| China is a large pear producing country and one of the origin countries of pear.Its cultivation area accounts for 70%of the world,and the main pear producing area is Dangshan and the surrounding area is the pear producing area.Anhui Dangshan is the largest continuous pear orchard in the world.Anhui is the largest pear orchard in the world.The golden pear is one of the main varieties of the Xiaoxian the Yellow River old road in Suzhou,Anhui.The Yellow phenomenon of iron deficiency is serious and the whole plant death of the pear trees is serious,which affects the productive interests of the fruit growers.In this study,the roots and rhizosphere soils of the Golden Pear were used as the trial materials in the Huanghe Old Road Garden in Xiaoxian,Suzhou,Anhui Province,The mineral elements in the rhizosphere soil were determined according to the method of soil agrochemical analysis by Bao Shidan,the composition and diversity of microorganisms in the rhizosphere soil were analyzed by metagenomic sequencing,the root pathogens were isolated by tissue separation method,and the pathogenic bacteria were identified by molecular biotechnology,According to Zhou Liquan’s method of soil enzymology,the enzyme activity in rhizosphere soil was studied,in order to find out the relationship between Pear Leaf Chlorosis and Rhizosphere micro environment,to provide a scientific basis for the production of pear,the main results are as follows:（1）The content of nitrogen,available potassium,available sulfur and exchangeable calcium in the rhizosphere soil of yellow leaf yellow is significantly higher than that of the control group.Both of them are no significant difference in the amount of phosphorus,boron,manganese,copper,zinc,available iron,effective phosphorus,effective boron,effective manganese,effective copper,effective zinc,exchangeable magnesium,exchangeable potassium,exchangeable sodium,organic matter,and TFe2O3content.so p H value does.The content of Cr in the rhizosphere soil of yellowing pear leaves was significantly lower than that of the control group.There was no significant difference in the contents of Ni,Pb,Mo,Hg and Cd between the two groups.The content of total nitrogen,available potassium and exchangeable calcium in the rhizosphere soil of yellow leaf yellow was enriched,and the absorption of nutrients in the root system changed obviously,which changed the proportion of nutrients in the tree,which was a kind of nutritional disorder.（2）The Urease activity of leaf yellowing and normal golden pear rhizosphere soil was significantly higher than that of the other three enzymes,and the Urease activity of the rhizosphere soil with pear tree of leaf yellowing was significantly lower than that of the control group.The activities of Invertase and Peroxidase in the rhizosphere soil with yellowing pear leaves were significantly higher than those of the control group,but there was no significant difference in Catalase activity.In a period of time,the rhizosphere soil of golden pear with yellow leaves has high fertility and fertility,and more nutrients are used for plant absorption,which is another manifestation of the symptoms of the imbalance of soil nutrition.（3）According to macro-sequencing analysis,The ratio of bacteria content in rhizosphere soil of pear with yellow leaves was significantly lower than that of control group,which was 70.3%and 78.2%respectively.The content of Archaea in the rhizosphere soil of pear with yellow leaves was significantly higher than that of the control group,13.2%and 5.4%respectively.There was no significant difference in the contents of Eukaryota and unclassified between them.The microbial content of Nitrososphaeraceae,Nitrososphaera,Nitrospira and Nitrososphaera viennensis in the golden pear rhizosphere soil were significantly lower than that of the control group from the three dimensions of the microbial species.The microbial diversity index of the golden pear rhizosphere soil-Shannon index,was not significantly different from the control group.Compared with the control group,the quality of the Rhizosphere Soil Microenvironment was not suitable for a large number of beneficial microbes in the soil.However,there is a small amount of ammonia oxidizing archaea in the control group,which may play an important role in the nitrogen cycle of the earth’s ecosystem.（4）Pythium spinosum,Fusarium solani,and Ilyonectria macrodidyma isolated from the roots of golden pear in the horticultural field of Huanghe Old Road Garden in Xiaoxian,Suzhou,Anhui Province.The fungus may cause root rot pathogens,but only Neurospora intermedia is isolated from the control group,which is a beneficial bacteria.The endophytic bacteria isolated from the root system of Golden Pear are non-pathogenic bacteria.According to the existing research,it can be initially identified that Pythium spinosum,Fusarium solani,and Ilyonectria macrodidyma are pathogens of the root rot of Golden Pear.After the roots were rotted,the pears can not absorb enough nutrients,resulting in weakened tree vigor and leaf yellowing. |
