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Using contaminated land to grow lignocellulosic crops can deliver biomass and, in the long term, improve soil quality. Biostimulants and microorganisms are nowadays an innovative approach to define appropriate phytomanagement strategies to promote plant growth and metal uptake. This study evaluated biostimulants and mycorrhizae application on biomass production and phytoextraction potential of four lignocellulosic crops grown under two metal-contaminated soils. Two greenhouse pot trials were setup to evaluate two annual species (sorghum, hemp) in Italy and two perennial ones (miscanthus, switchgrass) in China, under mycorrhizae (M), root (B2) and foliar (B1) biostimulants treatments, based on humic substances and protein hydrolysates, respectively, applied both alone and in combination (MB1, MB2). MB2 increased the shoot dry weight (DW) yield in hemp (1.9 times more), sorghum (3.6 times more) and miscanthus (tripled) with additional positive effects on sorghum and miscanthus Zn and Cd accumulation, respectively, but no effects on hemp metal accumulation. No treatment promoted switchgrass shoot DW, but M enhanced Cd and Cr shoot concentrations (+84%, 1.6 times more, respectively) and the phytoextraction efficiency. Root biostimulants and mycorrhizae were demonstrated to be more efficient inputs than foliar biostimulants to enhance plant development and productivity in order to design effective phytomanagement strategies in metal-contaminated soil. [ABSTRACT FROM AUTHOR]

Marginal land conversion to perennial energy crops can provide biomass feedstocks and climate change mitigation. However, the effect of perennial energy crop cultivation on soil organic carbon (SOC) sequestration and its underlying mechanism in marginal land still remains incomplete. Here, SOC turnover, stability, and its potential sequestration were evaluated based on 10 years of land use change from C3 grass‐dominated marginal land to C4 energy crops Miscanthus and switchgrass cultivation. The naturally occurring 13C signature down to 60 cm depth was used to determine the energy crops‐derived C. Compared to reference marginal land, Miscanthus plantation increased the SOC stock at 0–60 cm depth by 17.8% and 64.3% in bulk and root zone, respectively. Similarly, the SOC stock under switchgrass was also 16.5% and 93.0% higher in bulk and root zone than in reference marginal land, respectively. The higher SOC stock in the root zone of switchgrass relative to Miscanthus was supported by the higher contribution of C4‐derived C to SOC (44.5% vs. 32.4%). The mean residence time of old C was higher under switchgrass than Miscanthus in the bulk zone across 0–60 cm (p < 0.05) but remained the same at 0–20 cm in the root zone. Specific SOC mineralization and temperature sensitivity were lower in soils under Miscanthus and switchgrass compared to reference marginal land. The partial least squares path model revealed that perennial energy crop cultivation enhances soil C stock via increased C4‐derived C input and reduced mineralization. In conclusion, marginal land conversion to perennial energy crops is a win–win strategy for C sequestration to mitigate climate change and support the growing bioenergy sector with biomass supply. [ABSTRACT FROM AUTHOR]

