Effect of trickle irrigation on root development of the wet bulb and 'pera' orange tree yield in the state of São Paulo, Brazil

The aim of this study was to evaluate the effect of different microirrigation designs on root system distribution in wet bulb region, orange orchard yield and quality of orange fruits. The experiment was installed as random blocks with five treatments and four replicates in an orchard of 'Pêra' orange trees grafted on 'Cleopatra' mandarin rootstock. The treatments consisted of: one drip line (T1), two drip lines (T2), four drip lines (T3) per planting row, microsprinkler irrigation (T4) and without irrigation (T5). Irrigation treatments favored yield and ºBrix. The treatment with a single drip line (T1) showed the greatest quantity of roots in relation to the treatments T2 and T3.

Irrigation management in pruned coffee tree crop

It was evaluated the effect of irrigation management on the production characteristics of coffee cultivar Acaiá MG-1474, planted in spacing of 3.00 m x 0.60 m, pruned in 2004, and irrigated by drip since the planting, in 1997. The experimental designed used was of randomized blocks with five treatments and four replications. The treatments consisted of irrigation management strategies, applying or not applying controlled moisture deficit in layer of 0 to 0.4m, in dry seasons of the year: A = no irrigation (control), B = irrigation during all year considering the factor of water availability in the soil (f) equal to 0.75, C = irrigation during all year considering f = 0.25, D = irrigation during all year, but in January /February /March /July /October /November /December with f = 0.25 and April /May /June /August /September with f = 0.75, E = irrigation only during April /May /June /August /September with f = 0.25. From July /2005 to June /2007 the applied water depth was defined based on Class A pan evaporation (ECA) and the period from July/2007 to June/2008 based on readings of matric potential of soil obtained from Watermark® sensors. Each plot consisted of three rows with ten plants per row, considering as useful plot five plants of center line. The results indicated that the E irrigation management was the most suitable for technical reasons.

Technical and economic indicators of the yellow passion fruit tree irrigated with underground water supply

The research aimed to quantify technical and economic indicators of yellow passion fruit tree irrigated with fractions of irrigation with underground source of water, to generate information that helps farmers in decision making on the implementation of investment in irrigated fruit growing (yellow passion fruit). For this purpose, we used the passion fruit crop irrigated with Microjet type irrigation system, with conducting system in simple espaliers. The treatments consisted of five hours of application of the depth of water required by the crop with irrigation frequency of two days. The results showed that the highest yield (16660kg ha-1) was obtained with the fractionation of irrigation twice a day (50% to 7h and 50% to 21h30), which provided an increase in productivity of 54%, demonstrating the financial viability and being highly profitable to the interest rate of 2% per year, with low sensitivity of financial risk to real interest rates above the prevailing market.

Interactions between genes and alcohol on aggressive behavior and anger related traits : the oxytocin receptor gene as a candidate

Alkoholberusning är en av de starkaste riskfaktorerna för aggressivt beteende. Alla individer blir dock inte aggressiva under alkoholberusning. I sin doktorsavhandling undersökte Johansson ifall individens genetiska uppsättning kan förklara skillnader i vem som reagerar på alkohol med ökat aggressivt beteende och ilska och vem som inte gör det. Resultaten visade att individer som är bärare av en viss variant av genen som kodar för oxytocinets receptorer är i högre grad benägna att uppvisa aggressivt beteende än andra när de är alkoholberusade. Sambandet mellan alkohol och ilska påverkades även av individens genetiska uppsättning av två oxytocinreceptorgenvarianter, vilket antyder att dessa genvarianter även påverkar benägenheten att känna ilska under alkoholberusning. Oxytocinet, som fungerar både som ett hormon och en neurotransmittor, har i tidigare studier visats ha breda effekter på sociala förmågor hos människan, såsom förmåga till igenkännande av andras känslouttryck. Resultaten är de första att hos människan experimentellt påvisa att vissa individer beter sig mer aggressivt än andra när de är berusade, beroende på individens genetiska uppsättning. ”Det är viktigt att komma ihåg att genens effekt i det här fallet inte är av en sådan natur att den direkt och ofrånkomligen orsakar aggressivt beteende. Med andra ord är det orimligt i detta fall att tänka att en individ skulle tillmätas ansvarsfrihet i exempelvis ett våldsbrottmål om hon bär på en viss variant av denna gen”, påpekar Johansson. Oxytocinreceptorgenens effekter analyserades i två olika urval. I ett experimentellt upplägg indelades 116 män slumpässigt i två grupper: en grupp som tilldelades alkoholhaltiga drycker, och en kontrollgrupp som tilldelades alkoholfria drycker. Aggressivt beteende mättes med ett laboratorietest där försökspersonerna fick bestraffa en fiktiv motspelare genom att spela upp motbjudande ljud för denne. Resultaten replikerades i ett populationsbaserat urval av män och kvinnor (n = 3755) vilka besvarat frågor om deras aggressiva beteenden, ilska, och alkoholanvändning.

