The impact of soil salinity on the yield, composition and physiology of the bioenergy grass Miscanthus × giganteus

High salinity land may provide an alternative resource for the cultivation of dedicated biomass crops for renewable energy and chemicals, thus avoiding competition for land use with food crops. The commercial perennial grass Miscanthus × giganteus is a leading biomass crop; however, its response to salt stress is largely unknown. Miscanthus × giganteus was grown in pots irrigated with nine different NaCl concentrations (0, 2.86, 5.44, 7.96, 10.65, 14.68, 17.5, 19.97 and 22.4 dS m^-1). Biomass yield was reduced by 50% at 10.65 dS m^-1 NaCl. Root dry matter inhibition occurred at the highest salt concentration tested, while rhizome dry weight and the ratios of root/rhizome and below-/above-ground dry matter were not affected by elevated salinity. The accumulative effect of increasing salinity reduced stem height and elongation, while photosynthesis was reduced to a smaller extent. The duration and strength of salinity exacerbated the reduction. Water use efficiency (WUE) was maintained except at the highest salinity and plants maintained stomatal conductance (g_s) and leaf water content at low to moderate salinity. Miscanthus × giganteus showed strong induction of the osmoprotectant, proline and no significant increase in malondialdehyde content under increasing salinity. The ash content in leaves, increased, reducing the biomass quality at high salinity concentrations. The effects of salinity on the yield and the availability of land area in European geographical area for agriculture were investigated. Understanding the potential for growth of the C4 biomass crop Miscanthus on underutilized or abandoned land may offer a new range of targets for improved economics, crop management and breeding.