943 resultados para Barley Roots
Resumo:
The genetic variation existing in a set of barley (Hordeum vulgare L.) landrace samples recently collected in Morocco was estimated. Two kinds of genetic markers, seed storage proteins (hordeins) and random amplified polymorphic DNA (RAPD), were used. Only six out of 31 landraces were subjected to RAPD analysis. Both kinds of markers, RAPD and storage proteins, yielded similar results, showing that the level of variation observed in Moroccan barley was high: all landraces showed variability; 808 different storage protein patterns (multilocus associations) were observed among 1897 individuals (2.32 seeds per association, on average) with an average of 43 multilocus associations per accession. In general, genetic variation within accessions was higher than between accessions. The 100 polymorphic RAPD bands generated by 21 effective primers were able to generate enough patterns to differentiate between uniform cultivars and even between individuals in variable accessions. One of the aims of this work was to compare the effectiveness of RAPD versus storage protein techniques in assessing the variability of genetic resource collections. On average hordeins were more polymorphic than RAPDs: they showed more alternatives per band on gels and a higher percentage of polymorphic bands, although RAPDs supply a higher number of bands. Although RAPD is an easy and standard technique, storage protein analysis is technically easier, cheaper and needs less sophisticated equipment. Thus, when resources are a limiting factor and considering the cost of consumables and work time, seed storage proteins must be the technique of choice for a first estimation of genetic variation in plant genetic resource collections.
Resumo:
Fluvial islands are emergent landforms which form at the interface between the permanently inundated areas of the river channel and the more stable areas of the floodplain as a result of interactions between physical river processes, wood and riparian vegetation. These highly dynamical systems are ideal to study soil structure development in the short to medium term, a process in which soil biota and plants play a substantial role. We investigated soil structure development on islands along a 40 year chronosequence within a 3 km island-braided reach of the Tagliamento River, Northeastern Italy. We used several parameters to capture different aspects of the soil structure, and measured biotic (e.g., fungal and plant root parameters) and abiotic (e.g. organic carbon) factors expected to determine the structure. We estimated models relating soil structure to its determinants, and, in order to confer statistical robustness to our results, we explicitly took into account spatial autocorrelation, which is present due to the space for time substitution inherent in the study of chronosequences and may have confounded results of previous studies. We found that, despite the eroding forces from the hydrological and geomorphological dynamics to which the system is subject, all soil structure variables significantly, and in some case greatly increased with site age. We interpret this as a macroscopic proxy for the major direct and indirect binding effects exerted by root variables and extraradical hyphae of arbuscular mycorrhizal fungi (AMF). Key soil structure parameters such as percentage of water stable aggregates (WSA) can double from the time the island landform is initiated (mean WSA = 30%) to the full 40 years (mean WSA = 64%) covered by our chronosequence. The study demonstrates the fundamental role of soil biota and plant roots in aggregating soils even in a system in which intense short to medium term physical disturbances are common.
Resumo:
A substantial body of evidence suggest that well designed school based prevention programmes can be effective in improving a variety of social, health and academic outcomes for children and young people. This poster presents the methodology for evaluating the Roots of Empathy (ROE) programme. ROE is a universal programme delivered on a whole-class basis for one academic year. It consists of 27 lessons that run over a school year and is based around a monthly classroom visit by an infant and parent, typically recruited from the local community, whom the class 'adopts' at the start of the school year. The evaluation aims to evaluate the immediate and longer term impact of ROE on social and emotional wellbeing outcomes among 8-9 year old pupils, as well as evaluate the cost-effectiveness of the programme.
Resumo:
The practice of sustainable peace is a process that must be initiated, nourished and revised. The
“social energies” of conflict transformation – truth, mercy, justice, peace – offer a useful model to describe the transformative power of this practice. These social energies can be conceptualized as a combination of norms or values, on the one hand, and actions directed toward social reconstruction, on the other. As such, the social energies of conflict transformation are both the guideposts and the engine in the journey of practicing sustainable peace. This article begins by
linking psychological constructs of narrative/voice, empathy/altruism, individual/collective guilt, and security/fear with the social energies, highlighting the interdependence of processes and shifting the focus away from pathology toward an emphasis on harmony. An empirical application of how the four social energies contribute to the mobilization, maintenance and adaptations in on-going peace processes in post-war Guatemala is then presented. By analyzing the interaction among diverse actors and goals in the decade and a half since the signing of the 1996 Peace Accords, current theory is extended in two ways: a) differentiation between elite and grassroots initiatives, and b) specification and evaluation the impact of various efforts on episodic and structural violence. We conclude that although national and local processes have
had limited success, more integrated practices of truth, mercy, justice and peace are necessary if Guatemala is to make sustainable peace a reality. The findings from this case study have policy and practical implications for other countries facing protracted, violent conflict.
