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Drought adaptation characteristics of a giant reed mutant
No full textGiant reed (Arundo donax L.) is a spontaneous C3 perennial grass, which propagates only
vegetatively due to seed sterility. This prevents the development and establishment of
targeted improving breeding programmes. The development of mutants could improve the
performance and/or suitability of the species for bioenergy production purposes, especially in
stressful environments. Even though giant reed is considered a drought tolerant species,
nothing is known about the effects of mutagenesis on its morpho-productive and
physiological traits relevant to yield responses to drought. The objective of this study was to
characterise some phenotypic traits of mutagenised giant reed under drought conditions. The
trial was carried out under semi-controlled environmental conditions in a total of 16 rhizotrons
of one cubic meter capacity. Calibrated soil moisture probes were installed at different depths
in order to adjust the soil moisture content to 25% (field capacity) and 10% (v/v) in the wellwatered
and dry treatments, respectively. A mutant (UniBO3) developed by UniBO and
Genetic Lab through gamma-irradiation was selected from a pool of 100 mutants and
compared with the non-mutagenised precursor of local origin. Biometric, production, and
physiological parameters were evaluated at young and mature growth stages. Under wellwatered
conditions at both growth stages the tiller density of UniBO3 was significantly higher
than in the local genotype, but both genotypes showed similar biomass yield. The sustained
biomass yield of the droughted local genotype compared with the well-watered conditions
was related to unchanged number of tillers. On the other hand the reduced biomass yield of
the droughted mutant (UniBO3) was significantly correlated with reductions in photosynthetic
capacity (Pn), maximum carboxylation rate (Vcmax), potential electron transport rate (Jmax),
quantum yield (Fv/Fm), and leaf water potential (LWP) at young stages, while at mature
stages with Fv/Fm and LWP. In summary, the UniBO3 mutant showed a reduced tolerance
to drought at productive and physiological levels
Quantitative and Qualitative Biomass Production Potential of Giant Reed Mutants under Rainfed and Irrigated Conditions
No full textEffetti dell’epoca di semina e dell’inserimento di un intercalare sul comportamento bio-agronomico del sorgo da biomassa.
No full textEnhanced substrate degradation and methane yield with maleic acid pre-treatments in biomass crops and residues
Full text linkOrganic acids are envisaged as alternative catalysts to strong mineral acids, in pre-treatment of lignocellulosic biomass for anaerobic digestion (AD). To evaluate this hypothesis, an untreated control and four pre-treatments (25 C for 24 h) involving two levels of maleic acid (34.8 and 69.6 kg m3), alone and combined with sulphuric acid (4 kg m3), were studied in three agricultural substrates: Arundo (aka giant reed), Barley straw and B133 fibre sorghum. Methane production was assessed in a batch AD assay
(35 C for 51 days) with 4 g L1 of volatile solid (VS) load. Fibre composition and structure were investigated through chemical analysis and Fourier transform infrared (FTIR) spectrometry. Arundo and B133 that were the most and least recalcitrant substrate, respectively, staged the highest and lowest increase in methane with high maleic acid: þ62% over 218 cm3 g1 of VS in untreated Arundo; þ36% over 284 cm3 g1 of VS in untreated B133. Barley straw showed an intermediate behaviour (þ41% over 269 cm3 g1 of VS). H2SO4 addition to maleic acid did not improve CH4 output. The large increase in methane yield determined by pre-treatments was reflected in the concurrent decrease of fibre (between 14 and 39% depending on fibrous component). Based on FTIR spectra, bands assigned to hemicellulose and cellulose displayed lower absorbance after pre-treatment, supporting the hypothesis of solubilisation of structural carbohydrates and change in fibre structure. Hence, maleic acid was shown a suitable
catalyst to improve biodegradability of ligno-cellulosic biomass, especially in recalcitrant substrates as Arundo
Two-Year Old Giant Reed Ecotypes Adaptation to Drought
