间作模式下作物根际土壤代谢物对微生物群落的影响

Effect of the metabolites in rhizosphere soil on microbial communities of crop intercropping system

间作可通过根系互作改变土壤微生物群落结构,影响作物产量。本研究结合Eco-Biolog微平板法和液相色谱-串联质谱法(LC-MS),综合分析了玉米和高粱与大豆两种间作系统中不同年限作物产量、根际土壤理化性状、根际土壤微生物群落变化特征及根际土壤代谢物的差异,旨在探究不同种间互作影响复合作物群体产量的原因。结果表明:间作显著提高作物产量,且较第一年,产量上的间作优势在第二年中表现得更明显。与单作相比,间作能够增加速效养分的积累和吸收;间作玉米根际土壤中速效磷和速效钾、间作高粱根际土壤中碱解氮、速效磷和速效钾、玉米间作大豆中的大豆根际土壤中速效磷和速效钾以及高粱间作大豆中的大豆根际土壤中速效磷和速效钾含量均显著增加。与单作相比,间作条件下玉米、高粱和大豆的微生物量碳氮含量显著升高,根际土壤微生物的活性更强,微生物群落组成更加丰富。通过代谢组分析初步鉴定出不同作物根际土壤中可能影响土壤微生物富集的关键差异代谢组分,其中具有促进作用的差异代谢物在玉米、高粱和大豆中分别鉴定出4、2和1种,具有抑制作用的差异代谢物在玉米、高粱和大豆中各鉴定出1种。综合分析认为,玉米间作大豆和高粱间作大豆可通过种间根系互作改变根际土壤微环境,并重塑其中的微生物群落结构,进而加速根际土壤中速效养分的沉积,促进作物养分的吸收,提高作物产量。

In order to explore the reasons why interspecific interactions affects crop yield,we comprehensively analyzed the crop yield,the soil physicochemical properties,the rhizosphere soil microbial communities and the root exudates in maize(Zea mays)-soybean(Glycine max)and sorghum(Sorghum bicolor)-soybean intercropping systems in different years,combining the Eco-Biolog microplate method and liquid chromatography-mass spectrometry(LC-MS).Crop yield was significantly increased in the intercropping systems,and the increase of yield in 2020 was more significant than it in 2019.Compared with monoculture,intercropping increased the accumulation and absorption of available nutrients.The contents of available nutrients in the crop rhizosphere soil of the intercropping system were significantly increased.Compared with monoculture,microbial biomass carbon and nitrogen contents in maize,sorghum and soybean in intercropping systems were increased significantly;microorganism activities were also higher,and microbial community composition was more diverse in the rhizosphere soil of intercropped crops.Based on the metabolomic analysis,five key differential metabolites that might cause changes in microbial communities in maize rhizosphere soil were tentatively identified.Four of these appear to enrich the microorganism populations in maize rhizosphere soil,and one appears to be inhibitory.Three metabolites in sorghum rhizosphere soil were identified,two of which appear to enrich presence of microorganisms in sorghum rhizosphere soil,while the third appears to be inhibitory.Two bioactive metabolites in soybean rhizosphere soil were identified,one apparently faciliatory and one inhibitory towards microorganisms.Multivariate analysis showed that maize-soybean and sorghum-soybean intercropping systems changed the soil micro-environment and reshaped the soil microbial community structure through interspecific root interactions in rhizosphere soil,which accelerated the deposition of available nutrients,promoted the absorption of crop nutrients,and ultimately increased crop yield.