Effects of methylation and hydroxylation of sphingomyelins on their biophysical properties and interactions with cholesterol

Sfingomyeliner är viktiga sphingolipidmolekyler som finns i cellmembranets exoplastiska monolager. Sfingomyeliner är sällsynta i växter och mikroorganismer. Den enigmatiska sfingomelinmolekylen som Thudicum isolerade från hjärnvävnad i slutet på 1800-talet fick sitt namn på basen av det grekiska ordet”sfinx”. Sfingomyeliner återfinns speciallt rikligt i myelinskidorna i nervvävnad, var de sfingomyelinrika membranen bildar ett isolerande lager runt nervcellernas axoner. De polära sfingomyelinerna är viktiga beståndsdelar av ägg, mjölk och kött, och betraktas som viktiga näringsämnen speciellt för spädbarn. Det finns ett flertal sjukdomar uppstår på grund av defekter i sfingomyelinmetabolismen., t.ex. Niemann-Picks sjukdom, som är en obotlig ärftlig metabolisk sjukdom. Nyligen har det rapporterats att sfingomyelin tillsammans med kolesterol och specifika proteiner bildar funtionella domäner, s.k. membranflottar, i cellers membran. Membranflottar anses delta i många viktiga biologiska processer som t.ex. signalöverföring, lipid- och proteinsortering, apoptos, celladhesion, cellmigration och synapsers signalöverföring. Därför är det ytterst viktigt att förstå samverkan mellan sfingomyelin och kolesterol och hur denna samverkan påverkar bildandet membranflottar. I avhandlingen presenteras data från våra studier av sfingomyelin samverkan med kolesterol. För avhandlingen syntetiserade vi unika sfingomyelin molekyler genom att införa metyl- och hydroxylgrupper i olika positioner i sphingomyelinmolekylerna, med målet att lära oss mera om sphingomyelinets membranegenskaper och samverkan med kolesterol. Alla sfingomyelin molekyler som användes i avhandlingsarbetet är biologiskt relevanta. I studierna fann vi att hydroxyl- och amidgrupperna i sfingomyelin är viktiga i vätebindningar mellan sfingomyelinmolekyler samt mellan sfingomyelin och kolesterol. Vi upptäckte ytterligare att substition av metylgrupper i acylkedjan eller i interfasregionen hos sfingomyelinmolekyler signifikant destabiliserade sphingomyelin bilagret och försvagade/upphävde molekylernas samverkan med kolesterol. Hur sfingomyelinbilagrens stabilitet och sfingomyelinen-koleterol samverkan påverkades av hydroxylgrupper var beroende av hydrohygruppens position. Förekomst av en extra hydroxylgrupp i sfingomyelionmolekylens sfingoidbasen ökade stabilitetnen hos sfingomyelinbilagren samt stabiliserade sfingomyelinets samverkan med kolesterol.

