A partir de cette page vous pouvez :
Retourner au premier écran avec les dernières notices... |
Résultat de la recherche
2 résultat(s) recherche sur le mot-clé 'shoots'
trié(s) par (Pertinence décroissant(e), Titre croissant(e)) Affiner la recherche Générer le flux rss de la recherche
Extracellular ice management in the frost hardy horsetail Equisetum hyemale L / Rena Schott in Flora, vol. 234 (Année 2017)
[article]
Titre : Extracellular ice management in the frost hardy horsetail Equisetum hyemale L Type de document : Livre Auteurs : Rena Schott, Auteur ; Dagmar Voigt, Auteur ; Anita Roth-Nebelsick, Auteur Année de publication : 2017 Article en page(s) : pp. 207-214 Langues : Anglais Mots-clés : Equisetum hyemale acclimatation chlorenchyma cold storage cold tolerance cortex crystals freezing frost ice intercellular spaces pith scanning electron microscopy shoots été hiver Résumé : "Formation of extracellular ice at specific positions in the plant interior is a common and probably essential component of plant cold hardiness. Studies on extracellular freezing in spore-bearing plants are, however, scarce. In this study, extracellular ice formation in the cold hardy horsetail Equisetum hyemale L. is analyzed. Horsetails show an extensive system of intercellular air spaces which are probably crucial for internal ice storage during winter. Previous studies emphasized the spacious pith cavity as the main place for ice crystal growth. Shoots were studied during summer and in the frozen state in winter, after natural acclimatization, by using digital (incident light) microscopy, Scanning Electron Microscopy and Cryo Scanning Electron Microscopy. It was shown that the vallecular canals also contain a large share of ice bodies under freezing conditions. The vallecular canals, which are directly seated within the cortex and whose interior is directly connected to the cortex via gaps in the canal wall, were often and rapidly filled with ice. The pith cavity also contained ice, depending on the position along the shoot and the internode. The carinal canals contained almost no ice crystals. Furthermore, some ice crystals were detected in the intercellular spaces of the chlorenchyma and the substomatal chamber. The stomatal antechamber, however, was always ice-free, probably due to the presence of water-repellent wax crystals. The results of this study support available evidence for the crucial role of pre-existing extensive lacunae for extracellular ice formation in E. hyemale. Furthermore, the findings indicate that anatomical details of canal structure and position are important for the pattern of extracellular ice accumulation." Type de publication : périodique Référence biblio : Schott R., Voigt D., Roth-Nebelsick A., 2017 - Extracellular ice management in the frost hardy horsetail Equisetum hyemale L. Flora, 234 : 207-214. DOI : 10.1016/j.flora.2017.07.018 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=66244
in Flora > vol. 234 (Année 2017) . - pp. 207-214[article]Exemplaires
Cote Localisation Disponibilité aucun exemplaire Response of the clonal plant Apium repens (Jacq.) Lag. to extensive grazing / Gert Rosenthal in Flora, vol. 203 (Année 2008)
[article]
Titre : Response of the clonal plant Apium repens (Jacq.) Lag. to extensive grazing Type de document : Livre Auteurs : Gert Rosenthal, Auteur ; Dirk Lederbogen, Auteur Année de publication : 2008 Article en page(s) : pp. 141-151 Langues : Anglais Mots-clés : Apium grazing intensity pasture plants plant response summer dynamique des populations cattle spatial variation temporal variation rotational grazing stolons plant propagation statistical analysis shoots ecological competition Germany Résumé : "The target of this paper is the correlation of disturbance characteristics of a traditionally used extensive summer pasture in the Alpine foothills (Southern-Bavaria, Germany) and corresponding seasonal population dynamics of the clonal plant Apium repens (FFH Annex II species). The basic hypothesis is that an extensive cattle grazing of its habitats (flood meadows) provides an optimum disturbance regime for long-term persistence of the species. Spatial and temporal scales of the investigation were adapted to the dimensions of the most prominent disturbance impacts (rotation grazing and hoof trampling by cattle) and response rates of Apium which are mainly controlled by stolon propagation. A total of 603 microplots, each measuring 10cm×10cm, were arranged within three transects and surveyed for two seasons. Statistical analyses include spatial second order statistics and mixed linear models. Random Apium extinctions during grazing periods and fast re-invasions of gaps during subsequent resting periods result in strong population fluctuations. The probability of re-invasion depends on the distance to next Apium plant which must not exceed much more than 1dm. The morphological plasticity of stolon length indicates presence of “foraging behaviour” which facilitates the preoccupation of favourable gaps. Disturbances favour the coexistence of A. repens in the pasture due to a combined effect of reduced shoot competition (destruction of tall competitors) and more efficient “foraging” strategies. Attempts to explain Apium coexistence in these flood meadows must take into account both the fine-tuned balance between different disturbance parameters and corresponding functional plants traits." Type de publication : périodique Référence biblio : Rosenthal G., Lederbogen D., 2008 - Response of the clonal plant Apium repens (Jacq.) Lag. to extensive grazing. Flora, 203 (2) : 141-151. Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=67579
in Flora > vol. 203 (Année 2008) . - pp. 141-151[article]Exemplaires
Cote Localisation Disponibilité aucun exemplaire