The Rhizosphere Microbial Diversity During The Growth Period Of Continuous Cropping Potato And The Effect Of Fertilization

Continuous cropping obstacles are the most common problems in potato production.Due to inadequate research on its mechanism,rotation or fallow methods are currently used to overcome them.Current research on the mechanism of potato continuous cropping obstacles focuses on the physical and chemical properties of soil,enzyme activity,and accumulation of some toxic substances in continuous cropping.Only a few studies have involved soil microorganisms.Rhizosphere microorganisms are the key factors to maintain nutrient cycling in soil ecosystems,and their richness and diversity are responses to plant health,soil fertility,and climate change.At present,the soil microbial community has been intensively studied in many model crops,such as Arabidopsis,wheat,and rice.Although it has been proved that soil rhizosphere microorganisms are important for improving stress resistance,disease resistance,yield and quality,it is still unclear how the rhizosphere microbial community changes with crop growth and how it interacts with soil physical and chemical properties.However,there are few reports on the study on the change of rhizosphere microbial diversity in the whole growth period of continuous cropping potato by metagenomic method.This paper intends to reveal the obstacles and the continuous potato cropping obstacles by studying the law of dynamic changes of rhizosphere microorganisms during the whole growth period of potato,the correlation between soil rhizosphere microbial diversity and soil physical and chemical properties,and the effects of top dressing on rhizosphere microbial communities and soil physical and chemical properties.Revealing the relationship between potato continuous cropping obstacles,soil rhizosphere microbial diversity and soil physical and chemical properties,provides a theoretical basis for the development of new technologies and product development(such as biological bacterial fertilizer research and development,field fertilizer management,etc.)to overcome potato continuous cropping obstacles.This paper was conducted in the potato production area of Tengzhou,Shandong Province,using continuous cropping soil of 5 years.It was divided into 6 periods: planting period,seeding period,initial flowering period,full flowering period,end flowering period,and harvesting period,and the whole growth period was sampled for 2 years.At the same time,on the basis of continuous cropping,the effects of topdressing on the change characteristics of rhizosphere microbial diversity and the change of soil physical and chemical properties were determined and analyzed without topdressing.The sequences of bacterial 16 S r RNA in V3-V4 region and fungal ITS region were sequenced based on Illumina highthroughput sequencing technology,and the main nutrient content,enzyme activity,pH and electrical conductivity of potato rhizosphere soil at different stages were determined.The results showed that: 1.During the whole growth process of continuous cropping potato,soil rhizosphere microbial diversity changed significantly.The rhizosphere microbial community changed significantly at the seeding stage compared with the first stage of potato pre-planting and stabilized from the flowering stage,and then experienced relatively small changes until the potato matured.2.In the bacterial communities,Proteobacteria,Actinobacteria,Bacteroidetes and Acidobacteria had relative abundance of more than 70% in the whole growth process,which were the dominant phyla.Compared with that before planting,the relative abundance of Acidobacteria and Saccharibacteria increased significantly at harvesting stage,and that of Actinobacteria,Gemmatimonadetes,and Chloroflexi decreased significantly.3.In the fungal communities,the relative abundance of Ascomycota and Basidiomycota reached more than 70% in the whole growth period,which was the dominant fungi.Compared with the sowing period,Basidiomycota increased significantly and Ascomycota decreased significantly.4.With the change of growth period,soil physical and chemical properties and soil enzyme activities all changed to different degrees.The results of correlation analysis showed that there was a close correlation between the physical and chemical properties of soil and the diversity of microorganisms in rhizosphere soil,and the richness of bacteria and fungi was significantly correlated with the physical and chemical properties.5.The microbial diversity after topdressing showed an increasing trend,and the abundance of main phyla also changed significantly.For example,the relative abundance of Actinobacteria,Gemmatimonadetes,Chloroflexi,Firmicutes and Basidiomycota all increased significantly.The relative abundance of Proteobacteria,Bacteroidetes and Ascomycota decreased significantly.6.Application of topdressing increased the content of total nitrogen,total phosphorus,alkali-hydrolyzed nitrogen,available phosphorus,available potassium,urease and sucrase in soil.In summary,the rhizosphere microbial community diversity and soil physical and chemical characteristics of continuous cropping potato changed with different growth stages,and topdressing could reshape the rhizosphere microbial community structure and improve the microbial community diversity.