Reactive Oxygen Species and Antioxidant Enzymes Involved in Plant Tolerance to Stress

Plants are continuously exposed to several stress factors in field, which affect their production. These environmental adversities generally induce the accumulation of reactive oxygen species (ROS), which can cause severe oxidative damage to plants. ROS are toxic molecules found in various subcellular compartments. The equilibrium between the production and detoxification of ROS is sustained by enzymatic and nonenzymatic antioxidants. Due to advances in molecular approaches during the last decades, nowadays it is possible to develop economically important transgenic crops that have increased tolerance to stresses. This chapter discusses the oxidative stress and damage to plants. In addition, it reports the involvement of antioxidant enzymes in the tolerance of plants to various stresses

Citogenética vegetal: da era clássica à molecular.

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Compressive behaviour of dam concrete at higher strain rates

The mechanical behaviour of concrete when subjected to impact or blast has still many aspects requiring further study. Dam concrete is characterized by large coarse aggregates, hence large specimen sizes are needed in order to study a representative volume of the material. Exploiting an innovative equipment, based on Hopkinson bar techniques, the dynamic behaviour of concrete of 64~mm maximum aggregate size has been investigated. Direct dynamic compression tests have been performed on medium and large size cylindrical samples. Full stress-strain curves have been obtained, which have allowed the estimation of fracturing energies and of the relevant dynamic increase factor. The experimental campaign has also included a reference standard concrete in order to highlight the peculiarity of the dam concrete at high strain rates and to validate the transition of this type of testing to very large specimens.JRC.G.4-European laboratory for structural assessmen

Soybean Architecture Plants: From Solar Radiation Interception to Crop Protection

The soybean plant architecture in relation to better solar radiation interception and production gain is an aspect that requires a better understanding, since soybean is an important crop worldwide. The genetic traits, management and environmental conditions are points that further extend the range of issues on crop productivity. The light quality is measured by the red/far‐red (R/FR) ratio (R ∼ 660 nm, FR ∼ 730 nm). This affects the plant growth and morphological developments in different ways. The plant leaves change their angle during the day to better intercept radiation. This heliotropic movement and some computational models together have been used to enhance some agricultural practices. Soybean plant is dependent on the interaction between genotype and environment. Thus, the enhanced understanding in relation to photosynthetic activity, grain yield by light interception efficiency and culture protection managements in soybean are covered

Dynamic Behaviour of "Collapsible" Concrete

In this work a particular cement composite material for protection of structures and infrastructures against accidental actions, such as blast or impact, has been investigated. An experimental procedure has been developed in order to assess static and dynamic behaviour of energy absorbing cementitious composites. The granular cementitious composite has been studied focusing attention to compressive strength, high deformation and energy dissipation capacity which are important characteristics for an absorber material. An experimental characterization of the material behaviour under compressive static and dynamic loadings has been carried out. Different deformation velocities have been studied in order to define the material behaviour in a wide range of strain rates. The velocity range up to 0.1 m/s is investigated by means of a universal servo-hydraulic MTS 50 kN testing machine. Some preliminary results have been reported and discussed in the present work.JRC.G.4-European laboratory for structural assessmen

Grain productive efficiency of soybean plants under lactofen application

Adverse factors cause a decrease in the productive potential of crops. For soybean [(Glycine max (L.) Merrill], the excessive growth is a factor that results in plants with low effective efficiency. Thus, plants with an architecture that favours greater interception of solar radiation and deposition of pesticides tend to be more productive. The objective of this study is to evaluate the different application of lactofen, which is used as a growth inhibitor, improve the productive efficiency of soybeans by increasing the biological activity of the leaves. The study was conducted in the field with soybean cultivars NA 5909 RG and BMX Potência RR. The experiment followed a randomized complete block design with four treatments and five replicates: T1: control; T2: application of 140 g a.i ha-1 of lactofen in phenological stage V3; T3: application of 140 g a.i ha-1 of lactofen in phenological stage V6; and T4: application of 70 g a.i ha-1 of lactofen in phenological stage V3 + 70 g a.i ha-1 of lactofen in phenological stage V6. The interception of photosynthetically active radiation in the lower layer increased in all treatments. Lactofen application increased the percent area covered and the number of phytosanitary products spray droplets per cm² in the middle and lower layers of the plants. The lower third of the plants experienced the greatest effect of the treatments with regard to the number of pods, grains and grain weight, with treatment T2 presenting significant increases. The use of lactofen as a growth inhibitor at the beginning of pod development in soybean caused changes to plant architecture and root development, consequently enhanced the productive efficiency of the plant, primarily due to increased grain production in the lower layer. Future research using lactofen in different phenological stages and cultivars may provide more insights in to the performance of this growth inhibitor in soybean

