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Environmental benefits can be achieved by organic farming systems; however, weed pressure and timely crop nutrition remain important drawbacks for many field crops. Agroecological practices, such as double cropping (e.g., intercropping and relay cropping), using forage legume species can provide nitrogen (N) to the companion crop through biological N fixation and tackle weed issues by competing for light, water and land. The present study investigated the effect of intercropping (IC) and relay-cropping (RC) systems of durum wheat (Triticum turgidum subsp. durum (Desf.) Husn) and forage legumes (Trifolium subterraneum L., Medicago polymorpha L., and Lotus corniculatus L.) by varying organic N fertilization with the aim to reduce N-requirement and weed pressure and increase wheat grain yield and grain protein content in Mediterranean organic farming systems. N fertilizer significantly improved wheat grain yield and grain protein, while a null effect on legume and weed biomass yields was found. Double cropping (T. durum-M. polymorpha, and T. durum-L. corniculatus) enhanced wheat grain yield as compared to the control and the T. durum-T. subterraneum. IC significantly improved legume yield, grain protein and the land equivalent ratio (LER) and reduced weed dry biomass as compared with the RC and the control. Among legume species, T. subterraneum outperformed the others and was less affected by the wheat's competitive performance. Nonetheless, M. polymorpha was as effective as T. subterraneum in controlling weeds. Weed dry biomass was linearly reduced by increasing legume yield; the relationship improved by cumulating wheat grain yield to legume yield. Overall, this study indicated that double cropping, especially IC, can be a suitable agroecological practice to tackle weed issues and reduce N-requirement in Mediterranean organic cereal-based systems. [ABSTRACT FROM AUTHOR]

Agroforestry is gaining interest due to its potential in enhancing climate resilience and sustainability of farming systems. In this meta-analysis, the crop yield in agroforestry system compared to the control (sole crop) from thirty-six experimental field trials in Mediterranean countries was assessed. The response variable Wlog(RR) (i.e., the weighted natural logarithm of the response ratio) was analyzed by the 95% confidence intervals of mean and by fitting eight linear mixed models. Fixed effects, namely the tree cover (low, medium, high), the tree species (ash tree, chestnut, cork oak, holm oak, olive, poplar, walnut), and the crop species (alfalfa, barley, durum wheat, faba bean, forage, oat, pasture, pea, winter wheat) were significant (P = 0.030, P = 0.017, and P = 0.014, respectively), while the system type (alley cropping, silvo-arable, silvo-pastoral) was not. Among management practices (variety, pruning, fertilization, irrigation, crop age classes, imposed warming and drought, harvest time), only the fertilization significantly improved the response variable (P = 0.006), while the interaction of pruning × crop species was marginally significant (P = 0.065). Relatively large study heterogeneity was observed (Q = 72.6, I2 = 72%), which is quite common for agronomic meta-analysis. On the contrary, publication bias based on funnel plots and the Trim and Fill method suggested symmetrical distribution of studies. The sensitivity analysis for significant models identified room for improvements. Overall, we observed a negative effect of trees on crop yield that could be ascribed to the competition for light. Nonetheless, facilitation could be expected under extreme climate events, provided that agricultural practices will maximize synergies among tree cover, tree species, crop species, and management. Future works are encouraged to focus on the overall benefit agroforestry can provide at the field and landscape level, along with long-term monitoring to assess the whole lifespan of these systems and other companion planting options and designs in the Mediterranean region. [ABSTRACT FROM AUTHOR]

Growing industrial crops on marginal lands has been proposed as a strategy to minimize competition for arable land and food production. In the present study, eight experimental sites in three different climatic zones in Europe (Mediterranean, Atlantic and Continental), seven advanced industrial crop species [giant reed (two clones), miscanthus (M. × giganteus and two new seed‐based hybrids), saccharum (one clones), switchgrass (one variety), tall wheatgrass (one variety), industrial hemp (three varieties) and willow (eleven clones)], and six marginality factors alone or in combination (dryness, unfavorable texture, stoniness, shallow soil, topsoil acidity, heavy metal and metalloid contamination) were investigated. At each site, biophysical constraints and low‐input management practices were combined with prevailing climatic conditions. The relative yield of a site‐specific low‐input system compared with the site‐specific control was from small to large (i.e. from −99% in industrial hemp in the Mediterranean to +210% in willow in the Continental zone), due to the genotype‐by‐management interaction along with climatic variation between growing seasons. Genotype selection and improved knowledge on crop response to changing environmental, site‐specific biophysical constraint and input application has been detected as key to profitably grow industrial crops on marginal areas. This study may act to provide hints on how to scale up investigated cropping systems, through low‐input practices, under similar environmental and soil conditions tested at each site. However, further attention to detail on the agronomy of early plant development and management in larger multi‐year and multi‐location field studies with commercially scalable agronomies are needed to validate yield performances, and thereby to inform on the best industrial crop options. Growing industrial crops on marginal lands has been proposed as a strategy to minimize competition for arable land and food production. This study can bring an advancement to knowledge on the suitability of certain industrial crops to marginal and contaminated soils to mitigate indirect land‐use change (i‐LUC) in accordance with the RED II and to meet the European Green Deal towards an EU climate neutral in 2050. It ultimately can assist to make general recommendations of the most appropriate crop and management options at the different regions, climates, soils and marginal land types. [ABSTRACT FROM AUTHOR]

Highlights • Propagation by single-node stem cutting of giant reed (Arundo donax) was attempted. • Nutrients availability on the node plays a key role in rooting development. • In open field, the best period for node excision is July followed by May. • Nodes whose diameter exceed 2 cm showed higher rooting and plantlets development. • IBA resulted effective in promoting rooting in the worst excision dates. Abstract Giant reed (Arundo donax L.) is a warm-season, fast growing lignocellulosic crop suitable to Mediterranean and semi-arid environments. However, its sterility limits a cost-effective propagation along with environmental impacts associated with rhizome processing. In the present study, the effects of intrinsic (node size and node chemical composition) and extrinsic factors (node pretreatment with growth regulators) on root and shoot development were investigated under different excision time of node-cuttings in a controlled and open field conditions. Results indicated that nutrients availability of the propagation material plays a key role in rooting development. To enhance the success of giant reed propagation by single node stem-cuttings, the best period for node excision is July in open field trial, followed by the late spring (May). Nodes whose diameter exceed 2 cm resulted in higher rooting and plantlets development even in the less favorable excision dates. However, when big nodes are adopted in controlled environments even winter periods are eligible, being particularly useful for spring open field transplants of rooted plantlets. Among the growth regulators used in the present study, indole-3-butyric acid - IBA (in controlled environment) resulted effective in promoting rooting particularly in the worse excision date (April); in open field, IBA significantly improved rooting in the excision dates of February and May in the big nodes, and only in February in the small ones. NAA (1-naphthaleneacetic acid) was almost ineffective in enhancing rooting as compared to the control. The present study might open a new perspective to overcome one of the most significant drawbacks to establish giant reed, namely its agamic propagation. [ABSTRACT FROM AUTHOR]

