2,164 research outputs found
Early results of the effect of two varying celtic pig stocking densities on iberian-atlantic oakwoods (A Coruna, Spain)
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ASSESSMENT OF ENERGY CONSUMPTION IN GREENHOUSE PRODUCTION IN THE WEST REGION OF PORTUGAL
Greenhouse production is a very important activity in the West region of Portugal, with an area of approximately 800 ha where the regular production consists in two crops per year, one in winter-spring and the other in summer-autumn. Many growers are now prepared to better exploit market opportunities, since they know that the big export window opportunity is from June to September, when the production is difficult in other regions of south due to high temperatures.
Grower’s use new and more productive varieties, either in soil or hydroponic systems, mostly in unheated greenhouses, naturally ventilated, and equipped with modern fertigation systems. Greenhouse production causes some environmental impacts due to the high use of inputs. Several improvements in technologies and crop practices may contribute to increase the use efficiency of resources, decreasing the negative environmental impacts.
Greenhouse vegetable production in Northern EU countries is based on the supply of heating and differs significantly from the production system in the Southern EU countries. In the Northern countries, direct energy inputs, mostly for heating, are predominant while in the South the indirect energy input is also important, mainly associated with fertilizers, plastic cover materials and other auxiliary materials.
The main objective of this work was to characterise the greenhouse production systems in the West region of Portugal, in order to evaluate the energetic consumptions (direct and indirect), the GHH emissions, the production costs and the farmer’s income. With this work the mostly important inputs were identified, allowing proposing alternative measures to improve efficiency and sustainability.
All the data was obtained by surveys performed directly with growers, previously selected to be representative of the crop practices and greenhouse type of the region. However, more research should be performed in order to develop and to test technologies capable to improve resources use efficiency in greenhouse production
Molecular evolution of aphids and their primary ( Buchnera sp.) and secondary endosymbionts: implications for the role of symbiosis in insect evolution.
Aphids maintain an obligate, endosymbiotic association with Buchnera sp., a bacterium closely related to Escherichia coli. Bacteria are housed in specialized cells of organ-like structures called bacteriomes in the hemocoel of the aphid and are maternally transmitted. Phylogenetic studies have shown that the association had a single origin, dated about 200-250 million years ago, and that host and endosymbiont lineages have evolved in parallel since then. However, the pattern of deepest branching within the aphid family remains unsolved, which thereby hampers tin appraisal of, for example, the role played by horizontal gene transfer in the early evolution of Buchnera. The main role of Buchnera in this association is the biosynthesis and provisioning of essential amino acids to its aphid host. Physiological and metabolic studies have recently substantiated such nutritional role. In addition, genetic studies of Buchnera from several aphids have shown additional modifications, such as strong genome reduction, high A+T content compared to free-living bacteria, differential evolutionary rates, a relative increase in the number of non-synonymous substitutions, and gene amplification mediated by plasmids. Symbiosis is an active process in insect evolution cis revealed by the intermediate values of the previous characteristics showed by secondary symbionts compared to free-living bacteria and Buchnera
The XPF-ERCC1 endonuclease and homologous recombination contribute to the repair of minor groove DNA interstrand crosslinks inmammalian cells produced by the pyrrolo[2,1-c][1,4]benzodiazepine dimer SJG-136
SJG-136, a pyrrolo[2,1-c][1,4]benzodiazepine (PBD) dimer, is a highly efficient interstrand crosslinking agent that reacts with guanine bases in a 5'-GATC-3' sequence in the DNA minor groove. SJG-136 crosslinks form rapidly and persist compared to those produced by conventional crosslinking agents such as nitrogen mustard, melphalan or cisplatin which bind in the DNA major groove. A panel of Chinese hamster ovary (CHO) cells with defined defects in specific DNA repair pathways were exposed to the bi-functional agents SJG-136 and melphalan, and to their mono-functional analogues mmy-SJG and mono-functional melphalan. SJG-136 was >100 times more cytotoxic than melphalan, and the bi-functional agents were much more cytotoxic than their respective mono-functional analogues. Cellular sensitivity of both SJG-136 and melphalan was dependent on the XPF-ERCC1 heterodimer, and homologous recombination repair factors XRCC2 and XRCC3. The relative level of sensitivity of these repair mutant cell lines to SJG-136 was, however, significantly less than with major groove crosslinking agents. In contrast to melphalan, there was no clear correlation between sensitivity to SJG-136 and crosslink unhooking capacity measured using a modified comet assay. Furthermore, repair of SJG-136 crosslinks did not involve the formation of DNA double-strand breaks. SJG-136 cytotoxicity is likely to result from the poor recognition of DNA damage by repair proteins resulting in the slow repair of both mono-adducts and more importantly crosslinks in the minor groove
Energy consumption and greenhouse gas emissions of zucchini (Cucurbita pepo L.) cultivated in hydroponic greenhouses in the western region of Portugal
In recent years, there has been a significant increase in the consumption of
zucchini (Cucurbita pepo L.) in Portugal, which has led to increased production of this
vegetable. There is still a deficit of production in winter, but, in summer, production is
higher than demand, allowing exportation. At present, there is a positive ratio
between zucchini annual exportation/importation values. This means that it is an
