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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]

To evaluate the performance of dwarf castor hybrids ('C1012', 'C857', 'C856'), compared to a local selected genotype, in four subsequent sowing dates (SW1, SW2, SW3, SW4), a trial was conducted at the experimental farm of the University of Catania (Sicily, Italy). The length of the growing season decreased with the increase of the sowing date in the average genotypes from 160 to 94 days, respectively, for the first and the last sowing date. According to the RED—Renewable Energy Directive, the genotype 'C856' was the earliest (112 days), resulting in suitability as a catch crop for biomass production. The results showed that early spring sowings negatively impact dwarf hybrid production (1.2 and 1.5 Mg ha−1 in SW1 and SW2, in the average of the three hybrids), which reached the highest yield in the third sowing date (2.0 Mg ha−1), preferring warmer temperatures for the germination of seeds. On the contrary, the 'Local' genotype reached the highest yield (1.6 Mg ha−1) in the first sowing date and linearly decreased in the subsequent ones. Nonetheless, the third sowing date positively influenced the oil content and the oil yield in all dwarf genotypes except the 'Local' genotype, which showed the highest oil yield in the first sowing date. [ABSTRACT FROM AUTHOR]

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]

The restoration of polluted soils is crucial for ecosystem recovery services. Evidently, phytoremediation is a biological and sustainable technique that includes the use of plants to remediate heavy-metal-contaminated land; the plants should be tolerant to the contamination and capable of uptake or immobilization of the heavy metals in the soil. Moreover, defining an economically efficient approach to the remediation of a contaminated area, with the possibility of further utilization of phytoremediation biomass, renders energy crops a great option for this technique. Energy crops, in fact, are known for their ability to grow with low agricultural input, and later, the biomass product can be used to produce biofuels, bioenergy, and bioproducts in a sustainable and renewable way, creating economic potential, especially when these crops are cultivated in marginal lands. The aim of this work is to test two monoecious industrial hemp varieties in different levels of Cd, Pb, and Ni in soil. Both varieties were tolerant to levels of Cd and Pb contamination that were higher than the limit for commercial and industrial use, while Ni showed a significant effect at all the tested concentrations. The variety Futura 75 performed better than Kc Dora in terms of productivity and tolerance. [ABSTRACT FROM AUTHOR]

The promotion and gradual replacement of fossil fuels with renewable sources increasing the competition between food and fuel. Therefore, energy crops could be produced on unproductive marginal land due to unfavorable conditions, such as limitations in nutrient and water availability or the presence of contaminants such as hydrocarbons or heavy metals. In the case of soils contaminated with heavy metals, one option could be the use of plants to extract or immobilize the contaminants in the soil in a process called phytoremediation. Carthamus tinctorius L. is an annual herbaceous plant with a deep root system, and the oil extracted from the seeds is an excellent oil for conversion into biofuel. It appears suitable to be used in the phytoremediation process, increasing the opportunity to valorize polluted areas and reducing the risk of abandonment of these lands. In this study, C. tinctorius was tested in soils contaminated with zinc, cadmium, lead, and nickel at different concentrations to evaluate the effects on yield and heavy metal content in the different parts of the plant. The experiment highlights the tolerance of Safflower to the cultivation in heavy-metal-polluted soil; in fact, a low reduction in biomass yield was observed. Among the evaluated heavy metals, the higher susceptibility was observed at the highest concentrations of zinc and cadmium. Generally, safflower concentrates heavy metals in the belowground biomass. The relative low concentrations of heavy metals in some parts of the aboveground biomass could suggest the possibility of using it as a feedstock for bioenergy conversion. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]