Agronomic Evaluation of Alfalfa Cultivars in Rio Grande do Sul, Brasil

From April 1995 to June 1998, thirty five alfalfa (Medicago sativa L.) cultivars (cvs.) were evaluated in a field trial at the “Depressão Central” ecoclimatic region, in southern Brazil. Two years after sowing, 30 cultivars were excluded from the test due to their poor overall agronomic performance, mainly low forage DM yields. The remaining cultivars: Crioula (local genotype used as a check), Victoria, Rio and P 30 are hay-type cultivars while Alfagraze is a grazing-tolerant type. Twenty-two harvests were made and no significant differences were found for total DM yields among cvs. Crioula, Victoria, Rio and P 30; however, cv. Crioula yielded 25,854 kg.ha-1, showing a significant (P\u3c 0.05) superior performance compared to cv. Alfagraze (17,478 kg.ha-1). The highest average annual and seasonal DM yields were obtained by cv. Crioula and spring was the best growing season. Cv. Alfagraze showed the highest crude protein content and leaf to stem ratio. Incidence of foliar diseases was low, affecting all cultivars similarly. Cv. Victoria showed the lowest stand persistence. Alfalfa root density did not differ among cultivars and the highest average value was found at the 0-10 cm topsoil layer. Results indicate that cvs. Crioula and Alfagraze are well-adapted, productive and persistent alfalfa genotypes for hay production and grazing, respectively, under the soil and climatic conditions of the “Depressão Central” region

Estimativa da evapotranspiração de referência no Brasil: uma análise crítica.

RESUMO: Devido a necessidade de quantificar a perda de água pelas grandes culturas, diversos trabalhos tem sido desenvolvidos com o objetivo de encontrar um modelo de estimativa da evapotranspiração de referência (ETo) para uma região específica. Assim, o presente trabalho tem como objetivo analisar a produção científica brasileira na área de estimativa da evapotranspiração e identificando os principais métodos de estimativa da ETo utilizados para as diferentes condições climáticas brasileiras. Para isso, realizou-se uma revisão de bibliográfica de trabalhos de estimativa de ETo realizados no Brasil. Entre os 38 trabalhos encontrados para a presente discussão, foi possível concluir que os métodos mais adequados foram os métodos de Blaney-Criddle FAO-24 e Radiação Solar FAO-24 para o norte e nordeste, e Thornthwaite e Camargo para o sul e sudeste, onde as regiões norte, centro-oeste e sul necessitam de maiores estudos nesta área

Sistemi automatici di registrazione: nuove metodologie bioacustiche applicate a indagini ornitologiche in alcuni siti della Rete Natura 2000 del Veneto. Risultati e prospettive.

Il lavoro illustra i risultati di un progetto di monitoraggio acustico delle specie ornitologiche presenti in alcuni siti della Rete Natura 2000 del Veneto. Si descrive la metodologia impiegata, basata su registratori automatici programmabili e sull'analisi spettrografica delle registrazioni risultanti. Il progetto e' stato realizzato in collaborazione con il Corpo Forestale dello Stato

How grazing management can maximize erosion resistance of salt marshes

Combining natural saltmarsh habitats with conventional barriers can provide a sustainable and cost-effective alternative for fully engineered flood protection, provided that a minimal salt marsh width can be guaranteed for a long period. Hence, it is essential to understand both the key factors and management options driving the lateral erodibility/stability of salt marshes.We aimed to determine how salt marsh management (i.e. grazing by large vs. small grazers vs. artificial mowing), marsh elevation and marsh age affect soil stability (i.e. soil collapse) and intrinsic lateral erodibility of salt marshes (i.e. particle-by-particle detachment). Soil cores were collected in high and low marshes (above and below 0.5 m MHWL, respectively) of different ages. At these locations, we compared cores from grazed areas to cores inside grazer exclosures, with and without artificial mowing. All cores were exposed to waves in flumes to test their stability and lateral erodibility.All soil cores were characterized by a stable fine-grained layer deposited on top of readily erodible sand. The thickness of the fine-grained layer was a key parameter in reducing salt marsh instability (cliff collapse). This layer thickness increased with marsh age and at lower elevations, but decreased with cattle grazing due to compaction.The erosion resistance of the fine-grained layer increased with (a) large grazers that compacted the soil by trampling, (b) mowing that excluded soil-bioturbating species, and (c) grazing by small grazers that promoted vegetation types with higher root density.Synthesis and applications. Overall, marshes with thinner cohesive and/or fine-grained top layers are more sensitive to lateral erosion than marshes with deep cohesive soils, independently of the management. Grazing and artificial mowing can reduce the erodibility of fine-grained soils, making salt marshes more resilient to lateral erosion. However, compaction by large grazers simultaneously leads to thinner fine-grained layers and lower elevation, potentially leading to more inundation under sea-level rise. Hence, to effectively manage salt marshes to enhance their contribution to coastal protection, we recommend (a) moderate/rotational livestock grazing, avoiding high intensity grazing in sediment-poor systems sensitive to sea-level rise and (b) investigating measures to preserve small grazers.</p

Employability and involuntary occupational transitions management : an explorative research with workers on unemployment benefit

Fragmented nature of current careers has placed at the centre of attention the concept of employability. This paper presents an explorative study aimed at analysing employability during the occupational transition of dismissed workers. In the light of the psychosocial approach suggested by Fugate and colleagues, the principal goal was to explore the relationship between dispositional employability and two crucial aspects of outplacement, re-employment and physical and mental health, hypothesizing a mediating role of perceived employability and perceived utility of outplacement services. The research involved pharmaceutical workers on unemployment benefit. Our analysis confirmed that dispositional employability can be considered as a latent multidimensional construct which sparingly summarizes three latent dimensions (self-efficacy in managing work changes; social capital; work career proactivity). Results highlighted that dispositional employability has a fairly direct impact on physical and mental health, but it is not associated with reemployment. Moreover perceived employability mediates the relationship between dispositional employability and perceived utility of outplacement services, while it doesn\u2019t have a direct connection with psychophysical health. Implications on career counselling are discusse

Smooth kinematic and metallicity gradients between the Milky Way's nuclear star cluster and nuclear stellar disc. Different components of the same structure?