Perennial energy crops (PECs) such as Miscanthus spp. and switchgrass (Panicum virgatum L.) may have particular influence on microbial communities and their functions in soil organic carbon (C) utilization and mineralization (Cm). In this study, long‐term effects of PECs on Cm and soil hydrolase activities were examined in bulk and rhizosphere soils of Miscanthus and switchgrass grown on a red soil in South China. Long‐term cultivation (10 years) of PECs led to increases in soil organic C (SOC) and the absolute Cm of bulk and rhizosphere soils. Total Cm was correlated with dissolved organic C and dissolved organic nitrogen (N) in red soils. The specific Cm in bulk soils of switchgrass and Miscanthus were decreased by 11.73% and 20.67% comparing with the control group, respectively. Cultivation of PECs led to a relatively high C/N ratio. There was a difference in priming effect on activities of β‐glucosidase (BG), leucine amin peptidase, N‐acetyl‐β‐glucosaminidase (NAG), and phosphatase between rhizosphere and bulk soils. Compared with the control without PECs, BG activity did not change significantly in bulk soils of PECs, whereas NAG activity decreased significantly. Soil microorganisms were generally limited by soil C and phosphorus (P) in the red soil. The C and P limitations were significantly linearly related with relative Cm (p < 0.05). Phosphorus limitations in microbial communities were lower with PECs than in the control, indicating that cultivation of PECs could provide an optimal nutrient environment for both plants and microorganisms. Thus, long‐term cultivation of PECs increased SOC content but decreased specific Cm rates. However, because C and P limitations remain for plants and soil microbial communities, optimum fertilization is also necessary for sustainable growth of PECs on red soils. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The genus Miscanthus is a promising lignocellulosic feedstock crop for the production of bioenergy. Miscanthus is drawing attention because it can be grown on marginal land and avoid competition with food crops. Therefore, as measures of performance, biomass yield and quality of two parent species (Miscanthus sinensis and Miscanthus lutarioriparius) and 15 of their interspecific hybrids were evaluated in a saline–alkaline soil of the Yellow River delta in China. Ethanol and biogas production potentials were also estimated. A field trial with a randomised block design with five replicates of each genotype was conducted in 2014. Biomass yield, plant height, tiller number, stem diameter, and tiller mass of each parent and hybrid were measured at the end of the growing season in 2015, 2016, and 2017. Quality traits, including cellulose, hemicellulose, lignin and ash contents, were measured. There was large genotype variation in biomass yield and in most of the biometric parameters, and cellulose (range: 0.33 to 0.45 g/g), hemicellulose (0.32 to 0.43 g/g), lignin (0.07–0.13 g/g) and ash (0.02–0.06 g/g) contents were significantly different among the hybrids. The ash content of all hybrids was significantly lower than that of M. sinensis. The two‐year (2016 and 2017) average biomass yield of the 15 hybrids ranged from 9.87 to 23.11 t/ha, which was significantly higher than that of either parent (M. sinensis: 1.20 t/ha; M. lutarioriparius: 3.87 t/ha). Two hybrids, SL8 and SL15, were identified as potential genotypes suitable for the saline–alkaline soils of the Yellow River delta. These results demonstrate that interspecific hybridisation is crucial to improve Miscanthus biomass yield and quality under marginal conditions. [ABSTRACT FROM AUTHOR]

Background: Miscanthus, which is a leading dedicated-energy grass in Europe and in parts of Asia, is expected to play a key role in the development of the future bioeconomy. However, due to its complex genetic background, it is difficult to investigate phylogenetic relationships in this genus. Here, we investigated 50 Miscanthus germplasms: 1 female parent (M. lutarioriparius), 30 candidate male parents (M. lutarioriparius, M. sinensis, and M. sacchariflorus), and 19 offspring. We used high-throughput Specific-Locus Amplified Fragment sequencing (SLAF-seq) to identify informative single nucleotide polymorphisms (SNPs) in all germplasms. Results: We identified 257,889 SLAF tags, of which 87,162 were polymorphic. Each tag was 264–364 bp long. The obtained 724,773 population SNPs were used to investigate genetic relationships within three species of Miscanthus. We constructed a phylogenetic tree of the 50 germplasms using the obtained SNPs and grouped them into two clades: one clade comprised of M. sinensis alone and the other one included the offspring, M. lutarioriparius, and M. sacchariflorus. Genetic cluster analysis had revealed that M. lutarioriparius germplasm C3 was the most likely male parent of the offspring. Conclusions: As a high-throughput sequencing method, SLAF-seq can be used to identify informative SNPs in Miscanthus germplasms and to rapidly characterize genetic relationships within this genus. Our results will support the development of breeding programs with the focus on utilizing Miscanthus cultivars with elite biomass- or fiber-production potential for the developing bioeconomy. [ABSTRACT FROM AUTHOR]