Dynamic behaviour of HPFRCC: The influence of fibres dispersion

The promise of fibre-reinforced cementitious composites for dynamic loading application stems from their observed good response under static loading mainly due to fibre contribution. An experimental research aimed at contributing to the understanding of the behaviour of advanced fibre-reinforced cementitious composites subjected to low and high strain rates was carried out underlining the influence of fibres. The material behaviour was investigated at three strain rates (0.1, 1, and 150 s−1) and the tests results were compared with their static behaviour. Tests at intermediate strain rates (0.1–1 s −1) were carried out by means of a hydro-pneumatic machine (HPM), while high strain rates (150 s−1) were investigated by exploiting a modified Hopkinson bar (MHB). Particular attention has been placed on the influence of fibre and fibre dispersion on the dynamic behaviour of the materials: matrix, HPFRCC with random fibre distribution and aligned fibres were compared. The comparison between static and dynamic tests highlighted several relevant aspects regarding the influence of fibres on the peak strength and post-peak behaviour at high strain rate

Foliar fortification of Copper (Cu) in Glycine max L. for the protection against Asian Soybean Rust (Phakopsora pachyrhizi Syd. & P.Syd.)

The Asian Soybean Rust caused by the fungus Phakopsora pachyrhizi is one of the serious phytosanitary problems faced by soybean [Glycine max (L.) Merrill], which cause up to 80% yield loss. An alternative for the integrated management of the disease is the use of mineral nutrition together with phytosanitary treatments. Thus, the objective of this study is to understand the effect of foliar fortification with copper (Cu) along with phytosanitary treatments in the soybean reaction to Rust by lignin content variation in leaf tissues, and how it reflects the yield. The experimental design was a randomized block with four replicates. Four concentrations Cu (30, 60, 90, 120 g Cu ha-1) were tested in two distinct sources (cuprous oxide and copper carbonate) together with phytosanitary treatments. Evaluations were made to determine the progression of Asian Rust severity, micronutrient content in leaves and grains, as well as lignin content in leaves. The grain yield components and productivity were also evaluated. The Cu contents in the soybean leaves and grains were influenced by foliar spraying. Foliar spray with Cu retarded the disease progression, reducing the severity of Asian Rust and positively impacting grain yield. The amount of lignin present in the leaves was altered considerably with the application of the Cu associated with phytosanitary treatments. The results suggest that the leaf nutrition with copper together with phytosanitary treatments, may reduce the rust severity and improvement the plant performance. Future research with Cu application and analysis of specific enzymes, secondary metabolites and cell wall thickness may further contribute to the understanding of the role of Cu in defence against Asian Soybean Rust

Assessment of dynamic mechanical behaviour of reinforced concrete beams using a Blast Simulator

Critical infrastructures may become the target of terrorist bombing attacks or may have to withstand explosive loads due to accidents. The impulsive load connected to explosions is delivered to the structure in a few milliseconds forcing it to respond or fail in a peculiar mode. With reference to the above scientific framework this work presents an innovative apparatus designed and developed at the European Laboratory for Structural Assessment to reproduce a blast pressure history without using explosives. This apparatus is practically a hybrid nitrogen-spring-driven actuator that accelerates masses of up to 100 kg to a maximum velocity of about 25 m/s that impact against the tested structure. The pressure-load history applied to the structure is modulated and reshaped using appropriate layers of elastic soft materials (such as polymeric foams) placed between the specimen and the impacting masses. Specific instrumentation has extensively been utilised to investigate the blast simulator performance and to precisely measure the pressure loads applied to the specimen. A series of tests on real scale reinforced concrete beams/columns (250x250x2200 mm) has been performed to efficiently assess the performance and potentiality of the new blast simulator. Results are under evaluation. In addition to the experimental work, a series of numerical simulations by means of the explicit FEM code EUROPLEXUS have been carried out to support and improve the equipment design.JRC.G.4-European laboratory for structural assessmen

Review on resilience in literature and standards for critical built-infrastructure

A review of system resilience ideas found in literature and standards is conducted. Attention is particularly focused in the built-infrastructure, where both natural and man-made hazards are considered. In order to highlight the fragility of critical infrastructures and communities to hazards and the serious consequences of disruptions and failures, some examples of major disasters are presented. Various definitions for resilience are included and discussed in order to provide the necessary, basic concepts and background. An attempt is made to introduce some resilience properties and metrics in terms of functionality, recovery time etc. The interrelation of structural resilience and fragility curves is put into evidence and the need of some form of Guidelines along with the required research are indicated.JRC.G.4-European laboratory for structural assessmen