As a potential energy crop with high biomass yield, Miscanthus lutarioriparius (M. lutarioriparius), endemic to the Long River Range in central China, needs to be investigated for its acclimation to stressful climatic and soil conditions often found on the marginal land. In this study, traits related to acclimation and yield, including survival rates, plant height (PH), stem diameter (SD), tiller number (TN), water use efficiency (WUE), and photosynthetic rates (A), were examined for 41 M. lutarioriparius populations that transplanted to the arid and cold Loess Plateau of China. The results showed that the average survival rate of M. lutarioriparius populations was only 4.16% over the first winter but the overwinter rate increased to 35.03% after the second winter, suggesting that plants having survived the first winter could have acclaimed to the low temperature. The strikingly high survival rates over the second winter were found to be 95.83% and 80.85%, respectively, for HG18 and HG39 populations. These populations might be especially valuable for the selection of energy crops for such an area. Those individuals surviving for the two consecutive winters showed significantly higher WUE than those measured after the first winter. The high WUE and low stomatal conductance (g_s) observed in survived individuals could have been responsible for their acclimation to this new and harsh environment. A total of 61 individuals with productive growth traits and strong resistance to cold and drought were identified for further energy crop development. This study showed that the variation of M. lutarioriparius held great potential for developing energy crops following continuous field selection.

Miscanthus interspecific hybrids have been proved to have better adaptability in marginal lands than their parents. Miscanthus sacchariflorus and Miscanthus lutarioriparius were used as the parents to develop hybrids. We performed the transcriptome for 110 F1 hybrids of Miscanthus sacchariflorus × Miscanthus lutarioriparius and their parents that had been established on the Loess Plateau mine area, to estimate the population’s genetic expression variation, and illuminate the adaptive mechanism of the F1 population. The result speculated that the F1 population has mainly inherited the stress response metabolic pathway of its female parent (M. sacchariflorus), which may be responsible for its higher environmental adaptability and biomass yield compared with male parents. Based on PopART, we assembled a leaf reference transcriptome for M. sacchariflorus (LRTMS) and obtained 8116 high-quality transcripts. When we analyze the differential expression of genes between F1 population and parent, 39 and 56 differentially expressed genes were screened out in the female parent and male parent, respectively. The enrichment analysis showed that pathways of carbohydrate metabolism, lipid metabolism, biosynthesis of secondary metabolites and circadian rhythm-plant played a key role in resisting the harsh environment. The carbohydrate metabolism and lipid metabolism were also significantly enriched, and the synthesis of these substances facilitated the yield. The results provided an insight into breeding Miscanthus hybrids more suited to the harsh environment of the Loess Plateau.

The greenhouse gas (GHG) mitigation is one of the most important environmental benefits of using bioenergy replacing fossil fuels. Nitrous oxide (N2O) and methane (CH4) are important GHGs and have drawn extra attention for their roles in global warming. Although there have been many works of soil emissions of N2O and CH4 from bioenergy crops in the field scale, GHG emissions in large area of marginal lands are rather sparse and how soil temperature and moisture affect the emission potential remains unknown. Therefore, we sought to estimate the regional GHG emission based on N2O and CH4 releases from the energy crop fields. Here we sampled the top soils from two Miscanthus fields and incubated them using a short-term laboratory microcosm approach under different conditions of typical soil temperatures and moistures. Based on the emission measurements of N2O and CH4, we developed a model to estimate annual regional GHG emission of Miscanthus production in the infertile Loess Plateau of China. The results showed that the N2O emission potential was 0.27 kg N ha−1 year−1 and clearly lower than that of croplands and grasslands. The CH4 uptake potential was 1.06 kg C ha−1 year−1 and was slightly higher than that of croplands. Integrated with our previous study on the emission of CO2, the net greenhouse effect of three major GHGs (N2O, CH4 and CO2) from Miscanthus fields was 4.08 t CO2eq ha−1 year−1 in the Loess Plateau, which was lower than that of croplands, grasslands and shrub lands. Our study revealed that Miscanthus production may hold a great potential for GHG mitigation in the vast infertile land in the Loess Plateau of China and could contribute to the sustainable energy utilization and have positive environmental impact on the region.