Sustainable biomass production mostly relies on cultivation practices employing low external input supply. Wild germplasm might be suited for low-input techniques while providing enough output. The present study investigated four native Mediterranean perennial grasses ( Oryzopsis miliacea , Cymbopogon hirtus , Sorghum halepense , and Saccharum spontaneum L. ssp. aegyptiacum ), with an autumn and winter harvest regime in a 4-year field trial in Sicily (south of Italy). Species, cultivation year and harvest time had significant effects on whole season crop water use efficiency, energy efficiency and biomass quality. Species and cultivation year also significantly affected aboveground biomass yield and net energy yield. The total accumulated harvested yield over the 4-year experiment was the highest in Saccharum in both autumn and winter harvests (79.5 and 79.2 Mg DM ha −1 ), and the lowest in Cymbopogon (13.7 and 14.9 Mg DM ha −1 ). In both harvests, less than 20% of this total biomass was collected for all species at the first year (9.5–11.3% in Sorghum and 15.7–18.1% in Oryzopsis ). Peak biomass was reached at the third ( Saccharum and Sorghum ) or at the fourth year ( Orzyzopsis and Cymbopogon ) in autumn, and at the third year in winter harvest (all species). Water use efficiency was higher in the autumn than in the winter harvest (2.06 and 1.75 g L −1 , respectively), whilst the opposite was observed for energy efficiency (35.7 and 38.6 GJ ha −1 , respectively). Biomass structural compounds (hemicellulose, cellulose and acid detergent lignin) were higher in winter than autumn, while protein, lipid and ash contents were higher in autumn than winter. [ABSTRACT FROM AUTHOR]

Sustainable production of high value chemicals, biofuels and bioenergy relies on the replacement of fossil oil with low production cost feedstock and low environmental impact technologies. The present study evaluated the dry matter yield and feedstock properties of three different Arundo donax L. clones (Fontane Bianche, Piazza Armerina and Capo d’Orlando), two Miscanthus species ( M . × giganteus and M . sinensis “Goliath”) and Saccharum spontaneum L. spp. aegyptiacum (Willd.) Hack., all grown side-by-side in rainfed conditions for three consecutive years in semi-arid Mediterranean environment. Significant differences were observed among species, as well as among giant reed clones. F. Bianche and Saccharum were the highest yielding species in all growing seasons, followed by P. Armerina and C. Orlando, which did not differ. Out of Miscanthus, Giganteus overyielded Goliath. All species exhibited the highest dry matter yields in the wettest growing season. Saccharum and giant reed clones showed higher biomass water content than both Miscanthus. Ash content was the lowest in Giganteus and the highest in F. Bianche. Low heating value was the highest in Saccharum, both Miscanthus and giant reed P. Armerina. Generally, the bulk density was greater in giant reed and Saccharum than Miscanthus. Cellulose was the highest in both Miscanthus and hemicellulose in Saccharum. Lignin content was the lowest in giant reed clones. Several significant correlations occurred between biomass yield and raw material characteristics, as well as within feedstock properties. To support the development of a suitable bioenergy chain based on perennial grasses, besides biomass yield, feedstock properties should be rigorously considered. Further research is still required in crop management practices, logistic and technology front in order to tackle bottlenecks for improved quality of herbaceous biomass. [ABSTRACT FROM AUTHOR]

Within a framework of renewed interest in crambe ( Crambe abyssinica Hochst ex R.E. Fries) sourcing raw materials for the bio-based industry, the adaptability and productive performances of this oil crop have been evaluated under contrasting Mediterranean environments (i.e., a fertile site in the northern part of Po valley vs. a semi-arid site of southern Sicily) during two consecutive growing seasons, aiming at its possible stable introduction in this area. The trial set in northern Italy compared three commercial varieties of crambe (Galactica, Nebula and Mario) in spring sowing, while in southern Italy only the var. Mario was tested with autumn sowing. Regardless of location and variety, thermal time for maturity was quite stable (1200–1400 °C), and the crop provided satisfactory seed yields (grand mean 2.29 Mg hulled seeds ha −1 ), with average oil content of ∼400 g kg −1 (on dehulled seeds) and ∼52% of erucic acid. Significantly higher seed and oil yields were reached in northern than in southern Italy. Furthermore, crambe thermal use efficiency (THUE) was also higher in the north than in the south, possibly due to better environmental adaptability of the crop. The limited intraspecific variability within crambe was confirmed, with better productive performances showed by the domestic selection Mario. Promising traits were revealed in Nebula, showing greater seed weight, root length density and area, and thinner roots, although the root growth of crambe was generally modest compared with modern high erucic acid rapeseed hybrids. Available crambe varieties could be efficiently included in crop rotations across a wide range of environments within the Mediterranean basin. The short growth cycle represents an outstanding added value for this species, allowing the avoidance of prolonged drought and heat stress typical of late spring/early summer months under the Mediterranean climate. However, increased yields are needed to meet the market requests; nonetheless, the little genetic variability suggests that there is large scope for future breeding improvements, maybe exploiting advanced techniques to improve the existing genetic resources. [ABSTRACT FROM AUTHOR]

Long-storage tomato is a drought-tolerant plant traditionally cultivated under no water supply in semi-arid areas of Italy. In 2009, physiological traits of ten “long-storage” tomato lines cultivated under no irrigation were screened for low soil water tolerance. Leaf relative water content (RWC), proline content and leaf transpiration ( E ) were measured throughout the growing season. Instantaneous leaf water use efficiency was also calculated on a single date, as the ratio between net photosynthesis ( A ) and E . Close relationships were observed among the physiological parameters, positive for E vs . RWC and inverse for RWC and E vs . proline. Results indicate that the increase in proline concentration involves a water stress tolerance, and genotypes more sensitive to soil water deficit respond to drought stress through less proline in leaves. Close significant linear relationships (positive with RWC and E , negative with proline) were also found between fruit yield and all the physiological parameters examined. Among them, the most reliable indicator for yield prediction under water restriction was leaf transpiration rate as measured at the flowering stage. The study made it possible to understand the complex relationships between physiological processes, drought tolerance, and plant productivity in long-storage tomato, and to identify those traits that regulate plant physiology under low water availability. [ABSTRACT FROM AUTHOR]