No full textMorpho-physiological traits that convey two years-old giant reed (Arundo donax) ecotypes (Moroccan and Northern Italy) high drought tolerance and water use efficiency (WUE) have been evaluated in large rhizotrons under semi-controlled environmental conditions. No large differences between the two ecotypes tested was evident in terms of plant height, number of tillers or biomass production. However, an interesting physiological parameter that distinguished both ecotypes under drought was the predawn leaf water potential (LWP), which was closely related to photosynthesis and stomatal conductance but not to the photochemical reactions of photosynthesis. Stomatal control and LWP could be important attributes to improve drought tolerance in giant reed
Colture dedicate da biomassa e residui colturali per la produzione di CH4: effetto di trattamenti alcalini a moderata intensità
No full textPre-trattamenti alcalini a moderata aggressività sono stati applicati su tre substrati quali Arundo (specie poliennale da biomassa), B 133 (ibrido di sorgo annuale da biomassa) e paglia di orzo (sottoprodotto agricolo) per migliorare la produzione specifica di CH4. I pre-trattamenti sono stati condotti a 25 °C per 24 h, con NaOH a tre differenti concentrazioni (0,05;
0,10; 0,15 N), oltre a un testimone non trattato. L’incubazione anaerobica è stata condotta con un carico organico di 4 g SV l-1 a 35 °C per 58 gg. In tutti i pretrattamenti testati è stato osservato un incremento nella produzione specifica di CH4, rispetto al substrato non trattato. Il maggior incremento (30%) è stato ottenuto con NaOH 0,15 N in Arundo. Tali risultati
appaiono particolarmente interessanti, dimostrando come un modesto impiego di energia termica per il pre-trattamento si accompagni a significativi incrementi di CH4 prodotto. I pretrattamenti a base di soda non dovrebbero essere, inoltre, difficilmente implementabili nei moderni impianti di biogas
ANAEROBIC DIGESTION OF ALTERNATIVE ENERGY CROPS
No full textSUMMARY
Biomass crops deserve increasing interest among renewable energy sources. In this work we tested the biomass produced by Arundo, Switchgrass and two sorghum hybrids (B 133 and Trudan Headless), all grown without irrigation at moderate fertilization level, compared to irrigated, well fertilized Maize. The methane yield of the five crops was assessed in a batch experiment at 0.5 % VS organic load, incubated over 47 days at 35 °C. B 133 showed the highest dry biomass yield (29.2 Mg ha-1), followed by: Arundo, Switchgrass and Trudan Headless (26.8, 22.4 and 20.8 Mg ha-1, respectively); Maize achieved 27.8 Mg ha-1. Switchgrass showed the highest methane yield, 246 ml g-1 VS, followed by Trudan Headless, B 133, and Arundo (230, 193, 175 ml CH4 g-1 VS, respectively); Maize exhibited an intermediate yield (192 ml CH4 g-1 VS). Overall, the five crops displayed a remarkable methane yield; more specifically, the four annual and perennial biomass crops offer a promising alternative to Maize, achieving comparable biomass and methane yields in exchange for a lower need of cropping inputs
Colture dedicate per la digestione anaerobica
No full textIn questo lavoro è stata valutata la produzione potenziale di metano (CH4) di due colture poliennali (Arundo e Switchgrass) e di tre ibridi di sorgo annuale (Trudan H., B 133 e S 506), coltivati presso l’azienda agraria dell’Università di Bologna. Sulle biomasse sono stati determinati i principali zuccheri solubili (glucosio, fruttosio), carboidrati strutturali (cellulosa, emicellulosa) e lignina,
nonché la produzione specifica di CH4 attraverso un saggio di incubazione anaerobica (58 gg, 4 g SV l-1). Le colture annuali presentavano una maggiore biodegradabilità (66-70%) rispetto alle poliennali (56-58%), con conseguenti maggiori rese di CH4 (263 vs. 222 ml g-1 SV). La biodegradabilità di queste biomasse appare influenzata positivamente dal contenuto in carboidrati solubili, mentre quelli strutturali e la lignina presentano correlazioni negative. Le colture in esame, potenzialmente alternative al mais, meritano attenzione per i bassi input colturali, ma richiedono azioni di miglioramento della biodegradabilità, come un anticipo dell’epoca di raccolta e i pretrattamenti della biomassa, ai fini di una maggior resa specifica di CH4
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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