Volunteer Establishment of Miscanthus × giganteus Vegetative Propagules: Implications for Biofuel Production
Criticisms regarding the efficiency of first generation biofuel feedstock have prompted the development of sustainable alternatives in the form of dedicated perennial biomass crops. Perennial species are appealing due to high productivity and environmental plasticity, traits that are also consistent with invasive flora. While they present a viable alternative to maize-based ethanol, widespread cultivation of perennial biomass crops may provide opportunities for dissemination into novel environments. Of the top candidates being considered for production, Miscanthus × giganteus is believed to pose little risk, owing primarily to its putative sterility. Vegetative reproduction however, does not necessarily limit widespread invasion, as seen in giant reed (Arundo donax). In fact, little is known about the invasive potential of M.× giganteus even though production has already begun in the Midwest. In order to determine the establishment potential of M.× giganteus, vegetative propagules (plug plantlets, rhizomes, and stem cuttings) were placed under 5 cm of soil (control), underneath mulch, or on top of the soil surface (directly exposed to desiccation). Separate experiments were performed to assess the effect of competition and water addition on these treatments. The relative contribution of these factors on survival (the presence of above ground growth), shoot height, and shoot number were evaluated. Under field conditions, Miscanthus × giganteus plug plants and rhizomes generated shoots and continued to do so through a second year of growth; however, there was significant variation in overall performance, with plug plants being somewhat more successful (greater survival and shoot height) than rhizomes. Stem cuttings initially generated shoots across all planting treatments, but by mid-August all had died. Miscanthus × giganteus is more likely to establish from vegetative propagules when buried under 5 cm of soil or underneath mulch than when on the soil surface. Survival of surface planted propagules was low, but shoot height increased when neighboring plant density was high. Although water addition promoted shoot height early on in the growing season, it had no effect on final survival or shoot height. There is evidence, however, to suggest that water availability increased shoot production. Miscanthus × giganteus established under environmental conditions propagules may encounter upon escape. This is significant considering central Ohio was experiencing abnormally dry conditions throughout the duration of this experiment. This study is among the first to demonstrate the establishment potential of Miscanthus × giganteus vegetative fragments.
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