Does propagation method affect yield and survival? The potential of Miscanthus×giganteus in Iowa, USA

As a sterile hybrid, Miscanthus×giganteus must be vegetatively propagated. Previous work has shown that propagation method may negatively impact not only yield of M.×giganteus, but also winter survival. However, these studies only considered rhizome and micropropagated M.×giganteus. Recently, stem propagated plants have also become available to the US market. Similar to micropropagation, these propagules do not rely on rhizomes to produce planting stock, but little is known about the yield potential or survival of stem propagated plants in the field. Here we addressed these questions in a replicated, side-by-side comparison of rhizome and stem propagated plants at three sites in Iowa, USA. We found no propagule related differences in above- or belowground biomass, establishment losses or winter losses of M.×giganteus. Yields averaged 24.7 (±3.5)Mgha^-1. Though M.×giganteus productivity frequently peaks in the third year after planting, second year yields in Iowa were not significantly different than third. Additionally, winter mortality was very low, averaging only 1.2% during the first two winters. Establishment mortality, however, was significantly greater (P<0.0001) and averaged 23.7%. We found M.×giganteus is productive in Iowa, with yields similar or higher than other US trials, and that stem propagated M.×giganteus performed very similarly to rhizome propagated M.×giganteus. While much research has been conducted on cold tolerance and winter survival in M.×giganteus, future research should also address establishment losses to reduce planting costs, the major upfront expense in M.×giganteus production.