【作者】 闫伟；

【导师】 宛涛； 石凤翎；

【作者基本信息】 内蒙古农业大学 ， 草学， 2022， 博士

【摘要】 内蒙古黄河流域与土默川平原地区土壤盐碱化严重,已成为农牧业生产和生态环境可持续发展的重要限制因素之一。苜蓿(Medicago)不仅是一种优质的豆科牧草,更是盐碱地改良的理想草种,草原3号杂花苜蓿(M.varia Martin.cv.Caoyuan No.3)是在内蒙古中西部地区种植面积较大的品种之一,接种根瘤菌及植物根际促生菌(PGPR)是苜蓿高产栽培的重要措施,本研究以草原3号杂花苜蓿在盐碱地的高效种植及盐碱地改良为研究目标,从内蒙古中西部地区不同盐渍化程度的土壤中筛选高效的PGPR菌株,并与根瘤菌共接种,探究其对草原3号杂花苜蓿生长与土壤理化性质及酶活、根际微生物群落结构功能多样性的影响,为在盐渍化土壤中筛选出有利于苜蓿生长的促生菌群提供理论和实践依据。主要研究结果如下:1.不同盐碱化程度、不同生长年限草原3号杂花苜蓿根际土壤的微生物类群的优势菌门均是变形菌门(Proteobacteria),主要的差异菌是蓝菌门(Cyanophyta);在各分类水平上随着苜蓿生长年限的增加,其根际微生物多样性均逐渐递减、土壤α葡萄糖苷酶和碱性磷酸酶总体上亦呈降低趋势,而脲酶和蛋白酶则随着生长年限增加而增加。2.从草原3号杂花苜蓿根际土壤中分离出12株溶有机磷细菌、13株解无机磷细菌、16株固氮细菌、11株解钾细菌、19株分泌IAA细菌和8株铁载体分泌细菌菌株;按促生能力,各筛选出1株能力较强的菌,经16S r DNA初步鉴定解有机磷细菌SP-6为巨大芽孢杆菌(Bacillus megaterium sp),溶无机磷细菌SP-27为土壤杆菌(Agrobacterium sp)、解钾细菌PB-8为胶质芽孢杆菌(Bacillus mucilaginosus sp)、固氮细菌FN-12为假单胞菌(Pseudomonas sp)、分泌IAA细菌IAA-2为枯草芽孢杆菌(Bacillus subtilis sp)、铁载体分泌细菌SID-4为巨大芽孢杆菌(Bacillus megaterium sp)。3.将PGPR与根瘤菌共接种可显著提高草原3号杂花苜蓿的地上与地下部的生长能力;共接种效果优于单接种效果,且单接种PGPR效果优于单接种根瘤菌的效果;PGPR与根瘤菌共接种还可降低土壤p H与其含盐量,显著提高了土壤酶活和速效养分含量。4.PGPR与根瘤菌共接种增加了苜蓿单播根际土壤的变形菌门(Proteobacteria)丰度,而苜蓿与缘毛雀麦(Bromus ciliatus L.)混播则降低了放线菌门(Actinobacteria)的丰度;共接PGPR和根瘤菌将优势属黄杆菌属(Flavoacterium)变为了MND1和RB41,同时共接种增加了草原3号杂花苜蓿土壤碳氮磷硫循环相关基因的绝对丰度。更多还原

【Abstract】 The serious soil salinization in the Yellow River Basin and Tumochuan Plain area of Inner Mongolia has become one of the important limiting factors for the sustainable development of agricultural and animal husbandry production and ecological environment.Medicago is not only a high-quality leguminous forage grass,but also an ideal planting species for saline-alkali land improvement.Medicago varia Martin.cv.Caoyuan No.3 is one of the varieties with large planting area in central and western Inner Mongolia.Inoculation of rhizobia and PGPR is one of the high-yield cultivation methods of Medicago.In this study,the efficient planting and improvement of M.varia Martin.cv.Caoyuan No.3 in saline-alkali land were taken as the research objectives.Efficient PGPR strains were screened from the central and western regions of Inner Mongolia in different saline-alkalinity areas and coinoculated with rhizobia to explore their effects on the growth of M.varia Martin.cv.Caoyuan No.3,soil physical and chemical properties and enzyme activities,and the structure and functional diversity of rhizosphere microbial community.The main research results are as follows:1.In M.varia Martin.CV.Caoyuan No.3 with different salinization degree and different growth years,the dominant bacteria of microbial groups in rhizosphere soil were Proteobacteria,and the main difference bacteria were Cyanophyta.The diversity of rhizosphere microorganisms decreased with the increase of growth years at each taxonomic level.α-glucosidase and alkaline phosphatase decreased with the increase of growth years,while urease and protease increased with the increase of growth years.2.From the rhizosphere soil of M.Varia Martin.CV.Caoyuan No.3,12organophosphorus-solubating bacteria,13 inorganic phosphorus solubating bacteria,16 nitrogen fixing bacteria,11 potassium solubating bacteria,19 IAA-secreting bacteria and 8siderophore secreting bacteria were isolated.Bacillus megaterium sp was identified by 16 S r DNA as the organophosphorus-degrading bacterium SP-6.The inorganic phosphorus solubilizing bacterium SP-27 was Agrobacterium sp,the potassium solubilizing bacterium PB-8 was Bacillus mucilaginosus sp,and the nitrogen fixing bacterium FN-12 was Pseudomonas sp.The IAA-secreting bacterium IAA-2 was Bacillus subtilis sp,and ron bacteria carrier secretion SID-4 was Bacillus megaterium sp.3.PGPR and rhizobium co-inoculated in sterile indoor environment and field improved the growth indexes of M.varia Martin.CV.Caoyuan No.3 above and below ground.The effect of co-inoculation was better than that of single inoculation,and the effect of single inoculation of PGPR was better than that of single inoculation of rhizobia.PGPR and rhizobia co-inoculation reduced soil p H and salt content,and significantly increased soil enzyme activity and available nutrient content.4.PGPR and rhizobia co-inoculation increased the abundance of Proteobacteria;The mixed planting decreased the abundance of Actinobacteria.PGPR and rhizobia coinoculation changed the dominant genera of Flavoacterium to MND1 and RB41.The Coinoculation increased the abundance of genes related to C,N,P and S cycling in soil of M.varia Martin.CV.Caoyuan No.3.更多还原