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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]

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

• Sowing time and plant density effects on pigments content were studied in safflower. • Florets yield significantly decreased shifting the sowing from February to April. • High plant density increased heads and florets yield. • Negative relationships were described for pigments contents vs. air temperature. Safflower (Carthamus tinctorius L.), a multipurpose plant grown in many areas of the world primarily for oil extraction from seeds for food and industrial application, recently has been drawn attention as a source of natural colourants. A two-year study was carried out to examine the combined effects of sowing time (24 February, 28 March, 26 April, in 2017; 21 February, 28 March, 24 April, in 2018) and plant density (25 and 50 plants/m2) on florets and pigments (safflomins and carthamin) production in safflower (cv. Catima) in a semi-arid Mediterranean environment. Sowing delay from February to April led to a significant decrease in heads and florets yield. Indeed, crop growth period was shortened as sowing time was delayed, since flowering occurs when photoperiod requirements are fulfilled (photoperiodic control) irrespective of thermal time. Single plant was more productive at low plant density. However, heads production per unit area was greater at high plant density, i.e. increased plant population overcompensated for heads losses at individual level, irrespective of sowing time. Early sowings also resulted in a higher content of safflomins (up to 54.6 g/100 g) and carthamin (up to 2.97 g/100 g) in florets. Negative relationships described for both pigments vs. air temperatures reveal how their content tends to decrease with the raise of temperature during flowering. Plant density had no relevant effect on pigments content. Further research on the effects of the agronomic management on pigments production of safflower may help to promote the expansion and development of this still underutilized but economically important crop. [ABSTRACT FROM AUTHOR]

Abstract: The effects of reduced water potential (ψ) in NaCl and pre-osmopriming in PEG, on seed germination and early radicle growth at different temperatures were assessed in the laboratory for sweet sorghum [Sorghum bicolor (L.) Moench] cv. Roce. Five salt solutions (with a ψ of 0-control, −0.22, −0.42, −0.82 or −1.23MPa) and four temperatures of 10, 15, 25 or 35°C were used for germination tests. Daily and final germination, seed moisture at 4 and 24h of imbibition and radicle length 2 days after initial germination were recorded. Sorghum seeds seem to be more tolerant to reduced ψ at optimum temperature. Indeed, at 25°C, down to −0.82MPa seed germination was not affected. The increase in incubation temperature to 35°C determined a greater seed water content and a faster germination than at 25°C at all ψ s, despite the lower final germination percentage. With the lowering of temperature to 15°C, germination percentage significantly declined with the decrease of ψ and at −0.82MPa it reduced to less than 50%. At 10°C seeds failed to germinate at ψ <−0.22MPa due to combined depressive effects of reduced ψ and low temperature. Seed priming enhanced germination and shortened the delay in germination time due to the increase in saline stress, at suboptimal temperatures only. This effect could be explained by the faster water absorption occurring in primed seeds as compared to those unprimed, at these temperatures, regardless of salt concentration of the solution. Root growth was more sensitive than germination to salt stress. Indeed, the increase in NaCl concentration adversely affected root elongation at all temperatures. The beneficial effects of PEG-osmopriming were evident on root growth at all temperatures except the optimal one. From a practical point of view, when early sowings of sweet sorghum are requested, the use of primed seeds is suggested, as PEG-osmopriming is helpful in overcoming the negative effect imposed by reduced water potential upon seed germination under suboptimal thermal conditions. When saline water is available for irrigation at sowing, it may be useful to sow when optimal or nearly optimal temperature may be encountered in the soil in order to avoid the combined stress of temperature and salinity. [Copyright &y& Elsevier]

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]

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]

• 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]