85 research outputs found

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    FraĂźchement nommĂ© Ă  la direction du ThĂ©Ăątre National de Strasbourg en juin 2014, Stanislas Nordey a pris en charge, au pied levĂ©, l’organisation du troisiĂšme et dernier tour du concours d’entrĂ©e Ă  l’école qui se dĂ©roulait alors. Ce geste fort met en avant le formateur qu’est Stanislas Nordey, sa pratique pĂ©dagogique – engagĂ©e dans les annĂ©es 1980 aux cĂŽtĂ©s de VĂ©ronique Nordey et prolongĂ©e dans les annĂ©es 2000 Ă  l’École du ThĂ©Ăątre National de Bretagne – s’inscrivant au cƓur mĂȘme de son parcour..

    Analyse expĂ©rimentale et modĂ©lisation de l’hĂ©tĂ©rogĂ©nĂ©itĂ© de la qualitĂ© et de la maturitĂ© des mangues

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    One of the major difficulties involved in marketing fresh mango is to manage its quality. Mango quality includes several attributes such as size, total soluble solids content, acidity and color, all of which vary with growing conditions and during ripening. The aim of this thesis is to determine the impact of growing conditions on fruit quality and ripening through experimental and modeling approaches.Experimental studies have revealed that size, dry mass and maturity vary considerably between mangoes according to their position in the tree and fruit load. Measurements suggest that fruit growth is affected by the embolization of sap-conducting vessels. In addition to differences measured between mangoes, our results showed that quality attributes vary within fruits in relation to the maturity gradient.A physical model showed that climatic variations within the tree caused substantial temperature gradients within mangoes that change with the fruit position in the tree. These simulations revealed that quality differences within mangoes are not related to the temperature gradient, except for fruit color. Use of a model that simulates the biosynthetic pathway of ethylene indicated that maturity differences between mangoes are explained by differences in carbon supply and, to a much lesser extent, to differences in temperature. The integration of experimental results into a growth model revealed that the embolization of sap-conducting vessels caused the slowdown of fruit enlargement. Lastly, when all of these models were coupled to a model that simulates fruit growth in dry mass, it was demonstrated that variations in size, dry matter content and maturity between mangoes were caused by differences in fruit load, flowering time, fruit dry mass at the end of cell division and transpiration, rather than by differences in temperature.The multidisciplinary approach developed made it possible to better understand the processes involved in fruit quality and ripening and to open new areas of research.La qualitĂ© du fruit regroupe un ensemble d’attributs, comme le calibre, la teneur en composĂ©s solubles, l’aciditĂ© et la couleur, qui varient en fonction des conditions de croissance rencontrĂ©es par le fruit pendant son dĂ©veloppement et au cours de son murissement. Ce travail de thĂšse vise Ă  dĂ©terminer, par des approches expĂ©rimentales et de modĂ©lisation, l’impact des conditions de croissance de la mangue sur les processus impliquĂ©s dans l’élaboration de sa qualitĂ© et de son murissement. Les approches expĂ©rimentales ont rĂ©vĂ©lĂ© d’importantes variations de calibre, masse sĂšche, et maturitĂ© entre les mangues selon leur position dans l’arbre et la charge en fruits. Nos mesures ont suggĂ©rĂ© que la croissance des mangues est impactĂ©e par la diminution des flux de xylĂšme causĂ© par l’embolisation des vaisseaux conducteurs de sĂšve. En plus des diffĂ©rences mesurĂ©es entre les fruits, nos rĂ©sultats ont indiquĂ© des variations de couleur de peau et de pulpe, d’aciditĂ© et de teneur en composĂ©s solubles au sein mĂȘme des mangues qui s’expliquent en partie par les gradients de maturitĂ©. L’établissement d’un modĂšle thermodynamique a permis de montrer que les microclimats au sein de l’arbre gĂ©nĂšrent un gradient de tempĂ©rature au sein de la mangue qui varie en fonction de la position dans l’arbre. Il a Ă©tĂ© montrĂ© que ce gradient de tempĂ©rature n’explique pas les variations d’aciditĂ©, de couleur de pulpe et de teneur en composĂ©s solubles au sein de la mangue. L’utilisation d’un modĂšle simulant la synthĂšse de l’éthylĂšne dans la mangue a mis en Ă©vidence que les diffĂ©rences de maturitĂ© entre les mangues dans l’arbre s’expliquent davantage par les diffĂ©rences de disponibilitĂ© carbonĂ©e que par les diffĂ©rences de tempĂ©rature. L’intĂ©gration des rĂ©sultats expĂ©rimentaux dans un modĂšle de croissance en matiĂšre fraiche a permis de confirmer que l’embolisation des vaisseaux conducteurs de sĂšve est Ă  l’origine du ralentissement de croissance de la mangue. Enfin, le couplage de tous ces modĂšles Ă  un modĂšle de croissance en matiĂšre sĂšche a montrĂ© que les variations de calibre, teneur en matiĂšre sĂšche et maturitĂ© entre les mangues ne sont pas causĂ©es par les diffĂ©rences de tempĂ©rature, mais par les diffĂ©rences de charge en fruits, de pĂ©riode de floraison, de masse sĂšche des fruits Ă  la fin de la division cellulaire, et de transpiration.L’approche pluridisciplinaire, i.e., physique, Ă©cophysiologique et biochimique, utilisĂ©e dans ce travail de thĂšse a permis d’acquĂ©rir de nouvelles connaissances sur l’élaboration de la qualitĂ© du fruit et son murissement et ouvre de nouvelles perspectives de recherche

    Extension System for Improving the Management of Vegetable Cropping Systems

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    This research article published by Modestum, 2018Horticulture as the part of agriculture sector plays the role for food security, economic growth and nutrition improvement. In developing countries where agriculture is regarded as the backbone of most countries’ economy it draws attention for most governments as the main source of employment and livelihood for the majority. Agricultural extension has been the key facilitator for achieving high crop productivity and an enabler to knowledge resources for these countries. However, lack of clear information for vegetable cultivations, crop requirements, climatic information, pests and diseases to constantly help farmers to come up with proper potential yield of the vegetable crops reduce the potential of horticulture in improving the farmers livelihood and countries economic gain , Therefore, this study aims at bringing the ICT- enabled extension support system for farmers to help them make decision on proper ways of cultivating their crops based on locations’ and timely climatic condition

    Cold storage of ‘Palmer’ mangoes sorted based on dry matter content using portable near infrared (VIS-NIR) spectrometer

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    The objective of this study was to use dry matter (DM) calibration models to sort ‘Palmer’ mangoes prior cold storage and to evaluate the physiological and chemical changes during the storage period. PLS model developed with fruit from 2015/2016 season was not adequate to predict DM content in fruit from 2016/2017 (not adjusted R2). Therefore, VIS‐NIR spectra from 2016/2017 season were incorporated into data set and a new model was developed (RMSEcv of 10.5 g.kg−1, urn:x-wiley:01458892:media:jfpp13644:jfpp13644-math-0001 of 0.75). With the new model, ‘Palmer’ mangoes were sorted into two maturity stages (150 g.kg−1 and 110 g.kg−1) which resulted in quality differences mainly in relation to DM and SSC. Portable VIS‐NIR spectrometer can be used to sort fruit according to maturity stages based on DM content and this classification affect fruit quality during cold storage as fruit with higher DM (150 g.kg−1) presented better quality than fruit with lower DM (110 g.kg−1)
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