The innermost regions of most galaxies are characterised by the presence of extremely dense nuclear star clusters. Nevertheless, these clusters are not the only stellar component present in galactic nuclei, where larger stellar structures known as nuclear stellar discs, have also been found. Understanding the relation between nuclear star clusters and nuclear stellar discs is challenging due to the large distance towards other galaxies which limits their analysis to integrated light. The Milky Way's centre, at only 8 kpc, hosts a nuclear star cluster and a nuclear stellar disc, constituting a unique template to understand their relation and formation scenario. We aim to study the kinematics and stellar metallicity of stars from the Milky Way's nuclear star cluster and disc to shed light on the relation between these two Galactic centre components. We used publicly available photometric, proper motions, and spectroscopic catalogues to analyse a region of $\sim2.8'\times4.9'$ centred on the Milky Way's nuclear star cluster. We built colour magnitude diagrams, and applied colour cuts to analyse the kinematic and metallicity distributions of Milky Way's nuclear star cluster and disc stars with different extinction along the line of sight. We detect kinematics and metallicity gradients for the analysed stars along the line of sight towards the Milky Way's nuclear star cluster, suggesting a smooth transition between the nuclear stellar disc and cluster. We also find a bi-modal metallicity distribution for all the analysed colour bins, which is compatible with previous work on the bulk population of the nuclear stellar disc and cluster. Our results suggest that these two Galactic centre components might be part of the same structure with the Milky Way's nuclear stellar disc being the grown edge of the nuclear star cluster.Comment: Submitted to A&A. 13 pages, 9 figure

Multiple trait dimensions mediate stress gradient effects on plant biomass allocation, with implications for coastal ecosystem services

The plant economic spectrum (PES) predicts a suite of correlated traits in a continuum from resource conservation to rapid resource acquisition. In addition to competing for resources, plants need to cope with other environmental stresses to persist and reproduce. Yet, it is unclear how multiple strategies (i.e. traits uncorrelated with the PES) affect plant biomass allocation, hindering our ability to connect environmental gradients to ecosystem services.We examined intraspecific dimensionality of leaf and root traits in the salt marsh pioneer species Spartina anglica across salinity, redox and sand content gradients, and related them to above-ground and below-ground plant biomass—properties associated with wave attenuation and sediment stabilization in coastal marshes.Through principal component analysis, we did not find support for a single PES trait dimension (strategy), but instead identified four trait dimensions: (a) leaf economic spectrum (LES, leaf analogue of PES); (b) fine roots-rhizomes; (c) coarse roots; and (d) salt extrusion. Structural equation modelling showed a shift towards the conservative side of the LES under increasing salinity, while redox had a positive influence on the coarse roots dimension. In turn, these trait dimensions were strongly associated with above-ground and below-ground biomass (BLW biomass) allocation.These results indicate that under high salinity, plants will adopt a conservative strategy and will invest more in BLW biomass. Yet, high sediment redox would still allow plants to invest in above-ground biomass. Therefore, plants' trait-mediated biomass allocation depends on the specific combination of abiotic factors experienced at the local scale.Synthesis. Our study highlights the importance of considering multiple ecological strategies for understanding the effect of the environment on plants. Abiotic stresses can influence multiple trait strategy-dimensions, with consequences for ecosystem functioning

Universality of pseudogap and emergent order in lightly doped Mott insulators

It is widely believed that high-temperature superconductivity in the cuprates emerges from doped Mott insulators. The physics of the parent state seems deceivingly simple: The hopping of the electrons from site to site is prohibited because their on-site Coulomb repulsion U is larger than the kinetic energy gain t. When doping these materials by inserting a small percentage of extra carriers, the electrons become mobile but the strong correlations from the Mott state are thought to survive; inhomogeneous electronic order, a mysterious pseudogap and, eventually, superconductivity appear. How the insertion of dopant atoms drives this evolution is not known, nor whether these phenomena are mere distractions specific to hole-doped cuprates or represent the genuine physics of doped Mott insulators. Here, we visualize the evolution of the electronic states of (Sr1-xLax)2IrO4, which is an effective spin-1/2 Mott insulator like the cuprates, but is chemically radically different. Using spectroscopic-imaging STM, we find that for doping concentration of x=5%, an inhomogeneous, phase separated state emerges, with the nucleation of pseudogap puddles around clusters of dopant atoms. Within these puddles, we observe the same glassy electronic order that is so iconic for the underdoped cuprates. Further, we illuminate the genesis of this state using the unique possibility to localize dopant atoms on topographs in these samples. At low doping, we find evidence for much deeper trapping of carriers compared to the cuprates. This leads to fully gapped spectra with the chemical potential at mid-gap, which abruptly collapse at a threshold of around 4%. Our results clarify the melting of the Mott state, and establish phase separation and electronic order as generic features of doped Mott insulators.Comment: This version contains the supplementary information and small updates on figures and tex