Collection, Nutrient Cycling, Cold Hardiness, Photosynthetic Capacity, and Flowering Phenology of Miscanthus sacchariflorus, Miscanthus sinensis, and Their Natural Hybrids in Native Stands Ranging from Central to Northern Japan

Principal Investigator: Ryan Stewart, U of Illinois
Co-PIs: Fabian Fernandez, German Bollero
Faculty Researchers: Toshihiko Yamada, Aya Nishiwaki
Postdocs: Yo Toma, Lauren Quinn
Gradute Students (Hokkaido and Miyazaki Universities): Hiroya Matuura, Sachi Yamaguchi, Shotaro Kuwabara, Shohei Sato, Yahuhisha Kajihara, Natsumi Iizuka, Fuyuko Hazama, Yuuta Nabeoka, Ayano Kishimoto, Miya Okada, Akane Kitagawa
Consultant: Theresa Culley
Collaborators: Adam Davis, David Matlaga

Although a potential biofuel crop, Miscanthus, is native throughout much of Asia, the most promising cultivar to put into production in the United States is currently Miscanthus x giganteus, which was originally collected in Japan in the 1930s and is a cross between Miscanthus sacchariflorus and Miscanthus sinensis. Research has been done in Europe and the U.S. over the past 10-30 years to determine its agronomic potential. While this crop has many superior traits relative to other potential biofuel crops, limitations, disadvantages, and information gaps exist concerning this cultivar. These include factors such as a lack of needed genetic diversity; its unknown long-term nutrient requirements (most research on nutrient cycling has been on stands less than 12 years old); unknown nutrient uptake and carbon sequestration at different depths in the soil profile; poor overwintering performance at more northern latitudes in Europe; and the difficulty of making new crosses due to non-overlapping flowering times of its parent species.

The rich natural and extensive cultural histories of Miscanthus (common names: silvergrass, susuki) in Japan provides us with a unique opportunity to address these issues.  Several Miscanthus species are native throughout the islands of Japan and are the dominant species in many grassland communities. Many of these grasslands have been annually burned for several hundred years to prevent forest succession of this culturally valued species throughout Japan. Other Miscanthus grasslands have been grazed or mowed for many years. These unique cultural phenomena have resulted in unexpected benefits for the development of biofuel feedstocks.

We will be collecting much-needed data in Japan required to project the long-term impacts of Miscanthus production in the U.S. on carbon sequestration, nutrient cycling, and fertilizer requirements. Miscanthus has incredible potential because it represents an energy source from recycled carbon; it has been proposed that Miscanthus cultivation increases not only the amount of soil organic carbon, but also its long-term stability. We will be measuring nutrient uptake of established natural and semi-natural (i.e., annually burned) stands of M. sacchariflorus and M. sinensis in northern Japan. We will analyze both soil samples within the rooting profile of Miscanthus and vegetative tissue samples over the growing season.

We will also be assessing the depth of cold hardiness of M. sinensis, M. sacchariflorus, and their natural hybrids collected from central and northern Japan. Identifying selections of Miscanthus that are relatively cold hardy – particularly that of the natural hybrid – could expand the potential cultivation of this biofuel crop into areas with harsher climates, thus enabling larger harvests. It may also lead to earlier emergence of Miscanthus crops, which will potentially expand its growing season and subsequent yield. Depth of cold hardiness will be measured in field-based studies and laboratory freezer tests in northern Japan. These studies will be repeated over a three-year period.

In addition, we will be measuring the photosynthetic capacity of M. sinensis, M. sacchariflorus, and their natural hybrids in the same areas where plants were collected for the cold hardiness tests. We will be making leaf-level gas-exchange measurements over the course of a diurnal period on several days over three complete growing seasons.  Identifying selections of Miscanthus, particularly cold-hardy strains, which have similar or greater photosynthetic capacity than the widely cultivated M. x giganteus cultivar, may lead to greater yields in agricultural areas in the U.S.

We will also evaluate the environmental conditions that have allowed the flowering period of M. sacchariflorus and M. sinensis to overlap where the two species occur in the same areas. Certain factors limit the widespread use of the currently mass-propagated M. x giganteus cultivar, which include its limited freeze tolerance of the overwintering rhizome in northern latitudes, lack of genetic diversity, limited capability to fulfill all its potential uses, and the increased risk of disease by planting it over large areas. Attempts to cross the parent species to create new selections of M. x giganteus have been incredibly difficult; M. sacchariflorus and M. sinensis generally flower at different times of the year under the same climatic conditions.

While flowering time is considered to be a heritable trait, it is also sensitive to environmental cues such as temperature, moisture, and photoperiod. Monitoring these different parameters will enable us to shed light on the optimal method to artificially induce flowering in M. sacchariflorus and M. sinensis to develop improved selections of M. x giganteus.

Another objective of our project is to collect germplasm of M. sacchariflorus, M. sinensis, and their natural hybrids to develop a public germplasm collection at the University of Illinois Energy Farm.  The primary goal of the collection will be to understand the extent of variation in the wild germplasm.  Traits that will possibly be evaluated both at the Energy Farm and of identical selections in northern Japan (to gain a better understanding of the effect of the environment on the expressed traits) include, among others, yield potential, low-temperature tolerance, and disease resistance.

2009 Project Update:
Miscanthus sinensis and M. sacchariflorus germplasm was collected from several locations in northern Hokkaido, Japan that have severe winter climates. This past summer, putative natural hybrid seed of M. sinensis and M. sacchariflorus was also collected in southern Japan. The nutrient cycling patterns of a several-hundred-year-old M. sinensis grassland in southern Japan and a 40-year-old M. sinensis grassland in northern Japan were investigated. Stable isotope measurements indicate that C4 species have primarily contributed to carbon accumulation in the high soil-organic matter andisol soil at the site in southern Japan. Measurement of the carbon budget at the northern site indicates the grassland serves as a carbon sink. It also appears that phosphorus and potassium are limiting factors for growth of M. sinensis at this site. In order to characterize the potential differences between native and introduced populations of M. sinensis, several ecological traits of conspecific plants and their habitats were measured at five and seven populations in Japan and the United States, respectively. At each site, leaf samples were collected for DNA analysis to compare genetic structure within and among populations. Future studies will examine the influence of  soil properties as well as climate variables to determine environmental limitations for this species in both the native and introduced ranges.