Comparative Study On Root Physiology And Rhizosphere Soil Microenvironment Of Reed In Different Habitats

Phragmites australis is a perennial grass of Gramineae.Reed is highly adaptable to the environment,and it is one of the main constructive species in desert,marsh and wetland of northwest China.In recent years,significant progress has been made in the division of reed ecological types in different habitats,ecological functions,genetic variation and phenotypic plasticity of reeds in heterogeneous habitats.However,there are few reports on the relationship between rhizosphere soil microenvironment and root physiology of reed.Therefore,reed roots and rhizospheric soil in four habitats(sand dune habitat,transitional habitat from saline to sand dune,saline habitat,marsh habitat)of Linze county were used as the research material,the reed rhizospheric soil property indexes,soil microbial quantity,soil fertility indexes,reed rhizome indexes of growth and physiological indexes were measured and analysed.The results showed:(1)The water content of reed rhizosphere increased successively in sand dune habitat,transitional habitat from saline to sand dune,salt habitat and marsh habitat,the salt content of reed rhizosphere soil also increased successively in addition to marsh habitat.With the transition from saline habitat to sand dune habitat and then to marsh habitat,the contents of organic matter,alkali hydrolyzed nitrogen,available phosphorus and activities of invertase,catalase,urease and phosphatase increased gradually in rhizosphere soil of reed.The activity of reed roots were the weakest under saline habitat,and the superoxide anion production rate a nd the content of MDA,proline of the reed root in saline habitat was the highest among the four habitats,The content of MDA in roots of reed in saline habitat was 68.18%,39.49%and 34.61% higher than that in marsh habitat,sand dune habitat and transitional habitat from saline to sand dune,respectively.The content of soluble protein and soluble sugar reached the highest in the transitional habitat from saline to sand dune.The activities of antioxidant enzymes in reed roots were the highest in dune habitat,followed by saline habitat,transitional habitat from saline to sand dune and marsh habitat.(2)Compared with the development of rhizome in four habitats,from salt habitat to transitional habitat from saline to sand dune,sand dune habitat,and then to marsh habitat,which were manifested in the shortening trend of internodal length,the thickening trend of pitch diameter,the increasing trend of rhizome length,adventitious bud number,rhizome water content and biomass of rhizome.There were significant differences in the number of rhizospheric soil microorganisms among the four habitats,the highest salt content of reed rhizospheric soil,the largest number of soil fungi,the smallest number of bacteria and actinomycetes were found in salt habitat.The smallest number of fungi and the largest number of bacteria and actinomycetes existed in marsh habitat.The B/F values of marsh habitat,transitional habitat from saline to sand dune and dune habitat were 4.03 times,1.62 times and 2.92 times of that of saline habitat,respectively.(3)The correlation analysis of relevant data showed that the decrease of water content and the increase of salt content in rhizosphere soil of reed,the reed root activity reduced,membrane lipid peroxidation aggravated,and these changes were corresponded with the decrease of soil fertility related enzyme activity;and reed had adjusted antioxidant enzyme activity and osmotic solute in roots to adapt to the changing habitats.The number of soil bacteria,actinomycetes and B/F value were the main influencing factors of rhizome length,rhizome node diameter,rhizome b iomass,rhizome water content,plant height and basal diameter of reed,while soil fungi were the main influencing factors of rhizome node spacing of reed.Soil bacteria,fungi,actinomycetes and B/F were the main factors affecting the number of adventitio us buds.Soil bacteria,actinomycetes and B/F values were positively driven,while fungi were negatively driven.Therefore,in heterogeneous habitats,reed can adjust its rhizome characteristics and structure to adapt to different environmental factors.