Editorial overview: Physiology and metabolism: CO2 concentrating mechanisms in photosynthetic organisms: evolution, efficiency and significance for crop improvement

With a dry biomass production exceeding 40 Mg ha−1 in many environments, Miscanthus spp. is the most productive perennial C4 grass species thanks to five advantages over North American prairie tallgrasses. However, miscanthus has a slower nutrient remobilization system, resulting in higher nutrient concentrations at harvest. Perennial C4 grasses benefit from soil microbial associations, reducing their nutrient needs. For combustion purposes, grasses with low moisture content, high lignin and low nutrients are desired. For ethanol, preferred feedstock will have lower lignin, higher sugars, starch, or cellulose/hemicellulose depending on the conversion method. Species with high stem-to-leaf ratio provide better biofuel conversion efficiency and quality. Recently-developed transgenic switchgrass lines have much higher ethanol yields and lower transformation costs. Further selection and breeding are needed to optimize biomass quality and nutrient cycling.