1,093 research outputs found
Physiological and Agronomic Responses of Processing Tomatoes to Deficit Irrigation at Critical Stages in a Semi-Arid Environment
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
Evaluation Of The Methanogenic Potential Of Two Lignocellulosic Crops
Biogas production can be considered an important technology for the sustainable use of agricultural biomass as a renewable energy source even more when the substrates for anaerobic digestion are crop residues, livestock residues or energy crops that don’t compete with food crops for land use. The aims of this study were to evaluate the production of biogas and biomethane from two lignocellulosic crops suitable for the Mediterranean environment (Arundo donax L. and Saccharum spontaneum subsp. aegyptiacum (Willd.) Hack) and the efficiency of a thermal pretreatment to increase the biomethane production. The purpose of the pretreatment is to break the recalcitrant lignin layer, so that the cellulose and hemicellulose present in the biomass are hydrolyzed by microorganisms and converted into simple sugars to achieve greater energy yield
Prospects of Bioenergy Cropping Systems for A More Social-Ecologically Sound Bioeconomy
The growing bioeconomy will require a greater supply of biomass in the future for both bioenergy and bio-based products. Today, many bioenergy cropping systems (BCS) are suboptimal due to either social-ecological threats or technical limitations. In addition, the competition for land between bioenergy-crop cultivation, food-crop cultivation, and biodiversity conservation is expected to increase as a result of both continuous world population growth and expected severe climate change effects. This study investigates how BCS can become more social-ecologically sustainable in future. It brings together expert opinions from the fields of agronomy, economics, meteorology, and geography. Potential solutions to the following five main requirements for a more holistically sustainable supply of biomass are summarized: (i) bioenergy-crop cultivation should provide a beneficial social-ecological contribution, such as an increase in both biodiversity and landscape aesthetics, (ii) bioenergy crops should be cultivated on marginal agricultural land so as not to compete with food-crop production, (iii) BCS need to be resilient in the face of projected severe climate change effects, (iv) BCS should foster rural development and support the vast number of small-scale family farmers, managing about 80% of agricultural land and natural resources globally, and (v) bioenergy-crop cultivation must be planned and implemented systematically, using holistic approaches. Further research activities and policy incentives should not only consider the economic potential of bioenergy-crop cultivation, but also aspects of biodiversity, soil fertility, and climate change adaptation specific to site conditions and the given social context. This will help to adapt existing agricultural systems in a changing world and foster the development of a more social-ecologically sustainable bioeconomy
Caratterizzazione della dinamica produttiva di pascoli naturali italiani
This work studies herbage production and its seasonal distribution in indigenous pastures, and analyses the relationship
between the environmental factors (soil, clima, vegetation) and the productivity of these resources.
The investigations have been carried on during the period 1983-90 by the joint activity of 10 different University Istitutions
in 23 different environments distributed along the Italian peninsula and the main islands.
For each environment, pasture production has been measured with the Corrall and Fenlon method, analysing the more
important vegetational and ecological conditions; altogether the total yearly production and the seasonal pattern of herbage
production have been detected on 104 pastures.
The total herbage yield is not significantly influenced by the latitudinal gradient, and the overall regional (alps, central
Appenine, south Apennine and islands) production is about 2.3 t ha-1 year-1 The wide range (0.5-6.3 t ha-1 year-1) of
herbage production, on small or medium scale, seems to be due to evident changeof environmental or management factors.
Five types of seasonal distribution of herbage growth are evidenced with multivariate analysis methods, based on the
growing season and the amplitude of the growth. With mean temperature above 12°C and total rainfall below 800 mm,
herbage distribution shows a standstill during summer period and an evident regrowth in autumn. On the contrary, for
the 4 other distribution types, the winter standstill become important, and the types are distinct by summer growth amplitude
and by the growing season lenght. With cluster analysis method, for each type of herbage distribution, have been
pointed out under-types characterized by interannual herbage production variation.
Among the environmental factors, vegetation characheristics, expressed as Pasture Value following Daget and Poissonet
seems to be strictly correlated with total production. The comparative poor role played by the soil and climatic factor,
may be due to the strong past and present antropic influence, related with management and utilization techniques.
Il presente lavoro ha come scopo l'approfondimento delle conoscenze sulla produzione e sulla distribuzione stagionale
della crescita dell'erba dei pascoli naturali, nonché l'analisi delle interazioni tra i fattori ambientali, pedo-climatici e vegetazionali,
e la risposta produttiva di queste risorse.
La ricerca è stata condotta nel periodo 1983-90 da 10 diverse Istituzioni Universitarie, in 23 ambienti differenti, distribuiti
lungo tutta la penisola e le isole maggiori.
Per ogni ambiente, con il metodo di rilievo di Corrall e Fenlon, è stata saggiata la risposta produttiva di pascoli rappresentativi
delle principali situazioni vegetazionali e di giacitura; complessivamente sono state rilevate la produzione totale
annua e la curva di produttività media pluriennale di 104 pascoli.
Riguardo la produzione annua complessiva si è osservato che essa non presenta variazioni significative lungo il gradiente
latitudinale, collocandosi tra le diverse regioni (alpina, centro appenninica, suq, appenninica e insulare) attorno a 2.3
t ha-1 anno-1. La fitomassa raccolta è soggetta invece a variazioni sensibili (0.5-6.3 t ha-1 anno-1) riconducibili a fattori
ambientali e gestionali che si esprimono su piccola e media scala.
Con metodi di analisi multivariata si sono individuate 5 tipologie distributive della crescita dell'erba, in rapporto alla
stagione vegetativa e alle variazioni dell'intensità di crescita nel corso della stagione stessa. Con temperature medie e precipitazioni
annue rispettivamente maggiori di 12°C e minori di 800 mm, risulta evidente la stasi vegetativa nel trimestre
estivo e la ripresa vegetativa autunnale. Nel caso opposto la stasi è invernale e le 4 tipologie afferenti a questo modello,
sono distinguibili dall'entità della crescita nei mesi estivi e dalla durata della stagione vegetativa. Per ogni tipologia produttiva,
sono state evidenziate, tramite l'analisi cluster, sotto-tipologie distinte per la variabilità produttiva interannuale.
Tra i fattori ambientali, la vegetazione, espressa attraverso l'indice del valore pastorale di Daget e Poissonet, presenta
una buona capacità predittiva nei confronti del livello produttivo dei pascoli. Il contributo comparativamente modesto offerto
dai fattori pedoclimatici sembra attribuibile alla forte influenza antropica, pregressa e attuale, attraverso le cure colturali
e l'utilizzazione
Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions
We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe
Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC
Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe
Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV
Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe
Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV
Peer reviewe
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