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To date, economically and energy-costly vegetative propagation using rhizomes and tissue culture are the only options for the cultivation of Miscanthus spp. Some genotypes of miscanthus produce fertile seeds, offering a valid alternative to vegetative propagation. A preliminary study has been conducted on the seeds of two hybrids of miscanthus obtained via interspecific cross-pollination between M. sacchariflorus and M. sinensis: 'GRC14' (maternal: M. sacchariflorus) and 'GRC10B' (maternal: M. sinensis). Seeds were assessed for germination traits in a laboratory (at 25 °C in the dark) just after panicle harvest, and during 1-year storage at room temperature or at 8 °C. In a second experiment, the effects of gibberellic acid (GA3) solution at different concentrations (0, 50, 100, 300, 500 ppm) on the germination of freshly matured seeds were assessed. Poor germination just after harvest (<30%) indicates the occurrence of a physiological dormancy. Indeed, two months later, germination rose up to 76.7% in 'GRC14' and 50.8%, in 'GRC10B', and peaked at 95.6% in 'GRC14' and at 78% in 'GRC10B', 6 months after harvest. After a total of 12 months, germination was significantly reduced in both hybrids (≈60%). Seeds stored at room temperature lost dormancy earlier than those stored at 8 °C. Overall, germination was significantly improved by GA3, but the extent of the GA effect was genotype-dependent. In conclusion, a low establishment rate may result from direct seeding when fresh seed is used in the field. In this case, the use of GA3 is a possible strategy to ameliorate the impact of dormancy on seed germination. In the case of delayed sowings in late winter–early spring, seeds stored at room temperature after harvest may better perform than those stored at 8 °C. [ABSTRACT FROM AUTHOR]

In this paper the suitability of three perennial, herbaceous, lignocellulosic grasses (Arundo donax, Saccharum spontaneous spp. aegyptiacum and Miscanthus x giganteus) for the production of second-generation bioethanol in semi-arid Mediterranean environment was studied. Crops were established in spring 2002, supplying irrigation and nitrogen fertilization up to 2004/2005 growing season. Subsequently, crops were grown without any agronomic input and harvested annually. Data reported in this paper refers to 2008/2009 and 2009/2010 growing seasons. Aboveground dry matter (DM) yield was higher in Arundo (35.4±2.1 Mg ha-1 in 2009 and 32.2±1.9 Mg ha-1 in 2010 harvest) than in Saccharum (27.3±2.0 and 23.9±1.9 Mg ha-1, respectively) and Miscanthus (19.6±2.8 and 17.2±1.6 Mg ha-1, respectively). Structural polysaccharides of the raw material were higher in Miscanthus (63.4% w/w) followed by Saccharum (61.5% w/w) and Arundo (57.6% w/w). The same trend was identified for the cellulose content (41.0%, 36.8% and 34.6%, respectively). The highest values in the total hemicellulose complex were observed in Saccharum (24.7%), followed by Arundo (23.1%) and Miscanthus (22.4%). The composition of structural polysaccharides leads to a higher theoretical ethanol yield (TEY) from one dry ton of Miscanthus feedstock (kg DM Mg-1), followed by Saccharum and Arundo. On the other hand, the TEY per unit surface (Mg ha-1) was greater in Arundo than in Saccharum and Miscanthus. When compared to other lignocellulosic sources used in the second-generation bioethanol technology, such as agricultural residues, woody species and other herbaceous perennial crops, Arundo, Saccharum and Miscanthus showed a great potential in terms of TEY ha-1. Given the high levels of biomass yield and composition of structural polysaccharides, the three species might be introduced into the Mediterranean cropping systems to supply lignocellulosic biomass for second-generation industrial plants or bio-refineries. [ABSTRACT FROM AUTHOR]

Abstract: In the present study the effect of temperature, reaction time and dilute oxalic acid (OA) concentration during steam-pretreatment of Miscanthus × gigantueus has been evaluated using the combined severity factor (CS). At the highest CS glucan and lignin content in the water insoluble fraction (WIF) increased, while xylan content decreased. While glucose recovery in the water soluble fraction (WSF) was found at low concentration when mild CS were used (≤5.0 g L−1 at CS ≤ 2.17), xylose and arabinose concentrations were higher at low-mild CS (1.58–2.17) with a concentration peak at CS 2.03 (39.9 and 3.2 g L−1 for xylose and arabinose, respectively). The decrease in pentoses coincided with inhibitory formation in the WSF, namely acetic acid, furfural, HMF and phenolic compounds. Glucan conversion rose from 46.1% at CS 1.54 to 91.2% at CS 2.76. Likewise, maximum ethanol concentration was achieved at CS 2.76, corresponding to 20.2 g L−1 and a volumetric ethanol productivity of 0.28 g L−1 h−1. Negative correlations have been found between xylan vs. glucan conversion and xylan vs. ethanol production, suggesting that decreasing the xylan content in WIF increases both saccharification rate and ethanol concentration (R 2 0.91 and R 2 0.93, respectively). On the other hand, a positive correlation was found between ethanol production and glucan conversion (R 2 0.93). Fermentation of WSF by Scheffersomyces (Pichia) stipitis CBS 6054 at CS 1.54 produced 12.1 g L−1 of ethanol after 96 h incubation with a volumetric ethanol productivity of 0.13 g L−1 h−1. [Copyright &y& Elsevier]

