| Popis: |
Climate change and a desire for oil independency have stimulated interest in dedicated biomass crops for domestic biofuels production. Miscanthus × giganteus Greef et Deu., an exceptionally productive crop in the Midwestern USA, exhibits many ideal biomass crop traits, notably sterility which decreases invasive potential. Although a labor intensive process, rhizome propagation is the most common method for vegetatively propagating M. × giganteus. Stem propagation, investigated here, alleviates many challenges associated with rhizome production. Utilizing 30 °C soil and the first five nodal stem segments increased M. × giganteus propagation rates 12 fold of reported rhizome multiplication rates. Stem propagated plants (SPs) were field-tested at three sites in Iowa. I found that established SPs and rhizome propagated plants (RPs) yielded similarly, and averaged 24.7 Mg ha-1, similar to other Midwestern trials. Previous work showed that first-year M. × giganteus exhibited poor winter survival. In contrast, I found very high (> 99 %) first winter survival for both SPs and RPs. However, establishment losses for RPs and SPs were very high: 40 times greater than first winter losses. Winter survival was high in Iowa trials, but plants remained green until a killing frost; this observation is blamed for poor winter survival in early M. × giganteus trials. Here, the anecdotal assertion that first-year M. × giganteus exhibits minimal leaf senescence in the first autumn was supported quantitatively by photosynthetic and leaf N measurements. At the end of the first season, M. × giganteus exhibited photosynthetic rates, photosystem II efficiencies and leaf N up to 4, 4 and 2.4 times greater, respectively, than third-year plants, indicating delayed senescence. |
