Quantifying the relationship between temperature regulation in the ear and floret development stage in wheat (Triticum aestivum L.) under heat and drought stress

Thermal imaging is a valuable tool for the elucidation of gas exchange dynamics between a plant and its environment. The presence of stomata in wheat glumes and awns offers an opportunity to assess photosynthetic activity of ears up to and during flowering. The knowledge of spatial and temporal thermodynamics of the wheat ear may provide insight into interactions between floret developmental stage (FDS), temperature depression (TD) and ambient environment, with potential to be used as a high-throughput screening tool for breeders. A controlled environment study was conducted using six spring wheat (Triticum aestivum L.) genotypes of the elite recombinant inbred line Seri/Babax. Average ear temperature (AET) was recorded using a hand held infrared camera and gas exchange was measured by enclosing ears in a custom built cuvette. FDS was monitored and recorded daily throughout the study. Plants were grown in pots and exposed to a combination of two temperature and two water regimes. In the examined wheat lines, TD varied from 0.1°C to 0.6°C according to the level of stress imposed. The results indicated that TD does not occur at FDS F3, the peak of active flowering, but during the preceding stages prior to pollen release and stigma maturity (F1-F2). These findings suggest that ear temperature during the early stages of anthesis, prior to pollen release and full extension of the stigma, are likely to be the most relevant for identifying heat stress tolerant genotypes.

Hortus botanicus R. Academiae Monacensis , seu, Horti botanici, qui Monachii floret, historia breviter enarrata, et praesens conditio descripta : programma /

Pritzel (2nd ed.)

Mining wheat germplasm collections for yield enhancing traits

The material in genebanks includes valuable traditional varieties and landraces, non-domesticated species, advanced and obsolete cultivars, breeding lines and genetic stock. It is the wide variety of potentially useful genetic diversity that makes collections valuable. While most of the yield increases to date have resulted from manipulation of a few major traits (such as height, photoperiodism, and vernalization), meeting future demand for increased yields will require exploitation of novel genetic resources. Many traits have been reported to have potential to enhance yield, and high expression of these can be found in germplasm collections. To boost yield in irrigated situations, spike fertility must be improved simultaneously with photosynthetic capacity. CIMMYT's Wheat Genetic Resources program has identified a source of multi-ovary florets, with up to 6 kernels per floret. Lines from landrace collections have been identified that have very high chlorophyll concentration, which may increase leaf photosynthetic rate. High chlorophyll concentration and high stomatal conductance are associated with heat tolerance. Recent studies, through augmented use of seed multiplication nurseries, identified high expression of these traits in bank accessions, and both traits were heritable. Searches are underway for drought tolerance traits related to remobilization of stem fructans, awn photosynthesis, osmotic adjustment, and pubescence. Genetic diversity from wild relatives through the production of synthetic wheats has produced novel genetic diversity.

Programa de controle de surto de escorpião Tityus serrulatus, Lutz e Mello 1922, no município de Aparecida, SP (Scorpiones, Buthidae)

Os autores propuseram para o município de Aparecida, vale do Rio Paraíba, SP, região endêmica do Tityus serrulatus, um programa de controle do escorpionismo. Foram estudados a presença de focos do escorpião no campo e na cidade, as alterações ambientais periféricas à zona urbana e os novos ambientes de procriação e dispersão destes artrópodes. Além disso, foram avaliados os problemas básicos de infra-estrutura, tais como o acondicionamento e a coleta do lixo urbano público e domiciliar, o saneamento básico (esgotos e galerias pluviais) e a situação dos terrenos baldios e as construções da zona urbana. Após estudo epidemiológico, foram propostas medidas educativas, que constaram da confecção e distribuição de folhetos, de mutirões de limpeza, de visitas domiciliares e do engajamento de professores e alunos da rede de ensino pública e privada na campanha. Nos locais onde existiam focos de alto risco, em especial nas pré-escolas, foi proposto o emprego do controle químico. Dentro das normas sanitárias vigentes para a zona urbana, foi proposto ainda, o uso de predadores naturais no combate. Os autores concluem que as ações devem ser integradas e continuadas de forma ininterrupta por vários anos e propõem ação conjunta com a campanha da dengue. A instituição de uma semana por ano dedicada ao estudo do escorpionismo nas escolas dos municípios onde ocorre o problema seria uma medida educativa que viria contribuir sobremaneira para a prevenção dos acidentes e controle do escorpionismo.

