苜蓿绿肥对塔里木盆地苹果园土壤细菌多样性和功能的影响

Effect of Alfalfa Green Manure on Diversity and Function of Soil Bacteria in Apple Orchards in Tarim Basin

为探讨南疆干旱荒漠区苹果园种植覆盖作物苜蓿对果园土壤细菌群落结构与功能的影响,以苹果园间作苜蓿绿肥为处理(GMA)、清耕(CT)为对照,分别对0-20、20-40、40-60 cm土壤微生物16S rDNA基因组采用Illumina MiSeq高通量测序技术和PICRUSt基因预测分析,比较不同处理下果园不同耕层土壤细菌群落结构、多样性及代谢功能变化。结果表明,苹果园间作苜蓿绿肥显著影响园区土壤细菌群落多样性,细菌拷贝数、丰富度指数(Chao1、ACE指数)及多样性指数(Shannon指数)均显著提高。其中,GMA处理下变形菌门(Proteobacteria)、放线菌门(Actinobacteria)和拟杆菌门(Bacteroidetes)的相对丰度分别为10.15%、64.97%和82.31%,较CT显著提高。通过PICRUSt功能预测,间作苜蓿绿肥明显提高了果园0—20cm土层细菌功能的相对丰度,其中在7和9月提升最为显著,主要提高了土壤细菌对异物的生物降解能力,增强了土壤碳代谢、氮代谢相关功能菌的丰度。相关性分析表明,土壤细菌优势菌门与土壤全氮、总碳、碱解氮和有效钾含量呈显著正相关,与pH呈显著负相关。综上所述,苹果园种植苜蓿绿肥能显著改善土壤微生物群落组成,提高土壤细菌丰富度、多样性和拷贝数,显著提高土壤微生物功能,对果园土壤熟化、促进物质代谢及培肥地力具有重要作用。

To explore the effect of planting cover crop alfalfa on the structure and function of soil bacterial community in apple orchards in the arid desert area of southern Xinjiang,the apple orchard intercropping alfalfa green manure(GMA)was as treatment with clear tillage(CT)as control,and 16S rDNA gene Illumina MiSeq high-throughput sequencing technology and PICRUSt were used analyzed the structure and function of soil bacterial community in 0-20,20-40 and 40-60 cm soil,respectively.The bacterial community structure,diversity and metabolic function were compared between GMA and CT treatments.The results showed that cover crop alfalfa could significantly affect the diversity of soil bacterial community in the orchards,and the bacterial copy number and richness index(Chao1 and ACE index),diversity index(Shannon index)had been significantly improved.The relative abundances of Proteobacteria,Actinobacteria and Bacteroidetes in GMA treatment significantly increased than CT treatment,with 10.15%,64.97% and 82.31%,respectively.According to PICRUST function prediction,cover crop alfalfa could significantly increase the relative abundance of bacterial functions in 0-20 cm soil layer of the orchard,with the more significant increase ranges in July and September,which could improve the ability of soil bacteria to biodegrade foreign matter and increase soil carbon and nitrogen metabolism.The correlation analysis between soil factors and microbial diversity indicated that the dominant bacteria plylums were positively correlated with total nitrogen,total carbon,available nitrogen and available potassium,and negatively correlated with pH.In conclusion,cover crop alfalfa in apple orchard could significantly change the composition of soil microbial communities,increase soil bacterial richness,diversity and copy number,significantly improved soil microbial functions,and played an important role in orchard soil maturation,promotion of material metabolism and fertility.