Croissance et développement des plants de deux provenances de chêne-liège produits en pépinière dans des conteneurs de différentes profondeurs

La survie des plants de chêne-liège dans la majorité des sites de reboisement au Maroc reste très faible à cause principalement de l’utilisation des plants dotés d’un système racinaire peu développé qui ne peut pas satisfaire les besoins hydriques des plants dans des sites caractérisés par un déficit hydrique. L’objectif de ce travail consiste à comparer, en pépinière, la croissance et le développement des plants de deux provenances (montagne et plaine) de chêne-liège élevés, pendant cinq mois, dans quatre types de conteneurs de différentes profondeurs (T : témoin de 16 cm, C : court de 30 cm, M : moyen de 60 cm et L : long de 90 cm). La croissance des parties aériennes et racinaires des plants de chêne-liège, après cinq mois de culture, a été significativement influencée à la fois par le type du conteneur et par l’origine géographique des glands. Les conteneurs les plus profonds dotés d’une volumétrie élevée (M et L) ont augmenté significativement les valeurs des paramètres morphologiques incluant la hauteur, la longueur des racines, le diamètre au collet, la masse des racines et des parties aériennes par comparaison aux plants produits dans le conteneur témoin (500 cm3) utilisé généralement pour la production des plants de chêne-liège. Pour tous les types de conteneurs, les plants issus des glands de la subéraie de plaine ont montré une croissance relativement supérieure par rapport à celle des plants de la provenance de montagne. L’utilisation de conteneurs plus profonds pour la production des plants de chêne-liège a contribué significativement à l’amélioration de la croissance des racines et des parties aériennes. La présence d’un système racinaire pivotant long et assez développé permettrait aux plants d’accéder rapidement aux ressources hydriques après plantation tout en leur conférant une tolérance accrue à la sécheresse

Relations hydriques et croissance de plants soumis à un déficit hydrique édaphique graduel - Cas du cèdre de l’Atlas, du pin maritime de montagne et du cyprès de l’Atlas

Les perspectives du changement climatique au Maghreb prévoient des impacts très négatifs sur les écosystèmes forestiers. Quel sera l’avenir du cèdre de l’Atlas dans cette région ? Cet article présente les résultats d’un essai de recherche sur des espèces forestières autochtones plus résistantes à la sécheresse et capables de s’adapter à ce nouveau contexte climatique

Comprehensive review of morphological adaptations and conservation strategies of cactiform succulents: A case study of Euphorbia species in arid ecosystems

Cactiform succulents, belonging to the Euphorbia genus, are distinctive species found in the arid and semi-arid ecosystems of Macaronesia and the Arabian Peninsula. Resembling cacti in appearance, they exhibit unique morphological characteristics, such as succulent, green-stemmed structures with ribs, accompanied by a pair of stipular spines. These plants have evolved to thrive in well-draining substrates, including both surface and rocky soils, potentially as an adaptive strategy to combat edaphic drought conditions. Although initially associated solely with arid and desert environments, it is important to note that these cactiform succulents are not exclusively specialized for prolonged dry periods. Rather, they demonstrate morphological adaptations that help them endure arid conditions. The primary objective of this review is to provide an up-to-date synthesis of knowledge concerning cactiform succulents within the Euphorbia genus. It aims to underscore their capacity to flourish in both arid and semi-arid zones, while underscoring the pressing conservation challenges that threaten these plants with degradation and potential extinction. The prevailing climatic conditions, marked by extended and recurrent droughts exacerbated by escalating temperatures, climate fluctuations, and escalating human impact, collectively pose a formidable obstacle to conserving these cactiform succulents and their respective ecosystems. All these threats jeopardize these invaluable natural resources, which hold multifaceted significance spanning environmental, socio-economic, and medicinal domains

Ecological insights and conservation imperatives for Laurus azorica in Morocco

The Azores laurel Laurus azorica (Seub.) Franco is a highly esteemed forest species in Morocco due to its medicinal and aromatic properties. However, the natural habitats of this species are increasingly scarce, resulting in its classification as a rare species. This study comprehensively investigates the autoecology, plant communities, and distribution patterns of L. azorica, aiming to discern the crucial ecological factors underpinning its survival and shed light on its conservation status. Field surveys, including floristic relevés and environmental characterization, were conducted to identify the primary plant communities hosting remnants of L. azorica. Fieldwork and ecological analysis reveal five distinct plant communities associated with L. azorica: low elevation thermophilic holm oak woodland, mesophilic mid-altitude holm oak woodland, Quercus faginea, deciduous broadleaf mountain and Cytisus balansae plant communities. The study emphasizes the importance of ecological requirements such as oceanic exposure, rainfall, temperature, and forest mull soils in creating suitable habitats for L. azorica populations. Currently, L. azorica populations in Morocco are represented by small trees, shrubs, or bushes, often exhibiting distorted and damaged structures due to unregulated pruning. Natural regeneration of the species is completely absent. The value chain associated with L. azorica is limited, involving informal harvesters, intermediary herbalist grocers, and final consumers, due to the lack of a legal framework for resource evaluation caused by its severe depletion. To secure the survival of L. azorica in Morocco, it is crucial to address gaps in legislation, intensify conservation efforts, and promote sustainable development practices. Protecting and restoring the natural habitats of the species, along with implementing responsible harvesting practices, are essential steps towards conserving this valuable forest species

Illustrating the temperature and magnetic field effects on the magnetic hysteresis loops and specific absorption rate of superparamagnetic nanoparticles: new physical insights towards medical applications

Starting from the magnetic Langevin equation and its associated Fokker–Planck equation, governing the reversal magnetization of single-domain ferromagnetic nanoparticles elucidated by Brown’s model [W. F. Brown, Phys. Rev. 130 (1963) 1677; IEEE Trans. Mag. 15 (1979) 1196], the magnetic hysteresis loops and the specific absorption rate of nanoparticles with biaxial anisotropy are investigated. An illustration of the effect of the temperature and the applied magnetic field across a wide range of frequencies on both of the former quantities is revealed. Emerged new physical insights elucidated from the present study hold promise for realistic nanoscale medicinal applications and may pave the way for an accurate notable benefit of superparamagnetic nanoparticles having biaxial anisotropy in oncology

RF-MEMS packaging by using quartz caps and epoxy polymers

This work reports on RF MEMS chip capping to protect sensitive devices by quartz caps having a cavity to enclose MEMS devices and an epoxy film polymer as a sealing ring. Full hermeticity is not possible due to the permeability of polymer but the goal to protect the mobile parts of the devices during dicing and assembling was achieved. Good RF MEMS devices are produced by die-to-die bonding and a reliable fabrication process is defined while wafer-to-wafer process still needs improvement to increase the fabrication yield. In this paper the fabrication process for both die-to-die and wafer-to-wafer 0-level capping is presented. Good adhesion of caps to the substrate is demonstrated by shear tests, while RF measurements on CPW lines indicate a negligible insertion loss increase. Capping of both capacitive and ohmic contact switches is reported showing no loss of functionality but a modification of actuation voltage induced by thermal treatment