氧化钙、哈茨木霉及三种杀菌剂对花生苗期根际土壤微生物的影响

The Effects of Calcium Oxide,Trichoderma harzianum and Three Chemical Fungicides on the Rhizosphere Soil Microorganisms in Peanut Seedling Stage

为探究氧化钙(生石灰)、哈茨木霉(生物拮抗剂)及三种不同类型化学杀菌剂对花生根际土壤微生物的影响,在大田试验条件下,以当地主栽花生品种湘花2008为材料,利用16SrRNA、ITS高通量测序技术和生物信息学分析方法,分析了氧化钙基施、哈茨木霉拌种及常用的三种化学杀菌剂(甲基硫菌灵、噻呋酰胺、咯菌腈)拌种对花生苗期根际土壤微生物多样性及群落结构影响的差异。结果表明:①氧化钙基施和哈茨木霉拌种处理,特有的根际土壤细菌和真菌OTU数目远多于三种化学杀菌剂拌种处理。②Shannon指数、ACE指数分析表明,氧化钙和哈茨木霉处理明显提高细菌多样性和微生物丰富度,而三种化学杀菌剂处理的微生物多样性降低。③各处理优势细菌的门与属相对丰度比较,氧化钙处理蓝藻细菌门和硝化螺旋菌属丰度降低,绿弯菌门、芽单胞菌门、粘球菌门、拟杆菌门、芽单胞菌属丰度明显增加;哈茨木霉处理变形菌门和蓝藻细菌门丰度降低,拟杆菌门丰度增加;三种化学杀菌剂处理下拟杆菌门和蓝藻细菌门丰度明显大于其他处理。优势真菌的门与属相对丰度比较,氧化钙和哈茨木霉处理均降低了子囊菌门的丰度,其中氧化钙处理的被孢霉门、梳霉门、火丝菌属、柔膜菌属、伏革菌属相对丰度均高于其他处理,三种化学杀菌剂处理均增加了子囊菌门丰度。④LEfSe分析显示,氧化钙和不同杀菌剂处理均显著改变了花生苗期根际土壤细菌和真菌的群落结构,氧化钙处理的真菌优势菌群较多,哈茨木霉处理的细菌优势菌群最多。差异显著的细菌群落中,氧化钙处理下有Chthonomonadetes纲、Chthonomonadales目,哈茨木霉处理下有梭菌目、脱硫弧菌目、乳酸杆菌科、Bryobacteraceae科等。差异显著的真菌中,氧化钙处理下有粪壳菌科。这些菌群一定程度上利于根系营养物质吸收和转化,促进植株生长发育。综上,氧化钙和哈茨木霉的合理使用能提高根域微生物的多样性和丰富度,维持根际微生态平衡,而三种化学杀菌剂处理则降低土壤微生物多样性和丰富度,进一步印证了现代化学农药的大量投入对土壤生态环境的危害。

To explore the effects of lime(calcium oxide),Trichoderma harzianum,and three different types of fungicides on the rhizosphere soil microbiota of peanuts,a field experiment was conducted using the local mainly cultivated peanut variety Xianghua2008.The 16S rRNA,ITS high-throughput sequencing technology,and bioinformatics analysis methods were employed to analyze the differences in microbial diversity and community structure in the rhizosphere soil during seedling stage of peanut under the treatments of calcium oxide basal application,the biological antagonist(Trichoderma harzianum)seed dressing,and three commonly used chemical fungicides(thiophanate-methyl,thifluzamide,fludioxonil).The findings indicated that the number of bacterial and fungal OTUs in the rhizosphere soil was significantly higher in the treatments with calcium oxide and Trichoderma harzianum inoculation compared to the three chemical fungicide treatments.The analysis of Shannon index and ACE index indicated that calcium oxide and Trichoderma harzianum significantly increased bacterial diversity and microbial abundance,while the three chemical fungicides treatments decreased microbial diversity.Comparing the relative abundance of bacterial phyla and genera under different treatments,the abundance of Cyanobacteria and Nitrospira bacteria decreased,while the abundance of Chloroflexi,Gemmatimonadetes,Myxococcota,Bacteroidetes and Gemmatimonas increased significantly under the conditions of calcium oxide treatment.The abundance of Proteobacteria and Cyanobacteria decreased,while the abundance of Rhizobiales increased under the treatment of Trichoderma harzianum.Under the treatments of three chemical fungicides,the abundance of Cyanobacteria and Bacteroidetes was significantly higher than that of other treatments.The relative abundance of fungal phyla and genera of superiority fungi was compared.Both calcium oxide and Trichoderma harzianum treatments decreased the abundance of Ascomycota phylum.Among them,the relative abundance of Mortierellomycota,Kickxellomycota,Pyronemataceae,Helotiales and Corticiaceae were higher under the calcium oxide treatment compared to other treatments.All three chemical fungicide treatments increased the abundance of Ascomycota phylum.The LEfSe analysis revealed that the community structure of bacteria and fungi in the rhizosphere soil of peanut seedlings was significantly changed due to the application of calcium oxide and different fungicides.The fungal dominant taxa were more abundant under the calcium oxide treatment,while the bacterial dominant taxa were the most abundant under the Trichoderma harzianum treatment.Significant differences were observed in the bacterial communities,including the Chthonomonadetes and Chthonomonadales under the treatment of calcium oxide,and the bacterial communities included the Clostridiales,Desulfovibrionales,Lactobacillaceae and Bryobacteraceae under the Trichoderma harzianum treatment.In terms of significantly different fungi,the Sordariaceae was found under the calcium oxide treatment.These microbial communities may contribute to the absorption and transformation of root nutrients,promoting plant growth and development.In conclusion,the appropriate use of calcium oxide and Trichoderma harzianum can enhance the diversity and abundance of root-associated microorganisms,maintaining a balanced rhizosphere microbiome.On the other hand,the three chemical fungicides decreased diversity and abundance,further confirming the detrimental effects of excessive use of modern chemical pesticides on the soil microbiota and environment.