Study On Soil Microenviroment Of Bamboo Forests And Its Interplanting With Bletilla Striata

Bamboo and orchid are both important species of Chinese traditional culture plants.Because of their special aesthetic significance,bamboo and orchid are often seen in ancient and modern gardens in China.In recent decades,all kinds of bamboo have been widely used in urban green space system,forming a bamboo landscape with high ornamental value and certain ecological and economic value.However,in the process of bamboo landscape application,many problems were gradually exposed,such as bamboo forest undergrowth landscape mode single,few suitable ornamental plants under the forest and simple plant configuration,etc.,which led to some phenomena,such as monotonous landscape spatial structure of bamboo forest,low plant community diversity,miscellaneous shrub growth under the forest and bare soil,etc.Bletilla striata is a kind of perennial terrestrial orchid with high landscape and medicinal value.In recent years,domestic scholars have carried out some introduction screening and demonstration application studies in Shanghai and other areas,and found some problems,such as less configuration mode,sporadic cultivation under deciduous trees such as metasequoia;In small-scale open-air planting,the green leaf period is short and the leaves are scorched in midsummer.The flowering effect is not good under evergreen plants.In this study,the existing Phyllostachys edulis,Phyllostachys iridescens and Phyllostachys glauca forests interplanted with B.striata in The Bamboo Garden of Shanghai Chenshan Botanical Garden were selected as experimental plots.Using Illumina Miseq high-throughput sequencing technologies,the field experiment,soil physical and chemical index analysis and plant physiology experiment,carried out different urban green space landscape of bamboo soil microenvironment and understory planting B.striata research,clear the status of soil microenvironment in bamboo forest,understand the growth state of B.striata under bamboo forest and the community composition of endophytic fungi in its root.The combination pattern of bamboo forest and B.striata with good ornamental and ecological value was selected.It provides data support and research ideas for planting B.striata under different green bamboo forests.This paper has obtained the following research results:(1)The soil TP,AP,OM,TN,TK and EC in different bamboo stands were significantly changed.Actinobacteriota,Proteobacteria,Acidobacteriota and Chloroflexi were the dominant phyla of bamboo soil bacteria,while Ascomycota and Basidiomycota were the dominant phyla of fungi.The composition of soil microbial community varies greatly among different bamboo forests.The relative abundance of Actinobacteriota and Chloroflexi was the highest in P.glauca soil,while that of Proteobacteria and Myxococcota was the highest in P.edulis soil.There was no significant difference in dominant phylum of soil fungi among different bamboo forests,but there were significant changes in class and lower level,for example,Sordariomycetes,Leotiomycetes and Eurotiomycetes were the dominant bacteria in the soil of P.glauca forest,P.iridescens forest and P.edulis forest.In addition,at the level of OTU,soil bacterial Sobs index and Shannon index of P.edulis were the highest,while soil bacterial sobs index and Shannon index of P.glauca were the lowest.Bacterial community structure and abundance were significantly correlated with soil PH,NN,EC,TP,AN,MC,AK and MBC,while the fungal community was significantly affected by TP,EC and TK.Bamboo forest soil has strong metabolic capacity and high relative abundance of metabolic function genes,which is beneficial to promote the absorption and utilization of nutrients by plants.(2)The root endophytic fungal community composition of B.striata root was significantly differed under different bamboo forests and densities,and soil bulk density,light intensity and N:P had significant effects on the root endophytic fungal community composition of B.striata.The Ace and Shannon indices of B.striata endophytic fungi were the highest under P.iridescens forest,and the lowest under P.glauca forest.Basidiomycota and Serendipita are predominant in P.edulis and P.iridescens forests,while Ascomycota and Dactylonectria are predominant in P.glauca forests.The abundances of Basidiomycota and Serendipita increased with the increase of bamboo density in P.edulis forest,while the abundances showed an opposite trend in P.Iridescens forest.Basidiomycot and Serendipita may help the growth and development of B.striata.The abundance of Symbiotroph fungi in B.striata roots was the highest in P.edulis and P.iridescens forests,which varies with density,Saprotroph fungi were the most abundant in P.glauca.(3)Bamboo forest type and density significantly affected the growth and development of B.striata.P.edulis forest had the longest green period of B.striata,which provides the most suitable environment for the growth of roots,tubers,stems and leaves.However,B.striata under P.edulis forest had yellow leaf tips in mid-summer,and the landscape effect was poor.In P.iridescens,B.striata has the highest green stage under low density,and the plant height and leaf length have advantage among the three bamboo forests.Compared with underground,the growth of aboveground part is more important of B.striata in P.iridescens forests,the plant is tall and compact,veins are clear and obvious,which is suitable for landscape application.B.striata grew poorly in P.glauca forest,with the shortest green stage and little difference among density groups.(4)The physiological indexes of B.striata were significantly affected by different bamboo environments.B.striata had the highest net photosynthetic rate,stomatal conductance and transpiration rate under P.edulis forest,while P.iridescens and P.glauca forests had the lowest photosynthetic capacity and higher intercellular carbon dioxide concentration.There were no significant differences in photosynthetic parameters of B.striata leaves in different density groups under the P.iridescens and P.glauca forests,and the highest photosynthetic parameters of B.striata leaves in P.edulis forest were found in middle-density forest.The Fv/Fm of B.striata leaves was lower in P.edulis low-density forest,and q P and ETR decreased with the increase of bamboo density.Nitrogen and phosphorus were mainly concentrated in the tuber of B.striata under the bamboo forest,while potassium mainly existed in the root system.Nutrient contents of B.striata in P.glauca forest were superior,and nitrogen,phosphorus and potassium contents in plant organs were significantly higher than other two groups.In conclusion,there are significant differences in soil microenvironment under different landscape bamboo,and the growth status and endophytic fungal community of B.striata in different landscape have significant influence on bamboo forest environment.B.striata is the best in P.edulis forest medium density environment.B.striata in P.iridescens forest emphasizes the growth of aboveground part and is suitable for landscape application,while B.striata in P.glauca forest is inhibited,and the endophytic fungi are mainly Saprotroph and Pathotroph,so it is not suitable for promotion and application.