Kenaf (Hibiscus cannabinus L.) is a warm-season annual plant grown in the past for the bast fiber. In the last decades, this crop has been re-evaluated for many alternative industrial uses of its biomass (i.e., production of biofuel, biocomposite materials, bioproducts). In this paper, the interaction effects of sowing time (May and June) and plant population (P20 and P40, 20 and 40 plants m-2, respectively) on yield and some biomass parameters were analysed in two cultivars of kenaf (Tainung 2-TAI, and Everglades 41-EVER), in a two-year experiment in semi-arid environment, under irrigation. The aim of this paper was to assess the potential of this crop as an energy or industrial feedstock, in south Mediterranean environment where was never cultivated. Overall, plants from late sowing (June) were smaller and with less node, those at high plant density (P40) were thinner. In both seasons, plants of TAI were taller than those of EVER. Plant weight was greater in P20, and an overall significant negative correlation was found between plant weight and actual plant density (r = −0.76 **). The shift of sowing time reduced significantly the final dry biomass. Crop productivity did not change with plant density, however a higher percent bark corresponded to P40 in both years, cultivars, and sowing times, A simple model was developed to simulate and predict the course of LAI and dry biomass (AGB) with time, using field dataset of 2004, for calibration, and dataset of 2005, for validation. The minor response of LAI to plant population in 2005 led to a low accuracy of model approximation. This result suggests that other variables that are not considered in the model, may influence LAI. Nevertheless, the overall AGB model approximation of observed value was accurate. Concluding, the results revealed that biomass productivity is more influenced by sowing time than by plant density. However, plant population has been found to regulate the proportion of bark/core layers, with important implications for industrial (energy and pulp production) purposes. Further improvements on the simple model developed, e.g., including soil water nitrogen balances submodels, may be done, in order to explore the possibility of using the model under different conditions of soil water content and nitrogen fertilization. • Sowing time and plant density effects were studied in two cultivars of kenaf. • Dry biomass yield was significantly reduced shifting sowing from May to June. • Dry biomass did not change with plant density (20 or 40 plants m-2). • The % incidence of bark on core weight was greater in plants at higher density. • A simple model was developed to simulate and predict LAI and biomass in kenaf. [ABSTRACT FROM AUTHOR]

A general obstacle to the development of perennial grasses is the relatively high cost of propagation and planting. The objective of the present study was to investigate new propagation and planting methods of giant reed ( Arundo donax L.), miscanthus ( Miscanthus x giganteus Greef et Deuter) and switchgrass ( Panicum virgatum L.). Field and open-air pot trials were carried out in four different locations across Europe: hydro-seeding of switchgrass was tested in field trials at the experimental farm of the University of Bologna, Italy; stem propagation and bud activation methods of miscanthus were evaluated in field experiments in Péteri, Hungary; giant reed rhizome and stem propagations were compared in a field trial in Aliartos, Greece; finally, an open-air pot trial was carried out in Catania, Italy, using single-node stem cuttings of giant reed. Hydro-seeding emerged as a feasible and promising technique for switchgrass to ensure prompt seed emergence and weed control during plant establishment. Direct stem plantings of miscanthus were successful, and activated stem-buds were able to sprout in field conditions; however, timely stem transplant was determinant for shoot density and biomass yield. In giant reed, rhizome propagation showed a higher stem density and biomass yield than stem propagation; however, the yield gap was not significant from the second year onwards. Single-node rooting was mainly driven by air temperature. Nodes from basal stems showed higher rooting rates than median and apical ones. Growth regulator pretreatments enhanced rooting rate only at transplanting times under suboptimal air temperatures. In general, these experiments provided insights into propagation strategies aimed at enhancing the establishment phase of perennial grasses. [ABSTRACT FROM AUTHOR]

Dryness triggers soil degradation processes and land abandonment in the south Mediterranean environment. Becoming unsuitable for food crops, it can be usable by low-iLUC risk biomass crops able to withstand prolonged dry periods due to drought-resilience traits and high biomass yield. The present experiment ascertained the biomass dry matter yield (DMY), water use efficiency (WUE) and water footprint (WF) by modulating soil water availability of six warm-season perennial grasses in the semiarid Mediterranean for two consecutive growing seasons. Two ecotypes of giant reed (Arundo donax L., ARCT and ARMO, respectively), one ecotype of African fodder cane (Saccharum spontaneum L. subsp. aegyptiacum (Willd.) Hack., SAC) and three hybrids of Miscanthus (the commercial M. × giganteus J.M. Greef, Deuter ex Hodk., Renvoize - M×G, and two new seed-based hybrids, GNT9 and GNT10, respectively) were subjected to 100%, 50% and 0% of maximum crop evapotranspiration (ETm) restoration supplied during summer months. Crop water use (CWU) differed among crops, growing seasons and irrigation regimes, and significantly influenced DMY, WUE and WF. ARCT, ARMO and SAC had higher DMY and WUE, and lower WF than Miscanthus hybrids. Among Miscanthus , the new seed-based hybrids outperformed the M×G in all examined parameters. Genotypic response in DMY, WUE and WF by varying the CWU had different trends and rates of change. The relationship between WUE and WF combining data of all genotypes, growing seasons and irrigation regimes followed an exponential decay; it underlined the importance to select for crops with high resource use efficiencies to reduce the water required per ton of biomass. • Warm-seasons perennial grasses are suitable feedstock for dry areas. • Irrigation improved dry matter yield, but worsened water use efficiency and water footprint. • Different genotypic responses were observed by modulating the crop water use. • Water footprint can be improved by selecting high water use efficiency genotypes. • Improved knowledge on traits conferring higher water use efficiency as key for dry areas. [ABSTRACT FROM AUTHOR]

The aim of the present work was to evaluate the effect of soil water availability and nitrogen fertilization on yield, water use efficiency and agronomic nitrogen use efficiency of giant reed ( Arundo donax L.) over four-year field experiment. After the year of establishment, three levels for each factor were studied in the following three years: I 0 (irrigation only during the year of establishment), I 1 (50% ETm restitution) and I 2 (100% ETm restitution); N 0 (0 kg N ha −1 ), N 1 (60 kg N ha −1 ) and N 2 (120 kg N ha −1 ). Irrigation and nitrogen effects resulted significant for stem height and leaf area index (LAI) before senescence, while no differences were observed for stem density and LAI at harvest. Aboveground biomass dry matter (DM) yield increased following the year of establishment in all irrigation and N fertilization treatments. It was always the highest in I 2 N 2 (18.3, 28.8 and 28.9 t DM ha −1 at second, third and fourth year growing season, respectively). The lowest values were observed in I 0 N 0 (11.0, 13.4 and 12.9 t DM ha −1 , respectively). Water use efficiency (WUE) was significantly higher in the most stressed irrigation treatment (I 0 ), decreasing in the intermediate (I 1 ) and further in the highest irrigation treatment (I 2 ). N fertilization lead to greater values of WUE in all irrigation treatment. The effect of N fertilization on agronomic nitrogen use efficiency (NUE) was significant only at the first and second growing season. Giant reed was able to uptake water at 160–180 cm soil depth when irrigation was applied, while up to 140–160 cm under water stress condition. Giant reed appeared to be particularly suited to semi-arid Mediterranean environments, showing high yields even in absence of agro-input supply. [ABSTRACT FROM AUTHOR]

