摘要：

为探究土壤磷水平和外源菌剂对玉米根际土壤功能(土壤理化性质、土壤酶活和丛枝菌根真菌(AMF)组成和结构)的调节作用,采用大田试验的方式,通过设置低磷和正常磷2个水平与接种丛枝菌根真菌、解磷细菌(PSB)、AMF-PSB和不接种外源菌CK 4种处理的双因素交互试验来研究这2种因素对玉米不同生育期内根际土壤指标的影响。结果表明:玉米拔节期和吐丝期,土壤全磷含量在正常磷水平+AMF处理条件下最高,而拔节期和成熟期,土壤有效磷含量在正常磷水平+AMF处理条件下最高;玉米拔节期和吐丝期,碱性磷酸酶活性在低磷水平+AMF处理条件下最高,且该酶活性在低磷水平+AMF处理和低磷水平+PSB处理高于正常磷水平下的各处理;低磷水平下,全磷含量和有效磷含量在接种外源菌处理条件下高于CK处理,且提高率高于正常磷水平下对应处理组间的增量;低磷水平下,土壤pH值在接种外源菌处理条件下低于CK处理,正常磷水平在拔节期也低于CK处理;低磷水平下,最高观测AMF群落OTUs数目和α多样性指数出现在CK处理,而正常磷水平下,CK处理的观测OTUs数目和α多样性指数较AMF处理和PSB处理低;非度量多维尺度分析表明,土壤AMF群落组成和结构受接种外源菌种类的趋同调节。综上,中国北方低磷碱性玉米田接种AMF和PSB菌剂,能改善土壤理化性质,提高土壤碱性磷酸酶活性,但会增加土壤AMF间的竞争排除。

关键词: 丛枝菌根真菌, 解磷细菌, 碱性磷酸酶, AMF群落组成和结构

Abstract:

To explore the effects of soil phosphorus levels and exogenous microbial agents on soil functioning(soil physico-chemical properties,soil enzyme activities,and arbuscular mycorrhizal fungi(AMF)community composition and structure)of the rhizosphere soil of maize,a two-factor interaction experiment was conducted to study the effects of two levels of low phosphorus and normal phosphorus and four treatments of inoculation with AMF,phosphate-solubilizing bacteria(PSB),AMF-PSB and no inoculation of exogenous agent(CK)on rhizosphere soil indexes in different growth stages of maize.The results showed that the soil total phosphorus content was the highest at jointing stage and silking stage under the condition of normal phosphorus level+AMF treatment,while the soil available phosphorus content was the highest at jointing stage and mature stage under the condition of normal phosphorus level+AMF treatment.At jointing stage and silking stage,alkaline phosphatase activity was the highest under low phosphorus+AMF treatment,and the activity of alkaline phosphatase under low phosphorus+AMF treatment and low phosphorus+PSB treatment was higher than that under normal phosphorus level.Under low phosphorus level,total phosphorus content and available phosphorus content were higher than CK treatment,and the increase rate was higher than that under normal phosphorus level.At low phosphorus level,soil pH value was lower than CK treatment under the condition of inoculated foreign bacteria,and also lower than CK treatment under normal phosphorus level at jointing stage.Under the low phosphorus level,the CK treatment had the highest observed number of AMF community OTUs and α-diversity indexes,while under the normal phosphorus levels,the observed number of OTUs and α-diversity index in the CK treatment group were lower than those in the AMF and PSB treatments.Non-metric multidimensional scaling analysis indicated that the composition and structure of soil AMF communities were convergently regulated by the types of inoculated exogenous microorganisms.In summary,inoculating AMF and PSB agents in low-phosphorus alkaline maize fields in northern China can improve soil physicochemical properties and increase soil alkaline phosphatase activity,but it also increases competition and exclusion among soil AMFs.

Key words: Arbuscular mycorrhizal fungi(AMF), Phosphorus-solubilizing bacteria(PSB), Alkaline phosphatase, AMF community composition and structure