The role of van der Waals interactions in the case of H2 adsorption on ruthenium (0001) surface

Computational material science with the Density Functional Theory (DFT) has recently gained a method for describing, for the first time the non local bonding i.e., van der Waals (vdW) bonding. The newly proposed van der Waals-Density Functional (vdW-DF) is employed here to address the role of non local interactions in the case of H2 adsorption on Ru(0001) surface. The later vdW-DF2 implementation with the DFT code VASP (Vienna Ab-initio Simulation Package) is used in this study. The motivation for studying H2 adsorption on ruthenium surface arose from the interest to hydrogenation processes. Potential energy surface (PES) plots are created for adsorption sites top, bridge, fcc and hcp, employing the vdW-DF2 functional. The vdW-DF yields 0.1 eV - 0.2 eV higher barriers for the dissociation of the H2 molecule; the vdW-DF seems to bind the H2 molecule more tightly together. Furthermore, at the top site, which is found to be the most reactive, the vdW functional suggests no entrance barrier or in any case smaller than 0.05 eV, whereas the corresponding calculation without the vdW-DF does. Ruthenium and H2 are found to have the opposite behaviors with the vdW-DF; Ru lattice constants are overestimated while H2 bond length is shorter. Also evaluation of the CPU time demand of the vdW-DF2 is done from the PES data. From top to fcc sites the vdW-DF computational time demand is larger by 4.77 % to 20.09 %, while at the hcp site it is slightly smaller. Also the behavior of a few exchange correlation functionals is investigated along addressing the role of vdW-DF. Behavior of the different functionals is not consistent between the Ru lattice constants and H2 bond lengths. It is thus difficult to determine the quality of a particular exchange correlation functional by comparing equilibrium separations of the different elements. By comparing PESs it would be computationally highly consuming.

Functional Genomic Approaches for Deciphering Plant-Virus Interactions

Plant-virus interactions are very complex in nature and lead to disease and symptom formation by causing various physiological, metabolic and developmental changes in the host plants. These interactions are mainly the outcomes of viral hijacking of host components to complete their infection cycles and of host defensive responses to restrict the viral infections. Viral genomes contain only a small number of genes often encoding for multifunctional proteins, and all are essential in establishing a viral infection. Thus, it is important to understand the specific roles of individual viral genes and their contribution to the viral life cycles. Among the most important viral proteins are the suppressors of RNA silencing (VSRs). These proteins function to suppress host defenses mediated by RNA silencing and can also serve in other functions, e.g. in viral movement, transactivation of host genes, virus replication and protein processing. Thus these proteins are likely to have a significant impact on host physiology and metabolism. In the present study, I have examined the plant-virus interactions and the effects of three different VSRs on host physiology and gene expression levels by microarray analysis of transgenic plants that express these VSR genes. I also studied the gene expression changes related to the expression of the whole genome of Tobacco mosaic virus (TMV) in transgenic tobacco plants. Expression of the VSR genes in the transgenic tobacco plants causes significant changes in the gene expression profiles. HC-Pro gene derived from the Potyvirus Y (PVY) causes alteration of 748 and 332 transcripts, AC2 gene derived from the African cassava mosaic virus (ACMV) causes alteration of 1118 and 251transcripts, and P25 gene derived from the Potyvirus X (PVX) causes alterations of 1355 and 64 transcripts in leaves and flowers, respectively. All three VSRs cause similar up-regulation in defense, hormonally regulated and different stress-related genes and down-regulation in the photosynthesis and starch metabolism related genes. They also induce alterations that are specific to each viral VSR. The phenotype and transcriptome alterations of the HC-Pro expressing transgenic plants are similar to those observed in some Potyvirus-infected plants. The plants show increased protein degradation, which may be due to the HC-Pro cysteine endopeptidase and thioredoxin activities. The AC2-expressing transgenic plants show a similar phenotype and gene expression pattern as HC-Pro-expressing plants, but also alter pathways related to jasmonic acid, ethylene and retrograde signaling. In the P25 expressing transgenic plants, high numbers of genes (total of 1355) were up-regulated in the leaves, compared to a very low number of down-regulated genes (total of 5). Despite of strong induction of the transcripts, only mild growth reduction and no other distinct phenotype was observed in these plants. As an example of whole virus interactions with its host, I also studied gene expression changes caused by Tobacco mosaic virus (TMV) in tobacco host in three different conditions, i.e. in transgenic plants that are first resistant to the virus, and then become susceptible to it and in wild type plants naturally infected with this virus. The microarray analysis revealed up and down-regulation of 1362 and 1422 transcripts in the TMV resistant young transgenic plants, and up and down-regulation of a total of 1150 and 1200 transcripts, respectively, in the older plants, after the resistance break. Natural TMV infections in wild type plants caused up-regulation of 550 transcripts and down-regulation of 480 transcripts. 124 up-regulated and 29 down-regulated transcripts were commonly altered between young and old TMV transgenic plants, and only 6 up-regulated and none of the down-regulated transcripts were commonly altered in all three plants. During the resistant stage, the strong down-regulation in translation-related transcripts (total of 750 genes) was observed. Additionally, transcripts related to the hormones, protein degradation and defense pathways, cell division and stress were distinctly altered. All these alterations may contribute to the TMV resistance in the young transgenic plants, and the resistance may also be related to RNA silencing, despite of the low viral abundance and lack of viral siRNAs or TMV methylation activity in the plants.

