| Soil quality and fertility are the basis for measuring land productivity,soil microorganisms play an important role in indicating soil fertility.Master the changes in soil quality and the dynamic trends of nutrients,it plays an early warning and monitoring role in soil quality.As an important part of the soil ecosystem,soil fungus participate in the nutrient cycling process of the soil.Its senstive to environmental changes,mainly through fungal community structure and diversity.Soybean is an important cash crop in China,and its growth process is closely related to the rhizosphere soil microorganisms.Rhizosphere fungal community plays a key role in the rhizosphere nutrient cycling of soybean.The study on the community composition and diversity characteristics of rhizosphere soil fungus in different growth stages of soybean and to find out the main environmental factors related to the dynamic changes of fungus,evaluating the effects of growth stages on soil fungal diversity,and then it is of great significance to promote soybean production.In this study,the rhizosphere soil samples from four different soybean pre-planting,branching,flowering and pod-forming stages and maturity were selected as research areas in the ecological test field of the Academy of Agricultural Sciences of Heilongjiang Province,collect soil samples,and determine 7 soil physical and chemical properties indicators and 5 soil enzyme activity indicators,study on the changes of physical and chemical properties and enzyme activities in soybean rhizosphere soil with different growth stages;using the traditional microbial culture method to determine the fungus numbers,fungal community structure was determined by high throughput sequencing technology,to explore the relationship between the number of fungi,the composition of fungal community and the physicochemical property of soil and enzyme activities.In order to clarify the changes of rhizosphere fungal community structure,soil enzyme activity and soil physical and chemical properties in different growth stages,and providing a theoretical support for assessing changes in rhizosphere soil quality and nutrients during soybean growth.The main results were as follows:The analysis of soil physical and chemical properties indicated that during the growth of soybean,the pH value of rhizosphere soil ranged from 6.60 to 6.80,which was close to neutral.From branching to maturity,soil organic matter and total nitrogen showed a trend of increasing first and then decreasing,and the content of flowering and pod-forming period was higher;The content of available P and available potassium in the whole soil decreased first and then increased,and the content in the flowering and pod-forming period was lower.The conductivity decreased with the growth of the growth phase,and the EC value was the lowest at the flowering stage.The water content showed a continuous upward trend,the multiple physical and chemical properties of soybean rhizosphere soil have certain changes with the advancement of growth period.It indicated that nutrient accumulation in soybean rhizosphere soil during flowering and pod-forming period,and the rate of rapid nutrient absorption was faster.Therefore,before soy planting,base fertilizer can be applied to ensure the growth of the branching period,in the flowering period,it is necessary to chase the accelerated nutrient to meet the needs of plant growth.The soil enzyme activity analysis showed that the urease,acid phosphatase and catalase in the rhizosphere soil from branching to maturity increased first and then decreased,and the enzyme activity was highest in the flowering and pod-forming stage.The activity of cellulase in the rhizosphere soil of Y2 increased first and then decreased,while the activity of cellulase in the rhizosphere soil of ZP,Y1 and Y3 decreased first and then increased;The activities of invertase in the rhizosphere soil of ZP,Y2 and Y3 generally showed a trend of decreasing,while the activity of invertase in the rhizosphere soil of Y1 decreased first and then increased.It indicated that the level of enzyme activity in soybean rhizosphere soil showed certain changes due to the growth period,but it also showed certain differences due to different varieties.The number of fungi and community composition analysis showed that the number of rhizosphere fungi in ZP continued to decrease with the advancement of soybean growth period,while the number of rhizosphere fungi in Y1,Y2 and Y3 increased first and then decreased.The number of rhizosphere fungi is characterized by developmental growth period> pre-planting period;The dominant fungi of soybean rhizosphere soil include: Basidiomycota and Ascomycota(relative abundance>10%).The Shannon-Wiener index,Ace index and Chao index showed a trend of decreasing first and then increasing with the growth period.That is to say,the diversity of soybean rhizosphere fungi is shown as follows:pre-planting stage>maturation stage>flowering pod-forming stage>branched stage,it indicates that the change of soybean growth period determines the dynamic changes of rhizosphere fungal community,the alpha diversity of soil fungi increased significantly from the branching stage to the maturity stage.The correlation between the number and diversity of fungi and soil physical and chemical properties and enzyme activities showed that: pH mainly affects the number of ZP rhizosphere fungi and the Ace diversity index,water content mainly affects the number of rhizosphere fungi in Y2.acid phosphatase activity mainly affects the number of rhizosphere fungi in Y1 and Y3.Meanwhile,the number of rhizosphere fungi in Y3 was also significantly negatively correlated with the content of available phosphorus(P<0.05).The organic matter content mainly affects the Ace diversity and Chao diversity index of Y2 rhizosphere fungi,the available phosphorus content mainly affects the Ace diversity and Chao diversity index of Y3 rhizosphere fungi,while the Shannon diversity index is mainly affected by CAT activity.The results showed that the number and diversity of rhizosphere fungi were mainly influenced by multiple environmental factors. |
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