| Podocarpus macrophyllus is an ancient plant left over from the Cretaceous Tertiary.It has potential application value in landscape,medicine,forest interplanting and other fields,and has good social and economic benefits.In order to explore the effects of different compound fertilization ratios.Application on root nodulation and root microbial community diversity of P.macrophyllus.Use two-year-old seedlings of P.macrophyllus were selected as the research object.Three factors and three levels of orthogonal experiment design were adopted.The rhizosphere and non-rhizosphere soils of P.macrophyllus were collected with different ratios of nitrogen,phosphorus and potassium as influencing factors.The relationship between soil microbial diversity in rhizosphere environment of P.macrophy,llus and its combination of fertili Department.The internal change mechanism between microbial population diversity and richness of root soil of P.macrophyllus and the ratio of compound fertilization and nitrogen application level was revealed,and the optimum compound ratio affecting Rhizosphere Soil Microenvironment of P.macropjhyllus was screened out.The results are as follows:(1)The number of microbial bacteria,actinomycetes,fungi and nitrogen-fixing bacteria in root soil of P.macrophyllus reached 106,105,104 and 103 orders of magnitude respectively under different N,P and K fertilization ratios.The number of bacteria and actinomycetes decreased with the increase of nitrogen application level,while the number of fungi and nitrogen-fixing bacteria increased with the increase of nitrogen and phosphorus content.Among them,the number of nitrogen-fixing bacteria and fungi reached the maximum at N3P3K2 level,13.23*103Cfu/ml and 4.67*104Cfu/ml,respectively.The number of bacteria and actinomycetes reached the maximum at the ratio of N1P1K1 fertilization,18.10*106 Cfu/ml and 19.47*105Cfu/ml,respectively.There was a significant negative correlation between bacteria and fungal nitrogen-fixing bacteria and actinomycetes,a significant positive correlation between fungi and nitrogen-fixing bacteria,and a significant negative correlation between actinomycetes and fungi.Except actinomycetes,the total number of other three microorganisms was significantly higher than that of non-rhizosphere soil,and the total number of four microorganisms was the largest under N3P2K1 treatment,and bacteria>Actinomycetes>fungi>nitrogen fixing bacteria.(2)The activities of protease,invertase,phenoloxidase and peroxidase in rhizosphere soil of P.macrophyllus were higher than those in non-rhizosphere soil,and the activities of urease and acid phosphatase were lower than those in non-rhizosphere soil.The sucrose activity of protease,urease and acid phosphatase increased with the increase of nitrogen application level,while the activities of phenoloxidase and peroxidase decreased with the increase of nitrogen application level.At the same nitrogen level,acid phosphatase activity was positively correlated with phosphorus content,and increased with the increase of phosphorus content,sucrase activity was lower.The sucrase and protease in rhizosphere soil of P.macrophyllus were positively correlated,phenoloxidase and peroxidase were positively correlated,and sucrase was negatively correlated.Peroxidase and acid phosphatase were positively correlated with other enzymes respectively,and the changes of oxidase and peroxidase were similar in each treatment,but were poorer in each treatment.The difference is not obvious.Comprehensive analysis showed that the activity of soil enzymes in rhizosphere of P.macrophyllus was urease>protease>acid phosphatase>invertase>peroxidase>oxidase.(3)Microbial biomass C and N in rhizosphere soil of P.macrophyllus were higher than those in non-rhizosphere soil under different N,P and K fertilization ratios.Microbial biomass C increased with the increase of nitrogen application level,but there was no significant difference between the treatments with the same nitrogen level.Microbial biomass N increased first and then decreased with the increase of nitrogen application level,but the content of microbial biomass C and N in non-rhizosphere soil was low and the difference was not significant.SMBC/SMBN was higher in rhizosphere soil than in non-rhizosphere soil under different fertilization ratios.The microbial biomass C was negatively correlated with phenoloxidase,peroxidase activity,bacteria and actinomycetes,positively correlated with sucrase,protease,urease,acid phosphatase,fungi and azotobacter.Microbial biomass N was positively correlated with urease,protease,Azotobacter and fungi,and positively correlated with peroxidase and acid phosphatase.Enzyme activity,bacteria and actinomycetes were negatively correlated.(4)The AWCD values of root soils of P.macrophyllt.us were stable after 120 hours of cultivation,and N1>N2>CK>N3.AWCD values of non-rhizosphere soils were N1>N2>N3.Shannon diversity index was rhizosphere>non-rhizosphere,and it was N1>N2>N3,N1P1K1 was the best,Simpson index was rhizosphere>non-rhizosphere>CK,and N:2>N3>N1,N1P3K1 was the best,and N2P2K3 was the best in non-rhizosphere soil.McIntos index was higher than CK in the control group,and reached the highest level under N3 treatment.Pielou evenness index is N1>N2>N3.The diversity index of microorganisms in rhizosphere and non-rhizosphere soil was correlated with soil urease,and urease became the dominant enzyme activity factor affecting diversity index.(5)Based on the analysis of the composition of carbon sources used by microorganisms in rhizosphere soil of P.macrophyllus,the carbon sources used by microbial communities in rhizosphere and non-rhizosphere soil of P.macrophyllus are mainly carbohydrates,carboxylic acids,amino acids and polymers.PCI was 40.24%in rhizosphere soil,PC2 was 47.32%and the cumulative contribution rate was 87.56%.PC1 was 38.70%in non-rhizosphere soil,PC2 was 45.20%and the cumulative contribution rate was 83.90%.Both rhizosphere and non-rhizosphere principal components could better explain most of microbial information.(6)The number of nodules of P.macrophyllus increased first and then decreased with the increase of N application level,and the activity of nitrogenase decreased with the increase of N application level.The activity of nitrogenase was positively correlated with bacteria,actinomycetes,urease,phenoloxidase and peroxidase.(7)Comprehensive analysis showed that the soil indicators of P.macrophyllus showed good under the combination of N3 and P2,and the Rhizosphere Soil Microenvironment of P.macrophyllus under the combination of N3 and P2 fertilization was more suitable for root growth of P.macrophyllus. |
PDF Full Text Request