Resumo:
Here the mechanism of arsenite transport into paddy rice (Oryza sativa) roots, uptake of which is described by Michaelis-Menten kinetics, is reported. A recent study on yeast (Saccharomyces cerevisiae) showed that undissociated arsenite (its pKa is 9.2) was transported across the plasma membrane via a glycerol transporting channel. To investigate whether the same mechanism of transport was involved for rice, competitive studies with glycerol, which is transported into cells via aquaporins, were performed. Glycerol competed with arsenite for transport in a dose-dependent manner, indicating that arsenite and glycerol uptake mechanisms were the same. Arsenate transport was unaffected by glycerol, confirming that arsenate and arsenite are taken up into cells by different mechanisms. Antimonite, an arsenite analogue that is transported into S. cerevisiae cells by aquaporins, also competed with arsenite transport in a dose-dependent manner, providing further evidence that arsenite is transported into rice roots via glycerol transporting channels. Mercury (Hg2+) inhibited both arsenite and arsenate uptake, suggesting that inhibition of influx was due to general cellular stress rather than the specific action of Hg2+ on aquaporins. Arsenite uptake by pea (Pisum sativum) and wheat (Triticum aestivum) was also described by Michaelis-Menten kinetics.
Resumo:
To determine the effect of microbial metabolites on the release of root exudates from perennial ryegrass, seedlings were pulse labelled with [14C]-CO2 in the presence of a range of soil micro-organisms. Microbial inoculants were spatially separated from roots by Millipore membranes so that root infection did not occur. Using this technique, only microbial metabolites affected root exudation. The effect of microbial metabolites on carbon assimilation and distribution and root exudation was determined for 15 microbial species. Assimilation of a pulse label varied by over 3.5 fold, dependent on inoculant. Distribution of the label between roots and shoots also varied with inoculant, but the carbon pool that was most sensitive to inoculation was root exudation. In the absence of a microbial inoculant only 1% of assimilated label was exuded. Inoculation of the microcosms always caused an increase in exudation but the percentage exuded varied greatly, within the range of 3-34%. © 1995 Kluwer Academic Publishers.
Resumo:
With biochar becoming an emerging soil amendment and a tool to mitigate climate change, there are only a few studies documenting its effects on trace element cycling in agriculture. Zn and Cu are deficient in many human diets, whilst exposures to As, Pb and Cd need to be decreased. Biochar has been shown to affect many of them mainly at a bench or greenhouse scale, but field research is not available. In our experiment we studied the impact of biochar, as well as its interactions with organic (compost and sewage sludge) and mineral fertilisers (NPK and nitrosulfate), on trace element mobility in a Mediterranean agricultural field (east of Madrid, Spain) cropped with barley. At harvesting time, we analysed the soluble fraction, the available fraction (assessed with the diffusive gradients in thin gels technique, DGT) and the concentration of trace elements in barley grain. No treatment was able to significantly increase Zn, Cu or Ni concentration in barley grain, limiting the application for cereal fortification. Biochar helped to reduce Cd and Pb in grain, whereas As concentration slightly increased. Overall biochar amendments demonstrated a potential to decrease Cd uptake in cereals, a substantial pathway of exposure in the Spanish population, whereas mineral fertilisation and sewage sludge increased grain Cd and Pb. In the soil, biochar helped to stabilise Pb and Cd, while marginally increasing As release/mobilisation. Some of the fertilisation practises or treatments increased toxic metals and As solubility in soil, but never to an extent high enough to be considered an environmental risk. Future research may try to fortify Zn, Cu and Ni using other combinations of organic amendments and different parent biomass to produce enriched biochars.
Impact of the Roots of Empathy Programme on Social-Emotional Learning: A Randomized Controlled Trial
Resumo:
Roots of Empathy (ROE) is a universal, school-based social and emotional learning programme aimed at increasing prosocial behaviour and reducing difficult behaviour. This paper reports the findings of a cluster randomized controlled trial of the effects of ROE on 8-9 year old children. 74 schools and 1,181 children took part. The findings provide evidence that ROE is effective in increasing prosocial behaviour (g=+.20, p=.043) and some potential evidence that it may reduce difficult behaviour (g=-.15, p=.070). While ROE was found to lead to improvements in positive behaviour, these were not associated with improvements in empathy or other social and emotional learning outcomes.