Increasing energy demands and fossil fuel consumption causing global warming has motivated research to find alternative energy sources such as biofuels. Giant reed (Arundo donax L.), a lignocellulosic, perennial, rhizomatous grass has been proposed as an important bioenergy crop for advanced biofuel in the Mediterranean area. Anaerobic digestion for advanced biomethane seems to be a promising approach. However, the presence of lignin in lignocellulosic biomass represents the main obstacle to its production (due to its recalcitrance). Thus, to use effectively lignocellulosic biomass in anaerobic digestion, one or more pretreatment steps are needed to aid microorganisms access to the plant cell wall. To this end, the present study investigated the effect of fungal pretreatment of giant reeds obtained from two different harvesting time (autumn and winter) on biomethane production by anaerobic digestion using two white rot fungi (Pleurotus ostreatus and Irpex lactus, respectively). The highest biomass lignin degradation after 30 days incubation with P. ostreatus in both autumn (27.1%) and winter (31.5%) harvest time. P. ostreatus pretreatment showed promising results for anaerobic digestion of giant reed achieving a cumulative yield of 130.9 NmL g−1 VS for the winter harvest, whereas I. lacteus showed a decrease in methane yield as compared with the untreated biomass (77.4 NmL g−1 VS and 73.3 NmL g−1 VS for winter and autumn harvest, respectively). I. lacteus pretreatment resulted in a loss of both holocellulose and lignin, indicating that this strain was less selective than P. ostreatus. Further studies are necessary to identify white rot fungi more suitable to lignocellulosic biomass and optimize biological pretreatment conditions to reduce its duration. [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]

Highlights: [•] Giant reed biomass has been pretreated with dilute oxalic acid. [•] Enzymatic hydrolysis and SSF have been optimized through RSM. [•] Enzymatic hydrolysis showed a glucan conversion of 95%. [•] Ethanol production using Schefferomyces (Pichia) stipitis CBS 6054 reached 18gl−1. [•] Maximum theoretical ethanol yield was 75%. [ABSTRACT FROM AUTHOR]

Abstract: Biomass pretreatment is essential to overcome recalcitrance of lignocellulose for ethanol production. In the present study we pretreated giant reed (Arundo donax L.), a perennial, rhizomatous lignocellulosic grass with dilute oxalic acid. The effects of temperature (170–190 °C), acid loading (2–10% w/w) and reaction time (15–40 min) were handled as a single parameter, combined severity. We explored the change in hemicellulose, cellulose and lignin composition following pretreatment and glucan conversion after enzymatic hydrolysis of the solid residue. Two different yeast strains, Scheffersomyces (Pichia) stipitis CBS 6054, which is a native xylose and cellobiose fermenter, and Saccharomyces carlsbergensis FPL-450, which does not ferment xylose or cellobiose, were used along with commercial cellulolytic enzymes in simultaneous saccharification and fermentation (SSF). S. carlsbergensis attained a maximum ethanol concentration of 15.9 g/l after 48 h at pH 5.0, while S. stipitis, at the same condition, took 96 h to reach a similar ethanol value; increasing the pH to 6.0 reduced the S. stipitis lag phase and attained 18.0 g/l of ethanol within 72 h. [Copyright &y& Elsevier]

Abstract: Saccharum (Saccharum spontaneum L. ssp. aegyptiacum (Willd.) Hack.), is a rapidly growing, wide ranging high-yield perennial, suitable for second generation bioethanol production. This study evaluated oxalic acid as a pretreatment for bioconversion. Overall sugar yields, sugar degradation products, enzymatic glucan hydrolysis and ethanol production were studied as effects of temperature (150–190°C), reaction time (10–40min) and oxalic acid concentration 2–8% (w/w). Time and temperature were combined into a single parameter, Severity Factor (SF) [Log(R 0)], and related to oxalic acid using a response surface methodology. Maximum total sugar yield was attained at a SF of 2.93 and 6.79% (w/w) oxalic acid, while maximum formation of sugar degradation products was observed at the highest SF (4.05) and 5% (w/w) oxalic acid. These were also the conditions for maximum simultaneous saccharification and fermentation (SSF) of the residual solids. Commercial cellulases and Saccharomyces cerevisiae attained 89.9% glucan conversion and 17.8g/l ethanol. Pichia stipitis CBS 6054 fermented hemicellulosic hydrolysates from less severe conditions to ethanol with a yield of 0.35 (g e/g s). Maximal product yields were 69% of theoretical value and 90% of the SSF conversion efficiency for hydrolysate fermentation and SSF, respectively. [Copyright &y& Elsevier]

Sweet sorghum is a C4 plant with great biomass potential yield in semi-arid environments. Under growing conditions affected by water shortage and nutrient deficiency, the optimal combination of irrigation and nitrogen (N) fertilization rate is a central issue for sustainable farming systems. In this paper, a N balance study was applied to sweet sorghum cv. Keller, managed under three irrigation levels (I0, I50, I100: 0, 50, and 100% crop evapotranspiration—ETc restoration) and four N-fertilization rates (N0, N60, N120, N180: 0, 60, 120, and 180 kg ha−1). The 15N-labelled fertilization technique was used to assess the fate of N fertilizer within the agroecosystem. Dry biomass yield was significantly affected by the irrigation, while N rates had no effect. Across N and irrigation levels, the isotopic composition showed that approximately 34% of N applied by fertilization was used by the crop, 56% remained in the soil at the end of the cropping season, 1.83% was leached as nitrate, and 1.72% was volatilized as ammonia. N-fertilizer uptake was the lowest in I0, while in N0, the soil was strongly N-impoverished since sorghum showed a great aptitude to benefit from the soil N reserve. An even N input/output system (i.e., N-output corresponded to N-input) was observed in the N120 treatment, and the soil N reserve remained unchanged, while the system was N-enriched (positive input/output) in N180. However, although beneficial for crop nutrition and soil N reserve for subsequent crops in rotation, the N180 treatment is unsustainable due to many environmental side effects in the agroecosystem. [ABSTRACT FROM AUTHOR]