Abstract: Miscanthus × giganteus is one of the most promising biomass crops for non-food utilisation. Taking into account its area of origin (Far East), its temperature and rainfall requirements are not well satisfied in Mediterranean climate. For this purpose, a research was carried out with the aim of studying the adaptation of the species to the Mediterranean environment, and at analysing its ecophysiological and productive response to different soil water and nitrogen conditions. A split plot experimental design with three levels of irrigation (I1, I2 and I3 at 25%, 50% and 100% of maximum evapotranspiration (ETm), respectively) and three levels of nitrogen fertilisation (0kgha−1: N0, 60kgha−1: N1 and 120kgha−1: N2 of nitrogen) were studied. The crop showed a high yield potential under well-watered conditions (up to 27tha−1 of dry matter). M. × giganteus, in Mediterranean environment showed a high yield potential even in very limited water availability conditions (more than 14tha−1 with a 25% ETm restoration). A responsiveness to nitrogen supply, with great yield increases when water was not limiting, was exhibited. Water use efficiency (WUE) achieved the highest values in limited soil water availability (between 4.51 and 4.83gl−1), whilst in non-limiting water conditions it decreased down to 2.56 and 3.49gl−1 (in the second and third year of experiment, respectively). Nitrogen use efficiency (NUE) decreased with the increase of water distributed (from 190.5gg−1 of I0 to 173.2gg−1 of I2); in relation to N fertilisation it did not change between the N fertilised treatments (N1 and N2), being much higher in the unfertilised control (177.1gg−1). Radiation use efficiency (NUE) progressively declined with the reduction of the N fertiliser level (1.05, 0.96 and 0.86gd.m.MJ−1, in 1994, and 0.92, 0.91 and 0.69gd.m.MJ−1, in 1995, for N2, N1 and N0, respectively). [Copyright &y& Elsevier]

• Long-term perennial grasses were compared in two locations and four growing seasons. • The main driving factor of bioethanol production was the biomass yield. • Optimization of harvest time allowed to gain more ethanol per unit mass. • Giant reed was the most chemically consistent feedstock among study factors. • Bioethanol biorefineries may gain fourfold the energy invested. Advanced biofuel production requires feedstock with specific composition in terms of quantity and quality. Decisions about the harvest time of perennial energy grasses have important implications for bioconversion process as well as for the life-span of the plant stand. Four-year data from long term-field trials were used to identify the optimal crop-specific harvest date (autumn vs. winter), in relation to advanced biofuel production. Three different perennial energy grasses (i.e., switchgrass, giant reed and miscanthus) were grown at Bologna and Catania (Italy), under northern and southern Mediterranean climate, respectively, adopting a low input management. In addition to the biomass yield and composition, the net energy value (NEV) from agricultural activities, and the energy return on investment (EROI) at the biorefinery gate was also evaluated. At Bologna, switchgrass biomass yield and quality (hemicellulose, cellulose and acid detergent lignin – ADL) were significantly enhanced when harvested in winter. At Catania, giant reed productivity, cellulose and ADL content were unaffected by harvest date, while hemicellulose and ash content decreased in winter. Biomass composition of miscanthus was more stable in Catania than Bologna, however, yield and components resulted significantly higher in Bologna than Catania, due mainly to the more even precipitation distribution throughout the vegetative crop development. The NEV was positive for all energy crops, treatments and locations, with the highest value for miscanthus grown at Bologna. The EROI of lignocellulosic bioethanol ranged from 4.16 for switchgrass in the autumn harvest at Bologna to 4.37 for miscanthus grown at Catania, which showed also the highest theoretical bioethanol production (169.2 kg h−1) at a feeding rate of 300 kg h−1 of raw material. Nonetheless, miscanthus grown at Bologna attained the highest bioethanol yield (12,254 L ha−1). This study proved that investigated perennial grasses are worth to be grown as lignocellulosic feedstock under low input for at least one decade, upon which Mediterranean region biorefineries may gain fourfold the energy invested. [ABSTRACT FROM AUTHOR]