Membrane properties of structurally modified ceramides : effects on lipid lateral distribution and sphingomyelin-interactions in artificial bilayer membranes

Ceramides comprise a class of sphingolipids that exist only in small amounts in cellular membranes, but which have been associated with important roles in cellular signaling processes. The influences that ceramides have on the physical properties of bilayer membranes reach from altered thermodynamical behavior to significant impacts on the molecular order and lateral distribution of membrane lipids. Along with the idea that the membrane physical state could influence the physiological state of a cell, the membrane properties of ceramides have gained increasing interest. Therefore, membrane phenomena related to ceramides have become a subject of intense study both in cellular as well as in artificial membranes. Artificial bilayers, the so called model membranes, are substantially simpler in terms of contents and spatio-temporal variation than actual cellular membranes, and can be used to give detailed information about the properties of individual lipid species in different environments. This thesis focuses on investigating how the different parts of the ceramide molecule, i.e., the N-linked acyl chain, the long-chain sphingoid base and the membrane-water interface region, govern the interactions and lateral distribution of these lipids in bilayer membranes. With the emphasis on ceramide/sphingomyelin(SM)-interactions, the relevance of the size of the SMhead group for the interaction was also studied. Ceramides with methylbranched N-linked acyl chains, varying length sphingoid bases, or methylated 2N (amide-nitrogen) and 3O (C3-hydroxyl) at the interface region, as well as SMs with decreased head group size, were synthesized and their bilayer properties studied by calorimetric and fluorescence spectroscopic techniques. In brief, the results showed that the packing of the ceramide acyl chains was more sensitive to methyl-branching in the mid part than in the distal end of the N-linked chain, and that disrupting the interfacial structure at the amide-nitrogen, as opposed to the C3-hydroxyl, had greater effect on the interlipid interactions of ceramides. Interestingly, it appeared that the bilayer properties of ceramides could be more sensitive to small alterations in the length of the long-chain base than what was previously reported for the N-linked acyl chain. Furthermore, the data indicated that the SM-head group does not strongly influence the interactions between SMs and ceramides. The results in this thesis illustrate the pivotal role of some essential parts of the ceramide molecules in determining their bilayer properties. The thesis provides increased understanding of the molecular aspects of ceramides that possibly affect their functions in biological membranes, and could relate to distinct effects on cell physiology.

Phase variation in Flavobacterium psychrophilum : influence on host-pathogen interactions

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Weeds under the canopies of tree species submitted to different planting densities and intercropping

Assessing the growth and floristic composition of species that grow under the canopy of trees is important for weed control (WC). The objective of this study was to assess two experiments (E1 and E2), when the trees were two years and one year of age, respectively. In E1, sabiá (S) and gliricidia (G) were submitted to planting densities from 400 to 1.200 plants ha-1. In E2, growing systems consisting of S, G, and neem (N) combinations were compared: SSS, GGG, NNN, GSG, NSN, SGS, NGN, SNS, and GNG (each letter represents a row of plants). A random block design was adopted, with three (E1) and four (E2) replicates. In E1, treatments were arranged as split-plots (species in plots). In E2, the degrees of freedom for treatments (8) were partitioned into growing systems (treatments that involved the same species) and between growing system groups (2). Twenty-one weed species were found in E1. Gliricidia attained greater plant height than sabiá, but these species did not differ in canopy diameter, number of weed species per plot, and weed green and dry biomass of the shoot. Higher planting densities resulted in the reduction of all those traits. Twenty-six weed species were found in E2. Growing systems that included gliricidia showed canopies with greater diameters than growing systems that included neem. There were no differences between growing systems for number of weed species per plot and for weed green and dry biomass of the shoot.

