Akaline, saline and mixed saline-alkaline stresses induce physiological and morpho-anatomical changes in Lotus tenuis shoots

Saline, alkaline and mixed saline–alkaline conditions frequently co-occur in soil. In this work, we compared these plant stress sources on the legume Lotus tenuis, regarding their effects on shoot growth and leaf and stem anatomy. In addition, we aimed to gain insight on the plant physiological status of stressed plants. We performed pot experiments with four treatments: control without salt (pH = 5.8; EC = 1.2 dS·m−1) and three stress conditions, saline (100 mm NaCl, pH = 5.8; EC = 11.0 dS·m−1), alkaline (10 mm NaHCO3, pH = 8.0, EC = 1.9 dS·m−1) and mixed salt–alkaline (10 mm NaHCO3 + 100 mm NaCl, pH = 8.0, EC = 11.0 dS·m−1). Neutral and alkaline salts produced a similar level of growth inhibition on L. tenuis shoots, whereas their mixture exacerbated their detrimental effects. Our results showed that none of the analysed morpho-anatomical parameters categorically differentiated one stress from the other. However, NaCl- and NaHCO3-derived stress could be discriminated to different extents and/or directions of changes in some of the anatomical traits. For example, alkalinity led to increased stomatal opening, unlike NaCl-treated plants, where a reduction in stomatal aperture was observed. Similarly, plants from the mixed saline–alkaline treatment characteristically lacked palisade mesophyll in their leaves. The stem cross-section and vessel areas, as well as the number of vascular bundles in the sectioned stem were reduced in all treatments. A rise in the number of vessel elements in the xylem was recorded in NaCl-treated plants, but not in those treated exclusively with NaHCO3.Fil: Paz, Rosalia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mendoza. Instituto de Biología Agrícola de Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico Chascomús. Instituto de Investigaciones Biotecnológicas (sede Chascomús); ArgentinaFil: Reinoso, Herminda Elmira. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria. Departamento de Biología Agrícola. Cátedra de Morfología Vegetal; ArgentinaFil: Espasandin, Fabiana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); ArgentinaFil: Gonzalez Antivilo, Francisco Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mendoza. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Sansberro, Pedro Alfonso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); ArgentinaFil: Rocco, Ruben Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico Chascomús. Instituto de Investigaciones Biotecnológicas (sede Chascomús); ArgentinaFil: Ruiz, Oscar Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico Chascomús. Instituto de Investigaciones Biotecnológicas (sede Chascomús); ArgentinaFil: Menendez, Ana Bernardina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico Chascomús. Instituto de Investigaciones Biotecnológicas (sede Chascomús); Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentin

A Method for Determining Weight Reduction through Material Substitution in Automotive Structures of Equivalent Stiffness

The benefits of lighter auto bodies are discussed, and aluminum is compared to steel as an alternative material for auto body construction. The concept of a structural index, lambda, is developed using the simple example of a hollow beam of wall thickness, t, with a cantilever load case. It is shown that the bending stiffness, K, of the beam can be defined as a function of t^lambda, that 1 \u3c lambda \u3c 3, and that lambda can be used to predict the weight savings from material substitution where stiffness is held constant. It is then demonstrated that lambda can be used to predict the weight savings from material substitution in the more complex cases of the joints of a light truck cab

Improving drought and salinity tolerance in barley by application of salicylic acid and potassium nitrate

AbstractGrowth and physiological activities of barley (Hordeum vulgare L. cv. Gustoe) grown in soil cultures were evaluated to recognize the ameliorative role of salicylic acid (SA) and KNO3 against the negative effects of salt and water deficit stresses. Barley plants were subjected to three levels of NaCl (50, 100 and 150mM), three levels of water stress (80%, 70% and 50% of the soil water content (SWC) and the combination of 150mM NaCl+50μM SA, 150mM NaCl+10mM KNO3, 50% SWC+50μM SA and 50% SWC+10mM KNO3 for two weeks. Salt and water deficit stresses reduced the shoot growth, leaf photosynthetic pigments, K+ contents and provoked oxidative stress in leaves confirmed by considerable changes in soluble carbohydrate, proline, malondialdehyde (MDA), total phenolic compounds, antioxidant activity and Na+ contents. Leaf soluble protein of salt and water deficit treated plants was unaffected. The Na+/K+ ratio increased with increasing salt and water deficit treated plants. Application of 50μM SA or 10mM KNO3 to150mM NaCl and/or 50% SWC treated plants improved these attributes under salt and water stresses. Soluble carbohydrates in stressed plants may have a significant role in osmotic adjustment. It can be concluded that the addition of SA or KNO3 can ameliorate the oxidative stress in barley stressed plants. This ameliorative effect might be maintained through low MDA contents and decreased Na+/K+ ratio in leaves. This study also provided evidence for the ability of barley cultivation in salt and water deficit soils due to its capacity for osmotic adjustment