Low iLUC risk feedstocks, such as lignocellulosic no-food crops, have been indicated as sustainable crops for the transition to a bio-based economy. Given the high output to input ratio and the environmental benefits that can be obtained from renewable heat production replacing fossil fuels, the present study addressed the biomass yield, CO2-sequestration, and life cycle assessment of giant reed (Arundo donax L.) and miscanthus (Miscanthus × giganteus Greef et Deuter) growing under different soil water availability and nitrogen fertilization for three consecutive growing seasons in a semiarid Mediterranean environment. Giant reed outperformed miscanthus, showed a higher CO2-sequestration and a lower overall environmental impact. In case of both crops, the irrigation effect was significant, while the one of nitrogen fertilization was not apparent. While giant reed responded positively to reduced irrigation, compared to its highest level, as the plantation became older, miscanthus needed high water volume to get most out its potential yield. Nonetheless, the growing season had also a significant effect on both crops, mainly when low yields were achieved following the establishment year. Unlike the environmental benefits in the impact categories "non-renewable energy use" and "global warming potential", environmental burdens concerning ozone depletion, acidification, and eutrophication were observed, indicating that further improvements of the evaluation of impact assessment associated with bioenergy production might be necessary. [ABSTRACT FROM AUTHOR]

Raising water and energy productivity in agriculture can contribute to reducing the pressure on the limited freshwater availability and non-renewable energy sources. Bioenergy perennial grasses are efficient from a water perspective and can afford a low-energy cultivation system; however, crop selection and cultivation practices for minimizing land use change and maximizing resource use efficiencies remain a challenging task in view of sustainable bioeconomy development. The present work investigated the soil water effect on a long-term plantation of Saccharum (Saccharum spontaneum ssp. aegyptiacum), a bioenergy perennial grass holding great promise for semiarid Mediterranean areas. The plantation was in its 13th year following establishment and was subjected to three levels of irrigation for three successive growing seasons. Regression models between crop water use (CWU) and productivity, biomass composition, energy, and water indicators showed different prediction curves. Raising CWU (from 230 to 920 mm) enhanced the dry biomass yield (from 14.8 to 30.1 Mg ha−1) and the net energy value (from 257.6 to 511 GJ ha−1). On the same CWU range, unirrigated crops improved the energy efficiency (from 99.8 to 58.5 GJ ha−1), the energy productivity (from 5.6 to 3.4 Mg GJ−1) and the water productivity (from 114.5 to 56.1 MJ m−3) by reducing the water footprint (from 8.7 to 17.8 m3 GJ−1). Biomass composition was also superior in unirrigated crops, as the lower heating value, structural polysaccharides, and the acid detergent lignin were higher, while ash and soluble compounds were lower. Present findings demonstrated the good yield levels and persistence of Saccharum, improving our knowledge of plant responses to changing soil water availability to maximize energy and conserve natural resources, paving the way for sustainable bioeconomy development in the Mediterranean area. [ABSTRACT FROM AUTHOR]

Predictions of future climate scenarios indicate that yields from perennial biomass crops (PBCs) growing in the Mediterranean region are likely to decline due to prolonged drought. Among PBCs, Miscanthus grasses with C4 photosynthesis combine high yield potentials and water use efficiencies. However, the standard commercial clone M. x giganteus (Mxg), with minimal stomatal regulation, is too sensitive to drought for reliable yields in the Mediterranean regions. This paper screened a diverse panel of thirteen Miscanthus genotypes (M. sinensis, M. floridulus, M. sacchariflorus and Mxg) to identify which types could maximize yield under summer drought conditions typical in the South Mediterranean climate. In the second growing season, significant differences were observed for plant height (from 63 to 185 cm), stem number (from 12 to 208 stems plant−1), biomass yield (from 0.17 to 6.4 kg DM plant−1) and whole crop water use efficiency (from 0.11 to 7.0 g L−1). Temporal variation in net photosynthesis, stomatal conductance, transpiration rate and instantaneous water use efficiency identified different strategies adopted by genotypes, and that genotypes selected from M. floridulus and M. sinensis were better adapted to rainfed conditions and could produce six times more biomass than the Mxg. These accessions are being used as parents in experimental breeding aimed at producing future seed-based drought resilient hybrids. [ABSTRACT FROM AUTHOR]

• 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]

The aim of the present work was to assess the leaf area duration (LAD) and the radiation use efficiency (RUE) of six warm-season perennial biomass grasses (PBGs) in a two-year field trial in the semiarid Mediterranean climate under different soil water availability. Two ecotypes of giant reed (Arundo donax L., ARCT and ARMO), one ecotype of African fodder cane (Saccharum spontaneum L. subsp. aegyptiacum (Willd.) Hack., SAC) and three hybrids of Miscanthus (the commercial M. × giganteus J.M. Greef, Deuter ex Hodk., Renvoize, M × G, and two new seed-based hybrids, GNT9 and GNT10) were compared under three levels of soil water availability: rainfed, 50% and 100% of maximum crop evapotranspiration (ETm) restoration. The determination of RUE of perennial plants is controversial and has led to contrasting results in past studies. In the present work, LAD and RUE differed among crops and irrigation regimes, being positively affected by supplemental water inputs. SAC, ARCT and ARMO showed both high LAD and RUE, which determined the high biomass yield than both the commercial M × G and the improved Miscanthus hybrids GNT9 and GNT10. RUE was particularly high and less affected by soil water availability during the mid-season, while the effect of irrigation and the differences among the genotypes were larger during the late season. Adequate biomass yield can be achieved by sub-optimal soil water availability, thus reducing the water footprint and increasing the sustainability of these biomass perennial grasses selected for the Mediterranean climate. [ABSTRACT FROM AUTHOR]

Uncertainty in predictions of long-term yields of perennial grasses makes business plans untenable in the short run. Long-term data across varied environments, including marginal lands, will help in preventing uncertainty while providing farmers and entrepreneurs with sound information to estimate reliable and affordable strategies on what, where, and how long to grow perennial grasses. In the present study, the long-term yields (11 to 22 years) of switchgrass ( Panicum virgatum L.), miscanthus ( Miscanthus × giganteus Greef et Deuter), and giant reed ( Arundo donax L.) grown in northern and southern Mediterranean environments are reported. Switchgrass was grown in Greece and northern Italy, giant reed in southern and northern Italy, and miscanthus in southern Italy. Furthermore, lowland and upland switchgrass ecotypes were compared in Greece. Despite similar biomass productions (9.8 and 10.0 Mg DM ha for uplands and lowlands, respectively), the upland ecotypes showed a significantly higher yield stability (CV of 24 and 32 % for uplands and lowlands, respectively) over a 17-year period. Biomass yield varied considerably across years and locations; giant reed outperformed switchgrass under northern Italy environment (21.2 and 13.6 Mg DM ha for giant reed and switchgrass, respectively). Annual yield of switchgrass was 30 % higher in the north than south Mediterranean; miscanthus showed intermediate production compared to giant reed and switchgrass (average of 22 years) and a CV similar to switchgrass. In summary, these results evidence that multi-location, long-term trials are strongly needed to reduce uncertainties on crop yield variability and provide more accurate data from which optimized socio-economic and environmental predictions can be achieved. [ABSTRACT FROM AUTHOR]