Interactions between soybean and weeds in a replacement series system, considering the effects of water stress

Due to the increase of water deficiency in many farm regions and its meaning on weed interference, competitive interactions between soybean and three weeds were evaluated under water stress (20 to 40 days after transplanting) and no stress conditions. Three independent experiments were carried out in a growth chamber, being each one composed by the weeds Alternanthera tenella, Tridax procumbens or Digitaria ciliaris, along with the crop, in which soil water condition and plant composition effects were evaluated while in competition. A replacement series system was used, including both monoculture of each species and a mixture with a ratio of 50% between weed and soybean. A completely randomized design was used in factorial arrangement, with treatments distributed in three levels for plant composition factor (soybean and weeds monocultures, in addition to the soybean + weed mixture) and two levels for the water factor (with or without stress), amounting six treatments in each experiment. Soybean dry mass was higher than weed dry mass, when growing without water stress. However, under water stress conditions, the dry mass of soy was reduced in all experiments, mainly in the D. ciliaris comparative experiment. Water restriction was also significant in the plants' photosynthesis reduction in most of the experiments, reducing leaf area duration and efficiency of water use. Analysing all variables shows greater weed tolerance than soybean when submitted to water deficit and with distinct changes of their interactions and mechanism of competition, in each experiment.

Soil microorganisms and their role in the interactions between weeds and crops

The competition between weeds and crops is a topic of great interest, since this interaction can cause heavy losses in agriculture. Despite the existence of some studies on this subject, little is known about the importance of soil microorganisms in the modulation of weed-crop interactions. Plants compete for water and nutrients in the soil and the ability of a given species to use the available resources may be directly affected by the presence of some microbial groups commonly found in the soil. Arbuscular mycorrhizal fungi (AMF) are able to associate with plant roots and affect the ability of different species to absorb water and nutrients from the soil, promoting changes in plant growth. Other groups may promote positive or negative changes in plant growth, depending on the identity of the microbial and plant partners involved in the different interactions, changing the competitive ability of a given species. Recent studies have shown that weeds are able to associate with mycorrhizal fungi in agricultural environments, and root colonization by these fungi is affected by the presence of other weeds or crops species. In addition, weeds tend to have positive interactions with soil microorganisms while cultures may have neutral or negative interactions. Competition between weeds and crops promotes changes in the soil microbial community, which becomes different from that observed in monocultures, thus affecting the competitive ability of plants. When grown in competition, weeds and crops have different behaviors related to soil microorganisms, and the weeds seem to show greater dependence on associations with members of the soil microbiota to increase growth. These data demonstrate the importance of soil microorganisms in the modulation of the interactions between weeds and crops in agricultural environments. New perspectives and hypotheses are presented to guide future research in this area.

Chlorophyll fluorescence in guanandi tree (Calophyllum brasiliense) after herbicide application

Chlorophyll fluorescence is currently used as a rapid diagnostic and nondestructive method to detect and quantify damage on the photosynthetic apparatus of leaves on weeds, crops and ornamental/coniferous trees in response to both environmental stress and herbicides. This study aimed to evaluate chlorophyll fluorescence in guanandi plants (Calophyllum brasiliense) after application of different postemergence herbicides. The experiment was performed in a completely randomized design, with six treatments (control, bentazon, sulfentrazone, isoxaflutole, atrazine and glyphosate) and five replications. The herbicide treatments were applied with a stationary sprayer, and electron transport rate (ETR) was subsequently analyzed with OS5p Multi-Mode Chlorophyll Fluorometer. In the monitored period, guanandi plants subjected to atrazine showed higher sensitivity to chlorophyll fluorescence than the other treatments. Although bentazon is a photosystem II inhibitor, it showed no major changes in electron transport for the studied species and in the monitored period. In summary, ETR is a good parameter to evaluate the effect of some herbicides on Calophyllum brasiliense plants.