Influence Of Long-term Fertilization On AM Fungi Community In A Brown Soil

Arbuscular mycorrhizal fungi are widespread in field ecosystems where they form mutualistic associations with the roots of plants.AM fungi can improve the soil environment in the rhizosphere,activate mineral nutrients to facilitate nutrient uptake from the soil via an extensive extraradical mycelium;In addition,it can enhance disease resistance of crop,increase crop yield and improve product quality.The growth of AM fungi is affected by many factors,including soil types,soil nutrients,farming systems,planting patterns,and types and quantities of fertilization.Fertilization affects the community structure of AM fungi by changing the physical and chemical properties of soil,and understand how fertilization affects AM fungi community structure and find out its key impact factors can provide scientific basis for the regulation of AM fungi.At present,there are few studies on the influence of long-term rotation fertilization on structures of AM fungi community in a brown soil.This study is based on the long-term rotation fertilization for 38 years in a brown soil and using PCR-DGGE,cloning and sequencing techniques to analyze the change characteristics of AM fungi community,spores density,infection rate and soil nutrients,and explore the factors on the community structure and colonization of AM fungi under different fertilization treatments in order to provide a theoretical basis for improving soil fertility and increasing crop yield,and regulation of AM fungi in the future,the main results were as follows:?1?Long-term fertilization significantly changed the physical and chemical properties of soil,thus affecting the community structure of AM fungi in brown soil.The diversity index of AM fungi in single fertilizer treatment was significantly higher than that in CK and organic fertilizer,but the diversity of applying organic fertilizer area was lower than that of CK,especially with single application of organic fertilizer.Redundancy analysis showed that pH had significantly negative correlation with the diversity;Canonical Correlation analysis showed AP,AK,TC and NH₄⁺-N significantly influenced the species of AM fungi.Cluster analysis showed that the community structures of AM fungi were divided into two groups,namely,non fertilization group and fertilization group,and their similarity was only 42%under the long-term fertilization.?2?The diversity of AM fungi in soil and the roots of maize did not change uniformly with seasonal variation.Correlation analysis showed the seasonal variation of AM fungi diversity index in soil was positively correlated with soil available K,but the diversity index in root system was negatively correlated with alkali-hydrolysable N.?3?The result of sequencing showed that AM fungi species isolated from soil samples and roots were mainly glomeromycota.There was not only the common dominant population but also the unique dominant population.This showed that long-term fertilization significantly affected the community structure of AM fungi.In different fertilization treatments during the maize growth stage,the most AM fungi species were NPK treatment,while MNP treatments had the least number of species.Among Uncultured Glomus?KP773391.1?is unique dominant population in the treatment of single chemical fertilizer and non fertilization;Uncultured Glomus?EF041038.1??Uncultured Glomeromycota?KM365421.1?is unique dominant population in the treatment of organic fertilizer;Uncultured Glomus?EF041038.1?is the dominant species in maize root colonization.?4?The spore density of AM fungi with M and MNP significantly higher than that of single chemical fertilizer and CK.The spores density of AM fungi was positively correlated with soil nitrogen,soluble organic carbon,available phosphorus and available potassium?P<0.01?,and the infection rate was positively correlated with soil nitrate nitrogen?P<0.05?,and negatively correlated with water content?P<0.01?in soil.In conclusion,long-term fertilization changed AP?AK?TC?AHN?NH₄⁺-N?NO₃^--N?DOC of soil,which had a certain effect on the AM fungi community structure,soil spore density and infection status.Therefore,soil nutrients can be adjusted to improve the diversity,spores density and infection rate of colonization of AM fungi,so as to promote the sustainable development of agriculture.