Ácidos graxos no desempenho e nas respostas imunológicas de bovinos Nelore confinados

O objetivo deste trabalho foi avaliar os efeitos da adição de fontes de lipídeos naturais e protegidos no desempenho e nas respostas imunológicas de bovinos Nelore em confinamento. Utilizou-se o delineamento experimental inteiramente casualizado com medidas repetidas no tempo e três tratamentos, que foram: sem fonte adicional de lipídeo (CONTR); com fonte de lipídeo natural (torta de algodão) (GDESP); e com fonte de lipídeo protegido e rico em ácidos graxos poli-insaturados (GPROT). O estudo foi dividido em duas fases: pré-condicionamento e confinamento de 120 bovinos Nelore inteiros (24 baias, 5 animais por baia e 8 repetições por tratamento). O tratamento GDESP proporcionou maior ganho de peso na fase de pré-condicionamento, e, durante o período de confinamento, não houve diferenças entre os tratamentos quanto ao desempenho, às características de carcaça e ao acometimento de enfermidades. As concentrações plasmáticas de TNFα, IL-1β, haptoglobina e ceruloplasmina foram superiores no tratamento CONTR. A adição de lipídeos à dieta, independentemente da fonte, promove melhora no desempenho e nos parâmetros imunológicos de bovinos Nelore confinados.

Influence of "historic" photoperiod during stem elongation on the number of fertile florets in wheat

Extending the duration of the late reproductive phase in wheat has been proposed as a possible avenue to improve spike fertility. There is a positive correlation between the number of fertile florets and the duration of the stem elongation phase when this phase is varied by extended photoperiod. Photoperiod treatments imposed during the vegetative period also influence the duration of stem elongation. The present study analysed the effect of long photoperiod (19 h) of different duration (10, 12, 14, 18 or 22 d) imposed before the onset of stem elongation on floret fertility in wheat. It was found that the length of the stem elongation phase was modified by earlier ‘historic ’ photoperiod treatments imposed during previous phases. However, neither the number of fertile florets per spike nor the spikelet fertility was affected significantly by these historic treatments. The results of the study therefore showed that an increased duration of the late reproductive phase was ineffective in increasing the number of fertile florets, unless the length of that phase was directly altered by current photoperiod.

Sink limitations to yield in wheat : how could it be reduced?

Further genetic gains in wheat yield are required to match expected increases in demand. This may require the identification of physiological attributes able to produce such improvement, as well as the genetic bases controlling those traits in order to facilitate their manipulation. In the present paper, a theoretical framework of source and sink limitation to wheat yield is presented and the fine-tuning of crop development as an alternative for increasing yield potential is discussed. Following a top-down approach, most crop physiologists have agreed that the main attribute explaining past genetic gains in yield was harvest index (HI). By virtue of previous success, no further gains may be expected in HI and an alternative must be found. Using a bottom-up approach, the present paper firstly provides evidence on the generalized sink-limited condition of grain growth, determining that for further increases in yield potential, sink strength during grain filling has to be increased. The focus should be on further increasing grain number per m2, through fine-tuning pre-anthesis developmental patterns. The phase of rapid spike growth period (RSGP) is critical for grain number determination and increasing spike growth during pre-anthesis would result in an increased number of grains. This might be achieved by lengthening the duration of the phase (though without altering flowering time), as there is genotypic variation in the proportion of pre-anthesis time elapsed either before or after the onset of the stem elongation phase. Photoperiod sensitivity during RSGP could be then used as a genetic tool to further increase grain number, since slower development results in smoother floret development and more floret primordia achieve the fertile floret stage, able to produce a grain. Far less progress has been achieved on the genetic control of this attribute. None of the well-known major Ppd alleles seems to be consistently responsible for RSGP sensitivity. Alternatives for identifying the genetic factors responsible for this sensitivity (e.g. quantitative trait locus (QTL) identification in mapping populations) are being considered.

Alain CHARTIER, Opuscules divers.

Contient : Quadrilogue invectif ; L'Espérance, ou consolation des trois vertus ; « Oraison composée par sainct Gregoire, en son petit livre nommé Floret, se doibt dire quand on s'en va coucher »

Le changement social et l'État moderne en Mongolie

Ce mémoire propose une analyse socio-historique d'un cas extrême de changement social par son ampleur et sa rapidité: l'apparition ex-nihilo, à partir des années 1990, d'une population de plus de 100 000 mineurs artisanaux en Mongolie. Pour ce faire, il offre, premièrement, des outils théoriques au lecteur pour comprendre la tension entre permanence et mouvement qui anime les sociétés humaines. Deuxièmement, il identifie les tendances récurrentes de l'histoire mongole pour rendre le présent plus intelligible. Troisièmement, il détaille les principales caractéristiques contemporaines de ce nouveau phénomène, ainsi que ses potentialités pour le proche avenir. Mais surtout, à chaque étape, il construit une théorie locale et partielle du changement social, qui montre l'impact croissant de l'État moderne et de son idéologie du progrès et de la rationalité dans la vie de tous les individus, qui laisse les plus marginaux d'entre eux de plus en plus dépourvus d'influence sur leur environnement.

