| In the Loess Plateau region of China,the natural ecosystem is fragile,and the desertification and vegetation destruction is serious.Therefore,it is urgent to improve the ecological environment.The implementation of the national policy of returning farmland to forests and grasslands has effectively improved the ecological environment.Many studies have shown that the above-ground parts of different plants are inseparable from the underground part of the soil.Both the exudates of the roots of plants and the litter on the ground change the physical and chemical properties of the soil and the structure of the bacterial community of the soil..Therefore,the effective use of the ecological principle of rhizosphere allelopathy is conducive to the sustainable development of grassland ecosystems.In this paper,there are four typical forages in the Loess Plateau:Bothriochloa ischaemum(Bothriochloa ischaemum(L.)Keng.),Festucaelatior(Keng ex E.Alexeev),Melilotus(Melilotus suaveolens Ledeb.),Melissitus ruthenica(L.)CW Chang,a research object,used high-throughput sequencing technology to compare the diversity of bacteria in the rhizosphere soil between different species,and with the rhizosphere and non-rhizosphere soils.The main results of the correlation analysis between physicochemical properties and enzyme activities are as follows(1)The four species of grass roots richness(Chao1,Ace)index and diversity index(Shanno)were all expressed as grass rhinoceros>flat kidney bean>white sheep grass>tall fescue>non-rhizosphere soil.The non-rhizosphere soil bacteria Chaol,Ace,Shanno had the lowest.The rhizosphere soil bacteria Chao1,Ace and Shanno were the highest.The data shows that the bacteria richness in the rhizosphere soil of leguminous plants is higher than that in the rhizosphere soil of Gramineae plants.(2)It was found that the contents of catalase,sucrase,phosphatase,urease and protease in B.ischaemum were significantly higher than those in F.arundinacea,C.oleifera,M.ruthenica and non-root.Soil samples;the other three grass root soil enzyme activities and non-rhizosphere soil no significant difference.(3)The comparative study on the physicochemical properties of four grass-root and non-rhizosphere soils showed that the pH values of all four grasses were weakly alkaline;the rhizosphere effects of available potassium and available phosphorus in four grass roots were obvious;The available phosphorus content was the highest among several grasses.The available potassium of rhizosphere soil was the highest among the four grasses,and there was no significant difference between other nutrient substances and non-rhizosphere soil.(4)Using Pearson's correlation analysis,the relationship between five enzyme activities and eight soil physical and chemical properties of four herb plants was obtained:there was a significant positive correlation between protease and organic matter in rhizosphere soils,and rhizosphere soils.There was a very significant negative correlation between available potassium and sucrase,and at the same time there was a significant negative correlation between the content of available potassium and urease activity(5)Correlation analysis of soil bacterial community and soil physicochemical properties and soil enzyme activity resulted in the following conclusions:There was a significant positive correlation between catalase and actinomycetes,and the number and roots of acid bacteria bacilli.There is a significant positive correlation between the total phosphorus content in the soilTherefore,the abundance and diversity of bacteria in four rhizosphere soils are represented by rhizosphere soil of leguminous herb>rhizosphere soil of herbaceous plants>non-rhizosphere soil.The content of Actinobacteria in the rhizosphere soil of B.ischaemum was much higher than that in the non-rhizosphere soil at the level of the gate,and the planktonella in the four grass rhizosphere soil microorganisms showed obvious difference compared with the non-rhizosphere soil.Decrease;planting four kinds of grass make different changes in the levels of bacteria,gates,orders,families,and genus of soil.The results showed that the enzyme activities of the rhizosphere soil of B.ischaemum were the highest among the four grasses,and the physicochemical properties of B.japonica Rhizosphere soil organic matter content,R.arborescens quick-available potassium content,and available phosporous phosphorus content were the highest among the 8 properties.By using correlation analysis and partial correlation analysis,it was found that there was a negative correlation between available potassium,sucrase and urease,and there was a positive correlation between protease and organic matter;four kinds of grass catalase were positively correlated with actinomycetes,and total phosphorus and acid.Bacillus is positively related. |
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