Perennial grasses as lignocellulosic feedstock for second-generation bioethanol production in Mediterranean environment.

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

Physiological responses of Arundo donax ecotypes to drought: a common garden study

Genetic analyses have suggested that the clonal reproduction of Arundo donax has resulted in low genetic diversity. However, an earlier common garden phenotyping experiment identified specimens of A. donax with contrasting biomass yields (ecotypes 6 and 20). We utilized the same well-established stands to investigate the photosynthetic and stress physiology of the A. donax ecotypes under irrigated and drought conditions. Ecotype 6 produced the largest yields in both treatments. The A. donax ecotypes exhibited identical high leaf-level rates of photosynthesis (PN) and stomatal conductance (Gs) in the well-watered treatment. Soil drying induced reductions in PN and Gs, decreased use of light energy for photochemistry, impaired function of photosystem II and increased heat dissipation similarly in the two ecotypes. Levels of biologically active free-abscisic acid (ABA) and fixed glycosylated-ABA increased earlier in response to the onset of water deficit in ecotype 6; however, as drought progressed, the ecotypes showed similar increases in both forms of ABA. This may suggest that because of the low genetic variability in A. donax the genes responding to drought might have been activated similarly in the two ecotypes, resulting in identical physiological responses to water deficit. Despite the lack of physiological ecotypic differences that could be associated with yield, A. donax retained a high degree of PN and biomass gain under water deficit stress conditions. This may enable utilization of A. donax as a fast growing biomass crop in rain-fed marginal lands in hot drought prone climates

Future yields assessment of bioenergy crops in relation to climate change and technological development in Europe

Bioenergy crops are expected to play an important role in reducing CO2 emission, in energy supply and in European energy policy. However, a sustainable bioenergy supply must be resilient to climate change and the impacts on agriculture at both global and regional scale. The purpose of this study was to forecast the potential distribution of several bioenergy crops based on agronomic and environmental constrains under current conditions and future scenarios (2020 and 2030) in European Union. Potential biomass yield, according to the category end use product achievable in each environmental zone of Europe at present and in the future available land have been also studied. Future yields were assessed according to two factors: technological development and climate change: the former was based on prospect of DG-Agriculture for conventional crops and expert judgments for bioenergy crops, while the latter based on relevant research papers and literature reviews which used site-specific crop growth models. Yields are expected to increase in northern Europe due to climate change and technological development, while in southerneastern Europe the negative effect of climate change will be mitigated by the technological development. The estimated total biomass production in Europe, on the basis of future yields and surplus land made available for energy crops, may not be sufficient to meet the needs of bioenergy supply as claimed in the European directive 2009/28/EC

Evaluation Of The Methanogenic Potential Of Two Lignocellulosic Crops

Biogas production can be considered an important technology for the sustainable use of agricultural biomass as a renewable energy source even more when the substrates for anaerobic digestion are crop residues, livestock residues or energy crops that don’t compete with food crops for land use. The aims of this study were to evaluate the production of biogas and biomethane from two lignocellulosic crops suitable for the Mediterranean environment (Arundo donax L. and Saccharum spontaneum subsp. aegyptiacum (Willd.) Hack) and the efficiency of a thermal pretreatment to increase the biomethane production. The purpose of the pretreatment is to break the recalcitrant lignin layer, so that the cellulose and hemicellulose present in the biomass are hydrolyzed by microorganisms and converted into simple sugars to achieve greater energy yield

leaf appearance rate and final main stem leaf number as affected by temperature and photoperiod in cereals grown in mediterranean environment

In the present study, a two-year field trial was carried out with the aim to evaluate daylength and air temperature effects on leaf appearance and related rates in two durum wheat (Triticum durum Desf.), two bread wheat (Triticum aestivum L.) and two barley (Hordeum vulgare L.) cultivars, using six different sowing dates (SD). Significant effects of SD on final main stem leaf number (FLN), thermal leaf appearance rate (TLAR), daily leaf appearance rate (DLAR) and phyllochron (PhL) were found. Cultivars resulted inversely correlated to mean air temperature in the interval emergence - fifth leaf full expansion (E-V). Linear response of leaf number over days after sowing was shown for all SD and cultivars, with R2 higher than 0.95. FLN linearly decreased from the first to the last SD for durum wheat, while more variable behaviour was observed in bread wheat. TLAR and DLAR showed a linear increment of the rate from the first to the last SD in durum wheat, while did not for bread wheat and barley. PhL in durum wheat decreased from the first to the last SD. Barley and bread wheat showed the highest values on those SDs which did not reach flowering. The increase of TLAR was affected by photoperiod and photothermal units in durum wheat, while by temperatures only in barley and bread wheat. Present results might find practical application in the improvement of phenology simulation models for durum wheat, bread wheat and barley grown in Mediterranean area in absence of water and nutrient stress

Valorisation of typical products through characterising and promoting actions: morpho-biometric traits, sensory analysis and flavonol content in Cipolla di Giarratana

