长期不同供磷水平驯化的土壤微生物的遗留效应

The Soil Microbial Legacy Effects of Long-term Gradient P Fertilization Based on the Analysis of Plant Growth, Nutrient Absorption, Soil Enzyme Activity and Mycorrhizal Characteristics

在集约化农田生态系统中,长期过量施用磷肥导致土壤中磷的累积,本文研究了集约化农田生态系统中长期、不同水平的磷肥供应驯化(training)微生物形成的遗留效应(legacy effect)。依托长期定位玉米试验地(始于2007),以长期不同供磷水平(来源于施用P2O50、75、300 kg·hm^(–2)的处理,分别为P0、P75、P300)石灰性土壤中的微生物为研究对象,通过盆栽接种微生物,探究不同磷供应驯化下的土壤微生物,在2个基质供磷水平(不施磷No P和+P 30 mg·kg^(–1))下对玉米和三叶草植物生长、养分吸收、土壤酶活性及菌根特征的影响。结果表明,菌剂类型(灭菌处理,原位菌剂)显著影响玉米和三叶草地上部生物量和磷吸收量。在2个基质磷水平处理,相比于灭菌菌剂处理,接种原位菌剂显著提高了三叶草地上部生物量和磷吸收量,但三种菌剂之间差异不显著。在No P条件下,相比于灭菌处理,接种原位菌剂对玉米地上部生物量无显著影响。在+P条件下,接种原位菌剂显著降低了玉米的生物量;在2个基质供磷水平下,玉米地上部生物量在P300处理中显著高于P0和P75。菌剂和基质供磷水平共同影响土壤酶活性。与P0和P75相比,P300菌剂显著降低了三叶草土壤中过氧化物酶活性,提高了NoP条件下玉米土壤中过氧化物酶和几丁质酶的活性。在NoP条件下,接种P75显著提高了玉米土壤中酸性和碱性磷酸酶的活性。2种作物的菌根特征不同,接种位P300三叶草根系丛枝菌根真菌的侵染率显著低于P0和P75,而玉米根系的侵染率在三种菌剂之间差异不显著。综上,基质供磷水平以及植物种类共同影响累积磷驯化土壤微生物的效应,说明磷肥管理需要考虑植物-微生物的特性。

【Objective】Long-term excessive phosphorus(P) application in intensive agro-ecosystem leads to P accumulation in soil. Whether there was a legacy effect on accumulated P in soil.【Method】This study was based on a long-term experiment(started in 2007) in North China Plain. The microorganisms with different P supply levels(from P2O50, 75, 300 kg·hm^(–2), P0, P75,P300, respectively) in calcareous soil was selected as the research object. Pot microbial inoculation experiment was conducted to explore the soil microorganisms training with gradient P fertilization on plant growth, nutrition absorption, soil enzyme activities and mycorrhizal characteristics under two substrate P supply levels(0 mg·kg^(–1), 30 mg·kg^(–1), No P, + P, respectively).【Result】The type of inoculants(original inoculants, sterilization treatment) significantly affected the aboveground biomass and phosphorus uptake of plants. Inoculating original inoculants(P0, P75 and P300) significantly increased the aboveground biomass and P uptake of clover compared with sterilized inoculants under the condition of two substrate P levels, but there was no significant difference among the three original inoculants. The aboveground biomass of maize inoculated with original inoculants P300 was significantly higher than that in the treatments of P0 and P75. At the same time, the inoculant and substrate P supply level co-affected soil enzyme activities. Compared with P0 and P75 inoculants, P300 inoculant significantly decreased the peroxidase activities in the soil of clover under no P and + P conditions, and significantly increased the peroxidase and chitinase activities in the soil of maize under no P conditions. Also, compared with inoculating in original P0 and P300 inoculants, P75 inoculant significantly increased the activities of acid and alkaline phosphatase in maize soil under no P condition. In addition, the mycorrhizal colonization differed due to plant species. Compared with P0 and P75 inoculants, the colonization rate of arbuscular mycorrhizal fungi in clover root significantly reduced after inoculating with P300, but there was no significant difference among the three original inoculants in maize root.【Conclusion】The substrate P supply and plant species co-affect microorganisms training by accumulated P, suggesting that plant-microbial characteristics need to be considered in P fertilizer management.