EM复合菌对新疆色素辣椒生长及根际细菌群落的影响

【背景】Effective microorganisms （EM）复合菌在我国农业种植上的应用越来越广泛，但对色素辣椒的促生作用与根际细菌群落结构的影响未见报道。【目的】评估EM复合菌对新疆色素辣椒的促生长作用，并分析其对色素辣椒根际细菌群落组成的影响。【方法】通过随水灌溉方式将EM复合菌接种到色素辣椒根部，在收获期测定辣椒生长指标、土壤养分和酶活活性，明确EM复合菌对辣椒生长和土壤质量的影响；利用16S rRNA基因高通量测序技术测定EM复合菌对辣椒根系细菌群落组成和结构的影响。【结果】与对照组相比，EM复合菌的施用使辣椒株高、鲜重、单个果重和单株结果数分别提高23.89%、85.41%、42.31%和46.04%；土壤中碱解氮和速效磷含量分别提高5.83%和13.39%，土壤中脲酶、蔗糖酶和过氧化物酶的活性分别提高11.47%、9.42%和21.43%；施用EM复合菌显著改变辣椒根际微生物群落的α多样性和β多样性，提高有益菌群变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）、芽单胞菌门（Gemmatimonadetes）、放线菌门（Actinobacteria）和厚壁菌门（Firmicutes）的相对丰度，其中变形菌门黄单胞菌科（Xanthomonadaceae）的相对丰度增加119.32%；在属的水平上，施用EM复合菌显著增加了藤黄色杆菌属（Luteitalea）、藤黄单胞菌属（Luteimonas）、鞘脂单胞菌属（Sphingobacterium）和盐单胞菌属（Halomonas）的相对丰度，尤其是藤黄单胞菌属的丰度提高244.17%，同时显著降低黄杆菌属（Flavobacterium）的相对丰度。此外，与土壤理化指标呈正相关的微生物菌群相对丰度也显著升高。【结论】EM复合菌能够通过提高土壤营养成分与酶活活性，调控根系微生物群落结构，富集大量在盐碱地生存能力较强的有益菌群，进而起到促进色素辣椒生长的功效。

EM biofertilizer affects growth and rhizosphere bacterial community of pigment pepper in Xinjiang of China

Background] Effective microorganisms (EM) have been widely used in the farming in China, while the available information is limited regarding the impacts of EM biofertilizer on the growth and rhizosphere bacterial community structure of pigment pepper. Objective] To clarify the growth-promoting effect of EM biofertilizer on pigment pepper in Xinjiang of China and uncover the influence of the biofertilizer on rhizosphere bacterial community structure. Methods] The EM biofertilizer was inoculated into the roots of pigment pepper plants through irrigation. We determined the growth indexes, soil nutrient levels, and enzyme activities at the harvest stage to assess the impacts of EM biofertilizer on the pepper growth and soil quality. High-throughput sequencing of 16S rRNA was employed to investigate the impacts of EM biofertilizer on the composition and structure of rhizosphere bacterial community. Results] Compared with the control group, the application of EM biofertilizer increased the plant height, fresh weight, single fruit weight, and number of fruits per plant by 23.89%, 85.41%, 42.31%, and 46.04%, respectively. Moreover, it increased the available nitrogen, the available phosphorus, and the activities of urease, sucrase, and peroxidase in the soil by 5.83%, 13.39%, 11.47%, 9.42%, and 21.43%, respectively. The application of EM biofertilizer significantly altered the alpha and beta diversity of bacteria in the rhizosphere soil and increased the relative abundance of beneficial bacteria including Proteobacteria, Acidobacteria, Gemmatimonadetes, Actinobacteria, and Firmicutes. Especially, the relative abundance of Xanthomonadaceae belonging to Proteobacteria was increased by 119.32%. At the genus level, the application of EM biofertilizer increased the relative abundance of Luteitalea, Luteimonas, Sphingobacterium, and Halomonas. Among them, the relative abundance of Luteimonas was increased by 244.17%, whereas that of Flavobacterium was lower than that in the control group. The microbial taxa showing positive correlations with soil physicochemical indices presented significantly increased relative abundance after the application of EM biofertilizer. Conclusion] The application of EM biofertilizer regulates the rhizosphere microbial community structure by changing soil nutrient levels and enzyme activities, which further enriched beneficial bacteria with strong survival ability in saline-alkali land and promoted the growth of pigment pepper.