Side by side biomass productivities, harvesting time (autumn vs. winter) and frequency (annual vs. biennial) of three perennial grasses were compared under northern and southern Mediterranean climates. Miscanthus ( Miscanthus × giganteus Greef et Deu.) was compared to giant reed ( Arundo donax L.) in Catania (37°24′N, 15°03′E), and to switchgrass ( Panicum virgatum L.) in Bologna (44°55'N, 11°45′E). Generally, giant reed produced about 50% higher biomass than miscanthus in Catania. Miscanthus almost halved biomass productivity in the driest year, while giant reed reduced biomass yield by only 30% under the same conditions. In Bologna, miscanthus and switchgrass produced similar amounts of cumulative biomass over 6 years. Switchgrass kept more stable annual yields than miscanthus, which, however, evidenced a higher potential under favorable climate conditions. Autumn harvest significantly reduced biomass productivity and quality (moisture content, ashes, cellulose and hemicellulose), particularly under South Mediterranean climate. In Catania, autumn biomass was 50% (giant reed) to 85% (miscanthus) lower than winter biomass, while in Bologna, autumn cut reduced switchgrass yield by 20%. Biennial harvesting resulted in almost 40% lower cumulative biomass yield than annual cut, after 6 years. [ABSTRACT FROM AUTHOR]

Abstract: Fibre hemp can be grown under a wide range of agro-ecological conditions, but it requires special attention for several physiological features and crop management. A management strategy in order to reduce inputs and thus achieve acceptable yield could be achieved optimizing sowing time. With this respect, the effects of sowing date on hemp biology and yield was studied, using two monoecious and two dioecious genotypes. Field experiments were carried out in two subsequent years (2003–2004) in South of Italy, using drip irrigation system. Sowing time, in the two year period, ranged between March 10th and July 22nd. Optimal sowing time was observed between the end of April and the first three weeks of May; in that range, the dioecious Fibranova yielded the most in terms of aboveground biomass and stem dry yield, followed by Tiborszallasi, while the two monoecious showed the lowest yield. On the contrary, before and after that period, the shorter day length caused an early floral induction that strongly reduced stem and fibre elongation, and thus aboveground dry biomass and consequently stem yields. Based on this study a simulation model focusing on flowering prediction in Mediterranean environment was developed. [Copyright &y& Elsevier]

Background and Aims The development of Arundo donax as a biomass crop for use on drought-prone marginal lands in areas with warm to hot climates is constrained by the lack of variation within this species. We investigated the effect of morphological and physiological variation on growth and tolerance to drought under field conditions in three ecotypes of A. donax collected from habitats representing a climate gradient: a pre-desert in Morocco, a semi-arid Mediterranean climate in southern Italy and a warm sub-humid region of central Italy. Methods The three A. donax ecotypes were grown under irrigated and rain-fed conditions in a common garden field trial in a region with a semi-arid Mediterranean climate. Physiological and morphological characteristics, and carbohydrate metabolism of the ecotypes were recorded to establish which traits were associated with yield and/or drought tolerance. Key Results Variation was observed between the A. donax ecotypes. The ecotype from the most arid habitat produced the highest biomass yield. Stem height and the retention of photosynthetic capacity later in the year were key traits associated with differences in biomass yield. The downregulation of photosynthetic capacity was not associated with changes in foliar concentrations of sugars or starch. Rain-fed plants maintained photosynthesis and growth later in the year compared with irrigated plants that began to senescence earlier, thus minimizing the difference in yield. Effective stomatal control prevented excessive water loss, and the emission of isoprene stabilized photosynthetic membranes under drought and heat stress in A. donax plants grown under rain-fed conditions without supplementary irrigation. Conclusions Arundo donax is well adapted to cultivation in drought-prone areas with warm to hot climates. None of the A. donax ecotypes exhibited all of the desired traits consistent with an 'ideotype'. Breeding or genetic (identification of quantitative trait loci) improvement of A. donax should select ecotypes on the basis of stem morphology and the retention of photosynthetic capacity. [ABSTRACT FROM AUTHOR]

Increasing air temperature due to changing climate is projected to decrease the length of the growing season, hasten vegetative development and maturation, and ultimately affect yield of many C3 crops. Previous multilocation trials highlighted strong relationships between thermal trends in the interval "beginning of flowering‐end of grain filling" and grain yield, and protein content in durum wheat (Triticum turgidum subsp. durum (Desf.) Husn.). With the aim to confirm these relationships, nine durum wheat genotypes, including old (Capeiti 8, Senatore Cappelli and Trinakria) and modern (Amedeo, Arcangelo, Mongibello, Simeto, and Svevo) varieties and a Sicilian landrace (Russello) were grown at three different sites representing a climate gradient in Sicily, Italy. Moreover, the effect of post‐anthesis heat stress on these durum wheats was further investigated in two contrasting environments: open‐field (control—C) and greenhouse heat stress (HS). HS shortened the interval "beginning‐end of flowering" of 1.5 days across genotypes, and the "end of flowering‐beginning of grain filling" and maturation of 4.9 days, with a range of 1 day in Arcangelo to 11 days in Cappelli. Advances in main phenophases significantly decreased kernel weight (KW) and grain yield (GY), whereas grain protein content (PC) increased. As expected, a negative relationship was observed between GY and PC, while positive relationships were found for GY and grain‐filling duration (GFD), and GY and KW. Genotypes responded differently to heat stress, as evidenced by the net photosynthesis, transpiration rate, instantaneous water use efficiency and dry matter accumulation in kernels. Genotypes were ranked according to the heat susceptibility index (HSI): Amedeo, Arcangelo, Capeiti 8, Svevo and Trinakria resulted heat‐tolerant. These varieties were characterized by an early trigger of dry matter accumulation in kernels under HS (Amedeo, Arcangelo and Trinakria), or showed similar length of the GFD (Capeiti 8) between environments. The multilocation trial confirmed a negative relationship between maximum temperatures and grain yield, and a positive relationship between minimum temperatures and protein content during grain–filling periods. Research focusing on agronomic strategies, phenology and breeding for tolerance to heat stress is of strategic importance to cope with the detrimental effect of global warming in semi‐arid climates. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The aim of the present work was to ascertain, in a two-year field trial, leaf gas exchange, plant water status and radiation use efficiency of giant reed ( Arundo donax L.) under different nitrogen fertilization and soil water availability in semi-arid Mediterranean area. Three levels of nitrogen (0, 60 and 120 kg N ha −1 ) and three levels of soil water availability (rainfed, 50% ETm restitution and 100% ETm restitution) were compared. Throughout the crop growing season significant effects of soil water availability, nitrogen fertilization and time of measurement on net photosynthesis ( A ), transpiration rate ( E ), stomatal conductance (gs), canopy temperature (Tc), midday (ψ M ) and predawn leaf water potential (ψ PD ) were found. Significant interactions of soil water availability x time of measurement were also observed, while nitrogen x time of measurement was significant only for A , gs, E and ψ M . Radiation use efficiency (RUE) was lowest in rainfed and no-nitrogen fertilization (1.40 and 1.26 g MJ −1 in 1998 and in 1999, respectively) and highest in 100% ETm and 120 kg N ha −1 in both years (1.78 and 1.94 g MJ −1 in 1998 and in 1999, respectively). The fraction of intercepted PAR approached the asymptote when leaf area index was greater than 4.0, irrespective of soil water availability and nitrogen fertilization. The extinction coefficient ( k ) ranged from 0.38 to 0.44. Present results may have practical applications to help maximize physiological performances with improved WUE, optimized resource use efficiency and reduced irrigation demands. [ABSTRACT FROM AUTHOR]

