Effect of root exudates on beneficial microorganisms-evidence from a continuous soybean monoculture
Effect of root exudates on beneficial microorganisms-evidence from a continuous soybean monoculture
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DOI：
10.1007/s11258-012-0088-3
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发表时间：
2012-12-01
期刊：
影响因子：
1.7
通讯作者：
Wang, Jingguo
中科院分区：
文献类型：
--
作者：
Wang, Jinli;Li, Xiaoliang;Wang, Jingguo
东北地区大豆农业的特点是单作比例高，导致作物减产。在众多的生物和非生物因子中，根系活动引起的土壤微生物群落的变化，尤其是根系分泌物的变化，可能在这些影响中起着重要的作用。研究了连续13年单作大豆试验田土壤微生物生物量和两大有益微生物功能群氨氧化细菌（AOB）和丛枝菌根真菌（AMF）对根系分泌物的响应。结果表明，随着单作年限的增加，微生物生物量碳发生显着变化，并与根际染料木黄酮（r = 0.4399，P < 0.001）和大豆苷元（r = 0.4082，P < 0.05）浓度相关。根系分泌物对硝化菌群落的影响不大，但降低了根际硝化作用。染料木黄酮对AMF菌丝总长度有显著的促进作用（r = 0.5252，P < 0.01）。随着单作年限的增加，根际AMF孢子密度有增加的趋势，而AMF侵染率随时间的推移而保持不变，这可能是由于AMF与土传真菌病原菌之间的竞争，而黄酮类化合物对真菌群落尤其是真菌病原菌的刺激作用。我们的研究结果表明，在连续大豆单作开始产量下降，可以部分归因于氮的有效性和产量稳定后，几年对AMF的刺激作用。这些结果表明，某些植物根系分泌物在改变土壤微生物群落中起着至关重要的作用，地下生态系统的功能也受到微生物功能群之间相互作用的影响。
Soybean (Glycine max) agriculture is characterized by a high proportion of mono-cropping which results in reduced crop production in the Northeast China. Among all biotic and abiotic factors, changes in soil microbial communities induced by root activities, especially root exudates, might play an important role in these effects. The aim of the present study was to investigate response of microbial biomass and two major beneficial microbial functional groups, ammonia-oxidizing bacteria (AOB), and arbuscular mycorrhizal fungi (AMF), to root exudates in an experimental field under continuous soybean monoculture for 13 years. The results showed that microbial biomass carbon changed significantly with years of mono-cropping and correlated with concentrations of genistein (r = 0.4399, P < 0.001) and daidzein (r = 0.4082, P < 0.05) in the rhizosphere. However, root exudates had little effect on the nitrifier community, but reduced nitrification in the rhizosphere. In contrast, total AMF hyphal length was significantly stimulated by genistein (r = 0.5252, P < 0.01). There was a trend that AMF spore density increased in the rhizosphere with increasing years of mono-cropping, while AMF infection was constant over time, which might be attributed to competition between AMF and soil-borne fungal pathogens, as the results of stimulatory effect of flavonoids on fungal community, especially fungal pathogens. Our results suggested that the yield reduction in the beginning of continuous soybean monoculture could be partially attributed to nitrogen availability and yield stabilization after few years to stimulatory effects on AMF. These results imply that some of plant root exudates play a crucial role in changing the soil microbial community, and that underground ecosystem functioning is also affected by interactions among microbial functional groups.