Miscanthus, a perennial rhizomatous C4 grass, has emerged as a promising lignocellulosic crop. To avoid competition with food crops, marginal lands especially saline–alkaline soil are being recommended to grow Miscanthus across China. However, the challenges such as high cost and low reproduction coefficient associated with the propagation methods are impeding its large‐scale plantation in saline–alkaline soil. In this study, a "two‐steps" propagation method was designed, which was comprised of two phases: (1) seedling cultivation and (2) seedling strengthening. The parameters (substrate composition and plug size) for this method were determined. The optimal substrate composition of the seedling bed for M. sinensis, M. lutarioriparius, and their interspecific hybrids was peat and perlite at a ratio of 3:2, 3:1, and 3:3 by volume, respectively. The seedlings were transplanted into the plugs to deliver robust plantlets. The most appropriate plug size for M. sinensis, M. lutarioriparius, and their interspecific hybrids was 50 plugs (50 cm3/plug), 72 plugs (40 cm3/plug), and 72 plugs (40 cm3/plug), respectively. Three propagation methods, that is, direct sowing of seeds, rhizomes plantation, and "two‐steps" seed‐derived plugs for M. lutarioriparius were compared in saline–alkaline soil over 3 years (2014, 2015, and 2016). The establishment rate of the seeds directly planted was poor (zero). The performance (e.g., biomass yield) of the plants derived from the "two‐steps" seed‐derived plugs was better than that of the plants derived from rhizomes directly planted. Therefore, the "two‐steps" seed‐derived plugs can be regarded as an effective propagation method to upscale Miscanthus cultivation in saline–alkaline soil. [ABSTRACT FROM AUTHOR]

To understand the effects of different marginal land and environments on the growth, biomass yield, quality, and theoretical ethanol yield of different bioenergy grasses, and to compare the adaptability of different bioenergy grasses. This study was conducted in four representative marginal lands located in Chongqing, Liuyang, Nanyang, and Beijing. The agronomic traits, cell wall compositions, and theoretical alcohol yield of nine energy grasses containing 22 accessions were compared. The effects of environmental factors on biomass yield, quality, and theoretical ethanol yield of different accessions were evaluated via parametric and non-parametric statistics and AMMI analysis, and the stability and adaptability of all accessions were also compared. The results revealed that there were significant differences in biomass yield, quality, and theoretical alcohol yield among different species at the same trial site, and the same species also showed large differences between trial sites. Grasses exhibited divergent adaptability across trial sites, such as Saccharum arundinaceum and Miscanthus floridulus were sensitive to low temperatures and could not overwinter normally in Beijing. The biomass yield of Miscanthus sacchariflorus declined as the latitude decreased. Miscanthus × giganteus , Miscanthus lutarioriparius × sinensis , and Panicum virgatum exhibited greater resistance to environmental changes, indicating superior stability and environmental adaptability. [Display omitted] • Grass biomass and quality are significantly influenced by environmental factors. • Significant environmental adaptations are observed in different grass species. • Theoretical alcohol yield of grasses varies significantly between environments. • Unperturbed field trials were conducted on 4 marginal lands and climatic conditions. [ABSTRACT FROM AUTHOR]

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Core collections can act as a genetic germplasm resource for biologists and breeders. Thirty-seven phenotypic traits from 471 Miscanthus accessions in China were used to design 203 sampling schemes to screen the genetic variations in different sampling strategies. The sampling was analyzed using the unweighted pair group method with arithmetic mean (UPGMA) and the Euclidean distance (Euclid). Several parameters including the variance of phenotypic value (VPV), Shannon–Weaver diversity index (H), coefficient of variation (CV), variance of phenotypic frequency (VPF), ratio of phenotype retained (RPR), the mean difference percentage (MD%) and the variance difference percentage of traits (VD%), the range coincidence rate (CR%) and the variable rate of quantitative traits (VR%) were used to evaluate the level of representation of the primary core collections developed by the different sampling schemes. Based on the optimal sampling strategies of prior selecting accessions, a primary core collection was constructed that maintained > 99.5% of the VPV and a CR% of 100%. This study indicates that the optimal sampling scheme consisted of prior and deviation sampling methods (PD) combined with a logarithmic proportional sampling strategy (LG) of 37.4% of the actual sampling ratio. Sampling before clustering can improve several parameters including the H, CV, RPR, VPF, and CR%. Sampling strategies including the genetic diversity index (G), logarithmic proportional (LG) and the square root proportional strategy (SG) can improve the H, whilst the constant strategy (C) can improve the RPR and VPF when the sampling scale was >30%. Furthermore, the proportional strategy (P) can improve the VPV. [ABSTRACT FROM AUTHOR]

