Nicholas N. Boersma

Miscanthus: A Promising Biomass Crop

The C4 grass Miscanthus × giganteus is of increasing interest as a biomass feedstock for renewable fuel production. This review describes what is known to date on M. × giganteus from extensive research in Europe and more recently in the US. Research trials have shown that M. × giganteus productivity is among the highest recorded within temperate climates. The crops high productivity results from greater levels of seasonal carbon fixation than other C4 crops during the growing season. Genetic sequencing of M. × giganteus has identified close homology with related crop species such as sorghum (Sorghum bicolor (L.) Moench) and sugarcane (Saccharum officinarum L.), and breeding of new varieties is underway. Miscanthus × giganteus has high water use efficiency; however, its exceptional productivity causes higher water use than other arable crops, potentially causing changes in hydrology in agricultural areas. Nitrogen use patterns are inconsistent and may indicate association with N fixing microorganisms. Miscanthus × giganteus has great promise as an economically and ecologically viable biomass crop; however, there are still challenges to widespread commercial development.

Effects of temperature, illumination and node position on stem propagation of Miscanthus × giganteus

The sterile triploid Miscanthus × giganteus is capable of yielding more biomass per unit land area than most other temperate crops. Although the yield potential of M. × giganteus is high, sterility requires all propagation of the plant to be done vegetatively. The traditional rhizome propagation system achieves relatively low multiplication rates, i.e. the number of new plants generated from a single‐parent plant, and requires tillage that leaves soil vulnerable to CO2 and erosion losses. A stem‐based propagation system is used in related crops like sugarcane, and may prove a viable alternative, but the environmental conditions required for shoot initiation from stems of M. × giganteus are unknown. A study was conducted to investigate the effect of temperature, illumination and node position on emergence of M. × giganteus shoots. Stems of M. × giganteus were cut into segments with a single node each, placed in controlled environments under varied soil temperature or light regimes and the number of emerged shoots were evaluated daily for 21 days. At temperatures of 20 and 25 °C, rhizomes produced significantly more shoots than did stem segments (P = 0.0105 and 0.0594, respectively), but the difference was not significant at 30 °C, where 63% of stems produced shoots compared to 80% of rhizomes (P = 0.2037). There was a strong positive effect (P = 0.0086) of soil temperature on emergence in the range of temperatures studied here (15–30 °C). Node positions higher on the stem were less likely to emerge (P < 0.0001) with a significant interaction between illumination and node position. Planting the lowest five nodes from stems of M. × giganteus in 30 °C soil in the light resulted in 75% emergence, which represents a potential multiplication rate 10–12 times greater than that of the current rhizome‐based system.

Autumnal leaf senescence in Miscanthus × giganteus and leaf [N] differ by stand age.

Highlight This chronosequence field experiment found unexpected differences in leaf senescence symptoms between different aged Miscanthus×giganteus stands, potentially indicating differential senescence with plant age and nutrient status.