溶磷菌混施对土壤微生物群落及毛竹生长的影响

Effects of Phosphorus Solubilizing Bacterial Compound Suspensions on Growth of Moso Bamboo(Phyllostachys edulis)and Soil Microbial Community Structures

【目的】低磷低利用限制了酸性红壤的初级生产力。溶磷微生物作为磷素活化的主要执行者,能活化土壤磷素,加速土壤磷组分的循环,但其复合菌液对土壤磷素的转化机制尚不明晰。因此,试验通过向毛竹根际接种溶磷菌复合菌液,探究毛竹根际土壤磷素循环的机制及其对毛竹生长的影响。【方法】试验以盆栽毛竹为供试植物,以浇灌的方式向盆栽毛竹根际接种4种不同的溶磷菌复合液:劳尔菌(Ralstonia sp.)+雷伯氏菌(Klebsiella sp.)+肠杆菌(Enterobacter sp.)、劳尔菌+雷伯氏菌、劳尔菌+肠杆菌和雷伯氏菌+肠杆菌,空白对照接种等体积的去离子水,在大棚培育90 d后,测定毛竹根际土壤养分、微生物群落及毛竹生长指标,探究溶磷菌混施对毛竹生长、土壤化学性质、磷循环功能基因的丰度及微生物群落的影响。【结果】溶磷菌混施后,土壤无机磷溶解和有机磷矿化基因相对丰度分别比磷饥饿相关基因及磷吸收和转运相关基因相对丰度增加438.66%和383.15%,从而编码土壤磷酸酶矿化土壤有机磷,显著提高了土壤有效磷含量。溶磷菌混施提高了毛竹土壤速效钾、铵态氮、硝态氮的含量,改变了土壤pH,导致土壤微生物群落结构发生变化,且Verrucomicrobia(疣微菌门)和Nitrospirae(硝化螺旋菌门)在3株溶磷菌混合处理下显著富集。土壤速效养分的增加有利于毛竹的吸收利用,导致毛竹根系活力及叶绿素含量增加,从而增强毛竹根系从土壤中汲取养分的能力和增强叶片光合作用,加速毛竹生物量的积累。溶磷菌接种显著增加了毛竹的苗高、地径及生物量,且在3株溶磷菌混施下毛竹苗高、地径和生物量均最大,分别为61.57 cm、4.54 cm和17.00 g。【结论】溶磷菌混施种促进了盆栽毛竹土壤酶活性、磷循环功能基因及微生物群落结构转化土壤养分,加速毛竹吸收土壤速效养分,增加毛竹生物量,且3株溶磷菌混合接种后的效果最佳。研究结果可为土壤磷素肥力挖掘和亚热带植物科学施肥提供一定的理论依据。

[Objective]Low phosphorus(P)bioavailability limits the primary productive of acid red soils.As the major executor of P activation,phosphate-solubilizing bacteria(PSB)could activate soil P nutrient and accelerate soil P cycling.However,the mechanism of phosphorus solubilizing microorganisms compound suspensions for transforming of P is still unclear.In order to better understand the mechanism of soil P transformation and its effects on growth of moso bamboo,PSB compound suspensions are inoculated to Phyllostachys edulis(Moso bamboo)rhizosphere in the experiment.[Method]Potted moso bamboo seedling were used as the test plants,four different PSB compound suspensions(Ralstonia sp.Klebsiella sp.Enterobacter sp.;Ralstonia sp.Klebsiella sp.;Klebsiella sp.Enterobacter sp.;Ralstonia sp.Enterobacter sp.)were inoculated on rhizosphere of moso bamboo via watering,and the constant volume of deionized water was as the blank control(CK).After that,the potted moso bamboo was cultivated in the greenhouse for 90 days,then soil nutrients,microbial community structure and growth characteristics of moso bamboo were determined and the effects of different PSB compound were identified.[Result]After inoculation of PSB,the average relative abundances of representative genes responsible for microbial P-starvation response regulation were increased by 438.66%and 383.15%relative to that of P-starvation response regulation and P-uptake and transport,respectively.Therefore,increases in relative abundances of representative genes responsible for microbial P-starvation response regulation stimulated soil phosphatases activity,and further mineralized soil organic P into inorganic P,and then increased soil available P concentrations.Increment of concentration of available potassium(K),ammonium nitrogen(NH4+-N)and nitrate nitrogen(NO3--N),and altered soil pH shaped soil microbial community with the inoculation of PSB compound suspension.Moreover,the relative abundances of Verrucomicrobia and Nitrospirae were significantly increased in the three different PSB compound suspension treatments.Increases in soil available nutrient concentrations were beneficial to bamboo absorption,and it also enhanced root activity and chlorophyll concentrations,resulting in increasing biomass of moso bamboo.Four different PSB compound suspensions inoculation all significantly increased seedling height,ground diameter and biomass of moso bamboo.Particularly,the highest seedling height(61.57 cm),ground diameter(4.54 cm)and biomass(17.00 g)were also observed in the three PSB treatments,respectively.[Conclusion]The PSB compound suspensions stimulated soil enzyme activities,the P-transforming functional genes relative abundance and microbial community structure to transfer soil nutrient for absorption and utilization of msos bamboo,leading to high biomass of moso bamboo.The three PSB compound suspension treatments achieved the optimal outcome.The results of this study could provide theoretical basis for improving soil P nutrition and scientific fertilization of subtropical plants.