The sustainability of bioenergy cropping systems hinges on the dynamics of soil organic carbon (SOC). Switchgrass and Miscanthus , as the two leading perennial energy crops, have been extensively cultivated on marginal land for bioenergy production. However, the effects of their cultivation on SOC sequestration and its underlying mechanisms remain unclear. Herein, we quantified the contributions of plant– and microbial–derived C to SOC accumulation by tracing 13C natural abundance and amino sugars on switchgrass- and Miscanthus -planted lands (i.e. belongs to poor acidic red soil) experienced 10 years of C 3 –C 4 vegetation conversion. The results showed Miscanthus cultivation induced an approximately 6.3 times greater improvement in SOC compared to switchgrass. However, the organic C stability in Miscanthus -planted soil was comparatively lower than that of switchgrass. This was consistent with our global meta-analysis, whereby Miscanthus and switchgrass cultivation were observed to increase SOC by 16.0% and 7.1%, respectively. Miscanthus –cultivated soil was more replenished by plant–derived C stored in particulate organic C, owing to the greater biomass and lower root quality (reflected by the high ratio of lignin to nitrogen). In contrast, switchgrass–cultivated soil was enriched with more microbial–derived C, as its greater root quality induced a more efficient C utilization by the microbes. This was preferentially associated with the soil minerals. In conclusion, perennial energy crops cultivation on marginal land substantially enhances SOC sequestration, whereas the stability of SOC is dependent on the root traits. • Switchgrass and Miscanthus cultivation enhance SOC sequestration on marginal land. • Switchgrass cultivation stimulates more microbial-derived C accumulation. • Miscanthus -cultivated soils store more C 4 -derived C. • The SOC accrual contrasting pathway is dependent on root biomass and quality. [ABSTRACT FROM AUTHOR]

Miscanthus is an important plant resource in China, which has energy plant value, bio-material value, and ecological value. However, the taxonomy of Miscanthus remains poorly defined. To clarify the phylogenetic relationships among the Miscanthus species found in China, here we describe their morphological characters, simple sequence repeats (SSRs), inter simple sequence repeats (ISSRs), and trnL-F and rpl16 gene sequences. We identified M. sacchariflorus and M. lutarioriparius as the closest relatives of M. sinensis and M. floridulus , all of which constituted a major group. At the molecular levels, M. lutarioriparius and M. sacchariflorus were always grouped to form a monophyletic group. M. floridulus appeared as a stable secondary clade of M. sinensis. M. nepalensis , M. nudipes , and M. paniculatus were separated from the major group and more closely linked to an outgroup. M. paniculatus fell into an isolated position outside of the major group. Therefore, our findings support placing M. sacchariflorus and M. lutarioriparius in Miscanthus , treating M. lutarioriparius as a variety of M. sacchariflorus , treating M. floridulus as a subspecies of M. sinensis. We do not support merging M. nepalensis and M. nudipes into Miscanthus and propose the recognition of Diandranthus as a standalone genus, which includes D. nepalensis and D. nudipes. We do not support merging M. paniculatus into Miscanthus , and we support the recognition of Rubimons as a separate genus, including R. paniculatus. These data should help with efforts to evaluate and use Miscanthus germplasms. • Phylogenetic relationships between Chinese Miscanthus species and its relatives. • Morphological characters, SSR, ISSR, and trnL-F and rpl16 gene sequences. • Better evaluation and utilization of Miscanthus germplasm resources. • Miscanthus species were distinguished by morphological and molecular indicators. [ABSTRACT FROM AUTHOR]

