黑曲霉菌剂不同处理对西瓜根际细菌群落及土壤理化性质的影响

Effect of different treatments of Aspergillus niger agent on the rhizosphere bacterial community and soil physicochemical properties of watermelon

【背景】针对我国设施栽培西瓜土传病害发生严重、土壤理化性质劣变等问题,探究微生物菌剂对西瓜根际土壤微生物群落调控及土壤营养改良的作用。【目的】研究黑曲霉菌剂不同处理方式对设施栽培西瓜根际细菌多样性、群落结构及土壤理化性质的影响。【方法】通过高通量测序分析黑曲霉菌剂不同处理对西瓜根际土壤细菌多样性和群落结构的影响;采用分析化学方法测定西瓜根际土壤理化性质并解析驱动西瓜根际细菌群落动态变化的主要理化因素。【结果】黑曲霉菌剂(Y)、氨基寡糖素水剂(A)及黑曲霉菌剂与氨基寡糖素水剂配施(YA)处理,细菌α多样性指数如Chao1、ACE和Shannon等较对照均有所增加;不同处理西瓜根际优势细菌在门水平包括变形菌门(Proteobacteria)、放线菌门(Actinobacteriota)、绿弯菌门(Chloroflexi)、酸杆菌门(Acidobacteriota)等,其中Proteobacteria相对丰度最高,依次为A(28.26%)>Y(26.74%)>YA(22.61%);黑曲霉菌剂处理西瓜根际土壤芽单胞菌科(Gemmatimonadaceae)和类诺卡氏菌科(Nocardioidaceae)相对丰度较对照明显提高到4.06%和2.43%,氨基寡糖素水剂处理中根际土壤假单胞菌属(Pseudomonas)丰度显著提高(P<0.05),不同处理组微枝形杆菌属(Microvirga)相对丰度较对照均有所提高;黑曲霉菌剂单独或与氨基寡糖素水剂配施处理,西瓜根际土壤全氮、全磷及速效磷含量明显提高;冗余分析(redundancy analysis,RDA)表明,土壤pH、全氮、速效磷、速效钾与西瓜根际细菌群落结构具有显著相关性(P<0.05);Spearman相关性分析表明,根际假单胞菌科相对丰度与土壤全氮、全磷、速效磷、速效钾呈显著或极显著正相关。【结论】黑曲霉菌剂在设施栽培西瓜种植中单独或与氨基寡糖素水剂配施处理,具有提高西瓜根际土壤细菌多样性、增加有益菌群相对丰度、改良土壤理化性质从而提高土壤肥力的作用,该结果为黑曲霉菌剂产品开发及在设施栽培西瓜种植中合理应用提供了科学依据。

[Background]In view of the serious soil borne diseases and deteriorative soil physicochemical properties in protected cultivation of watermelon,we explored the effect of microbial agent on rhizosphere microbial community and soil nutrients of watermelon.[Objective]To study the effect of different treatments of Aspergillus niger agent on rhizosphere bacterial diversity and community structure,as well as soil physicochemical properties of watermelon.[Methods]Through high-throughput sequencing,we analyzed the effect of A.niger agent inoculation alone(Y),amino oligosaccharin water aqua(root irrigation)alone(A)or the combination of the two treatments(YA),on the rhizosphere soil bacterial diversity and community structure of watermelon.Analytical chemistry methods were used to detect the soil physicochemical properties and elucidate the main driving factors of their dynamic changes.[Results]The bacterialαdiversity indexes of Chao 1,ACE and Shannon indices increased in Y,A,and YA treatments compared with those in the control.The dominant bacterial phyla in the rhizosphere soil of watermelon consisted of Proteobacteria,Actinobacteriota,Chloroflexi,and Acidobacteriota,among which,Proteobacteria was the most abundant,with relative abundance in the order of A(28.26%)>Y(26.74%)>YA(22.61%).The relative abundance of Gemmatimonadaceae and Nocardioidaceae increased to 4.06% and 2.43% in Y treatment,respectively,while the relative abundance of Pseudomonas was obviously improved under A treatment(P<0.05).The relative abundance of Microvirga rose in all the three different treatments in comparison with that of the control.The content of soil total nitrogen,total phosphorus,and available phosphorus significantly elevated in Y and YA treatments.RDA suggested the significant correlation of bacterial community structure with soil pH,total nitrogen,available phosphorus,and available potassium(P<0.05),and Spearman correlation analysis suggested the significant or highly significant positive correlation of relative abundance of Pseudomonadaceae with the total nitrogen,total phosphorus,available phosphorus,and available potassium.[Conclusion]Application of A.niger agent alone or in combination with amino oligosaccharin water aqua in watermelon under protected cultivation can improve bacterial diversity,abundance of beneficial bacteria,soil physicochemical properties,and soil fertility.The findings lay a basis for the development of microbial agent with A.niger and the rational application in watermelon cultivation.