Genome biology of the paleotetraploid perennial biomass crop Miscanthus

Miscanthus is a perennial wild grass that is of global importance for paper production, roofing, horticultural plantings, and an emerging highly productive temperate biomass crop. We report a chromosome-scale assembly of the paleotetraploid M. sinensis genome, providing a resource for Miscanthus that links its chromosomes to the related diploid Sorghum and complex polyploid sugarcanes. The asymmetric distribution of transposons across the two homoeologous subgenomes proves Miscanthus paleo-allotetraploidy and identifies several balanced reciprocal homoeologous exchanges. Analysis of M. sinensis and M. sacchariflorus populations demonstrates extensive interspecific admixture and hybridization, and documents the origin of the highly productive triploid bioenergy crop M. × giganteus. Transcriptional profiling of leaves, stem, and rhizomes over growing seasons provides insight into rhizome development and nutrient recycling, processes critical for sustainable biomass accumulation in a perennial temperate grass. The Miscanthus genome expands the power of comparative genomics to understand traits of importance to Andropogoneae grasses.

Long-Term Productivity of Thirteen Lowland and Upland Switchgrass Ecotypes in the Mediterranean Region

Switchgrass (Panicum virgatum L.) has been identified in the USA as an ideal biomass crop, in relation to its wide environmental suitability, mainly linked to the availability of both upland and lowland ecotypes, allowing the possibility of growing this species in most of the North American region. Switchgrass is conventionally grown for forage, but more recently, it has been considered as a model biofuel crop. Early European studies on switchgrass as a bioenergy crop started in the late 1990s, when a multi-location field trial was established in Greece (Aliartos) and Italy (Ozzano) to compare the productivity of 13 switchgrass genotypes, including upland (Carthage, Blackwell, Caddo, CIR, Forestburg, SU 94-1, Summer) and lowland (Alamo, Kanlow, Pangburn, SL 93-2, SL 93-3, SL94-1) genotypes. The scope was to identify the most suitable ecotype within each environment and, possibly, the best performing variety. The trials lasted 17 years (1998–2014) in Greece and 13 years (1998–2010) in Italy. While in Italy the trial was rainfed and unfertilized, in Greece, where the soil was marginal, drip irrigation was always applied, and the plots were fertilized regularly. The biomass yields in Greece, as averages across the 17 years, were similar for the lowland and upland varieties (11.5 vs. 11.1 Mg ha−1, respectively), while in Italy, as averages across the 13 years, the differences were relevant: 15.4 vs. 11.3 Mg ha−1 for lowland and upland, respectively. Alamo (lowland) was the most productive variety, both in Greece and Italy, with average annual yields of 12.7 and 16.6 Mg ha−1, respectively; CIR in Greece (10.1 Mg ha−1) and Forestburg in Italy (9.1 Mg ha−1) (both upland) were the least productive genotypes. The present results demonstrate the good suitability of switchgrass as biomass crop for the Mediterranean climate. Despite the very marginal soil (i.e., very shallow and with a sandy texture) in the Greek trial, the application of regular fertilization and irrigation produced biomass yields above 11 Mg ha−1 (grand mean) in the present 17-year-long study.

The Impact of the Biomass Crop Assistance Program on the United States Forest Products Market: An Application of the Global Forest Products Model

As the largest consumer of petroleum and second highest producer of greenhouse gas emissions, the United States currently is a leading country in bioenergy production driven by a series of policies. One such public program that directly subsidizes biomass feedstock growers is the Biomass Crop Assistance Program (BCAP), which recently received attention for stimulating the development of bioenergy. However, critiques were also raised, concerning the possibility of intensifying the feedstock competition between bioenergy and forest products. This study, therefore, aimed at assessing the effects of BCAP on the forest product markets with the Global Forest Products Model (GFPM). Three alternative scenarios were designed to simulate three payments in BCAP. In the first scenario, the matching payment was simulated by adjusting the manufacturing cost of fuelwood and particleboard. In the second scenario, establishment payment was simulated by adjusting the supply rate of industrial roundwood. In the third scenario, the annual payment was simulated by linking the supply change rate with the soil rental rate for industrial roundwood. We found that, under the matching payment scenario, industrial roundwood and particleboard will experience a sharp decrease in production and an increase in price. For establishment payments, industrial roundwood will experience a continuous increase in production and a decrease in price. For annual payments, the industrial roundwood will experience a V-shape pattern production.