253 research outputs found
Decision support system for surface irrigation design
The SADREG decision support system was developed to help decision makers in the process of design and selection of farm
surface irrigation systems to respond to requirements of modernization of surface irrigation—furrow, basin, and border irrigation. It
includes a database, simulation models, user-friendly interfaces, and multicriteria analysis models. SADREG is comprised of two components:
design and selection. The first component applies database information, and through several simulation and computational tools,
produces a set of design alternatives in agreement with the user options. These alternatives are characterized by several hydraulic,
economic, and environmental indicators that allow appropriate selection and ranking. The selection component bases upon multicriteria
analysis using composite programming and ELECTRE II ranking models, which support the decision maker to select the best alternative.
The decision maker participates in all decision processes through a user-friendly interface that allows expressing design options and
priorities. SADREG was tested with data collected from field experiments. In addition to describing the modeling approach, an application
to a sector of the Lower Mondego Irrigation Project, Portugal, is presente
Field assessment of basin irrigation performance and water saving in Hetao, Yellow River basin: issues to support irrigation systems modernisation
Research PaperWater-saving irrigation needs to be implemented in Hetao irrigation district to help
satisfying the demand by other users in the Yellow River basin. Aiming at assessing the
potential irrigation performance and water saving at farm level, a set of traditional basins
and another of precision-levelled basins cropped with maize, wheat and sunflower and
managed by farmers were evaluated. Data were collected to characterise the basin sizes,
microtopography, inflow rates, advance and recession times, cut-off time and soil water
content. In addition, families of infiltration curves were derived from field observations and
subsequent use of model SIRMOD. Infiltration was higher for the precision-levelled basins
and decreased from the first to the next irrigation events. Infiltration data were used to
support the computation of distribution uniformity (DU), beneficial water use fraction
(BWUF) and deep percolation (DP). For traditional basins, DU and BWUF were low and DP
was high. When precise land levelling was practised, DU increased greatly to near 94% but
BWUF improved little, because irrigation scheduling was inadequate leading to excessive
water application; however, non-negligible water saving was achieved for maize and wheat
since they have higher irrigation demand. In contrast, simulating the application of an
appropriate irrigation scheduling through adjusting the cut-off time led to an approximately
unchanged DU but BWUF greatly increased and DP reduced to 10% on average. This
condition represents a potential water saving of 34e39%; however its achievement requires
improved design of farm systems, appropriate irrigation water deliveries and scheduling,
and the support and training of farmersinfo:eu-repo/semantics/publishedVersio
Drip vs. surface irrigation: a comparison focussing on water saving and economic returns using multicriteria analysis applied to cotton
Research PaperThis study explores the use of drip and surface irrigation decision support systems to select
among furrow, border and drip irrigation systems for cotton, considering water saving and
economic priorities. Data refers to farm field observations in Northeast of Syria. Simulation
of drip irrigation was performed with MIRRIG model for various alternatives: double and
single row per lateral, emitter spacing of 0.5 and 0.7 m, six alternative pipe layouts and five
self-compensating and non-compensating emitters. Furrow and border irrigation alternatives
were designed and ranked with the SADREG model, considering lasered and nonlasered
land levelling, field lengths of 50e200 m and various inflow discharges. A multicriteria
analysis approach was used to analyse and compare the alternatives based upon
economic and water saving criteria. Results for surface irrigation indicate a slight advantage
for long non-lasered graded furrows; non-lasered alternatives were selected due to economic
considerations. For drip irrigation, the best ranking is for systems having lower costs,
mainly with double rows per lateral and larger emitter spacing. Comparing surface and drip
irrigation systems, despite low cost, drip alternatives may lead to 28e35% water saving
relative to improved graded furrows, and increase water productivity from 0.43 kg m 3 to
0.61 kg m 3, surface irrigation provides higher farm returns. Drip irrigation is selected only
when high priority is assigned to water saving. Deficit irrigation does not change this pattern
of results. Apparently, adopting drip irrigation requires appropriate economic incentives to
farmers, changes in the structure of production costs and increased value of productioninfo:eu-repo/semantics/publishedVersio
Development of ternary diagrams for estimating water retention properties using geostatistical approaches
Most pedotransfer functions (PTFs) have adopted soil texture information as the main predictor to estimate
soil hydraulic properties, whether inputs are defined in terms of the relative proportion of different grain size
particles or texture-based classifications. The objective of this studywas to develop ternary diagrams for estimating
soil water retention (θ) at−33 and−1500 kPa matric potentials, corresponding to the field capacity and wilting
point, respectively, from particle size distribution using two geostatistical approaches. The texture triangle was
divided into a 1% grid of soil texture composition resulting in 4332 different soil textures. Measured soil water
