微生物菌剂施用对设施茄子根际土壤养分和细菌群落多样性的影响

Effects of microbial agents on nutrient and bacterial community diversity in rhizosphere soil of eggplant cultivated in facilities

[背景]设施茄子连作种植和化学肥料过量施用造成土壤养分失衡、微生物多样性降低、土传病害严重等土壤质量问题,微生物制剂是改善土壤环境质量的一项重要措施。[目的]确定微生物菌剂施用对设施茄子根际土壤养分及细菌群落多样性的影响。[方法]在河北省农林科学院鹿泉大河实验园区,以含有哈茨木霉和巨大芽孢杆菌的微生物菌剂为供试菌剂,采用传统的化学分析方法测定微生物菌剂处理和对照茄子开花期、拉秧期土壤的养分含量;采用稀释涂平板方法测定土壤可培养微生物的数量;采用高通量测序技术测定土壤细菌16S rRNA基因V3-V4区,分析处理和对照土壤的微生物多样性和群落分布规律。[结果]与对照相比,微生物菌剂处理提高了茄子开花期和拉秧期的根际土壤养分含量,拉秧期微生物菌剂处理根际土壤中全氮、碱解氮、有效磷、速效钾含量分别较对照增加13.85%、21.07%、31.51%和55.94%;施用微生物菌剂能够改变土壤可培养微生物的数量和构成,微生物菌剂处理土壤中细菌、真菌、放线菌的数量均显著增加,其中细菌、放线菌在微生物总量中所占比例增加,而真菌的占比则有所降低。微生物菌剂处理能够提高土壤微生物的Shannon指数、降低Simpson指数,ACE指数和Chao1指数差异不显著,表明微生物菌剂能够增加土壤的微生物群落多样性,对微生物群落丰富度影响不明显。从目水平上分析菌剂处理和对照的微生物组成,发现微生物菌剂处理增加了土壤中黄单胞菌目(Xanthomonadales)、红螺菌目(Rhodospirillales)、鞘脂杆菌目(Sphingobacteriales)、芽孢杆菌目(Bacillales)、纤维黏网菌目(Cytophagales)、假单胞菌目(Pseudomonadales)等优势菌目的占比,降低了伯克氏菌目(Burholderiales)、黄杆菌目(Flavobacteriales)等病原菌的占比。微生物菌剂的施入能够促进茄子营养生长,增加茄子的产量,增幅为18.52%。[结论]微生物菌剂作为一种新型环保肥料,具有改善土壤营养状况、增加土壤可培养微生物数量、提高土壤微生物多样性的作用,该结果为微生物菌剂的合理施用提供了科学依据。

[Background] Continuous cropping and excessive application of chemical fertilizers of eggplant in greenhouse cause a series of soil quality problems such as imbalance of soil nutrients, decrease of microbial diversity and serious soil-borne diseases. The application of microbial agents can improve soil environmental quality. [Objective] To investigate the effect of microbial agents application on the soil nutrients and bacterial community diversity of eggplant planting soil. [Methods] In the Dahe Experimental Station of Hebei Academy of Agricultural and Forestry Sciences, the microbial agents containing Trichoderma harzianum and Bacillus megaterium were used as fertilizers for eggplant planting in greenhouse. The soil nutrient were detected by traditional chemical methods. The number of culturable microorganisms in soil was measured by dilution plate method and the bacterial diversity and community distribution in rhizosphere were determined by high-throughput sequencing on PCR-amplified 16 S rRNA gene V3-V4 fragments. [Results] Compared with control group, microbial agents treatment increased the nutrients of rhizosphere soil in eggplant flowering and seedling-pulling stages. The total nitrogen, alkali-hydrolyzed nitrogen, available phosphorus and available potassium in the soil of microbial agents treatment at seedling-pulling stage increased by 13.85%, 21.07%, 31.51% and 55.94% respectively compared with that of control. Application of microbial agents changed the quantity and composition of culturable microorganisms in soil. Microbial agents increased the number of bacteria, fungi, actinomycetes and the proportion of bacteria and actinomycetes in the total microbial number. The Shannon index was higher and the Simpson index was lower in microbial agents treatment than that in control group. However, ACE index and Chao1 index had no significant difference between microbial agents treatment and control. The results indicated that microbial agents can increase the diversity of soil microbial communities, and have no significant impact on microbial community richness. Analysis of microbial communities of soil treated with microbial agents or not showed that microbial agents treatment increased the content of Xanthomonadales, Rhodospirillales, Sphingobacteriales, Bacillales, Cytophagales, Pseudomonadale and decreased the content of Burholderiales and Flavobacteriales in soil. The application of microbial agents could promote the vegetative growth of eggplant and increase the yield of eggplant by 18.52%. [Conclusion] As a new type of environmental protection fertilizer, microbial agents can improve soil nutrition, increase the number of culturable microorganisms and improve soil microbial diversity. The results provided a scientific basis for the rational application of microbial agents.