化肥减量配施有机肥对柠檬根际/非根际土壤细菌群落结构的影响

Effects of Chemical Fertilizer Reduction Combined with Organic Fertilizer Application on Bacterial Community Structure in Rhizosphere/Non-Rhizosphere Soil of Lemon

研究不同施肥方式对柠檬根际/非根际土壤理化性质及细菌群落结构的影响,可为果园科学合理地施肥提供理论依据.采用盆栽试验,设置对照(CK)、常规施肥(FM)、有机肥(P)、新鲜有机肥(NP)、 70%化肥+30%有机肥(70FP)和50%化肥+50%有机肥(50FP)这6个施肥处理.采用化学分析、实时荧光定量PCR技术和末端限制性片段长度多态性分析(T-RFLP)方法,研究不同施肥处理对根际/非根际土壤的理化性质、细菌16S rRNA基因的丰度和细菌群落结构的影响,并通过冗余分析(RDA)探究影响柠檬根际/非根际土壤细菌群落结构的环境因子.结果表明:(1)化肥减量配施有机肥(50FP和70FP)能显著提高根际/非根际土壤pH值、有机质、碱解氮、有效磷、速效钾和硝态氮的含量(P<0.05);与常规施肥(FM)和单施有机肥(P和NP)相比,化肥减量配施有机肥处理的土壤有效磷含量提高了24.76%~97.98%,速效钾含量提高了6.87%~45.11%,硝态氮含量提高了18.42%~55.82%.(2)化肥减量配施有机肥能显著提高土壤细菌丰度及土壤呼吸速率(P<0.05),其中50FP处理的土壤根际细菌群落丰度及土壤呼吸速率较常规施肥和单施有机肥处理分别提高了15.83%~232.98%和8.0%~162.5%;根际土壤细菌丰度与有机质、 pH、全氮和全磷含量呈极显著正相关.(3)PCoA和RDA分析结果表明,单施有机肥和化肥减量配施有机肥处理的根际土壤细菌群落结构与未添加有机肥的处理之间有较大差异,影响根际/非根际土壤细菌群落结构的主要环境因子是:有机质、全氮、全磷、全钾、碱解氮、硝态氮和速效钾.化肥减量配施有机肥能显著提高土壤养分含量和增加土壤细菌丰度,改变根际土壤细菌群落结构,且50FP处理的效果更佳.因此50%化肥+50%有机肥(50FP)是改善果园土壤理化性质、增加土壤细菌丰度和提高土壤呼吸速率的较好施肥方法.

The aim of this study was to examine the effects of different fertilization methods on the physicochemical properties and bacterial community structure of lemon rhizosphere/non-rhizosphere soil in order to provide theoretical basis for scientific and rational fertilization of orchards.A pot experiment was carried out,and six fertilization treatments were set up:control(CK),conventional fertilization(FM),organic fertilizer(P),fresh organic fertilizer(NP),70% chemical fertilizer+30% organic fertilizer(70FP),and 50% chemical fertilizer+50% organic fertilizer(50FP).Chemical analysis,real-time fluorescence quantitative PCR,and terminal restriction fragment length polymorphism(T-RFLP) were used to study the effects of different fertilization treatments on the physicochemical properties of rhizosphere and non-rhizosphere soils,the abundance of the bacterial 16S rRNA gene,and bacterial community structure.Redundancy analysis(RDA) was used to explore the environmental factors affecting the bacterial community structure of lemon rhizosphere/non-rhizosphere soil.The results showed the following:(1) the pH and contents of organic matter,alkali-hydrolyzed nitrogen,available phosphorus,available potassium,and nitrate nitrogen in rhizosphere/non-rhizosphere soil were significantly increased by reducing the amount of chemical fertilizer and applying organic fertilizer(50FP and 70FP)(P<0.05).Compared with conventional fertilization(FM) and single application of organic fertilizer(P and NP),the soil available P content,available K content,and nitrate nitrogen content increased by 24.76%-97.98%,6.87%-45.11%,and 18.42%-55.82%,respectively.(2) Fertilizer reduction combined with organic fertilizer significantly increased the abundance of soil bacteria and soil respiration intensity(P<0.05),and the abundance of soil rhizosphere bacteria and soil respiration intensity under the 50FP treatment increased by 15.83%-232.98% and 8.0%-162.5% compared with that under conventional fertilization and organic fertilizer alone,respectively.The bacterial abundance of rhizosphere soil was positively correlated with the pH and contents of organic matter,total nitrogen,and total phosphorus.(3) The PCoA and RDA analysis results showed that the single organic fertilizer and organic fertilizer and chemical fertilizer de-weighting of rhizosphere bacterial community structure and not adding fertilizer had a bigger difference between processing,and the main environmental factors influencing the rhizosphere/non rhizosphere bacterial community structure were organic matter,total nitrogen,total phosphorus,total potassium,alkali solution nitrogen,nitrate nitrogen,and available potassium.Fertilizer reduction combined with organic fertilizer could significantly increase soil nutrient content,increase soil bacterial abundance,and change the bacterial community structure of rhizosphere soil,and the 50FP treatment yielded better results.Therefore,50% Chemical fertilizer+50% organic fertilizer(50FP) was a better fertilization method to improve the physical and chemical properties of orchard soil,increase the abundance of soil bacteria,and improve the soil respiration intensity.