Émotions et rationalité dans la sociologie classique : les cas de Weber et Durkheim

Les débats sur la rationalité de l’action occupent, en sociologie, une place centrale. Le fait n’est pas nouveau puisque cette discipline s’est en partie édifiée en référence à l’économie classique, soit pour s’y opposer (Durkheim), soit pour s’en distinguer (Pareto), soit encore pour en élargir la portée (Weber). Les diatribes durkheimiennes contre l’individualisme et l’utilitarisme du paradigme économiste, tout comme le projet paretien de réserver à la sociologie l’étude des actions non rat..

Arabidopsis annexin1 mediates the radical-activated plasma membrane Ca2+ - and K+ -permeable conductance in root cells

Plant cell growth and stress signaling require Ca2+ influx through plasma membrane transport proteins that are regulated by reactive oxygen species. In root cell growth, adaptation to salinity stress, and stomatal closure, such proteins operate downstream of the plasma membrane NADPH oxidases that produce extracellular superoxide anion, a reactive oxygen species that is readily converted to extracellular hydrogen peroxide and hydroxyl radicals, OH_. In root cells, extracellular OH_ activates a plasma membrane Ca2+-permeable conductance that permits Ca2+ influx. In Arabidopsis thaliana, distribution of this conductance resembles that of annexin1 (ANN1). Annexins are membrane binding proteins that can form Ca2+-permeable conductances in vitro. Here, the Arabidopsis loss-of-function mutant for annexin1 (Atann1) was found to lack the root hair and epidermal OH_-activated Ca2+- and K+-permeable conductance. This manifests in both impaired root cell growth and ability to elevate root cell cytosolic free Ca2+ in response to OH_. An OH_-activated Ca2+ conductance is reconstituted by recombinant ANN1 in planar lipid bilayers. ANN1 therefore presents as a novel Ca2+-permeable transporter providing a molecular link between reactive oxygen species and cytosolic Ca2+ in plants

A root's ability to retain K+ correlates with salt tolerance in wheat

Most work on wheat breeding for salt tolerance has focused mainly on excluding Na+ from uptake and transport to the shoot. However, some recent findings have reported no apparent correlation between leaf Na+ content and wheat salt tolerance. Thus, it appears that excluding Na+ by itself is not always sufficient to increase plant salt tolerance and other physiological traits should also be considered. In this work, it was investigated whether a root's ability to retain K+ may be such a trait, and whether our previous findings for barley can be extrapolated to species following a ‘salt exclusion’ strategy. NaCl-induced kinetics of K+ flux from roots of two bread and two durum wheat genotypes, contrasting in their salt tolerance, were measured under laboratory conditions using non-invasive ion flux measuring (the MIFE) technique. These measurements were compared with whole-plant physiological characteristics and yield responses from plants grown under greenhouse conditions. The results show that K+ flux from the root surface of 6-d-old wheat seedlings in response to salt treatment was highly correlated with major plant physiological characteristics and yield of greenhouse-grown plants. This emphasizes the critical role of K+ homeostasis in plant salt tolerance and suggests that using NaCl-induced K+ flux measurements as a physiological ‘marker’ for salt tolerance may benefit wheat-breeding programmes

Le balancier sociologique français : entre individus et structures

I – En 1973, au plus fort du débat français sur l’école et les inégalités (Bourdieu et Passeron, 1970; Baudelot et Establet, 1971), Raymond Boudon publiait un ouvrage qui n’apportait pas seulement une contribution décisive à la sociologie de la scolarisation et de la mobilité sociale mais qui constituait aussi un événement théorique peut-être sans précédent dans l’histoire de la sociologie française. L’Inégalité des chances entreprenait en effet d’analyser un phénomène macrosocial – « la mobi..

Division du travail, inégalités sociales et ordre social. Note sur les tergiversations de l’analyse durkheimienne

« Durkheim n’est visiblement pas à l’aise dans cette partie finale de son livre [le Livre III de La division du travail social], très courte par rapport aux deux précédentes et aussi bien moins élaborée […]. De là, sans doute, un certain manque de clarté dans la construction de cette dernière partie du livre et même dans l’identification des pathologies de la société moderne. » Une question centrale de la sociologie durkheimienne est celle des conditions de l’ordre et de l’intégration dans un..