attractive crop for farmers, especially in the western region of Portugal, which has a
microclimate favourable for this crop. The mild winter conditions of the region allow
crop growth in unheated greenhouses, which is an advantage for reducing production
costs and energy consumption compared with other regions. Crop productivity, either
in soil or hydroponics, has increased through the use of better production techniques,
modern fertigation systems and new and more productive cultivars. Several
improvements in technology and crop practices may now contribute to increased
resource-use efficiency, decreasing the negative environmental impact sometimes
associated with greenhouse production. The main objective of this work was to
evaluate the energy consumption (direct and indirect) and the greenhouse gas (GHG)
emissions of greenhouse zucchini produced in the western region of Portugal. All the
data were obtained through questionnaires performed directly with growers, which
have been previously selected as representative of crop practices and greenhouse
type in the region. The results show total energy consumption varying between 4.69
and 6.57 GJ t-1, the electricity used for irrigation making up the largest contribution,
followed by the greenhouse material and fertilizers. With this work, the most
important inputs were identified, allowing the proposal of alternative measures to
improve efficiency and sustainabilit
Antibrowning and antimicrobial effects of onion essential oil to preserve the quality of cut potatoes
This study evaluated the effect of onion essential oil (OEO) (0, 0.5, 2.5, and 5 mg ml−1) on microbial growth, browning decay, and sensorial appealing of cut potatoes stored for 15 days at 4 °C. Dipropyl disulphide and dipropyl trisulphide were the main constituents identified in OEO, and its application at a dose of 0.5 mg mlt-1 was the most effective to prevent browning (38.5% inhibition respect to control) during storage, inhibiting PPO activity (39% respect to control) after the treatment. The higher the added OEO concentration the lower microbial growth of the treated product was, achieving a reduction of 1.27 log CFU g−1 for the 5 mg ml−1 treatment. The odour and flavour appealing of cut potatoes were well received by the panelists after 10 days of storage. Therefore, the use of OEO in cut potatoes has a potential as antimicrobial and antibrowning agent
Evaluation of the SALTMED model for tomato crop production in unheated greenhouses
The SALTMED model is one of the few available generic models that can be used
to simulate crop growth with an integrated approach considering water, crop, soil and
field management. It is a physically based model using the well-known water and solute transport, evapotranspiration, and water uptake equations. The possibility of using models able to simulate crop growth with this integrated approach can be very useful for farmers as a decision support tool, helping with decisions such as: what crop/variety to use, when to plant and harvest, when and how much to irrigate, what
yield to expect under a specific irrigation system or strategy, when using a certain
water quality, and also to allow increasing water use efficiency and crops productivity.
The SALTMED model has been calibrated and validated for several field crops, in several parts of the world, including field tomato. However, the greenhouse environment has specific conditions that are not always easy to simulate with generic crop growth models. The objective of this work was to evaluate SALTMED model for a tomato crop grown in unheated greenhouse conditions. Climatic data and crop parameters were recorded during two years, in two greenhouses with different ventilation management, and three different sets of data were used to calibrate and to validate the model. The results showed that the model can accurately simulate soil grown tomato crop yield under Mediterranean unheated greenhouse conditions
Enhancing the attractiveness of European study programs in Biosystems Engineering
The paper describes the Tools for enhancing the international attractiveness of European study programs in Agricultural/Biosystems Engineering (ABE), in Portugal; Implementation of ABE study programs in Portugal aimed at promoting their international image; the tools for promoting the multi-linguism in ABE study programs in Portugal; the topics of rare and/or disappearing knowledge that can be used as a tool for enhancing the attractiveness of ABE study programs
Third cycle university studies in Portugal: current schemes and possible structured programs of studies in agricultural engineering and in the emerging discipline of biosystems engineering
The present trend, even for the universities that have not been adjusted to the
Bologna related structured 3rd cycle degree is to organize the PhD programs,
offering doctoral courses to a maximum of 30 ECTS plus 150 ECTS for work
research. Normally the duration of these programs will be of three years divided in 6
semesters. The prerequisites required for these programs are normally associated
to the scientific area of the PhD but usually, the prerequisites are not very strict.
Some of the ECTS of the PhD courses have the objective of eliminating PhD
student’s formation handicaps and/or to give specific knowledge in areas considered important to each individual student according to its specific PhD thesis
ESTIMACIÓN DE LA BIOMASA FORESTAL PARA LAS ESPECIES QUERCUS ROTUNDIFOLIA Y QUERCUS SUBER BASADA EN IMÁGENES DEL SATÉLITE QUICKBIRD
para una buena gestión. Actualmente las técnicas de inventario y monitoreo de biomasa forestal son usualmente lentas,
muy trabajosas y de elevado coste, verificándose así la necesidad de desarrollar otras técnicas, que sean fiables y con
costes relativamente reducidos. El objetivo de este estudio es desarrollar una metodología para estimar la biomasa
forestal de las especies Quercus rotundifolia y Quercus suber basada en imágenes del satélite QuickBird. La estimación
de la biomasa forestal, fue obtenida con un error inferior a 5%, para valores de proyección horizontal de la copa
acumulada obtenida con imágenes de satélite superiores a 4000 m2
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