Miscanthus is characterized by high biomass production potential and low input requirements and therefore considered a leading candidate for second-generation energy crops. Because China has limited agricultural land resources, development of its miscanthus-based bioenergy industry must rely on the use of marginal land. This study focuses on the assessment of the production potential of miscanthus on China’s marginal land, which in this context is defined as land presently not used for agricultural production, residential purposes and other social uses. Geographic Information System (GIS) techniques and model simulation are adopted to identify the productive marginal areas for miscanthus and to estimate their biomass and bioenergy production potential. The results show that although a large marginal area of 17,163.54×10 4 ha is available for producing miscanthus, due to the limitation of low winter temperatures and low precipitation levels in some areas, the total suitable marginal area is only 769.37×10 4 ha. The Monteith radiation yield model was used to determine the potential miscanthus yield in Chinese climatic conditions. The simulation gave actual harvestable yield levels on arable land of 18.1–44.2 t ha −1 yr −1 . Taking the environmental stresses of marginal conditions into account then gave an achievable miscanthus yield potential on marginal land of 2.1–32.4 t ha −1 yr −1 (average for the different marginal lands). Based on these achievable yield levels, the total biomass production potential on the entire marginal area is 13,521.7×10 4 t yr −1 ; the bio-electricity generation and total greenhouse gas saving potential from these biomasses are 183.9 TW h yr −1 and 21,242.4×10 4 t CO 2 eq. yr −1 , respectively. The spatial distribution of the suitable marginal areas shows that they are mainly concentrated in the central part of Northeast China and the Loess Plateau. Both regions are recommended as priority development zones for the Chinese miscanthus-based bioenergy industry. [ABSTRACT FROM AUTHOR]

Miscanthus lutarioriparius is an endemic species in China and has been widely accepted as a promising eco-bioindustrial plant. Currently, predominantly used germplasms have narrow genetic diversity, which causes a gene resource utilization plateau. Therefore, this study was designed to map the geographic and genetic distribution of M. lutarioriparius. Grid search tuning technique was applied to combine occurrence sites, which was followed by the genetic diversity analysis using the Simple Sequence Repeat markers. The results have revealed that the natural distribution of M. lutarioriparius is in the area with altitude less than 300 m and enclosed by the eastern line of East China Sea, western boundary along the longitude line of 111° E, northern boundary of the Qinling-Huai River line, and the southern line of the 27–28° N in Hunan and Jiangxi, and the 30° N line in Zhejiang. The further analysis has demonstrated that the northern line is mainly determined by the climatic factors, whereas the other three boundaries by the dispersal barriers of the sea and high mountains. The genetic diversity of M. lutarioriparius across its distribution range is high with a total Nei's genetic diversity of 0.2462. Populations from the downstream of the Yangtze River generally have a higher genetic diversity than the relative upstream areas. The centeres of genetic diversity for the M. lutarioriparius across China are located in the central and the southern Jiangsu. Outcomes of this study will help expanding the M. lutarioriparius cultivation through improving breeding and subsequently accelerate the development of biobased industry. • Exact distribution range of M. lutarioriparius across China was firstly mapped. • Spatial distribution of M. lutarioriparius genetic variation was mapped. • M. lutarioriparius has a high genetic diversity than that of other monocots. • Key for the development of future biobased industry. • Central and southern Jiangsu are centers of M. lutarioriparius genetic variation. [ABSTRACT FROM AUTHOR]

