U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Crops Pathology and Genetics Research: Davis, CA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    Outreach Events
                        UC Davis Picnic Day
                                    Kinders go to College
                                    STEM Girls
                                    Future Scientist Program
                                    Agriculture Future of America
                                    Wallace-Carver Fellowship
                                    Young Scholars Program
                                    Annual Awards Banquet
                    About Us
                        About Us
                                    Our Mission
                                    Principal InvestigatorsSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Davis, California Crops Pathology and Genetics Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications
- Etiology and Biology of Tree Crop Diseases
- Rice Genetics
- Sustainable Floriculture
- Sustainable Viticulture

Title:   Author  item
                                            Baumgartner, Kendraitem
                                            CHENG, XIAOMEI - PLANT PATHOLOGY UC DAVIS
  Submitted to: American Society of Enology and Viticulture Annual Meeting Abstracts
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 4/1/2006
                                    Publication  Date: 6/29/2006
                                    Citation: Baumgartner, K., Cheng, X. 2006. Microbial utilization of nitrogen from vineyard cover crops. American Society of Enology and Viticulture Annual Meeting Abstracts.Interpretive Summary: Arbuscular mycorrhizal (AM) fungi are one of few groups of soil microbes that have been shown to benefit grapevine nutrition.  Previously, we showed that their fungal filaments (external hyphae) can serve as “bridges” for nitrogen (N) transfer from vineyard cover crops to grapevines.  The objectives of this study were to evaluate the contribution of AM fungi to N uptake from a cover crop that is incorporated into the soil, bur medic (Medicago polymorpha), and to characterize the soil microbial response to the decomposing cover crop under the influence of mycorrhizal roots or external hyphae.  Grapevines were grown in specially-designed containers, within which a mesh core was inserted.  The mesh allowed mycorrhizal roots (roots + hyphae), external hyphae alone, or neither to access ground cover crop shoots (leaves and stems) labeled with a stable isotope of N, 15N, and placed inside the mesh cores.  Grapevines and soils were harvested 0, 7, 14, and 28 days after addition of the cover crop, and analyzed for 15N content.  External hyphae increased 15N uptake from the litter (62 μg), but their contribution relative to that of the mycorrhizal roots (927 μg) was small.  We detected similar peaks in soil microbe populations supported by the hyphae alone (37 nm g-1 soil) and in soil microbe populations supported by mycorrhizal roots (38 nm g-1 soil).  Our results suggest that although grapevine roots play a dominant role in the direct uptake of nutrients from tilled cover crops, AM fungi may have a more important role in maintaining soil microbial communities associated with nutrient cycling.
                                Technical Abstract: Arbuscular mycorrhizal (AM) fungi are one of few groups of soil microbes that have been shown to benefit grapevine nutrition.  Previously, we showed that external hyphae of AM fungi can serve as bridges for nitrogen (N) transfer from no-till cover crops to grapevines.  The objectives of this study were to evaluate the contribution of AM fungi to N uptake from a tilled cover crop, bur medic (Medicago polymorpha), and to characterize the soil microbial response to the decomposing cover crop under the influence of mycorrhizal roots or external hyphae.  Grapevines were grown in specially-designed containers, within which a mesh core was inserted.  The mesh allowed mycorrhizal roots (mycorrhizosphere treatment), external hyphae (hyphosphere treatment), or neither to access 15N-labeled cover crop litter placed inside the cores, after 4 months of grapevine growth.  Grapevines and soils were harvested 0, 7, 14, and 28 days after addition of the litter.  External hyphae increased 15N uptake from the litter (62 μg), but their contribution relative to that of the mycorrhizal roots (927 μg) was small.  We detected similar peaks in soil microbial biomass in the hyphosphere (37 nm g-1 soil) and mycorrhizosphere treatments (38 nm g-1 soil) after addition of the litter, despite significantly lower microbial biomass in the hyphosphere treatment initially (10 nm g-1 soil).  Our results suggest that although grapevine roots play a dominant role in the direct uptake of nutrients from tilled cover crops, AM fungi may have a more important role in maintaining soil microbial communities associated with nutrient cycling.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov