Stomatal behavior of different grapevine cultivars in response to soil water status and air water vapor pressure deficit

Aims: Genetic variability in grapevine cultivars may influence their strategy to cope with drought through stomatal regulation of transpiration rate. The aim of the present study was to evaluate the stomatal sensitivity of five cultivars (Ekigaïna, Grenache, Marselan, Mourvèdre, and Syrah) to soil water status and air water vapor pressure deficit (VPD). Methods and results: Leaf gas exchange and canopy light interception efficiency (εi) were evaluated through a wide range of predawn leaf water potential (ΨPD) measurements in a field experiment in Southern France. Additionally, greenhouse experiments were carried out to monitor stomatal response to increasing VPD levels. Ekigaïna showed a strong isohydric behavior with the highest decrease in leaf gas exchange in response to soil water stress and VPD. Mourvèdre and Grenache showed a similar but relatively less extreme behavior. These three cultivars showed a constant leaf water status during the day through stomatal regulation and a strong decrease in εi. In contrast, Syrah and Marselan displayed anisohydric behavior as they presented a less sensitive stomatal control. Both cultivars showed fluctuating midday leaf water potential and Marselan was the least affected in terms of εi. Conclusion: This study demonstrated that grape cultivars differed in their stomatal response to soil water deficit and VPD. For a given cultivar, a similar stomatal behavior was found in response to both ΨPD and VPD. Significance and impact of the results: Adaptation to drought and viticulture viability in hot and dry environments could be achieved by identifying and breeding cultivars with drought tolerance traits.Objectifs : La variabilité génétique existante chez les cépages de vigne peut affecter leur stratégie d’adaptation à la sécheresse en régulant la transpiration au travers de la fermeture des stomates. L’objectif du travail a été d’évaluer la sensibilité des stomates de cinq cultivars (Ekigaïna, Grenache, Marselan, Mourvèdre et Syrah) à la disponibilité en eau du sol et au déficit de pression de vapeur (VPD). Méthodes et résultats : Les échanges gazeux des feuilles et l’efficience d’interception du rayonnement (ei) ont été évalués dans une large gamme des valeurs de potentiel hydrique de base (yPD) en conditions de terrain dans le Sud de la France. En outre, une expérimentation complémentaire en serre a été réalisée pour analyser la réponse des stomates face à une augmentation du VPD. L’Ekigaïna a présenté un caractère ioshydrique très marqué avec la plus grande diminution des échanges gazeux en réponse au déficit hydrique du sol et au VPD. Le Mourvèdre et le Grenache ont présenté un comportement similaire bien que moins extrême que l’Ekigaïna. Ces trois cultivars ont montré un potentiel hydrique foliaire constant pendant la journée à cause d’une forte régulation stomatique et une diminution de ei. Par contre, le Syrah et le Marselan, ont montré un comportement anisohydrique avec un control stomatique moins sensible. Les deux cultivars ont présenté une diminution du potentiel hydrique foliaire à midi tandis que le Marselan a été le moins affecté en termes de ei. Conclusions : La présente étude montre que les cultivars présentent des différences dans leur réponse au déficit hydrique du sol et au VPD. Pour un cultivar donné, un comportement stomatique similaire a été observé en réponse au yPD et au VPD. Impacts et signification des résultats : L’adaptation à la sécheresse et la viabilité de la viticulture sur de climats chauds et secs pourrait être atteint par la sélection de cultivars avec de caractères de tolérance.EEA MendozaFil: Prieto, Jorge Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina.Fil: Lebon, Eric. Institut National de la Recherche Agronomique. Unité Mixte de Recherche Montpellier; FranciaFil: Ojeda, Hernan. Institut National de la Recherche Agronomique. Unité expérimentale de Pech Rouge; Franci

Nonequilibrium entropy production for open quantum systems

We consider open quantum systems weakly coupled to a heat reservoir and driven by arbitrary time-dependent parameters. We derive exact microscopic expressions for the nonequilibrium entropy production and entropy production rate, valid arbitrarily far from equilibrium. By using the two-point energy measurement statistics for system and reservoir, we further obtain a quantum generalization of the integrated fluctuation theorem put forward by Seifert [PRL 95, 040602 (2005)].Comment: 4 pages, 1 figur

An empirical model that uses light attenuation and plant nitrogen status to predict within-canopy N distribution and upscale photosynthesis from leaf to whole canopy

Modelling the spatial and temporal distribution of leaf nitrogen (N) is central to specify photosynthetic parameters and simulate canopy photosynthesis. Leaf photosynthetic parameters depend on both local light availability and whole-plant N status. The interaction between these two levels of integration has generally been modelled by assuming optimal canopy functioning, which is not supported by experiments. During this study, we examined how a set of empirical relationships with measurable parameters could be used instead to predict photosynthesis at the leaf and whole-canopy levels. The distribution of leaf N per unit area (Na) within the canopy was related to leaf light irradiance and to the nitrogen nutrition index (NNI), a whole-plant variable accounting for plant N status. Na was then used to determine the photosynthetic parameters of a leaf gas exchange model. The model was assessed on alfalfa canopies under contrasting N nutrition and with N2-fixing and non-fixing plants. Three experiments were carried out to parameterize the relationships between Na, leaf irradiance, NNI and photosynthetic parameters. An additional independent data set was used for model evaluation. The N distribution model showed that it was able to predict leaf N on the set of leaves tested. The Na at the top of the canopy appeared to be related linearly to the NNI, whereas the coef- ficient accounting for N allocation remained constant. Photosynthetic parameters were related linearly to Na irrespective of N nutrition and the N acquisition mode. Daily patterns of gas exchange were simulated accurately at the leaf scale. When integrated at the whole-canopy scale, the model predicted that raising N availability above an NNI of 1 did not result in increased net photosynthesis. Overall, the model proposed offered a solution for a dynamic coupling of leaf photosynthesis and canopy N distribution without requiring any optimal functioning hypothesis.Fil: Louarn, Gaëtan. Institut National de la Recherche Agronomique; FranciaFil: Frak, Ela. Institut National de la Recherche Agronomique; FranciaFil: Zaka, Serge. Institut National de la Recherche Agronomique; FranciaFil: Lebon, Eric. Institut National de la Recherche Agronomique. Unité Mixte de Recherche; FranciaFil: Prieto, Jorge Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentin

Time-dependent sensitivity and uncertainty analyses of an agro-climatic model for the water status management of vineyard

International audienceThis work describes the global sensitivity analysis (SA) of an agro-climatic model embedded in a decision support system (DSS) for the water status management of vineyard in the Languedoc-Roussillon region, France

A functional–structural plant model that simulates whole- canopy gas exchange of grapevine plants (Vitis vinifera L.) under different training systems

Background and Aims: Scaling from single-leaf to whole-canopy photosynthesis faces several complexities related to variations in light interception and leaf properties. To evaluate the impact of canopy strucuture on gas exchange, we developed a functional–structural plant model to upscale leaf processes to the whole canopy based on leaf N content. The model integrates different models that calculate intercepted radiation, leaf traits and gas exchange for each leaf in the canopy. Our main objectives were (1) to introduce the gas exchange model developed at the plant level by integrating the leaf-level responses related to canopy structure, (2) to test the model against an independent canopy gas exchange dataset recorded on different plant architectures, and (3) to quantify the impact of intra-canopy N distribution on crop photosynthesis. Methods: The model combined a 3D reconstruction of grapevine (Vitis vinifera) canopy architecture, a light interception model, and a coupled photosynthesis and stomatal conductance model that considers light-driven variations in N distribution. A portable chamber device was constructed to measure whole-plant gas exchange to validate the model outputs with data collected on different training systems. Finally, a sensitivity analysis was performed to evaluate the impact on C assimilation of different N content distributions within the canopy. Key Results: By considering a non-uniform leaf N distribution within the canopy, our model accurately reproduced the daily pattern of gas exchange of different canopy architectures. The gain in photosynthesis permitted by the non-uniform compared with a theoretical uniform N distribution was about 18 %, thereby contributing to the maximization of C assimilation. By contrast, considering a maximal N content for all leaves in the canopy overestimated net CO2 exchange by 28 % when compared with the non-uniform distribution. Conclusions: The model reproduced the gas exchange of plants under different training systems with a low error (10 %). It appears to be a reliable tool to evaluate the impact of a grapevine training system on water use efficiency at the plant level.EEA MendozaFil: Prieto, Jorge Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina.Fil: Louarn, Gaëtan. Institut National de la Recherche Agronomique; FranciaFil: Perez Peña, Jorge Esteban. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; ArgentinaFil: Ojeda, Hernan. Institut National de la Recherche Agronomique. Unité expérimentale de Pech Rouge; FranciaFil: Simonneau, Thierry. Institut National de la Recherche Agronomique. LEPSE Montpellier; FranciaFil: Lebon, Eric. Institut National de la Recherche Agronomique. Unité Mixte de Recherche; Franci

Strontium isotope evidence for Pre-Islamic cotton cultivation in Arabia

With a view to understanding the dynamics of ancient trade and agrobiodiversity, archaeobotanical remains provide a means of tracing the trajectories of certain agricultural commodities. A prime example is cotton in Arabia, a plant that is non-native but has been found in raw seed and processed textile form at Hegra and Dadan, in the region of al-ʿUlā, north-western Saudi Arabia—sites of critical importance given their role in the trans-Arabian trading routes during Antiquity. Here, we demonstrate that the measurement of strontium isotopes from pre-cleaned archaeological cotton is methodologically sound and is an informative addition to the study of ancient plant/textile provenance, in this case, putting forward evidence for local production of cotton in oasis agrosystems and possible external supply. The presence of locally-grown cotton at these sites from the late 1st c. BCE–mid 6th c. CE is significant as it demonstrates that cotton cultivation in Arabia was a Pre-Islamic socio-technical feat, while imported cotton highlights the dynamism of trade at that time

Prevalence of asthma and allergic rhinitis among adults in Yaounde, Cameroon

BACKGROUND: Population-based estimates of asthma and allergic rhinitis in sub-Saharan African adults are lacking. We assessed the prevalence and determinants of asthma and allergic rhinitis in urban adult Cameroonians. METHODS: A community-based survey was conducted from December 2013 to April 2014 among adults aged 19 years and above (N = 2,304, 57.3% women), selected through multilevel stratified random sampling across all districts of Yaounde (Capital city). Internationally validated questionnaires were used to investigate the presence of allergic diseases. Logistic regressions were employed to investigate the determinants of allergic conditions. RESULTS: Prevalence rates were 2.7% (95% CI: 2.1-3.4) for asthma-ever, 6.9% (5.9-7.9) for lifetime wheezing, 2.9% (92.2-3.6) for current wheezing and 11.4% (10.1-12.7) for self-reported lifetime allergic rhinitis; while 240 (10.4%) participants reported current symptoms of allergic rhinitis, and 125 (5.4%) had allergic rhino-conjunctivitis. The prevalence of current asthma medication use and self-reported asthma attack was 0.8 (0.4-1.2) and 1 (0.6-1.4) respectively. Multivariable adjusted determinants of current wheezing were signs of atopic eczema [2.91 (1.09-7.74)] and signs of allergic rhinitis [3.24 (1.83-5.71)]. Age group 31-40 years [0.27(0.09-0.78), p = 0.016] was an independent protective factor for wheezing. Determinants of current rhinitis symptoms were active smoking [2.20 (1.37-3.54), p<0.001], signs of atopic eczema [2.84 (1.48-5.46)] and current wheezing [3.02 (1.70-5.39)]. CONCLUSION: Prevalence rates for asthma and allergic rhinitis among adults in this population were at the lower tails of those reported in other regions of the world. Beside the classical interrelation between allergic diseases found in this study, active smoking was an independent determinant of allergic rhinitis symptoms. Nationwide surveys are needed to investigate regional variations

The Generation R Study: design and cohort update 2010

The Generation R Study is a population-based prospective cohort study from fetal life until young adulthood. The study is designed to identify early environmental and genetic causes of normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on four primary areas of research: (1) growth and physical development; (2) behavioural and cognitive development; (3) diseases in childhood; and (4) health and healthcare for pregnant women and children. In total, 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. General follow-up rates until the age of 4 years exceed 75%. Data collection in mothers, fathers and preschool children included questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome wide association screen is available in the participating children. Regular detailed hands on assessment are performed from the age of 5 years onwards. Eventually, results forthcoming from the Generation R Study have to contribute to the development of strategies for optimizing health and healthcare for pregnant women and children

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat