Flora . vol. 229Paru le : 01/02/2017 |
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Ajouter le résultat dans votre panierFrom inselberg to inselberg : Floristic patterns across scales in French Guiana (South America) / Corinne Sarthou in Flora, vol. 229 (Année 2017)
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Titre : From inselberg to inselberg : Floristic patterns across scales in French Guiana (South America) Type de document : texte imprimé Auteurs : Corinne Sarthou ; Sandrine Pavoine ; Jean-Pierre Gasc ; Jean-Christophe (de) Massary ; Jean-François Ponge (1948-….) Année de publication : 2017 Article en page(s) : pp. 147-158 Langues : Français (fre) Mots-clés : inselbergs endémisme végétation Résumé : "Granitic outcrop vegetation was compared in 22 inselbergs of French Guiana, South America, using RLQ and fourth-corner analyses to identify the main relationships between environmental gradients and plant traits. At the scale of the whole territory the distribution of species and species traits was mostly driven by a spatially-structured gradient embracing regional climate (annual rainfall), forest matrix (canopy openness), and inselberg features (altitude, shape, habitats, summit forest, degree of epiphytism, fire events). Biogeographic, environmental and past historical factors contribute to explain the variation observed at coarse scale and two groups of inselbergs are identified. A first group occupies the southern peneplain in a semi-open forest matrix and exhibits a higher representation of suffrutescent species and climbers, a lower representation of upright shrubs, a lower degree of Guiana Shield endemism, and a higher incidence of human use and autochory. All these features suggest an adaptation to more disturbed environments linked to past climate changes and savannization and to human influences. A second group, characterized by opposite plant traits, occupies the northern part of French Guiana and the far south within a closed forest matrix. Within archipelagos (inselbergs at less than 7 km distance), C-score and Mantel tests revealed a random co-occurrence of plant species and an increase of floristic dissimilarity with distance without any concomitant change in plant traits, respectively, suggesting that spatially-structured stochastic factors (limitation by dispersal) were the driving force of vegetation change at fine scale." (source : auteurs) Type de publication : périodique Référence biblio : Sarthou C., Pavoine S., Gasc J.-P., Massary J.-C. (de), Ponge J.-F., 2017 - From inselberg to inselberg : Floristic patterns across scales in French Guiana (South America). Flora, 229 : 147-158. Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=66238
in Flora > vol. 229 (Année 2017) . - pp. 147-158[article]Exemplaires(0)
Disponibilité aucun exemplaire Interactive salt-Alkali stress and exogenous Ca2+ effects on growth and osmotic adjustment of Lolium multiflorum in a coastal estuary / Youyuan Chen in Flora, vol. 229 (Année 2017)
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Titre : Interactive salt-Alkali stress and exogenous Ca2+ effects on growth and osmotic adjustment of Lolium multiflorum in a coastal estuary Type de document : texte imprimé Auteurs : Youyuan Chen, Auteur ; Pengzhan Lu, Auteur ; Ping Sun, Auteur ; Guanglin Chen, Auteur ; Lai Wei, Auteur ; Dan Wu, Auteur Année de publication : 2017 Article en page(s) : pp. 92-99 Langues : Anglais (eng) Résumé : "Salt and pH levels in coastal estuaries are very high. In our study, different degrees of interactive salt − alkali stress were simulated to determine the effects of interactive salt − alkali stress on the growth and osmotic regulation of Lolium multiflorum (group A experiment). In addition, Ca2+ solutions were prepared to examine the mitigative effects of exogenous Ca2+ on interactive salt − alkali stress (group B experiment). In group A, five salinity levels (0‰, 5‰, 10‰, 15‰, 20‰) were set. Each salinity level was further categorized at three pH levels: 7±0.12, 8±0.22, and 9±0.16. In group B, five Ca2+ levels (0, 2, 4, 6, and 8mM) were added to the experiment. Damage of L. multiflorum by interactive salt − alkali stress was more pronounced than by single salt stress. The tolerable range was defined for pH 7 and salinity ≤10‰, and pH 8 and salinity ≤5‰, respectively, when the leaf relative electrical conductivity was not significantly increased, the chlorophyll