Soils of the Mediterranean area are subjected to erosion due to the cropping systems and crop managements adopted. This causes a loss of crop productivity that could be initially replaced with an increase of fertilizers, but in the end leads to land abandonment. The areas subjected to soil erosion in the Mediterranean area cover 1,309,000 km, equal to 15 % of the land of Mediterranean countries. In dry farming condition, the farmer's choices are often constrained by the prevailing climatic conditions. Rainfall amount and distribution represent the main constraints that lead farmers to choose annual autumn-winter crops. In this environment, the growing cycle of autumn-winter crops, such as durum wheat, determines a lack of soil covering during the first rains that occur in early autumn and winter. Soil losses by erosion also determine nutrient losses and affect soil organic matter content. All these aspects are evaluated by ongoing research started in 1996 in an area of the internal hills of Sicily (Italy) in the center of the Mediterranean basin. In this experimental site, on a 27 % slope, the effect of different cropping systems to determine surface runoff and soil losses was evaluated. In each plot, (40 × 8) m, a series of devices were installed in order to determine the amount of runoff and sediment: four covered trap channels were installed at the bottom of each plot, each channel drained into pipes which emptied into a tank to collect surface runoff and soil losses. After each erosive rainfall, the amount of water, of sediments, and the nitrate-nitrogen were measured. Soil organic matter was determined every fall at 0-30 and 31-60 cm depth. The highest annual values of soil losses were observed in the annual tilled crops, such as the typical Mediterranean crop rotation 'durum wheat-durum wheat-fallow' (11.2 t ha year). Very low soil losses were observed in the plots managed with perennial crops, alfalfa (0.34 t ha year), Italian ryegrass in pure stand and in mixtures with subterranean clover (3.2 t ha year), and subterranean clover (1.7 t ha year). The perennial giant miscanthus and moon trefoil reduced soil losses to 0.1 t ha year. The benefit of the cultivation of perennial crops instead of tilled crops was also highlighted in relation to organic matter content. The rotation 'giant miscanthus (from 1997 to 2001)-moon trefoil (from 2002 to 2015)' made it possible to increase soil organic matter from 1.03 to 2.51 % in the average of the first 60 cm soil depth. [ABSTRACT FROM AUTHOR]

Research is needed to look for plants or lines that can thrive on soils affected by water deficit or other constraints. The present work investigated the potentiality of Saccharum spontaneum L. spp. aegyptiacum (Willd.) Hack., a lignocellulosic, perennial, rhizomatous, no-food crop in semi-arid Mediterranean area. A 3-year field trial was carried out with the aim to evaluate its physiology, biomass yield, water use efficiency, and biomass quality under different soil water availability. During 2011/2012, 2012/2013, and 2013/2014 growing seasons (hereinafter referred as 2011, 2012, and 2013, respectively), three levels of maximum evapotranspiration restitution (ETm) were compared: I 100 (100% ETm restitution), I 50 (50% ETm restitution), and I 0 (rainfed condition). Net photosynthesis, stomatal conductance, and transpiration rate were strictly related to the available soil water content (ASWC), with maximum gas exchange at field capacity. However, gas exchange between plants and atmosphere was also measured when ASWC was close to wilting point. Biomass dry matter (DM) yield and main morpho-biometric traits (e.g., stem height and basal stem diameter) were significantly affected by ASWC. A non-linear model showed that maximum DM yield, 37.86 Mg ha −1 , can be achieved when 1150 mm of water were used by the crop. Water use efficiency (WUE) was always highest in rainfed condition ( I 0 ), however, only in 2013 I 0 was significantly higher than I 50 and I 100 (5.89 g L −1 vs 4.26 and 3.33 g L −1 ). Within the variables employed, a linear model showed that WUE was negatively related to crop water use (CWU). The fiber content was not affected by the irrigation treatments. In the average, hemicellulose, cellulose, and lignin accounted for 23.9 (% w/w), 35.0 (% w/w), and 19.9 (% w/w), respectively. On the other hand, moisture and ash content, bulk density, low heating value, and ash melting point resulted significantly affected by the treatment. Present results suggested that S. spontaneum spp. aegyptiacum possesses a range of agronomically desirable traits of biomass crop: C4 plant, high biomass yield, active assimilation rates during drought–stress periods, able to use water efficiently, and satisfactory biomass quality. [ABSTRACT FROM AUTHOR]

Highlights: [•] Monoecious and dioecious hemp were studied in Mediterranean semi-arid environment. [•] Later dioecious showed the highest aboveground and stem DM yield (tha−1) [•] WUE ranged between 2.73gl−1 in good water and 3.45gl−1 in water stress conditions. [•] Optimum of photosynthetic rate was achieved at 24°C. At 43°C hemp growth ceased. [•] As soil water availability increased, RUE increased and light extinction coefficient (k) decreased. [ABSTRACT FROM AUTHOR]

A field experiment with reed canary grass (Phalaris arundinacea L.) was carried out at LAMMC Vėžaičiai Branch (Western Lithuania) in 2010–2016 with the aim to evaluate the impact of liming and nitrogen on grass productivity, biomass chemical content and energetic parameters of the pellets. The site soil is the natural acidic loam Retisol (pH 4.2–4.6). Reed canary grass productivity was significantly affected by the year of growing and nitrogen fertilization. The average annual dry matter (DM) yield varied from 5442 to 11,114 t ha−1. The highest yields were obtained using the annual rate of 120 kg ha−1 N (nitrogen) fertilizers. Soil liming had a negligible effect on biomass productivity. Nitrogen utilization efficiency (NUE) varied greatly depending on the growing year and N fertilization rate. After analyzing the properties of reed canary grass and wood sawdust granules, it was found that the granules obtained a high density exceeding 1000 kg m−3 DM. The lowest calorific value of reed canary grass pellets was found to be quite high—17.4 MJ kg−1 DM. All harmful emissions did not exceed the permissible values. Summarizing the results, it can be stated that reed canary grass pellets may be recommended for burning in domestic boilers. [ABSTRACT FROM AUTHOR]

