Author
|
Submitted to: American Society of Enology and Viticulture Annual Meeting Proceedings
Publication Type: Proceedings Publication Acceptance Date: 4/2/2006 Publication Date: 6/30/2006 Citation: Baumgartner, K. 2006. The role of beneficial mycorrhizal fungi in grapevine nutrition. American Society of Enology and Viticulture Annual Meeting Proceedings. Interpretive Summary: Arbuscular mycorrhizal fungi are beneficial organisms that colonize plant roots. The fungus actually grows within the root itself, within the space between the cell walls and cell membranes of the root cortex. Their fungal filaments or hyphae extend outside of the root into the soil. This increases the surface capacity of the root system since the hyphae are very fine relative to the root dimensions (10 µm in diameter as compared to 3 mm). Mycorrhizal grapevines have improved shoot and root growth, higher tissue concentrations of phosphorus, and improved water relations and drought tolerance. Given the clear benefits of these mycorrhizal fungi, it is important to understand when and how they associate with root systems. The fungi can associate with a wide range of plants. Mycorrhizal weeds and cover crops can, therefore, be an important reservoir or source of these fungi for young grapevine roots. The fungi can also form large colonies or networks in the soil spanning the root systems of multiple plants. A mycorrhizal network may be simultaneously associated with a cover crop and a grapevine. The external hyphae serve as a “bridge” for nitrogen transfer between plants and can take up nitrogen from decaying cover crops that can then be transferred to the grapevine. Since the fungi receive carbon directly from the grapevine, turnover of their external hyphae provides an important source of carbon to feed other microbes in the soil. Technical Abstract: Arbuscular mycorrhizal fungi are beneficial organisms that colonize plant roots. The fungus actually grows within the root itself, within the space between the cell walls and cell membranes of the root cortex. Their fungal filaments or hyphae extend outside of the root into the soil. This increases the surface capacity of the root system since the hyphae are very fine relative to the root dimensions (10 µm in diameter as compared to 3 mm). Mycorrhizal grapevines have improved shoot and root growth, higher tissue concentrations of phosphorus, and improved water relations and drought tolerance. Given the clear benefits of these mycorrhizal fungi, it is important to understand when and how they associate with root systems. The fungi can associate with a wide range of plants. Mycorrhizal weeds and cover crops can, therefore, be an important reservoir or source of these fungi for young grapevine roots. The fungi can also form large colonies or networks in the soil spanning the root systems of multiple plants. A mycorrhizal network may be simultaneously associated with a cover crop and a grapevine. The external hyphae serve as a “bridge” for nitrogen transfer between plants and can take up nitrogen from decaying cover crops that can then be transferred to the grapevine. Since the fungi receive carbon directly from the grapevine, turnover of their external hyphae provides an important source of carbon to feed other microbes in the soil. |
