides (Fu2), and Heterodera (H3) in the soybean rhizosphere were significantly higher than those in the non-rhizosphere soil (P < 0.01). The results showed that the total number of nematodes and Simpson''s diversity (Dom) in rhizosphere soil were significantly higher than those in the non-rhizosphere soil (P < 0.01). In addition, the number of nematode species (S), and species richness index (SR) in the rhizosphere were significantly lower. These results indicate that the rhizosphere effect of soybean increased the abundance of soil nematodes, but reduced the complexity of the nematode community structure. The abundance of fungivores (FF), bacterivores (BF), and plant-parasitic nematodes (PP) were significantly higher in the rhizosphere than in the non-rhizosphere soil (P < 0.01). The proportion of plant-parasitic nematode (PP) taxa in rhizosphere was significantly lower than that in non-rhizosphere soil (P < 0.01). Furthermore, the ratios of microbivorous nematodes (FF and BF) in soybean rhizosphere soil increased significantly (P < 0.01). The ratio of fungi-feeding to bacteria-feeding nematodes (F/B) indicated that the soybean rhizosphere bacterial biomass was relatively higher than the fungal biomass.