retention values determined in 742 soil horizons/layers located in Portugal were then used to develop and
validate the hydraulic ternary diagrams. The development subset included two-thirds of the data, and the
validation subset the remaining samples. The measured soil water content values were displayed in the ternary
diagram according to the coordinates given by the particles size distribution determined in the same soil
samples. The volumetric water content values were then predicted for the entire ternary diagram using two
different geostatistical interpolation algorithms (ordinary kriging and the empirical best linear unbiased
predictor). Uncertainty analysis resulted in a root mean square error below 0.040 and 0.034 cm3 cm−3 when
comparing the interpolated water contents at −33 and −1500 kPa matric potential values, respectively, with
the measured ones included in the validation dataset. The estimation variance calculated with both methods
was also considered to access the uncertainty of the predictions. The available water content of Portuguese
soils was then derived from θ−33 kPa and θ−1500 kPa ternary diagrams developed with both approaches. The
hydraulic ternary diagrams may thus serve as simplified tools for estimating water retention properties from
particle size distribution and eventually serve as an alternative to the traditional statistical regression and data
mining techniques used to derive PTFsinfo:eu-repo/semantics/publishedVersio
Balancing act: tubulin glutamylation and microtubule dynamics in Toxoplasma gondii
The success of Toxoplasma gondii (intracellular parasite) host cell invasion relies on the apical complex, a specialized microtubule cytoskeleton structure associated with secretory organelles. The genome encodes three isoforms of both α- and β-tubulin which are altered by specific post-translational modifications (PTMs), changing the biochemical/biophysical proprieties of microtubules, and modulating their interaction with associated proteins. Tubulin PTMs are a powerful and evolutionarily conserved mechanism to generate tubulin diversity, forming a biochemical ‘tubulin code’ that can be ‘read’ by microtubule-interacting factors. The T. gondii tubulin PTMs are: α-tubulin acetylation, α-tubulin detyrosination, Δ5α-tubulin, Δ2α-tubulin, α- and β-tubulin polyglutamylation, and α- and α-tubulin methylation. Tubulin glutamylation is a key candidate to assist microtubule remodeling in Toxoplasma, being involved in the regulation of microtubule stability, dynamics, interaction with motor proteins, and severing enzymes. The correct balance of tubulin glutamylation is achieved by the coordinated action of polyglutamylases and deglutamylating enzymes. In this work, we will review and discuss the current knowledge on T. gondii tubulin glutamylation. By in silico identification of mammalian protein orthologs, we explored and updated the identification of putative proteins related to glutamylation, contributing to a better understanding of the role of tubulin glutamylation in T. gondii.info:eu-repo/semantics/publishedVersio
Soil hydraulic properties in different soil texture classes
Soil texture influences significantly soil hydraulic properties, which due to soil he-terogeneity normally present large spatial variability. The variability of soil reten-tion θ(h), and hydraulic conductivity K(h) curves, in 11 of the 12 texture classes of the diagram of Gomes e Silva (1962) was studied. For each textural class, average, maximum, minimum, and the standard deviation values for the Mualem van Ge-nuchten parameters are presented based on 558 θ(h) and 245 K(h) curves deter-mined in undisturbed soil samples which are included in the PROPSOLO database of Estação Agronómica Nacional. An av-erage function describing θ(h) and K(h) in each textural class is also presente
Biochemical parameters of silver catfish (Rhamdia quelen) after transport with eugenol or essential oil of Lippia alba added to the water
The transport of live fish is a routine practice in aquaculture and constitutes a considerable source of stress to the animals. The addition of anesthetic to the water used for fish transport can prevent or mitigate the deleterious effects of transport stress. This study investigated the effects of the addition of eugenol (EUG) (1.5 or 3.0 mu L L-1) and essential oil of Lippia alba (EOL) (10 or 20 mu L L-1) on metabolic parameters (glycogen, lactate and total protein levels) in liver and muscle, acetylcholinesterase activity (AChE) in muscle and brain, and the levels of protein carbonyl (PC), thiobarbituric acid reactive substances (TBARS) and nonprotein thiol groups (NPSH) and activity of glutathione-S-transferase in the liver of silver catfish (Rhamdia quelen; Quoy and Gaimard, 1824) transported for four hours in plastic bags (loading density of 169.2 g L-1). The addition of various concentrations of EUG (1.5 or 3.0 mu L L-1) and EOL (10 or 20 mu L L-1) to the transport water is advisable for the transportation of silver catfish, since both concentrations of these substances increased the levels of NPSH antioxidant and decreased the TBARS levels in the liver. In addition, the lower liver levels of glycogen and lactate in these groups and lower AChE activity in the brain (EOL 10 or 20 mu L L-1) compared to the control group indicate that the energetic metabolism and neurotransmission were lower after administration of anesthetics, contributing to the maintenance of homeostasis and sedation status.Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS/PRONEX) [10/0016-8]; Conselho Nacional de Pesquisa e Desenvolvimento Cientifico (CNPq) [470964/2009-0]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); CNPqinfo:eu-repo/semantics/publishedVersio
The design and evaluation of travelling gun irrigation systems: enrolador software
Technical Paperinfo:eu-repo/semantics/publishedVersio
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