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United States Department of Agriculture

Agricultural Research Service

Research Project: SOIL AND CROP MANAGEMENT SYSTEMS FOR IMPROVED NATURAL RESOURCE QUALITY AND EFFICIENCY

Location: North Central Agricultural Research Laboratory

Title: Increasing diveristy of arbuscular mycorrhizal fungi in agroecosystems using specific cover crops

Authors
item Taheri, Wendy
item Lehman, R

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 20, 2014
Publication Date: March 4, 2014
Citation: Taheri, W.I., Lehman, R.M. 2014. Increasing diveristy of arbuscular mycorrhizal fungi in agroecosystems using specific cover crops. Proceedings of Great Plains Soil Fertility Conference, Denver CO, March 4-5, 2014.

Interpretive Summary: Cover crops reduce fallow periods and provide a plant host for obligate symbiotic arbuscular mycorrhizal fungi (AMF) during these otherwise fallow periods. The fungi, AMF, colonize the roots of most crops and provide the crop with multiple benefits in terms of soil fertility, drought protection, pest protection, and pathogen resistance. Many conventional agricultural practices can reduce AMF numbers. Cover cropping increases AMF numbers in soil and their colonization of cash crop roots, and increases plant P uptake and growth. Host plant benefits may vary according to the individual AMF species; however, there are little data regarding how AMF species diversity varies with agricultural management practices. We examined four prospective cover crops (oats, spring wheat, hairy vetch, crimson clover) for the diversity of AMF colonizing their roots. The four cover crop species were compared for their ability to retain AMF present in a diverse soil inoculum. Using DNA analyses, we found that oats retained the highest AMF diversity compared to the other three cover crops. Wheat retained the least AMF diversity and was predominately colonized by a single AMF species. Hairy vetch and crimson clover had intermediate AMF diversity indicating that legumes may stimulate additional benefits to plants via soil microorganisms, beyond fixed nitrogen. Cover crop mixtures that include oats seem particularly likely to increase AMF numbers and diversity and produce the largest amount of benefits for following cash crops.

Technical Abstract: Fall-planted cover crops provide a plant host for obligate symbiotic arbuscular mycorrhizal fungi (AMF) during otherwise fallow periods and thus may increase AMF numbers in agroecosystems. Increased AMF numbers should increase mycorrhizal colonization of the subsequent cash crops, which has been linked to more efficient utilization of soil nutrients by crops as well as drought resistance, pathogen resistance, and pest protection. Host plant benefits may vary according to the individual AMF species; however, there are little data regarding how AMF species diversity varies with agricultural management practices. We examined four prospective cover crops (oats, spring wheat, hairy vetch, crimson clover) for the diversity of AMF colonizing their roots. A replicated greenhouse study was conducted where the four cover crop species were compared for their ability to retain AMF present in a diverse soil inoculum. Using rRNA gene sequence analyses, we found that oats retained the highest AMF diversity compared to the other three cover crops. Wheat retained the least AMF diversity and was predominately colonized by a single AMF species (Rhizophagus sp.). Hairy vetch and crimson clover had intermediate AMF diversity indicating that legumes may stimulate additional benefits to plants via soil microorganisms, beyond fixed nitrogen. Cover crop mixtures that include oats seem particularly likely to increase AMF numbers and diversity.

Last Modified: 10/20/2014
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