Miscanthus has been used to breed a variety of energy crops suitable for cultivation in various adverse environments. The collection, conservation, characterization and maintenance of Miscanthus genetic resources are the basic premises for improving Miscanthus crop varieties and their utilization. Large datasets will be generated at the same time. A system designed to manage and analyse those large datasets of Miscanthus germplasms in a coherent and systematic manner is urgently needed. In the present study, the Miscanthus Germplasm Database (MGDB) is constructed to rationalize the storage, update, query and analysis of Miscanthus germplasm data for a multiuser environment. A multi-criteria decision-making model has been introduced into the MGDB to help evaluate Miscanthus and screen elite germplasm. Four hundred eighty-five representative materials of Miscanthus were evaluated and the results are described below. 1. Assessment of the energy potential: Miscanthus lutarioriparius (particularly accession A0118) and Miscanthus floridulus (particularly accession C0540) are the best species to use for combustion for power generation (CPG)/pyrolysis for bio-oil production (PBP) and fermentation for ethanol production (FEP)/fermentation for biogas production (FBP), respectively. 2. Assessment of the breeding potential: The optimal crossing combination is M. lutarioriparius and M. floridulus because of the parental advantages and complementarity. The C0602/C0540 accessions (M. floridulus) represent a suitable parent together with A0118 to breed new varieties for CPG and PBP; A0118 represents as an alternative parent for breeding to improve C0540 for use in FEP and FBP. 3. Prediction of the species distribution: The elite germplasm resources of M. floridulus are mainly distributed in ten floristic regions: IIID9a, IIID9b, IIID9c, IIID9d, IIID10c, IIID11a, IIID11b, IIID11c, IIID11d and IIID12a. The elite germplasm resources of M. lutarioriparius are mainly distributed in four floristic regions: IIID9a, IIID9b, IIID9d and IIID10c. • A Miscanthus Germplasm Database is constructed to rationalize the storage, update, query and analysis of data. • The Miscanthus Germplasm Database can be used to screen elite germplasms. • The occurrence rate of elite germplasms in the floristic regions can be predicted using the Miscanthus Germplasm Database. • Parental materials for breeding different varieties can be selected using the Miscanthus Germplasm Database. [ABSTRACT FROM AUTHOR]

• Biomass yield of M. lutarioriparius was higher than that of switchgrass. • Hybrids and M. lutarioriparius were more sensitive to rainfall than switchgrass. • Ash content of M. lutarioriparius and switchgrass was not significantly different. • The highest potential ethanol production of Miscanthus genotype was 14,600 L/ha. The lignocellulosic biomass derived from Miscanthus Anderss. and switchgrass (Panicum virgatum L.) has been widely investigated; however, large−scale production is obstructed by the lack of suitable genotypes for their growth on marginal land. To breed new varieties that can adapt to specific marginal lands, a four-year (2014−2017) field experiment was conducted using switchgrass and 12 Miscanthus genotypes on marginal land in the Yellow River Delta (YRD). The performances of Miscanthus and switchgrass were evaluated and climatic factors limiting their biomass yield were identified. During each year of the trial, 13 genotypes were harvested in winter and their biometric characteristics (biomass yield, plant height, stem diameter, and tiller number) were measured. Quality parameters (cellulose, hemicellulose, lignin, and ash) were determined in the third growing season. The three-year average biomass yield of switchgrass was 5.66 Mg/ha. The three-year average biomass yield of the 12 Miscanthus genotypes ranged from 1.99 to 32.09 Mg/ha. The biomass yields of M. lutarioriparius and hybrids were significantly higher than that of switchgrass, however, these were more sensitive to rainfall than switchgrass. No significant difference was found between the ash contents of M. lutarioripariu s, M. sacchariflorus , and switchgrass. The contents of hemicellulose, cellulose, and lignin were 377.69, 526.10, and 109.33 g/kg, respectively for switchgrass, and 247.56−391.28 g/kg, 473.52−619.85 g/kg, and 83.03−132.88 g/kg, respectively, for Miscanthus. Combining biomass yield and quality, the potential ethanol productions of M. lutarioriparius and Miscanthus hybrids were higher than that of switchgrass, and the Miscanthus hybrid h1 reached 14,600 L/ha. The results of this study provide fundamental information for the development and utilization of biomass crops on marginal land in the YRD. [ABSTRACT FROM AUTHOR]