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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #163158
Title: ARBUSCULAR MYCORRHIZAL FUNGI-MEDIATED NITROGEN TRANSFER FROM VINEYARD COVER CROPS TO GRAPEVINES

Author
item CHENG, XIAOMEI - UC-SAREP
item Baumgartner, Kendra

Submitted to: Biology and Fertility of Soils
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2004
Publication Date: 8/10/2004
Citation: Cheng, X., Baumgartner, K. 2004. Arbuscular mycorrhizal fungi-mediated nitrogen transfer from vineyard cover crops to grapevines. Biology and Fertility Soils. 40: 406-412.

Interpretive Summary: Cover crops are often planted in between vineyard rows to reduce soil erosion, increase soil fertility, and improve soil structure. Roots of both grapevines and cover crops are colonized by beneficial root-inhabiting soil microbes known as arbuscular mycorrhizal (AM) fungi. Root systems of grapevines and cover crops may be connected by the vegetative fungal strands (hyphae), through which nutrients may be transferred from one plant to the other. To study nutrient transfer from cover crops to grapevines through AM fungal links, we grew grapevines and cover crops in specially-designed containers in the greenhouse that restricted their root systems to separate compartments, but allowed AM fungi to colonize both root systems. There were two cover crop treatments: a grass (Bromus hordeaceus) and a legume (Medicago polymorpha). We applied a stable isotope of nitrogen (label), 15N, to cover crop leaves and collected grapevine leaves at two, five, and ten days after labeling. At five and ten days after labeling, we detected 15N in grapevines leaves, demonstrating that N can be transferred from grapevines to cover crops via AM fungal links. N transfer was significantly greater from the grass to the grapevine than from the legume to the grapevine. Possible reasons for the differences between the two cover crops include lower 15N in legume roots, higher biomass of grass roots, and/or differences in AM fungal community composition. Further studies are needed to investigate N transfer from grapevines to cover crops and determine the net N transfer between the two plant species throughout their growing seasons, in order to understand the significance of AM fungi-mediated interplant nutrient transfers to grapevines grown in the field.

Technical Abstract: Cover crops are often planted in between vineyard rows to reduce soil erosion, increase soil fertility, and improve soil structure. Roots of both grapevines and cover crops can form mutualistic symbioses with arbuscular mycorrhizal (AM) fungi, and may be interconnected by AM hyphae. To study nutrient transfer from cover crops to grapevines through mycorrhizal links, we grew grapevines and cover crops in specially-designed containers in the greenhouse that restricted their root systems to separate compartments, but allowed AM fungi to colonize both root systems. There were two cover crop treatments: a grass (Bromus hordeaceus) and a legume (Medicago polymorpha). We labeled cover crop leaves with 99 atom% 15N solution for 24 hours and analyzed 15N content of grapevine leaves at two, five, and ten days after labeling. Our results showed evidence of AM fungi-mediated 15N transfer from cover crops to grapevines at five and ten days after labeling. N transfer was significantly greater from the grass to the grapevine than from the legume to the grapevine. Possible reasons for the differences between the two cover crops include lower 15N enrichment in legume roots, higher biomass of grass roots, and/or differences in AM fungal community composition. Further studies are needed to investigate N transfer from grapevines to cover crops and determine the net N transfer between the two plant species throughout their growing seasons, in order to understand the significance of AM fungi-mediated interplant nutrient transfers to grapevines grown in the field.