Variability of root traits in common bean genotypes at different levels of phosphorus supply and ontogenetic stages.

Selection of common bean (Phaseolus vulgaris L.) cultivars with enhanced root growth would be a strategy for increasing P uptake and grain yield in tropical soils, but the strong plasticity of root traits may compromise their inclusion in breeding programs. The aim of this study was to evaluate the magnitude of thegenotypic variability of root traits in common bean plants at two ontogenetic stages and two soil P levels. Twenty-four common bean genotypes, comprising the four growth habits that exist in the species and two wild genotypes, were grown in 4 kg pots at two levels of applied P (20 and 80 mg kg -1) and harvested at the stages of pod setting and early pod filling. Root area and root length were measured by digital image analysis. Significant genotype × P level and genotype × harvest interactions in analysis of variance indicate that the genotypic variation of root traits depended on soil nutrient availability and the stage at which evaluation was made. Genotypes differed for taproot mass, basal and lateral root mass, root area and root length at both P levels and growth stages; differences in specific root area and length were small. Genotypes with growth habits II (upright indeterminate) and III (prostrate indeterminate) showed better adaptation to limited P supply than genotypes of groups I (determinate) and IV (indeterminate climbing). Between the two harvests, genotypes of groups II and III increased the mass of basal and lateral roots by 40 and 50 %, respectively, whereas genotypes of groups I and IV by only 7 and 19 %. Values of the genotypic coefficient of determination, which estimates the proportion of phenotypic variance resulting from genetic effects, were higher at early pod filling than at pod setting. Correlations between shoot mass and root mass, which could indicate indirect selection of root systems via aboveground biomass, were higher at early pod filling than at pod setting. The results indicate that selection for root traits in common bean genotypes should preferentially be performed at the early pod-filling stage

Biased cosmological parameter estimation with galaxy cluster counts in the presence of primordial non-Gaussianities

The redshift dependence of the abundance of galaxy clusters is very sensitive to the statistical properties of primordial density perturbations. It can thus be used to probe small deviations from Gaussian initial conditions. Such deviations constitute a very important signature of many inflationary scenarios, and are thus expected to provide crucial information on physical processes which took place in the very early Universe. We have determined the biases which may be introduced in the estimation of cosmological parameters by wrongly assuming the absence of primordial non-Gaussianities. Although we find that the estimation of the present-day dark energy density using cluster counts is not very sensitive to the non-Gaussian properties of the density field, we show that the biases can be considerably larger in the estimation of the dark energy equation of state parameter $w$ and of the amplitude of the primordial density perturbations. Our results suggest that a significant level of non-Gaussianity at cluster scales may be able to reconcile the constraint on the amplitude of the primordial perturbations obtained using galaxy cluster number counts from the Planck Sunyaev-Zeldovich Catalog with that obtained from the primary Cosmic Microwave Background anisotropies measured by the Planck satellite.Comment: 4 pages, 1 figur

Old beacon of hope when nothing else works

publishersversionpublishe

Electron Beam Adjustment in PLATO RTS 2 Including the Effect of Air Gaps

Background and Purpose: Beam characterization for electron dose calculations in PLATO RTS 2 treatment planning system requires the tuning of two adjustment parameters: sqx (the initial angular spread) and FMCS (a "fudge" multiple Coulomb scattering parameter). This work provides a set of suggestions to optimise electron dose calculations with PLATO, taking into account the effect of air gaps between the electron applicator and the patient skin. Material and Methods: Two adjustment criteria have been followed: one which uses just one input data set corresponding to the standard (null) air gap and another one that takes into account the whole range of clinically used distances between the electron applicator and the patient surface. The adjusted values of sqx were compared with experimental data and GEANT3 Monte Carlo code results. A systematic study has been carried out of the effect of both adjustment parameters on electron dose calculations in water. Comparisons of dose distributions and point dose values have been done between PLATO RTS2, GEANT3 Monte Carlo code and experimental data. Also the dependence on field size has been assessed. The values of sqx for the different electron energies obtained through the different approaches are discussed. Results and conclusions: The first adjustment criteria yield unrealistic dose distributions whenever the air gap is different from the standard one. A sqx balanced with a proper FMCS parameter leads to reasonably good dose distributions and point dose values that agree with experimental results within less than 1%

Uso de modelos de simulação sócio-bio-econômico integrado como ferramenta para o desenvolvimento agrário na região sudoeste do Rio Grande Sul.

Suporte tecnológico tem sido oferecido aos produtores com a finalidade de aumentar a eficiência produtiva e fornecer subsídios para as suas tomadas de decisões; entretanto, os métodos tradicionais de pesquisa e extensão estão sendo cada vez mais questionados, principalmente quanto ao custo e tempo necessário para oferecer soluções aos problemas enfrentados pelos produtores.bitstream/item/109814/1/USO-DE-MODELOS-DE-SIMULACAO.pd

Does it still hold?

publishersversionpublishe

Necessidades de pesquisa e desenvolvimento no Brasil nas culturas da banana e do mamão - percepções das cadeias produtivas.

Para que as ações de pesquisa e desenvolvimento (P&D) de instituições públicas sejam melhor direcionadas às demandas do setor produtivo, é necessária interação direta com o mesmo. Em 2011 ocorreram no Brasil dois importantes encontros das cadeias produtivas da banana e do mamão: o Simpósio Internacional Promusa ? ISHS ? Bananas e Plátanos: Produção global sustentável e usos alternativos; o Papaya Brasil 2011 ? V Simpósio do Papaya Brasileiro. Os dois eventos reuniram uma série de especialistas, produtores, extensionistas, representantes dos setores de insumos e pesquisadores envolvidos com essas culturas