Impacts of Soil-Moisture Stress On Growth of Cultivars of Miscanthus Sinensis, a Species Important to Bioenergy Crop Development

Although it has been observed that Miscanthus sinensis, which is a widely cultivated ornamental crop and a candidate bioenergy feedstock, tolerates extreme water conditions in its native range in East Asia, not much is known about how extreme water conditions impact its growth and development. We postulated that while M. sinensis grown under well-watered conditions will exhibit high levels of growth, low levels of water availability will not negatively impact plant growth nor carbon-fixation rates. Potted replicates of two high-yielding ornamental cultivars Miscanthus sinensis ‘ Silverfeather‘ and Miscanthus sinensis ‘Malepartus‘ were subjected under greenhouse conditions to three levels of soil moisture: flooded (45% volumetric water content (VWC)), well-watered (25% VWC), and drought (15% VWC).  Soil moisture was maintained by an automatic irrigation system that monitored and maintained the prescribed moisture of each plant.  Agronomic traits such as height, tiller number, and mass were recorded to compare treatment effects. Across treatments, plants in the high-moisture treatment developed more tillers than those in the medium and low-moisture treatments.  Root-to-shoot ratio was highest in the high-moisture treatment.  Interestingly, photosynthetic activity of both cultivars was lowest at the high-moisture level. Across treatments, M. sinensis ‘Malepartus’ appeared to be best suited to the range of soil moistures, generating more mass, height, and exhibiting higher net photosynthetic rates, but further research is needed to confirm these findings.  This research may motivate those in the field of bioenergy production to consider selecting both M. sinensis cultivars for further development.  If M. sinensis is able to sustain tolerance to extremes in water availability in the field, it is possible it could be produced where the highly productive Miscanthus x giganteus is unable to develop high yields under unirrigated conditions.