Species selection determines carbon allocation and turnover in Miscanthus crops: Implications for biomass production and C sequestration

• Published in: The Science of the total environment Vol. 887; p. 164003
• Main Authors: Briones, M.J.I., Massey, A., Elias, D.M.O., McCalmont, J.P., Farrar, K., Donnison, I., McNamara, N.P.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.08.2023
• Subjects: 13CO2 pulse labelling; Biomass; Carbon; Carbon Dioxide; Carbon storage; Crops, Agricultural; Miscanthus lutarioriparius; Miscanthus sinensis; Miscanthus × giganteus; Poaceae - physiology; Soil; Soil respiration; Miscanthus × giganteus; 13CO2 pulse labelling; Miscanthus sinensis; Miscanthus lutarioriparius; Soil respiration; Carbon storage; CO pulse labelling
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.164003

Growing Miscanthus species and hybrids has received strong scientific and commercial support, with the majority of the carbon (C) modelling predictions having focused on the high-yield, sterile and noninvasive hybrid Miscanthus × giganteus. However, the potential of other species with contrasting phenotypic and physiological traits has been seldom explored. To better understand the mechanisms underlying C allocation dynamics in these bioenergy crops, we pulse-labelled (13CO2) intact plant-soil systems of Miscanthus × giganteus (GIG), Miscanthus sinensis (SIN) and Miscanthus lutarioriparius (LUT) and regularly analysed soil respiration, leaves, stems, rhizomes, roots and soils for up to 190 days until leaf senescence. A rapid isotopic enrichment of all three species was observed after 4 h, with the amount of 13C fixed into plant biomass being inversely related to their respective standing biomass prior to pulse-labelling (i.e., GIG < SIN < LUT). However, both GIG and LUT allocated more photoassimilates in the aboveground biomass (leaves+stems = 78 % and 74 %, respectively) than SIN, which transferred 30% of fixed 13C in its belowground biomass (rhizomes+roots). Although less fixed 13C was recovered from the soils (<1 %), both rhizospheric and bulk soils were signficantly more enriched under SIN and LUT than under GIG. Importantly, the soils under SIN emitted less CO2, which suggests it could be the best choice for reaching C neutrality. These results from this unique large-scale study indicate that careful species selection may hold the success for reaching net GHG mitigation. [Display omitted] •A better understanding of the C allocation dynamics in Miscanthus bioenergy crops is needed.•We pulse-labelled (13CO2) intact plant-soil systems of three Miscanthus species for up to 190 days.•Miscanthus giganteus and M. lutarioriparius allocated more photosynthates into above-ground biomass.•M. sinensis crops transferred 30 % of fixed 13C in its belowground biomass and emitted less CO2.•Careful selection of Miscanthus species may hold the success for reaching net GHG mitigation.