content and root vigor were not significantly reduced, and the mortality rate of L. multiflorum was low. However, growth was decreased by more than 90% (at pH≥8 and salinity ≥15‰), and osmotic regulation of L. multiflorum was drastically impaired beyond the tolerance range. Under single salt stress, the content of proline, Na+/K+ ratio and Cl− content were lower than that under interactive salt − alkali stress, while the contents of Ca2+ and Mg2+ were higher. The optimum exogenous Ca2+ concentration was 6mM for L. multiflorum. At this concentration, leaf relative electrical conductivity, proline content and Na+/K+ were lowest, and chlorophyll content, root vigor and Mg2+ content were highest. Overall, L. multiflorum could tolerate a certain degree of interactive salt − alkali stress, which can be beneficial for the ecological restoration of coastal waters. " Type de publication : périodique Référence biblio : Chen Y., Lu P., Sun P., Chen G., Wei L., Wu D., 2017 - Interactive salt-Alkali stress and exogenous Ca2+ effects on growth and osmotic adjustment of Lolium multiflorum in a coastal estuary. Flora, 229 : 92-99. DOI : 10.1016/j.flora.2017.02.018 Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=66239
in Flora > vol. 229 (Année 2017) . - pp. 92-99[article]Exemplaires(0)
Disponibilité aucun exemplaire Reproductive biology of Sorghum halepense (L.) Pers. (Poaceae; Panicoideae; Andropogoneae) in relation to invasibility / Rajdavinder Kaur in Flora, vol. 229 (Année 2017)
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Titre : Reproductive biology of Sorghum halepense (L.) Pers. (Poaceae; Panicoideae; Andropogoneae) in relation to invasibility Type de document : texte imprimé Auteurs : Rajdavinder Kaur, Auteur ; Amarjit Singh Soodan, Auteur Année de publication : 2017 Article en page(s) : pp. 32-49 Langues : Anglais (eng) Catégories : [Espèces (in biblio)] Sorghum halepense
[Thèmes] Pollinisation, pollen, nectar
[Thèmes] ReproductionMots-clés : diaspore endozoochorie xénogamie phénologie florale Résumé : "Sorghum halepense (L.) Pers. is the most aggressive grass weed of the world resulting from an efficient system of its reproduction and propagation through a combination of vegetative and sexual means. However, reproductive biology of the species is not understood in sufficient details and had serious gaps of information on its pollen and pollination system, breeding behaviour, fruit and dispersal biology. The species was found to be chasmogamous with an andromonoecious sexual system of well-developed bisexual and male spikelets in pairs and terminal triads. Precocious extrusion of receptive stigmas preceding anther dehiscence, abundant pollen of high fertility and longevity and a high pollen-ovule ratio strongly indicate xenogamy in the species. Laser Confocal Microscopy revealed rapid germination of pollen and growth of pollen tubes down the pistil to the ovule which caused high fruit set and facilitated the amphimictic cycle. The present study is presumably the first report on the role of several insect pollinators mainly from the order Diptera (Isomyia paurogonita Fang & Fan.) and Hymenoptera (Hylaeus sp., Sphecodes ephippius Linnaeus , Megachile sp.). The visitation time of insect pollinators closely synchronized with peak anthesis resulting in high pollen loads. Breeding experiments revealed significantly higher fruit set in open pollinated in comparison to bagged synflorescences. The diaspore enclosed a well-developed caryopsis surrounded by accessory bracts along with persistent pedicels and a rachis segment preparing them for dispersal through autochory and endozoochory. Thus, cosmopolitan and invasive nature of S. halepense could be attributed to a combination of xenogamous breeding system, high seed production and efficient fruit dispersal through resistant diaspores. This study on the reproductive system of S. halepense shall provide a framework for developing management strategies both for the control of this invasive grass species as also for its propagation as a fodder crop in vacant rangelands." (source : auteurs) Type de publication : périodique Référence biblio : Kaur R., Soodan A., 2017 - Reproductive biology of Sorghum halepense (L.) Pers. (Poaceae; Panicoideae; Andropogoneae) in relation to invasibility. Flora, 229 : 32-49. Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=66240
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