Asynchronous flowering and within-plant flowering diversity in wheat and the implications for crop resilience to heat

Self-pollination dominates in wheat , with a small level of out-crossing due to flowering asynchrony and male sterility. However, the timing and synchrony of male and female flowering in wheat is a crucial determinant of seed set and may be an important factor affecting gene flow and resilience to climate change. Here, a methodology is presented for assessing the timing and synchrony of flowering in wheat. From the onset of flowering until the end of anthesis, the anther and stigma activity of each floret was assessed on the first five developing ears in potted plants grown under ambient conditions and originating from cv Paragon or cvs Spark-Rialto backgrounds. At harvest maturity, seed presence, size and weight was recorded for each floret scored. The synchrony between pollen dehiscence and stigma collapse within a flower was dependent on its relative position in a spike and within a floret. Determined on the basis of synchrony within each flower, the level of pollination by pollen originating from other flowers reached approximately 30% and did not change throughout the duration of flowering. A modelling exercise parameterised by flowering observations indicated that the temporal and spatial variability of anther activity within and between spikes may influence the relative resilience of wheat to sudden, extreme climatic events which has direct relevance to predicted future climate scenarios in the UK.

Decimal growth stages for precision wheat production in changing environments?

The utility of the decimal growth stage (DGS) scoring system for cereals is reviewed. The DGS is the most widely used scale in academic and commercial applications because of its comprehensive coverage of cereal developmental stages, the ease of use and definition provided and adoption by official agencies. The DGS has demonstrable and established value in helping to optimise the timing of agronomic inputs, particularly with regard to plant growth regulators, herbicides, fungicides and soluble nitrogen fertilisers. In addition, the DGS is used to help parameterise crop models, and also in understanding the response and adaptation of crops to the environment. The value of the DGS for increasing precision relies on it indicating, to some degree, the various stages in the development of the stem apex and spike. Coincidence of specific growth stage scores with the transition of the apical meristem from a vegetative to a reproductive state, and also with the period of meiosis, is unreliable. Nonetheless, in pot experiments it is shown that the broad period of booting (DGS 41–49) appears adequate for covering the duration when the vulnerability of meiosis to drought and heat stress is exposed. Similarly, the duration of anthesis (61–69) is particularly susceptible to abiotic stresses: initially from a fertility perspective, but increasingly from a mean grain weight perspective as flowering progresses to DGS 69 and then milk development. These associations with DGS can have value at the crop level of organisation: for interpreting environmental effects, and in crop modelling. However, genetic, biochemical and physiological analysis to develop greater understanding of stress acclimation during the vegetative state, and tolerance at meiosis, does require more precision than DGS can provide. Similarly, individual floret analysis is needed to further understand the genetic basis of stress tolerance during anthesis.

Renegociação de créditos inadimplentes : o comportamento do cliente perante o processo de cobrança

Este trabalho analisa como aprimorar o processo de renegociação, realizado por uma grande instituição financeira brasileira, com clientes de baixa renda, em atraso no pagamento de dívidas contraídas no cartão de crédito. O tema se torna relevante, à medida que a oferta de crédito vem aumentando nos últimos anos, principalmente para a população de baixa renda, permitindo um aumento do consumo e possibilitando o desenvolvimento do país. A pesquisa procura investigar o processo decisório utilizado pelo cliente para solucionar seu problema financeiro, quando está sendo cobrado pela instituição financeira. Utiliza-se uma abordagem interpretativa, voltada a avaliar o comportamento do cliente, por meio de entrevistas semi-estruturadas, perante fatores individuais, sócio-culturais e situacionais. Os resultados indicam que a falta de educação financeira e fatores situacionais, como desemprego, doenças e visão de curto prazo, levam a população de baixa renda a não utilizar adequadamente o crédito disponível, incorrendo em dificuldades em manter o pagamento de suas dívidas em dia. A interação entre o cliente e o operador de cobrança, mostra-se decisiva para que o processo decisório ocorra de forma consistente, estabelecendo-se um acordo concreto de reestruturação da dívida. Finalmente, sugere-se que o processo de cobrança passe a se preocupar com a retenção do cliente, buscando maximizar seu valor no tempo.