Effects of nitrogen rates on grain yield and nitrogen agronomic efficiency of durum wheat genotypes under different environments

Durum wheat is an important staple food crop in Tunisia and other Mediterranean countries and is grown in various climatic conditions. Production and yield are however severely limited not only by drought events but also by reduced levels of nitrogen fertilisation. A study was carried out at two locations in the sub-humid area of Tunisia: Mateur in 2009–10 and 2010–11 and Beja in 2011–12 and 2012–13 under rainfed conditions. Four durum wheat genotypes (landraces: Bidi, Azizi; improved: Om Rabia, Khiar) were evaluated for nitrogen agronomic efficiency and related agronomic traits under various nitrogen rates: 0, 50, 100, 150, 200 and 250 kgNha−1, with three replications. There was a significant interaction effect (P ≤ 0.001) environments × genotypes ×N treatments for grain yield (GY), biomass yield (BY), harvest index (HI), partial factor productivity of applied nitrogen (PFPN) and nitrogen agronomic use efficiencies (NAE). GY was the most affected trait by nitrogen applied showing an increase of 94% under high N treatment (250 kgNha−1) compared to control plots without N treatments. A significant linear regression exists between GY (0 N) and GY for the different N rates (r =0.70; P < 0.001). This effect was more pronounced for improved genotypes than landraces for all parameters excepting BY and NAEBY. BY showed +11% increase in landraces than improved genotypes. PFPN showed an average decrease of 65% under high-N fertilisation with 10% prevalence for improved genotypes. Landraces tend to promote vegetative growth while grain filling efficiency was higher for improved genotype

Caracterización fisicoquímica del yeso natural de Mauritania

Gypsum from "Nderhamcha", a region in Mauritania, has been studied through three techniques: thermo-gravimetry, thermo-differential analysis, and X ray diffraction. It has been proved that the dehydration of this material happens in two stages, characterized by the closeness of their temperature. The thermal study as certains the two transformations due to the gypsum dehydration and those due to soluble and insoluble anhidrite.El yeso de Mauritania, de la región "Nderhamcha", ha sido estudiado a través de tres técnicas instrumentales: termogravimetría, análisis térmico-diferencial y difracción de rayos X. Se comprueba que la deshidratación de este material se efectúa en dos etapas, caracterizadas por temperaturas muy próximas. En el estudio térmico se comprueban las dos transformaciones debidas a la deshidratación del yeso y las debidas a la anhidrita soluble e insoluble

Variation of Grain Yield, Grain Protein Content and Nitrogen Use Efficiency Components under Different Nitrogen Rates in Mediterranean Durum Wheat Genotypes

Nitrogen (N) is a crucial nutrient for plant growth and development. To optimize agricultural environments, N fertilizers represent a critical tool to regulate crop productivity. The improvement of nitrogen use efficiency (NUE) represents a promising tool that may enable cereal production to meet future food demand. Wheat reported contrasting behaviors in N utilization showing specific abilities depending on genotype. This study selected two landraces and two improved genotypes from Northern Africa to investigate grain yield (GY), grain protein content (GPC) and NUE. Plants were grown under three levels of N supply: 0, 75, 150 kg N ha−1 and for two consecutive years. Results reported a better NUE (0.40 kg.kg N−1) obtained under 150 kg N ha−1, while N utilization efficiency (NUtE) showed a 13% increase using 75 kg N ha−1 compared with 150 kg N ha−1. Under low nitrogen rate (0 N), crop N supply (CNS) and N uptake efficiency (NUpE) were shown as determinant factors for improved genotypes GY (R2 = 0.72), while NUtE represented the most determinant component for GPC in landraces (R2 = 0.92). Multivariate regression models explained the dependence in GPC on NUE, NUpE, and NUtE. In conclusion, our results recognize GPC and NUtE as suitable selection traits to identify durum wheat with higher NUE

Tobacco Upregulates P. gingivalis Fimbrial Proteins Which Induce TLR2 Hyposensitivity

Tobacco smokers are more susceptible to periodontitis than non-smokers but exhibit reduced signs of clinical inflammation. The underlying mechanisms are unknown. We have previously shown that cigarette smoke extract (CSE) represents an environmental stress to which P. gingivalis adapts by altering the expression of several virulence factors - including major and minor fimbrial antigens (FimA and Mfa1, respectively) and capsule - concomitant with a reduced pro-inflammatory potential of intact P. gingivalis.We hypothesized that CSE-regulation of capsule and fimbrial genes is reflected at the ultrastructural and functional levels, alters the nature of host-pathogen interactions, and contributes to the reduced pro- inflammatory potential of smoke exposed P. gingivalis. CSE induced ultrastructural alterations were determined by electron microscopy, confirmed by Western blot and physiological consequences studied in open-flow biofilms. Inflammatory profiling of specific CSE-dysregulated proteins, rFimA and rMfa1, was determined by quantifying cytokine induction in primary human innate and OBA-9 cells. CSE up-regulates P. gingivalis FimA at the protein level, suppresses the production of capsular polysaccharides at the ultrastructural level, and creates conditions that promote biofilm formation. We further show that while FimA is recognized by TLR2/6, it has only minimal inflammatory activity in several cell types. Furthermore, FimA stimulation chronically abrogates the pro-inflammatory response to subsequent TLR2 stimulation by other TLR-2-specific agonists (Pam3CSK4, FSL, Mfa1) in an IkappaBalpha- and IRAK-1-dependent manner.These studies provide some of the first information to explain, mechanistically, how tobacco smoke changes the P. gingivalis phenotype in a manner likely to promote P. gingivalis colonization and infection while simultaneously reducing the host response to this major mucosal pathogen

Modélisation du comportement élastoplastique d’un revêtement Fe-Zn (GA) par nanoindentation : approche inverse basée sur les plans d’expériences et les algorithmes génétiques multiobjectifs

International audienc

Synthesis and characterization of GaAs thin films grown on ITO substrates

Gallium arsenide (GaAs) thin films have been deposited on ITO-coated glass substrates from acid aqueous solution by electrodeposition technique. The structure and the morphology of the samples were analyzed by X-ray diffraction (XRD) and atomic force microscope (AFM). The optical characteristics were investigated at room temperature using a UV-Vis spectrometer. At lower deposition time, the XRD patterns exhibit a mixture of both cubic and orthorhombic GaAs phases. With further increase of the film thickness, only orthorhombic structure was observed with a preferred (100) orientation. By applying the Debye-Scherrer method, the estimated crystallite size for the (200) orientation ranged from 30 to 50 nm, whereas for the (022) orientation was found to be 13–22 nm. From the AFM measurements, the rms surface roughness ranged between 11.4 and 18.4 nm. The analysis of the optical absorption data of the annealed GaAs film deposited at different times revealed direct band gap energy in the range of 1.60–1.85 eV. The large blueshifts observed in this study can be fully explained by the Burstein-Moss effect

Modified Adomian Decomposition Method to Solve Generalized Emden–Fowler Systems for Singular IVP

An adeptness modified Adomian decomposition method (MADM) is proposed to solve a generalized system of Emden–Fowler type. By a few examples, it is shown that this method can overcome a singular initial value problem