Emery, S. M., E. R. Kinnetz, L. Bell-Dereske, K. A. Stahlheber, K. L. Gross, and D. Pennington. 2018. Low variation in arbuscular mycorrhizal fungal associations and effects on biomass among switchgrass cultivars. Biomass and Bioenergy 119:503-508.
Switchgrass (Panicum virgatum) is a leading perennial bioenergy feedstock crop candidate in North America, with more than 20 cultivars commercially available. In native prairies, switchgrass is known to be strongly dependent on arbuscular mycorrhizal fungi (AMF), but little is known about AMF in switchgrass bioenergy systems. AMF can alter crop yield and belowground ecosystem functioning, so knowing if AMF vary among switchgrass cultivars may improve development of sustainable bioenergy systems. Using a common garden experiment in Michigan, USA, we examined whether twelve switchgrass cultivars, representing both lowland and upland ecotypes, were associated with shifts in AMF, and if this variation was related to aboveground or belowground crop biomass. Cultivars did not differ in AMF root colonization, extraradical hyphal growth, or soil AMF diversity. However, AMF root colonization was 6% higher in lowland compared to upland ecotypes. While cultivars differed in above- and belowground biomass, only one measure of AMF – root colonization – was significantly correlated with root biomass, and no measures of AMF were correlated with yield. AMF are often more important to plant production in sites that are nutrient or water stressed, and so AMF effects on switchgrass establishment and growth may be more important when grown on marginal lands. Future studies of AMF associations with and effects on production of switchgrass cultivars should be done across a range of conditions reflective of the environments in which they will be grown for bioenergy feedstock.
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