Several Crop Root Exudates Effects On Soil Microbes

The study of the relationship between root exudates and rhizosphere is an important field of rhizo-microecological research in recent years, which connects plants with rhizosphere microorganisms, and it promotes the rhizosphere microbial research and has an important theoretical and practical significance. Previoμsly, most of studies focused on collecting rhizosphere soil in the process of crop-farming and analysed the changes of microbial activity, which could not avoid the interference of soil inhomogeneity and natural factors. In this paper, sugar beet, corn, and soybean were cultivated by water culture method till the end of seedling stage, the components of root exudates were analyzed, which were colleted separately with aqueous solution extracting and light. Then the root exudates were inoculated into soil samples again, the changing tendency of various microbial activity were observed in the culture process.Sugar beet, soybean, and corn were cultivated in light for 40 days by water culture method. We got three kinds of treated root exudates of the plants that were not subject to nutritional stress and analyzed the components of root exudates from one gram of each fresh plant root that grew for one hour: the total carbon of sugar beet was 5.7722μg and nitrogen was 1.2663μg, three kinds of amino acids was 0.2573μg in total, five kinds of organic acids was 29.9908μg in total, one kind of soluble carbohydrate was 15.7264μg; the total carbon of corn was 9.1007μg, total nitrogen was 1.6127μg, eight kinds of amino acids was 0.3628μg in total , seven kinds of organic acids was 38.6488μg in total, one kind of soluble carbohydrate was 6.9676μg; the total carbon of soybean was 5.6177μg, total nitrogen was 1.1807μg, ten kinds of amino acids was 0.6013μg, three kinds of organic acids was 13.5299μg, one kind of soluble carbohydrate was 16.2011μg.After re-inoculating root exudates into soil samples in the corresponding volume of rhizosphere soil, the soil microorganisms were cultured for 14 days and the changing tendency of various microbial activity were observed: the biomass of bacteria; the biomass of fungi; the biomass of actinomycetes; soil respiratory capacity; microbial biomass Carbon; microbial biomass Nitrogen; the activity of soil enzyme. The trends of the targets indicated that the feature of rhizosphere effect in sugar beet, corn and soybean.THE METHOD IN THE THESIS WAS ADAPT TO STUDY THE RELATIONSHIP BETWEEN ROOT EXUDATES AND RHIZOSPHERE MICROORGANISMS, THE EXCHANGING PROCESS OF ELEMENTS, SUCH AS CARBON AND NITROGEN. A LARGE AMOUNT OF EXPERIMENTAL DATA WAS ACCUMULATED AND CONTRIBUTED TO FUTURE RESEARCH.