Deficit irrigation is a valid alternative to conventional irrigation to save water while maintaining high productivity in tomatoes. However, crop sensitivity to water stress due to deficit irrigation may change with the growth stage. To assess the physiological and agronomic responses of processing tomatoes to deficit irrigation applied at critical stages, a field experiment was conducted in a coastal site of Southern Italy, where seven irrigation treatments differing for daily evapotranspiration (ETc) restored (100%—full or 50%—deficit) and the time of watering (long-season or limited to the vegetative period or to flowering) were applied to processing tomatoes cv. Hypeel F1. Plants continuously irrigated and those irrigated only at flowering maintained higher rates of leaf transpiration (E) and stomatal conductance (gs) over those irrigated only during the vegetative period. Fruit yield was the greatest under long-season full irrigation (51 t ha−1). Severe soil water deficit during flowering, more than during the vegetative period, adversely affected crop productivity. Irrigation water use efficiency (IWUE) was maximized under long-season deficit irrigation (>19 kg m−3) or deficit irrigation during flowering (>16 kg m−3). E and gs measured at early or mid-flowering may be adopted as valuable indicators to predict crop productivity; however, they may be altered under high vapor pressure deficit (VPD). Predawn water potential, being little affected by VPD, is a more reliable parameter than leaf transpiration and stomatal conductance under these climatic conditions. [ABSTRACT FROM AUTHOR]

• Castor might be grown as rainfed crop in semi-arid Mediterranean environments. • Autumn or winter sowings allowed to increase phenological intervals and seed yield. • Photoperiod corrected growing degree unit equations showed the lowest variability. • Suitable areas for autumn sowings were identified in Sicily. Castor (Ricinus communis L.) is an oilseed crop holding great promise for semi-arid environments. In regions where minimum temperature during winter is high enough to allow plants to survive, it would be worth to explore the adaptability of the species by performing autumn sowings, thus enabling rainfed cropping systems. A two-year field experiment under different sowing times (from November to June) was conducted in Southern Italy using castor Hy. Hazera. Autumnal sowings extended the plant vegetative period; nevertheless, flowering was simultaneous with all sowing dates. Only with the latest spring sowing (that of June) both floral induction and seed ripening were postponed. Seed yield with January and February sowings was the highest (3.92 Mg/ha on average). Using the wide variability of temperature and photoperiod conditions of the different growing periods, thermal and photothermal sums to predict the length of the main phenological intervals were calculated using different models. Overall, the best predicting model was that using sums of thermal units from minimum temperatures > 8 °C and maximum temperatures of 30 °C minus the degrees exceeding 30 °C, multiplied by photoperiod. The model allowed to develop zonation maps predicting the latest sowing date and the earliest seed ripening date in Sicily for autumn-spring and spring-summer growing season. The zonation procedure indicates that castor can be sown in autumn in coastal areas, while spring sowings are more suited to colder inland and hilly areas of Sicily. The work might find practical application to individuate suitable Mediterranean areas to grow castor in winter sowings. [ABSTRACT FROM AUTHOR]

Chemical input reduction in agricultural systems is strongly demanded with the aim to improve the quality and the safety of food/feed products in an environmental sustainable perspective. Durum wheat is the most important food crop widely grown across the Mediterranean basin. However, the choice of tailored-genotypes can represent a key strategy in resource limiting conditions. The present study investigated the performance of fourteen commercial durum wheat varieties, in terms of morphologic, productive and quality traits under two cropping systems, conventional (CH) and no-chemical input (NC), for two growing seasons. The NC cropping system affected plant phenology, grain yield, and its components (i.e., ears m−2 and test weight). However, the negative influence exerted by the NC depended by the growing season (significant interaction between growing season and cropping system), which in turn affected the production behavior of genotypes (significant interaction between growing season and genotype). The additive main effect and multiplicative interaction (AMMI) analysis showed that genotype (G) effect explained the 4.3% of the total variability, the environment (E) the 71.7% and the G × E interaction the 9.4%. The AMMI stability value (ASV) indicated that Meridiano, Claudio, Saragolla, and Normanno were the most stable genotypes among environments (combination of years and management systems). An integrated environmental assessment, including a soil nitrogen balance, can help to provide a more holistic approach to the sustainability of the no-chemical Mediterranean cropping systems based on cereal-legume rotation. [ABSTRACT FROM AUTHOR]

Miscanthus, a C4 perennial grass native to Eastern Asia, is being bred to provide biomass for bioenergy and biorenewable products. Commercial expansion with the clonal hybrid M. × giganteus is limited by low multiplication rates, high establishment costs and drought sensitivity. These limitations can be overcome by breeding more resilient Miscanthus hybrids propagated by seed. Naturally occurring fast growing indigenous Miscanthus species are found in diverse environments across Eastern Asia. The natural diversity provides for plant breeders, the genetic resources to improve yield, quality, and resilience for a wide range of climates and adverse abiotic stresses. The challenge for Miscanthus breeding is to harness the diversity through selections of outstanding wild types, parents, and progenies over a short time frame to deploy hybrids that make a significant contribution to a world less dependent on fossil resources. Here are described the strategies taken by the Miscanthus breeding programme at Aberystwyth, UK and its partners. The programme built up one of the largest Miscanthus germplasm collections outside Asia. We describe the initial strategies to exploit the available genetic diversity to develop varieties. We illustrate the success of combining diverse Miscanthus germplasm and the selection criteria applied across different environments to identify promising hybrids and to develop these into commercial varieties. We discuss the potential for molecular selections to streamline the breeding process. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study deals with approaches for a social-ecological friendly European bioeconomy based on biomass from industrial crops cultivated on marginal agricultural land. The selected crops to be investigated are: Biomass sorghum, camelina, cardoon, castor, crambe, Ethiopian mustard, giant reed, hemp, lupin, miscanthus, pennycress, poplar, reed canary grass, safflower, Siberian elm, switchgrass, tall wheatgrass, wild sugarcane, and willow. The research question focused on the overall crop growth suitability under low-input management. The study assessed: (i) How the growth suitability of industrial crops can be defined under the given natural constraints of European marginal agricultural lands; and (ii) which agricultural practices are required for marginal agricultural land low-input systems (MALLIS). For the growth-suitability analysis, available thresholds and growth requirements of the selected industrial crops were defined. The marginal agricultural land was categorized according to the agro-ecological zone (AEZ) concept in combination with the marginality constraints, so-called 'marginal agro-ecological zones' (M-AEZ). It was found that both large marginal agricultural areas and numerous agricultural practices are available for industrial crop cultivation on European marginal agricultural lands. These results help to further describe the suitability of industrial crops for the development of social-ecologically friendly MALLIS in Europe. [ABSTRACT FROM AUTHOR]