不同浓度植物根系分泌物微生态效应研究

探讨夹竹桃(Nerium oleander)根系分泌物对土壤微生物量碳、呼吸强度等微生物学特征及土壤微生物群落功能多样性的影响,深入揭示夹竹桃根系分泌物的微生态效应,通过向土壤中添加植物根系分泌物溶液的方法,研究了不同浓度(CK,15 mL去离子水作为对照;LC,5 mL分泌物+10 mL去离子水;MC,10 mL分泌物+5 mL去离子水;HC,15 mL分泌物)的外源植物根系分泌物对土壤理化性质、土壤微生物群落功能多样性、微生物量碳、微生物熵、基础呼吸和代谢熵的影响。结果表明,不同浓度根系分泌物处理pH值显著低于CK(P<0.05);有机碳、含水量、全氮、碱解氮、速效磷含量显著高于CK(P<0.05),其大小表现为HC>MC>LC>CK;而土壤全磷无明显差异(P>0.05)。细菌、真菌、放线菌和微生物总数均显著高于对照(P<0.05),不同处理之间差异均显著(P<0.05),其大小表现为HC>MC>LC>CK。微生物量碳、微生物熵和基础呼吸均显著高于对照(P<0.05),不同处理之间差异均显著(P<0.05),其大小表现为HC>MC>LC>CK。土壤代谢熵表现为HC>MC>LC>CK,HC和MC差异不显著(P>0.05)。平均吸光值、物种丰富度指数、Mcintosh指数均显著高于对照(P<0.05),不同处理之间差异均显著(P<0.05),其大小表现为HC>MC>LC>CK。不同处理间优势度指数差异不显著(P>0.05)。主成分分析表明:中浓度根系分泌物处理的土壤与CK土壤微生物群落代谢特征相近,其明显不同于高浓度根系分泌物处理的土壤,说明它们对单一碳源的利用能力不同,其群落代谢特征存在差异。总体来看,高浓度的根系分泌物能够显著改变土壤微生物学特性及群落功能多样性。

Study on Microecological Effects of Root Exudates of Garden Plantswith Different Concentrations

To investigate the effects of root exudates of Nerium Oleander on soil microbial biomass carbon,respiration intensity and functional diversity of soil microbial community,and to further reveal the microecological effects of root exudates of Nerium Oleander.Studied the different concentration(CK15 mL deionized water as control],LC+10 mL deionized water]5 mL secretion,MC+5 mL deionized water]10 mL secretion,HC]15 mL secretion)of exogenous plant root secretion on soil physical and chemical properties,soil microbial community functional diversity,microbial biomass carbon,microbial entropy,the influence of the respiratory and metabolic entropy.The results showed that the pH value of root exudates treated with different concentrations was significantly lower than CK(P<0.05).The contents of organic carbon,water content,total nitrogen,alkaloid-hydrolyzed nitrogen and available phosphorus in root exudates of different concentrations were significantly higher than CK(P<0.05).However,there was no significant difference in soil total phosphorus(P>0.05).The total number of bacteria,fungi,actinomycetes and microorganisms under the treatment of plant root exudates with different concentrations was significantly higher than that of the control group(P<0.05),and the difference among different treatments was significant(P<0.05).The size was shown as:HC>MC>LC>CK.Microbial biomass carbon,microbial entropy and basal respiration were significantly higher than those in the control group under the treatment of plant root exudates with different concentrations(P<0.05),and there were significant differences among different treatments(P<0.05).Their sizes were successively shown as:HC>MC>LC>CK.The metabolic entropy of soil showed HC>MC>LC>CK,and no significant difference between HC and MC(P>0.05).The average light absorption value,species richness index and Mcintosh index of plant root exudations of different concentrations were significantly higher than those of the control group(P<0.05),and the differences among different treatments were significant(P<0.05).The values were successively shown as:HC>MC>LC>CK.The difference of dominance index between different treatments was not significant(P>0.05).Principal component analysis showed that the microbial community metabolism characteristics of soil treated with medium-concentration root exudates were similar to those of CK soil,and they were significantly different from those treated with high-concentration root exudates,indicating that they had different utilization capacity for a single carbon source and had different community metabolism characteristics.In general,high concentration of root exudates can significantly change soil microbial characteristics and community functional diversity.