Abstract The long-term continuous mono-cropping and application of large amount of chemical fertilizers have led to a dramatic degradation of soil quality in the intensive vegetable production system. It is important to develop more sustainable, environmentally friendly and high-efficiency agroecosystems for vegetable production in plastic shed systems. Field experiments were performed to explore the impacts of Bacillus megaterium application on cucumber yields, the bioavailability of soil phosphorus (P) and potassium (K), properties of soil microbial communities in a plastic shed production system with cucumber mono-cropped for more than 15 years. The field trails were set up with four treatments of conventional fertilization as control (CON), conventional fertilization with Bacillus megaterium (CON + BM), conventional fertilization reduced by 10 % P and 10 % (or 5 %) K from chemical fertilizer with Bacillus megaterium (CON + BM - PK1), conventional fertilization reduced by 20 % P and 20 % (or 10 %) K from chemical fertilizer with Bacillus megaterium (CON + BM - PK2). Results illustrated that CON + BM treatment significantly increased the cucumber yields by 11.8 %–15.2 % and P and K accumulation in cucumber fruits and roots by 27.5 %–46.1 % and 17.8 %–45.1 %, respectively. The treatments of CON + BM - PK1 and CON + BM - PK2 did not decrease the yields and quality of cucumber, and the bioavailability of soil P and K compared with CON + BM. Moreover, the strain of Bacillus megaterium can efficiently colonize the soil at the early stage of inoculation and improved the richness of soil bacterial and fungal communities significantly. High-throughput sequencing identified that the application of Bacillus megaterium did not change the compositions of the predominant bacterial phyla Proteobacteria, Acidobacteria, Actinobacteria, Firmicutes, and predominant fungal phylum Ascomycota in soil, but increased the relative abundances of the beneficial bacterial genera and fungal orders and suppressed the development of pathogenic bacterial genus significantly. Principal coordinate analysis revealed that the structures of soil bacterial and fungal communities in the CON + BM treatment were dramatically separated from CON at the early stage of inoculation. Moreover, soil pH, available K (AK), total P (TP), and total K (TK) were dramatically related to the changes of soil bacterial community structure, while soil AK and TK were dramatically linked to the variations of soil fungal community structure. The findings indicated that the application of Bacillus megaterium might contribute to the development of a more sustainable production system of vegetables in plastic shed via improving the properties of soil microbial community and the bioavailability of soil P and K.

中文翻译：

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巨大芽孢杆菌对华北塑料棚系统土壤微生物群落组成、土壤磷钾生物有效性及黄瓜生长的影响

摘要 在集约化蔬菜生产系统中，长期连续单作和大量施用化肥导致土壤质量急剧下降。为塑料棚系统中的蔬菜生产开发更可持续、环保和高效的农业生态系统非常重要。进行了田间试验，探讨了在单作黄瓜 15 年以上的塑料棚生产系统中，巨大芽孢杆菌施用对黄瓜产量、土壤磷（P）和钾（K）的生物有效性、土壤微生物群落特性的影响。年。田间试验以常规施肥作为对照（CON）、巨大芽孢杆菌常规施肥（CON + BM）、常规施肥从含有巨大芽孢杆菌 (CON + BM - PK1) 的化肥中减少 10 % P 和 10 %（或 5 %）K，常规施肥从含有巨大芽孢杆菌的化肥中减少 20 % P 和 20 %（或 10 %）K巨大芽孢杆菌 (CON + BM - PK2)。结果表明，CON + BM 处理显着增加了黄瓜产量 11.8 %–15.2 %，黄瓜果实和根中磷和钾的积累分别增加了 27.5 %–46.1 % 和 17.8 %–45.1 %。与CON+BM相比，CON+BM-PK1和CON+BM-PK2处理没有降低黄瓜的产量和品质，以及土壤P和K的生物有效性。此外，巨大芽孢杆菌菌株可在接种初期高效定殖土壤，显着提高土壤细菌和真菌群落的丰富度。高通量测序发现，巨大芽孢杆菌的应用并未改变土壤中优势菌门变形菌门、酸菌门、放线菌门、厚壁菌门和优势真菌门子囊菌门的组成，但增加了有益菌属和真菌目的相对丰度并显着抑制病原菌属的发展。主坐标分析表明，在接种早期，CON+BM处理中土壤细菌和真菌群落的结构与CON显着分离。此外，土壤pH、速效钾（AK）、全磷（TP）和全钾（TK）与土壤细菌群落结构的变化显着相关，而土壤 AK 和 TK 与土壤真菌群落结构的变化显着相关。研究结果表明，巨大芽孢杆菌的应用可能通过改善土壤微生物群落的特性和土壤磷、钾的生物有效性，促进塑料棚蔬菜生产系统的发展。