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New miscanthus R&D projects at INRA
Relatively unknown in Europe, Miscanthus giganteus is now in the European spotlight as a biofuel crop. It is high yielding, rich in lignocellulose and requires little agricultural inputs. Growing this crop on a large-scale in France will involve developing cropping systems that seek to optimise energy balances and minimise environmental impact. Several INRA teams have joined forces with other research teams to combine the adaptation of crop management sequences with genetic improvement of the plant.
ADVANTAGES OF MISCANTHUS
Miscanthus giganteus is a perennial grass originally from Asia It boasts two particularly interesting qualities for biofuel production: it produces a large amount of biomass and requires few inputs.
The exceptionally high yield of miscanthus is due to its "C4" carbon metabolism, which is similar to other plants of tropical origin such as maize, sugarcane and sorghum. This type of metabolism means it can more efficiently capture carbon gas and transform it into organic material.
Moreover, miscanthus is a perennial plant, coming back every year based on rhizomes that it has developed underground. After being planted, it will produce crops for more than 15 years. The first year is delicate because it is the time during which the plant establishes its root system. Plant growth is slow and competition with weeds is steep. The use of herbicides allows the plant to establish itself satisfactorily. At the end of the first year, the crop is ground and returned to the soil, thus creating a surface bed that limits weed growth. In the following years, the crop grows quickly and does not require herbicides. Nor does miscanthus call for the use of fungicides or insecticides.
ADAPTATION OF CROP MANAGEMENT SEQUENCES
Optimal crop conditions are required for miscanthus to express its full potential. In 2006, INRA researchers set up experimental miscanthus plantations as part of the REGIX project (1).
These trials began simultaneously with seven potentially attractive species for energy production. These included three "C4" species (miscanthus, switchgrass and sorghum, the first two of which are perennial), three annual "C3" species (triticale, alfalfa and fescue) and plantations of poplars as short-rotation coppice (SRC).
Researchers will measure the quantity and quality of the biomass with respect to each species and for varying crop conditions. INRA researchers will study the quality of the biomass for its transformation into fuel : depending on whether the conversion of lignocellulose into ethanol or wood is based on a biological or thermochemical method, the crucial parameters are (i) the content of minerals, such as silica or chlorine, that are undesirable in the thermochemical method, and (ii) the water content and lignin/cellulose ratio, which influence the fermentation yield in the biological method.
Ideally, miscanthus should be harvested in the months of February and March, when the leaves have fallen and restored nitrogen levels to the soil. It is, however, possible to harvest earlier in order to use the leaf biomass. In this case, it is necessary to carry out nitrogenous fertilisation in order to provide for the following year's needs. It is also important to consider the risks involved in soil compaction due to winter harvesting in moist soil. Researchers will analyse all these crop conditions and their consequences on long-term soil development, as well as the physical and organic state of the soil.
In addition to these studies, a project was initiated in 2007 to study the genetic variability of miscanthus for agriculturally valuable traits, including production of above-ground biomass, traits associated with flowering biology and physiology of nitrogen metabolism. This research is the first step in studying the genetic determinism of miscanthus biomass production under abiotic stress (nitrogen availability, temperature conditions of the air and soil, water availability, etc.) in view of creating varietal innovations designed for Northern Europe and for use in bioenergy.
Within the framework of the French “Pole de Compétitivité” "Industries et Agro-ressources" situated in the Picardy and Champagne-Ardenne regions, the entire inter-disciplinary programme involves, on a local level, the agronomists and geneticists from INRA, Lille and the Estrées-Mons agro-environmental platform, and on a regional level, the biologists from Université de Lille and the physiologists of nitrogen metabolism from Université d'Amiens as well as specialists in biofuels from INRA-Reims.
More broadly, all the agronomic and genetic research falls under the "Renewable Carbon Resources" topic, which INRA seeks to expand by recruiting additional researchers. This research will be conducted in collaboration with other INRA teams and, at European level, with the leading agronomists and geneticists specialising in miscanthus (e.g. BBSRC, Wageningen University and Research Centre, Bioenergy NoE).