The performances of 9 accessions of Cipolla di Giarratana landrace were evaluated at 5 different sites located 2 in the area where this landrace is traditionally grown (South-Eastern Sicily, 550 m asl), 2 in the neighbor areas with similar average altitude, and one on the South East coast of Sicily (sea level). Biometric and morphological traits, flavonol content and sensory profile were all considered in the valorisation of a typical product of a marginal area of Sicily. Data on the actual yield and crop management at farm scale were also obtained involving more than half of the growers actually cultivating Cipolla di Giarratana , and measuring yield, plant density, and bulb weight directly on the farms. The Cipolla di Giarratana landrace is characterised by a large and heavy bulb (535 g), strongly flattened at the poles, with the maximum diameter at the central section, and white in colour. Significant differences in bulb weight and diameter were found among accessions and locations, but there were no interactions between them and one accession reported the highest bulb weight value in all of the locations studied. With regards to bulb weight, farm scale data confirm the results we obtained at the experimental locations. Fifty percent of registered yield at farm scale ranged between 86 and 152 t ha –1 with a median of 119 t ha –1 , and measured plant density revealed that 50% of the farmers planted 20-27 plants per square meter. Analysis of the UV-vis and mass spectra showed the presence of 10 different flavonols with Quercetin as the most represented flavonol. The sensory profile of Cipolla di Giarratana onion showed that this landrace is characterised by a high intensity of sweet, typical fresh flavour and texture perception

Economic and environmental assessment of seed and rhizome propagated Miscanthus in the UK

Growth in planted areas of Miscanthus for biomass in Europe has stagnated since 2010 due to technical challenges, economic barriers and environmental concerns. These limitations need to be overcome before biomass production from Miscanthus can expand to several million hectares. In this paper we consider the economic and environmental effects of introducing seed based hybrids as an alternative to clonal M. x giganteus (Mxg). The impact of seed based propagation and novel agronomy was compared with current Mxg cultivation and used in ten commercially relevant, field scale experiments planted between 2012 and 2014 in the UK, Germany and Ukraine. Economic and greenhouse gas (GHG) emissions costs were quantified for the following production chain: propagation, establishment, harvest, transportation, storage and fuel preparation (excluding soil carbon changes). The production and utilisation efficiency of seed and rhizome propagation were compared. Results show that new hybrid seed propagation significantly reduces establishment cost to below ?900 ha-1. Calculated GHG emission costs for the seeds established via plugs, though relatively small, was higher than rhizomes because fossil fuels were assumed to heat glasshouses for raising seedling plugs (5.3 and 1.5 kg CO2 eq. C Mg (dry matter (DM))-1), respectively. Plastic mulch film reduced establishment time, improving crop economics. The breakeven yield was calculated to be 6 Mg DM ha-1 y-1, which is about half average UK yield for Mxg; with newer seeded hybrids reaching 16 Mg DM ha-1 in second year UK trials. These combined improvements will significantly increase crop profitability. The trade-offs between costs of production for the preparation of different feedstock formats show that bales are the best option for direct firing with the lowest transport costs (?0.04 Mg -1 km-1) and easy on-farm storage. However if pelleted fuel is required then chip harvesting is more economic. We show how current seed based propagation methods can increase the rate at which Miscanthus can be scaled up; ~x100 those of current rhizome propagation. These rapid ramp rates for biomass production are required to deliver a scalable and economic Miscanthus biomass fuel whose GHG emissions are ~1/20th those of natural gas per unit of heatpublishersversionPeer reviewe

Prospects of Bioenergy Cropping Systems for A More Social-Ecologically Sound Bioeconomy

The growing bioeconomy will require a greater supply of biomass in the future for both bioenergy and bio-based products. Today, many bioenergy cropping systems (BCS) are suboptimal due to either social-ecological threats or technical limitations. In addition, the competition for land between bioenergy-crop cultivation, food-crop cultivation, and biodiversity conservation is expected to increase as a result of both continuous world population growth and expected severe climate change effects. This study investigates how BCS can become more social-ecologically sustainable in future. It brings together expert opinions from the fields of agronomy, economics, meteorology, and geography. Potential solutions to the following five main requirements for a more holistically sustainable supply of biomass are summarized: (i) bioenergy-crop cultivation should provide a beneficial social-ecological contribution, such as an increase in both biodiversity and landscape aesthetics, (ii) bioenergy crops should be cultivated on marginal agricultural land so as not to compete with food-crop production, (iii) BCS need to be resilient in the face of projected severe climate change effects, (iv) BCS should foster rural development and support the vast number of small-scale family farmers, managing about 80% of agricultural land and natural resources globally, and (v) bioenergy-crop cultivation must be planned and implemented systematically, using holistic approaches. Further research activities and policy incentives should not only consider the economic potential of bioenergy-crop cultivation, but also aspects of biodiversity, soil fertility, and climate change adaptation specific to site conditions and the given social context. This will help to adapt existing agricultural systems in a changing world and foster the development of a more social-ecologically sustainable bioeconomy